WO2023005879A1 - 换流器的控制方法、控制系统、计算机设备和存储介质 - Google Patents

换流器的控制方法、控制系统、计算机设备和存储介质 Download PDF

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Publication number
WO2023005879A1
WO2023005879A1 PCT/CN2022/107634 CN2022107634W WO2023005879A1 WO 2023005879 A1 WO2023005879 A1 WO 2023005879A1 CN 2022107634 W CN2022107634 W CN 2022107634W WO 2023005879 A1 WO2023005879 A1 WO 2023005879A1
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Prior art keywords
current
voltage
converter
reference value
sref
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PCT/CN2022/107634
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English (en)
French (fr)
Inventor
汪楠楠
田杰
卢宇
董云龙
詹长江
李海英
王新宝
邹凯凯
王仙荣
殷子寒
马秀达
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NR Electric Co Ltd
NR Engineering Co Ltd
Changzhou NR Electric Power Electronics Co Ltd
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NR Electric Co Ltd
NR Engineering Co Ltd
Changzhou NR Electric Power Electronics Co Ltd
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Priority to BR112023027254A priority Critical patent/BR112023027254A2/pt
Priority to EP22848484.6A priority patent/EP4362261A4/en
Priority to MX2024000580A priority patent/MX2024000580A/es
Publication of WO2023005879A1 publication Critical patent/WO2023005879A1/zh
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/38—Arrangements for feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel
    • H02J3/40—Synchronisation of generators for connection to a network or to another generator
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0009—Devices or circuits for detecting current in a converter
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Definitions

  • the present application relates to the field of flexible direct current transmission systems of electric power systems, and in particular, relates to a control method, a control system, computer equipment, and a storage medium of a converter.
  • the characteristics of power electronic converters such as low inertia and no damping will have a negative impact on the stable operation of the system and pose challenges to the stable operation of the power grid.
  • the power system cannot yet support the access of large-scale new energy sources.
  • Flexible direct current transmission technology has the advantages of flexible control and a large control range, which can effectively realize a large-scale new energy grid connection, and ensure the efficient collection and flexible transmission of new energy.
  • the control of the converter is mainly divided into two types: grid tracking control and grid configuration control.
  • the external characteristics of the power supply of the grid-following type controlled converter are current source characteristics.
  • Typical representatives include traditional grid commutated converters, double-fed induction generators, and voltage source converters with direct current control.
  • the external behavior of the power supply of a grid-configuration-controlled converter appears as a voltage source characteristic.
  • Typical representatives include voltage source converters using amplitude-phase control (or indirect current control) or power synchronous control (including virtual synchronous machine control, etc.).
  • the power grid configuration control learns from the operation principle of the traditional synchronous generator to improve the output characteristics of the converter.
  • the typical grid configuration control is virtual synchronous generator (VSG, virtual synchronous generator) technology.
  • both the grid tracking control and the grid structure control need to carry out current limiting control.
  • conventional overcurrent limiting methods include three types: dq-axis current proportional limitation, d-axis current priority limitation, and q-axis current priority limitation.
  • the converter will become a current source and lose the characteristic capability of simulating a synchronous machine. Realizing that the converter maintains the voltage source characteristics similar to the synchronous machine under both steady state and fault conditions is one of the difficult problems to be solved in the new power system with flexible DC access to new energy as the main body.
  • Each exemplary embodiment of the present application provides a control method, a control system, a computer device and a storage medium of an inverter, which avoid the problem that the traditional current limiting method causes the inverter to enter a current source control characteristic.
  • a control method for a converter is proposed, wherein the control method is applied to a flexible direct current transmission system, and the flexible direct current transmission system includes one or more voltage source type converters.
  • the control methods mentioned above include:
  • Step 1 determine the internal potential E of the converter, the phase ⁇ of the internal potential E, the AC voltage U s , the grid-side current I s of the converter, the impedance fixed value X Lset and the commutation
  • the current limit value I max of the device
  • Step 2 according to the internal potential E, the phase ⁇ , the impedance fixed value X Lset , and the grid-side current I s of the converter, calculate the voltage reference value U sref of the connected bus of the converter;
  • Step 3 calculating the current command reference value I sref according to the error between the voltage reference value U sref of the connecting busbar and the AC voltage U s ;
  • Step 4 controlling the current of the converter to follow the current command reference value I sref according to the current command reference value I sref ;
  • control method also includes an overcurrent limiting link, and when the converter is in the command current limiting mode, according to the AC voltage U s , the internal potential E, the phase ⁇ and the commutation
  • the current limit value I max of the device is used to calculate the current command reference value of the command current limit mode through the series inductance characteristic of the positive sequence voltage source, and use it as the current command reference value I sref of the step 3.
  • the magnitude of the internal potential E of the converter ranges from 0pu to 2pu;
  • phase ⁇ simulates the rotor motion equation of the synchronous generator:
  • P m is the mechanical power
  • P e is the electromagnetic power
  • J is the virtual inertia
  • D is the virtual damping factor
  • ⁇ is the rotor angular frequency of the simulated generator
  • ⁇ 0 is the rated rotor angular frequency of the system.
  • the amplitude of the internal potential E of the converter is calculated based on port voltage or reactive power, and is calculated according to a function relationship determined by droop characteristics and the like.
  • the voltage reference value U sref includes a positive sequence d-axis component U srefdp , a positive sequence q-axis component U srefqp , a negative sequence d-axis component U srefdn and a negative sequence q-axis component U srefqn , and satisfies:
  • I sdp is the positive-sequence d-axis component of the converter grid-side current I s
  • I sqp is the positive-sequence q-axis component of the converter grid-side current I s
  • I sdn is the positive-sequence q-axis component of the converter grid-side current I s
  • I sqn is the negative-sequence q-axis component of the grid-side current I s of the converter.
  • control method further includes:
  • I srefdp is the current positive sequence d-axis reference value of the current command reference value I sref
  • I srefqp is the current positive sequence q-axis reference value of the current command reference value I sref
  • I srefdn is the current command reference value
  • I sref is the current negative sequence d-axis reference value
  • I srefqn is the current negative sequence q-axis reference value of the current command reference value I sref .
  • control method further includes: when the actual current is greater than the current limit value I max , the converter is in the command current limit mode.
  • the step of calculating the current command reference value of the command current limiting mode according to the series inductance characteristic of the positive sequence voltage source includes:
  • the current command reference value I after command limitation is calculated according to the voltage vector of the AC voltage U s , the internal potential E and the current-limiting impedance X L sref , the current command reference value I sref includes current positive sequence d-axis reference value I srefdp , current positive sequence q-axis reference value I srefqp , current negative sequence d-axis reference value I srefdn and current negative sequence q-axis reference value I srefqn .
  • the impedance fixed value X Lset takes the value of the current limiting impedance X L ;
  • the impedance fixed value X Lset ranges from 0pu to 5pu.
  • the step of calculating the current-limiting impedance X L of the command current-limiting mode according to the current limit value I max includes:
  • the step of calculating the current command reference value I sref according to the error between the voltage reference value U sref of the connecting busbar and the AC voltage U s includes:
  • the step 3 uses a PI controller, wherein the input is the error between the voltage reference value U sref of the connecting bus and the AC voltage U s , and the output is the current command reference value I sref , and when the When the converter is in the command current limiting mode, the value of the current command reference value I sref is the current command reference value output by the overcurrent limiting link.
  • the reference voltage command is obtained by using the current command reference value I sref and the grid-side current I s of the converter, and the reference voltage command Inverse Park transformation is performed to obtain the three-phase reference voltage command U Cabc , and the three-phase reference voltage command U Cabc is sent to the subsequent converter valve control link to realize the control of the converter.
  • a control method of a converter is proposed, the control method is applied to a flexible direct current transmission system, and the flexible direct current transmission system includes one or more voltage source converters, the control method include:
  • the current of the converter is controlled to follow the current command reference value I sref .
  • the magnitude of the internal potential E of the converter ranges from 0pu to 2pu, and the phase ⁇ simulates the rotor motion equation of a synchronous generator:
  • P m is the mechanical power
  • P e is the electromagnetic power
  • J is the virtual inertia
  • D is the virtual damping factor
  • ⁇ is the rotor angular frequency of the simulated generator
  • ⁇ 0 is the rated rotor angular frequency of the system.
  • the amplitude of the internal potential E of the converter is calculated based on a functional relationship determined by port voltage or reactive power according to droop characteristics and the like.
  • the step of calculating the current command reference value I sref of the command current limiting mode according to the series inductance characteristic of the positive sequence voltage source includes:
  • the current command reference value I after the command limit is calculated according to the voltage vector of the AC voltage U s , the internal potential E and the current limiting impedance X L sref , the current command reference value I sref includes current positive sequence d-axis reference value I srefdp , current positive sequence q-axis reference value I srefqp , current negative sequence d-axis reference value I srefdn , current negative sequence q-axis reference value I srefqn .
  • the voltage vector of the current-limiting reactance X L is calculated according to the vector difference between the AC voltage Us and the internal potential E, and then according to the modulus of the voltage vector and the The current limiting reactance X L is obtained by dividing the current limiting value I max .
