JPH084366B2 - Generator protector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a protective device for a transformer, which determines a generator when a plurality of generators operating in parallel fails in the excitation system. .

[Conventional technology]

FIG. 4 is a circuit diagram of a conventional generator protecting device disclosed in, for example, Japanese Patent Publication No. 51-37422. Each of the generators 1a and 1b operated in parallel has a characteristic that the voltage decreases with a delayed reactive current and increases with a reactive current as a cross current compensation. The generated voltage of the generators 1a and 1b is given to the reactive power detectors 12a and 12b, respectively, and the breaker
It is given to the bus A via 3 _a1 and 3 _b1, and is given to the load 6 via the bus A. The output of the reactive power detector 12a is given to the average value calculation circuit 13 and the comparison amplification circuit 14a, and the output of the reactive power detector 12b is given to the average value calculation circuit 13 and the comparison amplification circuit 14b. The output of the average value calculation circuit 13 is given to the comparison and amplification circuits 14a and 14b. The output of the comparison and amplification circuit 14a is given to the exciter 2a and the logical operation circuit 16a, and the output of the exciter 2a is given to the generator 1a. The output of the comparison amplification circuit 14b is given to the exciter 2b and the logical operation circuit 16b, and the output of the exciter 2b is given to the generator 1b. On the other hand, the voltage of the bus A is given to the bus voltage comparison circuit 15 to which the bus voltage setter 15a is connected, and the output of the bus voltage comparison circuit 15 is sent to the comparison amplification circuits 14a and 14b and the logical operation circuits 16a and 16b. Has been given. And which gives an output of logic circuit 16a in the trip coil 3 _a2 of the circuit breaker 3 _a1, giving an output of logic circuit 16b to the trip coil 3 _b2 of the circuit breaker 3 _b1. The logical operation circuits 16a and 16b are configured to determine a failed generator based on the reactive power sharing deviation from the comparison amplifier circuits 14a and 14b and the bus voltage deviation from the bus voltage detector 15.

When the generators 1a, 1b are operated in parallel, the reactive power of the generators 1a, 1b is detected by the reactive power detectors 12a, 12b, and both outputs of the reactive power detectors 12a, 12b are output to the average value calculation circuit 13. input. As a result, the average value calculation circuit 13 compares the output obtained by calculating the reference reactive power per generator with the comparison amplification circuit 14
Give to a, 14b. The comparison amplification circuits 14a and 14b respectively compare the reference reactive power and the reactive power detected by the reactive power detectors 12a and 12b, and the reactive power of the generators 1a and 1b is larger than the reference reactive power. On the contrary, the generator with the smaller voltage is supplied with the output of the voltage increase to the exciters 2a and 2b so that the reactive power of both generators 1a and 1b is equally divided. Further, during such reactive power sharing control, the voltage of the bus A is compared with the set voltage given by the bus voltage setter 15a in the bus voltage comparison circuit 15, and if the rise or fall of the bus voltage is detected, the comparison amplification circuit is detected. The reactive power sharing control in 14a, 14b is temporarily suspended, and the output of voltage reduction or voltage increase is generated by the exciter 2a, 2b.
To keep the bus voltage constant.

When the exciter becomes abnormal in such an operating state and the generator fails, the deviation between the reactive power and the reactive power reference value, which is the output of the comparison amplification circuits 14a, 14b, that is, the reactive power sharing deviation, The deviation between the bus voltage output from the bus voltage comparison circuit 15 and the set value of the bus voltage, that is, the bus voltage deviation, is compared by the logic operation circuits 16a and 16b, respectively, and the generator that has failed according to the operation table shown in Table 1 below. Is being determined.

That is, in the case of a failure in which the voltage of the generator rises, the reactive power