  • the control system includes a system parameter acquisition module, a reference voltage generation module, a voltage outer loop module, a current inner loop module and an overcurrent limiting module, wherein,
  • the acquisition system parameter module is used to acquire the internal potential E of the converter, the phase ⁇ of the internal potential E, the impedance fixed value X Lset , the AC voltage U s , the converter grid side current I s and the current Limit value I max , the magnitude of the internal potential E ranges from 0pu to 2pu, and the phase ⁇ simulates the rotor motion equation of the synchronous generator;
  • the reference voltage generation module is used to calculate the voltage of the connected bus of the converter according to the internal potential E, the phase ⁇ , the impedance fixed value X Lset , and the grid-side current I s of the converter. Voltage reference value U sref ;
  • the voltage outer loop module is used to calculate the current command reference value I sref according to the error between the voltage reference value U sref of the connecting bus and the collected AC voltage U s ;
  • the current inner loop module is configured to control the current of the converter to follow the current command reference value I sref according to the current command reference value I sref ;
  • the overcurrent limiting module is used for when the current command reference value I sref of the converter is greater than the current limit value I max or the actual current is greater than the current limit value I max of the converter , according to the collected AC voltage U s , the internal potential E, the phase ⁇ and the current limit value I max of the converter, and according to the series inductance characteristic of the positive sequence voltage source
  • the current command reference value I sref of the command current limiting mode is calculated, and the current command reference value I sref is used as an input of the current inner loop module.
  • a computer device including a memory, a processor, and a computer program stored in the memory and operable on the processor, when the processor executes the computer program, the following The steps of the aforementioned control method.
  • a computer-readable storage medium on which a computer program is stored, wherein, when the computer program is executed by a processor, the steps of the above-mentioned method are implemented.
  • both the grid tracking control and the grid structure control need to limit the current control.
  • conventional overcurrent limiting methods include three types: dq-axis current proportional limitation, d-axis current priority limitation, and q-axis current priority limitation.
  • the inventors found that when the above current limiting scheme is adopted, the converter will become a current source and lose the characteristic capability of simulating a synchronous machine. Therefore, realizing the voltage source characteristics of the converter similar to the synchronous machine under both steady state and fault conditions is one of the difficult problems to be solved in the new power system with flexible DC access to new energy as the main body.
  • a control method, a control system, a computer device, and a storage medium for a converter that perform current limitation according to the series inductance characteristics of a positive sequence voltage source avoid the traditional current limiting method. Insufficient problems that bring the converter into current source control characteristics.
  • the external characteristic of the control system of the provided converter in the whole process of steady state and transient state is the series controlled inductance characteristic of the positive sequence voltage source, so as to provide the grid with Consistent inertia support for synchronous generators.
  • capacitive reactive current can be injected into the fault point, which is beneficial to improve the protection of the action sensitivity.
  • FIG. 1 is a schematic diagram of the relationship between modules of a control system of an inverter according to an embodiment of the present application.
  • Fig. 2 is a flowchart of a method for controlling a converter according to an embodiment of the present application.
  • Fig. 3 is a block diagram of generating a phase ⁇ of an internal potential of a converter according to an embodiment of the present application.
  • Fig. 4 is a flow chart of a method for controlling an inverter according to an embodiment of the present application.
  • Fig. 5 is a block diagram of a control system of an inverter according to an embodiment of the present application.
  • Fig. 6 is a converter control system according to an embodiment of the present application.
  • FIG. 7 is an internal structural diagram of a computer device according to an embodiment of the present application.
  • Fig. 8 is an equivalent circuit diagram of a converter control method according to an embodiment of the present application to realize converter control
  • Fig. 9 is a fault ride-through effect diagram of a converter control method according to an embodiment of the present application.
  • the pu in this application refers to the unit of per-unit value in the per-unit system.
  • Fig. 1 shows a schematic diagram of the relationship between modules of a control system of a converter according to an exemplary embodiment of the present application.
  • FIG. 1 the relationships among modules of a control system for a converter according to an exemplary embodiment of the present application will be described in detail.
  • Fig. 1 shows a control system of a converter according to an exemplary embodiment of the present application, including a system parameter acquisition module 1, a reference voltage generation module 2, a voltage outer loop module 3, a current inner loop module 4 and an overcurrent limiting module 5 .
  • the u dqpn used in Fig. 1 is a vector form including the positive sequence d-axis component U sdp , the positive sequence q-axis component U sqp , the negative sequence d-axis component U sdn , and the negative sequence q-axis component U sqn of the AC voltage U S
  • i dqpn is a vector form including positive sequence d-axis component I sdp , positive sequence q-axis component I sqp , negative-sequence d-axis component I sdn , and negative-sequence q-axis component I sqn of converter grid side current I s , namely:
  • the grid-side current I s of the converter refers to the current on the AC side (ie, the three-phase grid side) of the converter.
  • the collected three-phase grid-side voltage u s of the converter undergoes sequence decomposition and park(abc/dq) transformation (Park Transformation) to obtain the positive sequence d-axis components of the AC voltage U sdp , The positive sequence q-axis component U sqp of the AC voltage, the negative sequence d-axis component U sdn of the AC voltage, and the negative sequence q-axis component U sqn of the AC voltage.
  • Park Transformation Park Transformation
  • the amplitude E of the internal potential of the acquisition system parameter module 1 ranges from 0pu to 2pu, optionally 1pu.
  • the amplitude E of the internal potential can also be calculated based on the functional relationship determined by the port voltage or reactive power according to the droop characteristic and the like.
  • phase ⁇ of the internal potential E simulates the rotor motion equation of the synchronous generator, as shown in formula (2).
  • P m is the mechanical power
  • P e is the electromagnetic power
  • J is the virtual inertia
  • D is the virtual damping factor
  • ⁇ is the rotor angular frequency of the simulated generator
  • ⁇ 0 is the rated rotor angular frequency of the system.
  • the overcurrent limiting module 5 is used for calculating a current command reference value when the converter is in the command current limiting mode.
  • the input of the overcurrent limiting module 5 is the internal potential E, the converter current limiting value I max , and the AC voltage u dqpn .
  • the current limiting impedance X L satisfying the current limiting value I max of the converter can be calculated.
  • the reference value of the current command after the command limit can be calculated from the internal potential E, the AC voltage u dqpn and the current limiting impedance X L
  • the impedance setting X Lset is the current limiting impedance X L .
  • X Lset is equal to the fixed value X L0 determined according to system research.
  • the value range of fixed value X L0 is 0pu to 5pu.
  • the impedance fixed value X Lset takes a value of 0.1pu.
  • the reference voltage generation module 2 is used to calculate the voltage reference value of the connected bus of the converter
  • the input of the reference voltage generation module 2 is the internal potential E, the impedance fixed value X Lset and the current sampling i dqpn .
  • calculate the voltage reference value of the connecting bus of the converter that satisfies the series inductance characteristics of the positive sequence voltage source is a four-dimensional vector [U srefdp , U srefqp , U srefdn , U srefqn ], and corresponds to u dqpn .
  • the voltage outer loop module 3 is used to calculate the current command reference value of the converter in the non-command current limiting mode.
  • Voltage outer ring module 3 according to The deviation from u dqpn produces a current command reference value that satisfies the series inductance characteristics of the positive sequence voltage source in the case of non-limiting current
  • the voltage outer loop module 3 may adopt a PI controller.
  • the final current command reference value is determined. That is, when the converter is in the command current limiting mode, the current command reference value output for the overcurrent limit module 2 When the converter is in the non-command current limiting mode, the current command reference value is output by the voltage outer loop module 3 Additionally, when in command current-limit mode, a Perform controller limiting.
  • the current inner loop module 5 is used to obtain a voltage reference command.
  • the current inner loop module 5 according to the reference value of the current command The deviation from the sampling current i dqpn is obtained as a reference voltage command.
  • the reference voltage command output by the current inner loop module 5 is transformed by inverse Park(dq/abc) to obtain the three-phase reference voltage command U Cabc , and U Cabc is sent to the subsequent converter valve control link to realize the conversion streamer control.
  • FIG. 2 shows a flowchart of a method for controlling an inverter according to an exemplary embodiment of the present application. A method for controlling a converter according to an exemplary embodiment of the present application will be described below with reference to FIG. 2 .
  • control method shown in FIG. 2 is applied to a flexible direct current transmission system, and the flexible direct current transmission system includes one or more voltage source converters.
  • step S201 determine the internal potential E of the converter, the phase ⁇ of the internal potential E, the AC voltage U s , the grid-side current I s of the converter, the impedance fixed value X Lset and the current limit of the converter Value I max .
  • the value range of the internal potential E of the converter is 0pu to 2pu.
  • the value of the potential E in the converter is 1pu.
  • an excitation or reactive power adjustment strategy similar to a synchronous machine can also be added to adjust the value of E.
  • phase ⁇ of the internal potential E of the converter simulates the rotor motion equation of the synchronous generator.
  • the rotor motion equation of the simulated synchronous generator is shown in formula (2).
  • the impedance setting value X Lset ranges from 0 pu to 5 pu.
  • the impedance fixed value X Lset takes a value of 0.1pu.
  • Fig. 3 shows a block diagram of generating the phase ⁇ of the internal potential E of a converter according to an exemplary embodiment of the present application.
  • the input P m is the mechanical power, which is equivalent to the active power command value for the converter.
  • the input P e is the electromagnetic power, which is the active power obtained by collecting and calculating the port voltage and current of the converter, J is the virtual inertia, D is the virtual damping factor, ⁇ is the phase of the internal potential of the converter, and ⁇ is the simulated Rotor angular frequency of the generator, ⁇ 0 is the rated rotor angular frequency of the system.
  • the virtual moment of inertia J and the virtual damping factor D are determined according to the system research.
  • step S203 according to the internal potential E, the phase ⁇ , the impedance fixed value X Lset , and the grid-side current I s of the converter, the voltage reference value U sref of the connected bus bar of the converter is calculated .
  • the voltage reference value U sref includes a positive sequence d-axis component U srefdp , a positive sequence q-axis component U srefqp , a negative sequence d-axis component U srefdn and a negative sequence q-axis component U srefqn , and satisfies formula (3) .
  • I sdp is the positive-sequence d-axis component of the converter grid-side current I s
  • I sqp is the positive-sequence q-axis component of the converter grid-side current I s
  • I sdn is the positive-sequence q-axis component of the converter grid-side current I s
  • the negative-sequence d -axis component, I sqn is the negative-sequence q-axis component of the converter grid side current Is.
  • step S205 the current command reference value I sref is calculated according to the error between the voltage reference value U sref connected to the bus and the AC voltage U s .
  • the current command reference value I sref includes a positive sequence d-axis reference value I srefdp of the current, a positive sequence q-axis reference value I srefqp of the current, a negative sequence d-axis reference value I srefdn of the current, and a negative sequence current sequence reference value I srefdn .
  • the q-axis reference value I srefqn includes a positive sequence d-axis reference value I srefdp of the current, a positive sequence q-axis reference value I srefqp of the current, a negative sequence d-axis reference value I srefdn of the current, and a negative sequence current sequence reference value I srefdn .
  • the current command reference value I sref adopts a PI controller and is obtained according to the error between the voltage reference value U sref connected to the bus and the AC voltage U s .
  • the current limiting reactance X L for realizing current limiting is calculated first.
  • the command-limited current command reference value I sref is calculated according to the series inductance characteristic of the positive-sequence voltage source.
  • Park transformation is performed on the AC voltage Us according to the phase ⁇ , and the positive sequence d-axis component U sdp of the AC voltage Us, the The positive sequence q-axis component U sqp of the AC voltage Us, the negative sequence d-axis component U sdn of the AC voltage Us, the negative sequence q-axis component U sqn of the AC voltage Us.
  • the current-limiting reactance when the converter is in the commanded current-limiting mode, is calculated according to the voltage vector of the current-limiting reactance X L and the current-limiting reactance X L , and according to the series inductance characteristic of the positive sequence voltage source The current vector on X L is used as the current command reference value I sref .
  • I srefdp is the current positive sequence d-axis reference value of the current command reference value I sref
  • I srefqp is the current positive sequence q-axis reference value of the current command reference value I sref
  • I srefdn is the current negative sequence of the current command reference value I sref
  • the sequence d-axis reference value, I srefqn is the current negative sequence q-axis reference value of the current command reference value I sref .
  • step S207 according to the current command reference value I sref , the current of the converter is controlled to follow the current command reference value I sref .
  • the controlling the current of the converter to follow the current command reference value I sref means that when the current command reference value I sref increases, the current of the converter can be controlled to increase. When the current command reference value I sref decreases, the current of the converter can be controlled to decrease.
  • the reference voltage command is obtained by using the current command reference value I sref and the grid-side current I s .
  • the reference voltage command is obtained by using the current command reference value I sref and the grid side current I s .
  • the three-phase reference voltage command U Cabc is obtained by inverse Park(dq/abc) transformation on the reference voltage command, and U Cabc is sent to the subsequent converter valve control link to implement converter control.
  • a current limiting method is provided to limit the current according to the series inductance characteristic of the positive sequence voltage source. This avoids the problem of traditional current limiting methods that make the converter into a current source, resulting in insufficient control characteristics.
  • its external characteristic is the series controlled inductance characteristic of the positive sequence voltage source, so that it can provide the power grid consistent with the synchronous generator in the event of a fault. inertia support.
  • Fig. 4 shows a flowchart of a method for controlling an inverter according to an exemplary embodiment of the present application. Referring to Fig. 4, a method for controlling a converter according to an exemplary embodiment of the present application will be described in detail below.
  • step S401 determine the internal potential E of the converter and the phase ⁇ of the internal potential E, the AC voltage U s , the grid-side current I s of the converter, the impedance fixed value X Lset and the current limit value I max of the converter.
  • the value range of the internal potential E of the converter is 0pu to 2pu.
  • the value of the internal potential E of the converter is 1pu.
  • an excitation or reactive power adjustment strategy similar to a synchronous machine can also be added to adjust the value of E.
  • phase ⁇ models the rotor equation of motion of a synchronous generator.
  • the rotor motion equation of the simulated synchronous generator is shown in formula (2).
  • the impedance setting value X Lset ranges from 0 pu to 5 pu.
  • the impedance fixed value X Lset takes a value of 0.1pu.
  • step S403 the current command reference value I sref of the command current limiting mode is calculated according to the AC voltage U s , the internal potential E, the phase ⁇ , the current limit value I max , and according to the series inductance characteristic of the positive sequence voltage source.
  • the AC voltage Us is subjected to Park transformation according to the phase ⁇ , and the positive sequence d-axis component U sdp of the AC voltage Us, the positive sequence q-axis component U sqp of the AC voltage Us, and the negative sequence d of the AC voltage Us are calculated.
  • the current limiting impedance X L of the command current limiting mode is calculated according to the current limiting value I max .
  • the current limiting value I max For example, calculate the voltage vector UL of the current-limiting reactance according to the vector difference between the AC voltage Us and the internal potential E, and then divide the modulus of UL by the current limit value I max of the converter to obtain the current-limiting impedance X L .
  • the current command reference value I sref after command limitation is calculated according to the series inductance characteristic of the positive sequence voltage source.
  • the current command reference value I sref includes a current positive-sequence d-axis reference value I srefdp , a current positive-sequence q-axis reference value I srefqp , a current negative-sequence d-axis reference value I srefdn , and a current negative-sequence q-axis reference value I srefqn .
  • the current vector on the current-limiting reactance X L is calculated and used as the current command reference value I sref , including the current positive sequence d-axis reference value I srefdp , current Positive sequence q-axis reference value I srefqp , current negative sequence d-axis reference value I srefdn , current negative sequence q-axis reference value I srefqn .
  • the controlling the current of the converter to follow the current command reference value I sref means that when the current command reference value I sref increases, the current of the converter can be controlled to increase. When the current command reference value I sref decreases, the current of the converter can be controlled to decrease.
  • the reference voltage command is obtained by using the current command reference value I sref and the grid-side current I s .
  • the reference voltage command is obtained by using the current command reference value I sref and the grid side current I s .
  • the three-phase reference voltage command U Cabc is obtained by inverse Park(dq/abc) transformation on the reference voltage command, and U Cabc is sent to the subsequent converter valve control link to implement converter control.
  • Fig. 5 shows a block diagram of a control system of an inverter according to an exemplary embodiment of the present application.
  • the control system includes a system parameter acquisition module 501 , a reference voltage generation module 503 , a voltage outer loop module 505 , a current inner loop module 507 and an overcurrent limiting module 509 .
  • the acquisition system parameter module 501 is used to acquire the internal potential E of the converter, the phase ⁇ of the internal potential E, the impedance fixed value X Lset , the AC voltage U s , the converter grid side current I s , the impedance fixed value X Lset and the current Limit value I max .
  • the magnitude of the potential E in the converter ranges from 0 pu to 2 pu, and the phase ⁇ of the converter simulates the rotor motion equation of the synchronous generator.
  • a reference voltage generation module 503 configured to calculate the voltage reference of the converter connecting bus according to the internal potential E, the phase ⁇ , the impedance fixed value X Lset , and the converter grid-side current I s value U sref ;
  • the voltage outer loop module 505 is used to calculate the current command reference value I sref according to the error between the voltage reference value U sref connected to the bus and the collected AC voltage U s ;
  • the current inner loop module 507 is used to control the current of the converter to follow the current command reference value I sref according to the current command reference value I sref ;
  • the over-current limiting module 509 is used for when the current command reference value I sref of the converter is greater than the current limit value I max or the actual current is greater than the converter current limit value I max , according to the collected AC voltage U s , the internal potential E and the phase ⁇ , the converter current limit value I max , and calculate the current command reference value I sref of the command current limit mode according to the series inductance characteristics of the positive sequence voltage source, the The current command reference value I sref is used as the input of the current inner loop module.
  • Fig. 6 shows an inverter control system according to an embodiment of the present application.
  • the reference voltage command output by the control system to the current inner loop module 5 undergoes inverse Park(dq/abc) transformation to obtain a three-phase reference voltage command U Cabc , and sends U Cabc to the subsequent valve control (i.e. , converter valve control link) to realize converter control.
  • Fig. 7 is a computer device according to an embodiment of the present application.
  • the control system shown in FIG. 7 includes a memory, a processor, and a computer program stored in the memory and executable on the processor.
  • the processor shown in FIG. 7 executes the computer program, the control logic shown in FIGS. 2 and 4 is realized, specifically steps S201-S107 and steps S401-S405.
  • control method is not limited to the above-mentioned exemplary embodiments, but additional and optional other operations/steps can also be implemented, and some operations/steps can also be decomposed , and some operations/steps can be combined or partially combined, so the actual order of execution may change according to the actual situation.
  • the computer device may be a terminal, and its internal structure diagram may be as shown in FIG. 7 .
  • the computer device may include a processor, memory, network interface, display screen, and input device connected by a system bus. Wherein, the processor of the computer device is used to provide calculation and control capabilities.
  • the memory of the computer device includes a non-volatile storage medium and an internal memory.
  • the non-volatile storage medium stores an operating system and computer programs.
  • the internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium.
  • the computer device may include a network interface for communicating with an external terminal via a network connection. When the computer program is executed by the processor, the above method for controlling the converter can be realized.
  • the computer device may also include a display screen, which may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covered on the display screen, or a key set on the casing of the computer device, A trackball or a touchpad, or an external keyboard, touchpad, or mouse.
  • a display screen which may be a liquid crystal display screen or an electronic ink display screen
  • the input device of the computer device may be a touch layer covered on the display screen, or a key set on the casing of the computer device, A trackball or a touchpad, or an external keyboard, touchpad, or mouse.
  • FIG. 7 is only a block diagram of a part of the structure related to the solution of this application, and does not constitute a limitation to the computer equipment on which the solution of this application is applied.
  • the specific computer equipment can be More or fewer components than shown in the figures may be included, or some components may be combined, or have a different arrangement of components.
  • Each exemplary embodiment of the present application also provides a computer-readable storage medium on which a computer program is stored.
  • the coordinated control method of the distributed compensator provided by each embodiment of the present application is implemented. step. It can be understood and understood that the steps of the implemented control method are not limited to the above-mentioned exemplary embodiments, but can also implement additional and optional other operations/steps, and some operations/steps can also be It can be decomposed, and some operations/steps can be combined or partially combined, so the actual order of execution may be changed according to the actual situation.
  • Fig. 8 shows an equivalent circuit diagram for implementing inverter control according to an inverter control method according to an embodiment of the present application.
  • X REAL is the actual impedance in the system
  • X Lset -X REAL is the impedance realized by the aforementioned converter control method
  • Ee j ⁇ is the positive sequence voltage source. Therefore, by adopting the aforementioned converter control method, the converter exhibits the characteristics of the series inductance X Lset of the positive sequence voltage source Ee j ⁇ .
  • Fig. 9 shows the fault ride-through effect of the converter control method according to the embodiment of the present application.
  • U saref , U sbref , U scref are voltage reference values of the three-phase connected bus calculated according to formula (3)
  • U sa , U sb , U sc are sampling voltages of the three-phase connected bus. It can be seen from Figure 9 that when a single-phase ground fault occurs at 3s, the voltage of the three-phase bus temporarily deviates from the command value. Then the three-phase bus voltage can keep following the command value. Therefore, the converter shown in FIG. 9 can quickly return to the voltage source control state after losing the voltage source control characteristic for a short time.
  • a new current limiting method for current limiting based on the series inductance characteristics of the positive sequence voltage source is proposed, which avoids the control characteristics of the converter entering the current source in the traditional current limiting method the problem of insufficiency.
  • control system of the converter provided by each exemplary embodiment of the present application, it can have the external characteristics of the series controlled inductance characteristics of the positive sequence voltage source in the whole process of steady state and transient state, and can provide The grid provides inertial support consistent with the synchronous generator.
  • capacitive reactive current can be injected into the fault point in case of fault, which is beneficial to improve the sensitivity of protection action.

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Abstract

本申请提出一种换流器的控制方法、控制系统和计算机设备，应用于柔性直流输电系统，柔性直流输电系统包括一个或多个电压源型换流器，控制方法包括确定换流器内电势、相位、交流电压、换流器网侧电流、阻抗定值和换流器的电流限制值；根据内电势、所述相位、阻抗定值、换流器网侧电流，计算换流器连接母线的电压参考值；根据连接母线的电压参考值和交流电压的误差，计算电流指令参考值；根据电流指令参考值，控制换流器的电流跟随电流指令参考值；控制方法还包括过流限制环节，当换流器处于指令限流模式时，根据交流电压U s，内电势E和相位θ，换流器的电流限制值I max，根据正序电压源串联电感特性计算指令限流模式的所述电流指令参考值，并作为电流指令参考值。

Description

换流器的控制方法、控制系统、计算机设备和存储介质
相关申请
本申请要求于2021年7月27日提交中国专利局、申请号为2021108502453、申请名称为“换流器的控制方法和控制系统”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电力系统柔性直流输电系统领域，具体而言，涉及一种换流器的控制方法、控制系统、计算机设备和存储介质。
背景技术
随着新能源发电量、占比、利用水平持续提升，新能源等非同步机电源将会在电网中占非常高的比重，导致电力系统的运行特性发生本质变化。
随着新能源发电渗透率的提高，电力电子变流器的低惯性、无阻尼等特点将对系统的稳定运行产生负面影响，对电网的稳定运行带来了挑战。目前，电力系统尚不能支撑大规模新能源电源的接入。
在以新能源电源为主体的新型电力系统中，由于同步机投入占比的减小，同步机的惯性不足以保证整个电网中所有同步机电源与非同步机电源之间的同频率，并存在功率稳定性的问题。
柔性直流输电技术具备控制灵活，可控范围大的优点，能够有效地实现大范围的新能源并网，保证新能源的高效汇集，灵活传递。
目前，柔性直流输电技术中，对换流器的控制主要分为两类：电网跟踪型控制和电网构造型控制。电网跟踪型控制的换流器的电源的外部特性表现为电流源特性。典型代表包括传统电网换相换流器、双馈感应发电机以及采用直接电流控制的电压源型换流器。电网构造型控制的换流器的电源的外部特性表现为电压源特性。典型代表包括采用幅相控制 (或称间接电流控制)或功率同步控制(包括虚拟同步机控制等)的电压源换流器。电网构造型控制借鉴传统同步发电机的运行原理，改善变流器的输出特性。比较典型的电网构造型控制是虚拟同步发电机(VSG，virtual synchronous generator)技术。
由于柔性直流输电技术的换流器故障过流能力较弱，当电网发生故障时，为了避免短路电流烧毁开关器件，不管是电网跟踪型控制还是电网构造型控制均需要进行限流控制。
目前，常规的过流限制方式包括三类：dq轴电流等比例限制、d轴电流优先限制和q轴电流优先限制。采用上述限流方案时，换流器将变为电流源，将失去模拟同步机的特性能力。实现换流器在稳态和故障情况下均保持类似同步机的电压源特性，是柔性直流接入新能源为主体的新型电力系统需要解决的难题之一。
发明内容
本申请各示例性实施例提供了一种换流器的控制方法、控制系统、计算机设备和存储介质，其避免了传统的限流方法使换流器进入电流源控制特性的不足的问题。
根据本申请的一方面，提出一种换流器的控制方法，其中，所述控制方法应用于柔性直流输电系统，所述柔性直流输电系统包括一个或多个电压源型的换流器，所述控制方法包括：
步骤1，确定所述换流器的内电势E、所述内电势E的相位θ、交流电压U s、所述换流器的网侧电流I s、阻抗定值X Lset和所述换流器的电流限制值I max；
步骤2，根据所述内电势E、所述相位θ、所述阻抗定值X Lset、所述换流器网侧电流I s，计算所述换流器的连接母线的电压参考值U sref；
步骤3，根据所述连接母线的所述电压参考值U sref和所述交流电压U s的误差，计算电流指令参考值I sref；以及
步骤4，根据所述电流指令参考值I sref，控制所述换流器的电流跟随所述电流指令参考值I sref；
其中，所述控制方法还包括过流限制环节，并且当所述换流器处于指 令限流模式时，根据所述交流电压U s、所述内电势E、所述相位θ和所述换流器的所述电流限制值I max，通过正序电压源的串联电感特性计算所述指令限流模式的所述电流指令参考值，并作为所述步骤3的所述电流指令参考值I sref。
在一实施例中，所述换流器的所述内电势E的幅值取值为0pu至2pu；
所述相位θ模拟同步发电机的转子运动方程：
Figure PCTCN2022107634-appb-000001
其中，P m为机械功率，P e为电磁功率，J为虚拟惯量，D为虚拟阻尼因子，ω为模拟发电机的转子角频率，ω 0为系统额定转子角频率。
在一实施例中，所述换流器的所述内电势E的所述幅值基于端口电压或无功功率，根据下垂特性等确定的函数关系进行计算得到。
在一实施例中，所述电压参考值U sref包括正序d轴分量U srefdp、正序q轴分量U srefqp、负序d轴分量U srefdn和负序q轴分量U srefqn，且满足：
Figure PCTCN2022107634-appb-000002
其中，I sdp为所述换流器网侧电流I s的正序d轴分量，I sqp为所述换流器网侧电流I s的正序q轴分量，I sdn为所述换流器网侧电流I s的负序d轴分量，I sqn为所述换流器网侧电流I s的负序q轴分量。
在一实施例中，所述控制方法还包括：
当所述步骤3计算的所述电流指令参考值I sref的幅值大于所述电流限制值I max时，即，满足如下公式时，所述换流器处于所述指令限流模式：
Figure PCTCN2022107634-appb-000003
其中，I srefdp为所述电流指令参考值I sref的电流正序d轴参考值，I srefqp为所述电流指令参考值I sref的电流正序q轴参考值，I srefdn为所述电流指令参考值I sref的电流负序d轴参考值，以及I srefqn为所述电流指令参考值I sref的电流负序q轴参考值。
在一实施例中，所述控制方法还包括：实际电流大于所述电流限制值 I max时，所述换流器处于所述指令限流模式。
在一实施例中，所述根据所述正序电压源的所述串联电感特性计算所述指令限流模式的所述电流指令参考值的步骤，包括：
根据所述相位θ对所述交流电压U s进行Park变换，以计算所述交流电压U s的包括正序d轴分量U sdp、所述交流电压U s的正序q轴分量U sqp、所述交流电压U s的负序d轴分量U sdn、所述交流电压U s的负序q轴分量U sqn的电压向量；
根据所述电流限制值I max计算所述指令限流模式的限流阻抗X L；
基于所述正序电压源的所述串联电感特性，根据所述交流电压U s的所述电压向量、内电势E和所述限流阻抗X L计算指令限制后的所述电流指令参考值I sref，所述电流指令参考值I sref包括电流正序d轴参考值I srefdp、电流正序q轴参考值I srefqp、电流负序d轴参考值I srefdn和电流负序q轴参考值I srefqn。
在一实施例中，当所述换流器处于所述指令限流制模式时，所述阻抗定值X Lset取值为所述限流阻抗X L；
当所述换流器在非所述指令限流模式时，所述阻抗定值X Lset取值为0pu至5pu。
在一实施例中，根据所述电流限制值I max计算所述指令限流模式的所述限流阻抗X L的步骤包括：
根据所述交流电压Us和所述内电势E的向量差计算所述限流电抗X L的电压向量，然后根据所述电压向量的模与所述换流器的所述电流限制值I max相除得到所述限流电抗X L。
在一实施例中，当所述限流电抗X L大于所述阻抗定值X Lset时，则判定所述换流器处于所述指令限流模式。
在一实施例中，所述根据所述连接母线的所述电压参考值U sref和所述交流电压U s的误差，计算所述电流指令参考值I sref的步骤，包括：
所述步骤3采用PI控制器，其中，输入为所述连接母线的所述电压参考值U sref和所述交流电压U s的误差，输出为所述电流指令参考值I sref，且当所述换流器处于所述指令限流模式时，所述电流指令参考值I sref取值为所述过流限制环节输出的所述电流指令参考值。
在一实施例中，所述步骤3采用PI控制器时，利用所述电流指令参考 值I sref和所述换流器的所述网侧电流I s得到参考电压指令，对所述参考电压指令进行反Park变换得到三相参考电压指令U Cabc，并将所述三相参考电压指令U Cabc发送至后续的换流阀控制环节实现所述换流器的控制。
根据本申请的一方面，提出一种换流器的控制方法，所述控制方法应用于柔性直流输电系统，所述柔性直流输电系统包括一个或多个电压源型换流器，所述控制方法包括：
确定所述换流器的内电势E、所述内电势E的相位θ、交流电压U s、所述换流器的网侧电流I s、阻抗定值X Lset和所述换流器的电流限制值I max；
根据所述交流电压U s、所述内电势E、所述相位θ以及所述电流限制值I max，并根据正序电压源的串联电感特性计算指令限流模式的电流指令参考值I sref；以及
根据所述电流指令参考值I sref，控制所述换流器的电流跟随所述电流指令参考值I sref。
在一实施例中，所述换流器的所述内电势E的幅值取值为0pu至2pu，所述相位θ模拟同步发电机的转子运动方程：
Figure PCTCN2022107634-appb-000004
其中，P m为机械功率，P e为电磁功率，J为虚拟惯量，D为虚拟阻尼因子，ω为模拟发电机的转子角频率，ω 0为系统额定转子角频率。
在一实施例中，所述换流器的所述内电势E的所述幅值基于端口电压或无功功率根据下垂特性等确定的函数关系进行计算得到。
在一实施例中，其中，所述根据正序电压源的所述串联电感特性计算所述指令限流模式的所述电流指令参考值I sref的步骤，包括：
根据所述相位θ对所述交流电压U s进行Park变换，计算所述交流电压U s的包括正序d轴分量U sdp、所述交流电压U s的正序q轴分量U sqp、所述交流电压U s的负序d轴分量U sdn、所述交流电压U s的负序q轴分量U sqn的电压向量；
根据所述电流限制值I max计算所述指令限流模式的限流阻抗X L；以及
基于所述正序电压源的所述串联电感特性，根据所述交流电压U s的电压向量、内电势E和所述限流阻抗X L计算所述指令限制后的所述电流指令 参考值I sref，所述电流指令参考值I sref包括电流正序d轴参考值I srefdp、电流正序q轴参考值I srefqp、电流负序d轴参考值I srefdn、电流负序q轴参考值I srefqn。
在一实施例中，根据所述交流电压Us和所述内电势E的向量差计算所述限流电抗X L的电压向量，然后根据所述电压向量的模与所述换流器的所述电流限制值I max相除得到所述限流电抗X L。
根据本申请的一方面，提出一种换流器的控制系统，
所述控制系统包括获取系统参数模块、参考电压产生模块、电压外环模块、电流内环模块和过流限制模块，其中，
所述获取系统参数模块，用于获取所述换流器的内电势E、所述内电势E的相位θ、阻抗定值X Lset、交流电压U s、换流器网侧电流I s和电流限制值I max，所述内电势E的幅值的取值为0pu至2pu，所述相位θ模拟同步发电机的转子运动方程；
所述参考电压产生模块，用于根据所述内电势E、所述相位θ、所述阻抗定值X Lset、所述换流器网侧电流I s，计算所述换流器的连接母线的电压参考值U sref；
所述电压外环模块，用于根据所述连接母线的所述电压参考值U sref和采集的所述交流电压U s的误差，计算电流指令参考值I sref；
所述电流内环模块，用于根据所述电流指令参考值I sref，控制所述换流器的电流跟随所述电流指令参考值I sref；以及
所述过流限制模块，用于当所述换流器的所述电流指令参考值I sref大于所述电流限制值I max或实际电流大于所述换流器的所述电流限制值I max时，根据采集的所述交流电压U s、所述内电势E、所述相位θ以及所述换流器的所述电流限制值I max，并根据所述正序电压源的所述串联电感特性计算所述指令限流模式的所述电流指令参考值I sref，所述电流指令参考值I sref作为所述电流内环模块的输入。
根据本申请的一方面，提出一种计算机设备，包括存储器、处理器以及存储在所述存储器中并可在所述处理器上运行的计算机程序，所述处理器执行所述计算机程序时实现如前所述的控制方法的步骤。
根据本申请的另一方面，提供一种计算机可读存储介质，其上存储有计算机程序，其中，所述计算机程序被处理器执行时实现上述所述的方法的步骤。
由于柔性直流输电技术的换流器在故障时的过流能力较弱，因此当电网发生故障时，为了避免短路电流烧毁开关器件，不管是电网跟踪型控制还是电网构造型控制均需要进行限流控制。
目前，常规的过流限制方式包括三类：dq轴电流等比例限制、d轴电流优先限制和q轴电流优先限制。
发明人发现，采用上述限流方案时，换流器将变为电流源，将失去模拟同步机的特性能力。因此，实现换流器在稳态和故障情况下均保持类似同步机的电压源特性，是柔性直流接入新能源为主体的新型电力系统需要解决的难题之一。
根据本申请各示例性实施例提供的一种根据正序电压源的串联电感特性进行电流限制的换流器的控制方法、控制系统、计算机设备和存储介质，避免了在传统的限流方法中使换流器进入电流源控制特性的不足的问题。此外，根据本申请的一些实施例，提供的换流器的控制系统在稳态和暂态全过程中的外特性为正序电压源的串联受控电感特性，从而在故障时向电网提供与同步发电机一致的惯性支撑。另外，在交流系统故障时，可以向故障点注入容性无功电流，有利于提高对动作灵敏性的保护。
附图说明
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本申请一实施例的一种换流器的控制系统的各模块关系示意图。
图2是本申请一实施例的一种换流器的控制方法流程图。
图3是本申请一实施例的一种换流器的内电势的相位θ的产生框图。
图4是本申请一实施例的一种换流器的控制方法流程图。
图5是本申请一实施例的一种换流器的控制系统框图。
图6是本申请一实施例的一种换流器控制系统。
图7是本申请一实施例的计算机设备的内部结构图。
图8是本申请一实施例的一种换流器控制方法实现换流器控制的等效电路图
图9是本申请一实施例的换流器控制方法故障穿越效果图。
具体实施方式
现在将参考附图更全面地描述各示例性实施例。然而，示例实施例能够以多种形式实施，且不应被理解为限于在此阐述的实施例。相反，提供这些实施例使得本申请将全面和完整，并将示例实施例的构思全面地传达给本领域的技术人员。在图中相同的附图标记表示相同或类似的部分，因而将省略对它们的重复描述。
所描述的特征、结构或特性可以以任何合适的方式结合在一个或更多实施例中。在下面的描述中，提供许多具体细节从而给出对本公开的实施例的充分理解。然而，本领域技术人员将意识到，可以实践本公开的技术方案而没有这些特定细节中的一个或更多，或者可以采用其它的方式、组元、材料、装置或操作等。在这些情况下，将不详细示出或描述公知结构、方法、装置、实现、材料或者操作。
附图中所示的流程图仅是示例性说明，不是必须包括所有的内容和操作/步骤，也不是必须按所描述的顺序执行。例如，有的操作/步骤还可以分解，而有的操作/步骤可以合并或部分合并。因此实际执行的顺序有可能根据实际情况改变。
本申请的说明书和权利要求书及上述附图中的术语“第一”、“第二”等是用于区别不同对象，而不是用于描述特定顺序。此外，术语“包括”和“具有”以及它们任何变形，意图在于覆盖不排他的包含。例如包含了一系列步骤或单元的过程、方法、系统、产品或设备没有限定于已列出的步骤或单元，而是可选地还包括没有列出的步骤或单元，或可选地还包括对于这些过程、方法、产品或设备固有的其他步骤或单元。
本申请中的pu指标幺系统(per-unit system)中的标幺值的单位。
下面将参照附图，对根据本申请的具体实施例进行详细说明。
图1示出根据本申请示例实施例的一种换流器的控制系统的各模块 关系示意图。
下面参照图1，对根据本申请示例实施例的一种换流器的控制系统的各模块关系进行详细说明。
图1示出根据本申请示例实施例的一种换流器的控制系统，包括获取系统参数模块1、参考电压产生模块2、电压外环模块3、电流内环模块4和过流限制模块5。
图1中采用的u dqpn为包括交流电压U S的正序d轴分量U sdp、正序q轴分量U sqp、负序d轴分量U sdn、负序q轴分量U sqn的向量形式，i dqpn为包括换流器网侧电流I s的正序d轴分量I sdp、正序q轴分量I sqp、负序d轴分量I sdn、负序q轴分量I sqn的向量形式，即：
Figure PCTCN2022107634-appb-000005
所述换流器网侧电流I s为是指换流器的交流侧(即三相网侧)的电流。
在公式(1)中，采集到的换流器的三相网侧电压u s，经过序分解以及park(abc/dq)变换(Park Transformation)后得到交流电压的正序d轴分量U sdp、交流电压的正序q轴分量U sqp、交流电压的负序d轴分量U sdn、交流电压的负序q轴分量U sqn。相同地，采集到的换流器三相网侧电流I s，经过序分解以及park(abc/dq)变换后得到交流电流的正序d轴分量I sdp、交流电流的正序q轴分量I sqp、交流电流的负序d轴分量I sdn、交流电流的负序q轴分量I sqn。
获取系统参数模块1的内电势的幅值E的取值为0pu至2pu，可选地为1pu。内电势的该幅值E也可基于端口电压或无功功率根据下垂特性等确定的函数关系进行计算得到。
内电势E的相位θ模拟同步发电机的转子运动方程，如公式(2)所示。
Figure PCTCN2022107634-appb-000006
其中，P m为机械功率，P e为电磁功率，J为虚拟惯量，D为虚拟阻尼因子，ω为模拟发电机的转子角频率，ω 0为系统额定转子角频率。
过流限制模块5用于当换流器处于指令限流模式时计算电流指令参考值。
过流限制模块5的输入为内电势E、换流器电流限制值I max、交流电压u dqpn。根据电路原理可计算得到满足小于换流器电流限制值I max的限流阻抗X L。随后根据正序电压源的串联电感特性由内电势E、交流电压u dqpn和限流阻抗X L可计算指令限制后的电流指令参考值
Figure PCTCN2022107634-appb-000007
当换流器处于指令限流模式时，阻抗定值X Lset为限流阻抗X L。在非指令限流模式时，X Lset等于根据系统研究确定的定值X L0。定值X L0的取值范围为0pu至5pu。例如，阻抗定值X Lset取值0.1pu。
参考电压产生模块2用于计算换流器的连接母线的电压参考值
Figure PCTCN2022107634-appb-000008
参考电压产生模块2的输入为内电势E、阻抗定值X Lset以及电流采样i dqpn。根据公式(3)计算满足正序电压源的串联电感特性的换流器的连接母线的电压参考值
Figure PCTCN2022107634-appb-000009
为四维向量[U srefdp,U srefqp,U srefdn,U srefqn]，且与u dqpn对应。
电压外环模块3用于计算换流器在非指令限流模式下的电流指令参考值。
电压外环模块3根据
Figure PCTCN2022107634-appb-000010
与u dqpn的偏差产生非限流情况下满足正序电压源的串联电感特性的电流指令参考值
Figure PCTCN2022107634-appb-000011
电压外环模块3可采用PI控制器。
根据换流器是否处于指令限流模式，确定最终的电流指令参考值。也即，当换流器处于指令限流模式时，电流指令参考值
Figure PCTCN2022107634-appb-000012
为过流限制模块2输出的
Figure PCTCN2022107634-appb-000013
当换流器处于非指令限流模式时，电流指令参考值为电压外环模块3输出的
Figure PCTCN2022107634-appb-000014
此外，当处于指令限流模式时，还需采用
Figure PCTCN2022107634-appb-000015
进行控制器限幅。
电流内环模块5用于得到电压参考指令。
电流内环模块5根据电流指令参考值
Figure PCTCN2022107634-appb-000016
与采样电流i dqpn的偏差得到参考电压指令。
采用PI控制器，对电流内环模块5的输出的参考电压指令经过反Park(dq/abc)变换得到三相参考电压指令U Cabc，并将U Cabc发送至后续的换流阀控制环节实现换流器控制。
图2示出根据本申请示例实施例的一种换流器的控制方法流程图。下面将参照图2，对根据本申请示例实施例的一种换流器的控制方法进行说明。
在一实施例中，图2所示的控制方法应用于柔性直流输电系统，柔性直流输电系统包括一个或多个电压源型换流器。
在步骤S201，确定所述换流器的内电势E、内电势E的相位θ、交流电压U s、换流器网侧电流I s、阻抗定值X Lset和所述换流器的电流限制值I max。
在一实施例中，换流器的内电势E的取值范围为0pu至2pu。例如，换流器内电势E的取值为1pu。在一实施例中，也可增加类似同步机的励磁或无功调节策略来调整E的值。
在一实施例中，换流器的内电势E的相位θ模拟同步发电机的转子运动方程。模拟同步发电机的转子运动方程如公式(2)所示。
在一实施例中，阻抗定值X Lset取值范围为0pu至5pu。例如，阻抗定值X Lset取值0.1pu。
图3示出根据本申请示例实施例的的一种换流器的内电势E的相位θ的产生框图。输入P m为机械功率，其对于换流器等效为有功功率指令值。输入P e为电磁功率，为通过采集换流器的端口电压和电流并计算得到的有功功率，J为虚拟惯量，D为虚拟阻尼因子，θ为换流器的内电势的相位，ω为模拟发电机的转子角频率，ω 0为系统额定转子角频率。虚拟惯量J和虚拟阻尼因子D根据系统研究确定。
在步骤S203，根据所述内电势E、所述相位θ、所述阻抗定值X Lset、所述换流器网侧电流I s，计算所述换流器的连接母线的电压参考值U sref。
在一实施例中，电压参考值U sref包含正序d轴分量U srefdp、正序q轴分量U srefqp、负序d轴分量U srefdn和负序q轴分量U srefqn，且满足公式(3)。
Figure PCTCN2022107634-appb-000017
其中，I sdp为换流器网侧电流I s的正序d轴分量，I sqp为换流器网侧电流I s的正序q轴分量，I sdn为换流器网侧电流I s的负序d轴分量，I sqn为换流器网侧电流I s的负序q轴分量。
在步骤S205，根据连接母线的电压参考值U sref和交流电压U s的误差， 计算电流指令参考值I sref。
在一实施例中，电流指令参考值I sref包括电流的正序d轴参考值I srefdp、电流的正序q轴参考值I srefqp、电流的负序d轴参考值I srefdn、电流的负序q轴参考值I srefqn。
根据本申请的一些实施例，当换流器处于非指令限流模式时，电流指令参考值I sref采用PI控制器，并根据连接母线的电压参考值U sref和交流电压U s的误差得到。
根据本申请的一些实施例，当换流器处于指令限流模式时，首先计算实现电流限制的限流电抗X L。根据所述正序电压源的串联电感特性计算指令限制后的所述电流指令参考值I sref。
在一实施例中，当换流器处于指令限流模式时，根据所述相位θ对所述交流电压Us进行Park变换，并计算所述交流电压Us的正序d轴分量U sdp、所述交流电压Us的正序q轴分量U sqp、所述交流电压Us的负序d轴分量U sdn、所述交流电压Us的负序q轴分量U sqn。根据交流电压Us和内电势E的向量差计算限流电抗X L的电压向量，然后根据电压向量的模与换流器的电流限制值I max相除得到限流电抗X L。
在一实施例中，当换流器处于指令限流模式时，根据限流电抗X L的电压向量和限流电抗X L，并根据所述正序电压源的串联电感特性来计算限流电抗X L上的电流向量，作为电流指令参考值I sref。
在一实施例中，当计算的电流指令参考值I sref的幅值大于换流器的电流限制值I max时，即满足如公式(4)时，则判定换流器处于指令限流模式：
Figure PCTCN2022107634-appb-000018
其中，I srefdp为电流指令参考值I sref的电流正序d轴参考值、I srefqp为电流指令参考值I sref的电流正序q轴参考值、I srefdn为电流指令参考值I sref的电流负序d轴参考值、I srefqn为电流指令参考值I sref的电流负序q轴参考值。
在一实施例中，当所计算的限流电抗X L大于阻抗定值X Lset时，则判定换流器处于指令限流模式。
在步骤S207，根据电流指令参考值I sref，控制换流器的电流跟随电流指令参考值I sref。
所述控制换流器的电流跟随电流指令参考值I sref是指当电流指令参考值I sref增大时，可以控制换流器的电流增大。当电流指令参考值I sref减小时，可以控制换流器的电流减小。
在一实施例中，利用电流指令参考值I sref和网侧电流I s得到参考电压指令。例如，采用PI控制器，利用电流指令参考值I sref和网侧电流I s得到参考电压指令。
在一实施例中，对参考电压指令进行反Park(dq/abc)变换得到三相参考电压指令U Cabc，并将U Cabc发送至后续的换流阀控制环节实现换流器控制。
在一实施例中，通过提供一种根据正序电压源的串联电感特性进行电流限制的限流方法。这避免了传统的限流方法使换流器进入电流源，从而导致控制特性不足的问题。另外，在一实施例中，在控制系统的稳态和暂态全过程中，其外部特性为正序电压源的串联受控电感特性，从而可在故障时向电网提供与同步发电机一致的惯性支撑。
图4示出根据本申请示例实施例的一种换流器的控制方法流程图。下面参照图4，对根据本申请示例实施例的一种换流器的控制方法进行详细说明。
在步骤S401，确定换流器内电势E和内电势E的相位θ，交流电压U s、换流器网侧电流I s、阻抗定值X Lset和换流器的电流限制值I max。
在一实施例中，换流器的内电势E的取值范围为0pu至2pu。例如，换流器的内电势E的取值为1pu。在一实施例中，也可增加类似同步机的励磁或无功调节策略以调整E的值。
在一实施例中，相位θ模拟同步发电机的转子运动方程。模拟同步发电机的转子运动方程如公式(2)所示。
在一实施例中，阻抗定值X Lset取值范围为0pu至5pu。例如，阻抗定值X Lset取值0.1pu。
在步骤S403，根据交流电压U s、内电势E、相位θ、电流限制值I max，并根据正序电压源的串联电感特性来计算指令限流模式的电流指令参考值I sref。
在一实施例中，将交流电压Us，根据相位θ进行Park变换，计算交流 电压Us的正序d轴分量U sdp、交流电压Us的正序q轴分量U sqp、交流电压Us的负序d轴分量U sdn和交流电压Us的负序q轴分量U sqn。
在一实施例中，根据电流限制值I max计算指令限流模式的限流阻抗X L。例如，根据交流电压Us和内电势E的向量差计算限流电抗的电压向量U L，然后将U L的模与换流器的电流限制值I max相除得到限流阻抗X L。
在一实施例中，根据正序电压源的串联电感特性计算指令限制后的所述电流指令参考值I sref。电流指令参考值I sref包括电流正序d轴参考值I srefdp、电流正序q轴参考值I srefqp、电流负序d轴参考值I srefdn、电流负序q轴参考值I srefqn。例如，根据限流电抗的电压向量U L以及限流阻抗X L，计算限流电抗X L上的电流向量，并作为电流指令参考值I sref，包括电流正序d轴参考值I srefdp、电流正序q轴参考值I srefqp、电流负序d轴参考值I srefdn、电流负序q轴参考值I srefqn。
在S405，根据电流指令参考值I sref，控制换流器的电流跟随电流指令参考值I sref。
所述控制换流器的电流跟随电流指令参考值I sref是指当电流指令参考值I sref增大时，可以控制换流器的电流增大。当电流指令参考值I sref减小时，可以控制换流器的电流减小。
在一实施例中，利用电流指令参考值I sref和网侧电流I s得到参考电压指令。例如，采用PI控制器，利用电流指令参考值I sref和网侧电流I s得到参考电压指令。
在一实施例中，对参考电压指令进行反Park(dq/abc)变换得到三相参考电压指令U Cabc，并将U Cabc发送至后续的换流阀控制环节实现换流器控制。
图5示出根据本申请示例实施例的一种换流器的控制系统框图。
下面参照图5，对根据本申请示例实施例的一种换流器的控制系统进行详细说明。
所述控制系统包括获取系统参数模块501、参考电压产生模块503、电压外环模块505、电流内环模块507和过流限制模块509。
获取系统参数模块501用于获取换流器的内电势E、内电势E的相位θ、阻抗定值X Lset，交流电压U s、换流器网侧电流I s、阻抗定值X Lset和电流限 制值I max。
在一实施例中，换流器内电势E的幅值的取值为0pu至2pu，换流器相位θ模拟同步发电机的转子运动方程。
参考电压产生模块503，用于根据所述内电势E、所述相位θ、所述阻抗定值X Lset、所述换流器网侧电流I s，计算所述换流器连接母线的电压参考值U sref；
电压外环模块505用于根据连接母线的所述电压参考值U sref和采集的所述交流电压U s的误差，计算电流指令参考值I sref；
电流内环模块507用于根据所述电流指令参考值I sref，控制该换流器的电流跟随所述电流指令参考值I sref；
过流限制模块509用于当所述换流器的电流指令参考值I sref大于所述电流限制值I max或实际电流大于换流器电流限制值I max时，根据采集的所述交流电压U s，所述内电势E和所述相位θ，所述换流器电流限制值I max，并根据正序电压源串联电感特性计算指令限流模式的所述电流指令参考值I sref，所述电流指令参考值I sref作为所述电流内环模块的输入。
图6示出本申请一实施例的换流器控制系统。在本实施例中，控制系统对电流内环模块5的输出的参考电压指令经过反Park(dq/abc)变换得到三相参考电压指令U Cabc，并将U Cabc发送至后续的阀控(即，换流阀控制环节)实现换流器控制。
图7为根据本申请实施例的一种计算机设备。图7所示的控制系统包括存储器、处理器以及存储在存储器中并可在处理器上运行的计算机程序。图7中所示的处理器执行计算机程序时实现图2和图4所示的的控制逻辑，具体为步骤S201～S107以及步骤S401～S405。
可以理解的是，所实现的控制方法的步骤并不限于上述的各示例性实施例，而是说还可以例如实现额外的和可选的其他操作/步骤，并且有的操作/步骤还可以分解，而有的操作/步骤可以合并或部分合并，因此实际执行的顺序有可能根据实际情况改变。
可以理解的是，该计算机设备可以是终端，其内部结构图可以如图7所示。该计算机设备可以包括通过系统总线连接的处理器、存储器、网络接口、显示屏和输入装置。其中，该计算机设备的处理器用于提供 计算和控制能力。该计算机设备的存储器包括非易失性存储介质、内存储器。该非易失性存储介质存储有操作系统和计算机程序。该内存储器为非易失性存储介质中的操作系统和计算机程序的运行提供环境。该计算机设备可以包括网络接口，该网络接口用于与外部的终端通过网络连接通信。该计算机程序被处理器执行时以实现上述换流器的控制方法。该计算机设备还可以包括显示屏，该显示屏可以是液晶显示屏或者电子墨水显示屏，该计算机设备的输入装置可以是显示屏上覆盖的触摸层，也可以是计算机设备外壳上设置的按键、轨迹球或触控板，还可以是外接的键盘、触控板或鼠标等。
本领域技术人员可以理解，图7中示出的结构，仅仅是与本申请方案相关的部分结构的框图，并不构成对本申请方案所应用于其上的计算机设备的限定，具体的计算机设备可以包括比图中所示更多或更少的部件，或者组合某些部件，或者具有不同的部件布置。
本申请各示例性实施例，还提供了一种计算机可读存储介质，其上存储有计算机程序，计算机程序被处理器执行时实现本申请各实施例提供的分布式补偿器的协调控制方法的步骤。可以理解以理解的是，所实现的控制方法的步骤并不限于上述的各示例性实施例，而是说还可以例如实现额外的和可选的其他操作/步骤，并且有的操作/步骤还可以分解，而有的操作/步骤可以合并或部分合并，因此实际执行的顺序有可能根据实际情况改变。
图8示出根据本申请实施例的一种换流器控制方法实现换流器控制的等效电路图。其中，X REAL系统中实际存在的阻抗，X Lset-X REAL是通过前述换流器控制方法实现的阻抗，Ee jθ为正序电压源。因此，通过采用前述换流器控制方法，换流器呈现正序电压源Ee jθ的串联电感X Lset的特性。
图9示出根据本申请实施例的换流器控制方法的故障穿越效果。其中，U saref、U sbref、U scref为根据公式(3)计算的三相连接母线的电压参考值，U sa、U sb、U sc为三相连接母线的采样电压。由图9可知，在3s时刻发生单相接地故障时，三相母线电压短暂偏离指令值。随后三相母线电压均能保持跟随指令值。因此，图9所示的换流器在短时失去电压源控制特性后能够快速回到电压源控制状态。
根据本申请提供的各示例性实施例，提出了一种根据正序电压源的串联电感特性进行电流限制的全新限流方法，避免了传统的限流方法使换流器进入电流源出现控制特性的不足的问题。
根据本申请各示例性实施例提供的一种换流器的控制系统，可以在稳态和暂态全过程中，具有正序电压源串联受控电感特性的外部特性，并可在故障时向电网提供与同步发电机一致的惯性支撑。此外，可在故障时将向故障点注入容性无功电流，有利于提高保护动作灵敏性。
以上对本申请实施例进行了详细介绍，本文中应用了具体个例对本申请的原理及实施方式进行了阐述，以上实施例的说明仅用于帮助理解本申请的方法及其核心思想。同时，本领域技术人员依据本申请的思想，基于本申请的具体实施方式及应用范围上做出的改变或变形之处，都属于本申请保护的范围。综上所述，本说明书内容不应理解为对本申请的限制。

Claims (20)

  1. 一种换流器的控制方法，其中，所述控制方法应用于柔性直流输电系统，所述柔性直流输电系统包括一个或多个电压源型的换流器，所述控制方法包括：
    步骤1，确定所述换流器的内电势E、所述内电势E的相位θ、交流电压U s、所述换流器的网侧电流I s、阻抗定值X Lset和所述换流器的电流限制值I max；
    步骤2，根据所述内电势E、所述相位θ、所述阻抗定值X Lset、所述换流器网侧电流I s，计算所述换流器的连接母线的电压参考值U sref；
    步骤3，根据所述连接母线的所述电压参考值U sref和所述交流电压U s的误差，计算电流指令参考值I sref；以及
    步骤4，根据所述电流指令参考值I sref，控制所述换流器的电流跟随所述电流指令参考值I sref；
    其中，所述控制方法还包括过流限制环节，并且当所述换流器处于指令限流模式时，根据所述交流电压U s、所述内电势E、所述相位θ和所述换流器的所述电流限制值I max，通过正序电压源的串联电感特性计算所述指令限流模式的所述电流指令参考值，并作为所述步骤3的所述电流指令参考值I sref。
  2. 根据权利要求1所述的控制方法，其中，
    所述换流器的所述内电势E的幅值取值为0pu至2pu；
    所述相位θ模拟同步发电机的转子运动方程：
    Figure PCTCN2022107634-appb-100001
    其中，P m为机械功率，P e为电磁功率，J为虚拟惯量，D为虚拟阻尼因子，ω为模拟发电机的转子角频率，ω 0为系统额定转子角频率。
  3. 根据权利要求2所述的控制方法，其中，所述换流器的所述内电势E的所述幅值基于端口电压或无功功率，根据下垂特性等确定的函数关系进行计算得到。
  4. 根据权利要求1所述的控制方法，其中，
    所述电压参考值U sref包括正序d轴分量U srefdp、正序q轴分量U srefqp、负序d轴分量U srefdn和负序q轴分量U srefqn，且满足：
    Figure PCTCN2022107634-appb-100002
    其中，I sdp为所述换流器网侧电流I s的正序d轴分量，I sqp为所述换流器网侧电流I s的正序q轴分量，I sdn为所述换流器网侧电流I s的负序d轴分量，I sqn为所述换流器网侧电流I s的负序q轴分量。
  5. 根据权利要求1所述的控制方法，其中，所述控制方法还包括：
    当所述步骤3计算的所述电流指令参考值I sref的幅值大于所述电流限制值I max时，即，满足如下公式时，所述换流器处于所述指令限流模式：
    Figure PCTCN2022107634-appb-100003
    其中，I srefdp为所述电流指令参考值I sref的电流正序d轴参考值，I srefqp为所述电流指令参考值I sref的电流正序q轴参考值，I srefdn为所述电流指令参考值I sref的电流负序d轴参考值，以及I srefqn为所述电流指令参考值I sref的电流负序q轴参考值。
  6. 根据权利要求1所述的控制方法，其中，所述控制方法还包括：实际电流大于所述电流限制值I max时，所述换流器处于所述指令限流模式。
  7. 根据权利要求1所述的控制方法，其中，所述根据所述正序电压源的所述串联电感特性计算所述指令限流模式的所述电流指令参考值的步骤，包括：
    根据所述相位θ对所述交流电压U s进行Park变换，以计算所述交流电压U s的包括正序d轴分量U sdp、所述交流电压U s的正序q轴分量U sqp、所述交流电压U s的负序d轴分量U sdn、所述交流电压U s的负序q轴分量U sqn的电压向量；
    根据所述电流限制值I max计算所述指令限流模式的限流阻抗X L；
    基于所述正序电压源的所述串联电感特性，根据所述交流电压U s的所述电压向量、内电势E和所述限流阻抗X L计算指令限制后的所述电流指令参考值I sref，所述电流指令参考值I sref包括电流正序d轴参考值I srefdp、电流 正序q轴参考值I srefqp、电流负序d轴参考值I srefdn和电流负序q轴参考值I srefqn。
  8. 根据权利要求7所述的控制方法，其中，当所述换流器处于所述指令限流制模式时，所述阻抗定值X Lset取值为所述限流阻抗X L；
    当所述换流器在非所述指令限流模式时，所述阻抗定值X Lset取值为0pu至5pu。
  9. 根据权利要求7所述的控制方法，其中，根据所述电流限制值I max计算所述指令限流模式的所述限流阻抗X L的步骤包括：
    根据所述交流电压Us和所述内电势E的向量差计算所述限流电抗X L的电压向量，然后根据所述电压向量的模与所述换流器的所述电流限制值I max相除得到所述限流电抗X L。
  10. 根据权利要求7至9中任一项所述的控制方法，其中，当所述限流电抗X L大于所述阻抗定值X Lset时，则判定所述换流器处于所述指令限流模式。
  11. 根据权利要求1所述的控制方法，其中，所述根据所述连接母线的所述电压参考值U sref和所述交流电压U s的误差，计算所述电流指令参考值I sref的步骤，包括：
    所述步骤3采用PI控制器，其中，输入为所述连接母线的所述电压参考值U sref和所述交流电压U s的误差，输出为所述电流指令参考值I sref，且当所述换流器处于所述指令限流模式时，所述电流指令参考值I sref取值为所述过流限制环节输出的所述电流指令参考值。
  12. 根据权利要求1所述的控制方法，其中，所述步骤3采用PI控制器时，利用所述电流指令参考值I sref和所述换流器的所述网侧电流I s得到参考电压指令，对所述参考电压指令进行反Park变换得到三相参考电压指令U Cabc，并将所述三相参考电压指令U Cabc发送至后续的换流阀控制环节实现所述换流器的控制。
  13. 一种换流器的控制方法，其中，所述控制方法应用于柔性直流输电系统，所述柔性直流输电系统包括一个或多个电压源型换流器，所述控制方法包括：
    确定所述换流器的内电势E、所述内电势E的相位θ、交流电压U s、所 述换流器的网侧电流I s、阻抗定值X Lset和所述换流器的电流限制值I max；
    根据所述交流电压U s、所述内电势E、所述相位θ以及所述电流限制值I max，并根据正序电压源的串联电感特性计算指令限流模式的电流指令参考值I sref；以及
    根据所述电流指令参考值I sref，控制所述换流器的电流跟随所述电流指令参考值I sref。
  14. 根据权利要求13所述的控制方法，其中，
    所述换流器的所述内电势E的幅值取值为0pu至2pu，所述相位θ模拟同步发电机的转子运动方程：
    Figure PCTCN2022107634-appb-100004
    其中，P m为机械功率，P e为电磁功率，J为虚拟惯量，D为虚拟阻尼因子，ω为模拟发电机的转子角频率，ω 0为系统额定转子角频率。
  15. 根据权利要求14所述的控制方法，其中，所述换流器的所述内电势E的所述幅值基于端口电压或无功功率根据下垂特性等确定的函数关系进行计算得到。
  16. 根据权利要求14所述的控制方法，其中，所述根据正序电压源的所述串联电感特性计算所述指令限流模式的所述电流指令参考值I sref的步骤，包括：
    根据所述相位θ对所述交流电压U s进行Park变换，计算所述交流电压U s的包括正序d轴分量U sdp、所述交流电压U s的正序q轴分量U sqp、所述交流电压U s的负序d轴分量U sdn、所述交流电压U s的负序q轴分量U sqn的电压向量；
    根据所述电流限制值I max计算所述指令限流模式的限流阻抗X L；以及
    基于所述正序电压源的所述串联电感特性，根据所述交流电压U s的电压向量、内电势E和所述限流阻抗X L计算所述指令限制后的所述电流指令参考值I sref，所述电流指令参考值I sref包括电流正序d轴参考值I srefdp、电流正序q轴参考值I srefqp、电流负序d轴参考值I srefdn、电流负序q轴参考值I srefqn。
  17. 根据权利要求16所述的控制方法，其中，根据所述交流电压Us和所述内电势E的向量差计算所述限流电抗X L的电压向量，然后根据所述 电压向量的模与所述换流器的所述电流限制值I max相除得到所述限流电抗X L。
  18. 一种换流器的控制系统，其中，
    所述控制系统包括获取系统参数模块、参考电压产生模块、电压外环模块、电流内环模块和过流限制模块，其中，
    所述获取系统参数模块，用于获取所述换流器的内电势E、所述内电势E的相位θ、阻抗定值X Lset、交流电压U s、换流器网侧电流I s和电流限制值I max，所述内电势E的幅值的取值为0pu至2pu，所述相位θ模拟同步发电机的转子运动方程；
    所述参考电压产生模块，用于根据所述内电势E、所述相位θ、所述阻抗定值X Lset、所述换流器网侧电流I s，计算所述换流器的连接母线的电压参考值U sref；
    所述电压外环模块，用于根据所述连接母线的所述电压参考值U sref和采集的所述交流电压U s的误差，计算电流指令参考值I sref；
    所述电流内环模块，用于根据所述电流指令参考值I sref，控制所述换流器的电流跟随所述电流指令参考值I sref；以及
    所述过流限制模块，用于当所述换流器的所述电流指令参考值I sref大于所述电流限制值I max或实际电流大于所述换流器的所述电流限制值I max时，根据采集的所述交流电压U s、所述内电势E、所述相位θ以及所述换流器的所述电流限制值I max，并根据所述正序电压源的所述串联电感特性计算所述指令限流模式的所述电流指令参考值I sref，所述电流指令参考值I sref作为所述电流内环模块的输入。
  19. 一种计算机设备，包括存储器、处理器以及存储在所述存储器中并可在所述处理器上运行的计算机程序，所述处理器执行所述计算机程序时实现如权利要求1至17任一项所述的控制方法的步骤。
  20. 一种计算机可读存储介质，其上存储有计算机程序，其中，所述计算机程序被处理器执行时实现权利要求1至17中任一项所述的方法的步骤。
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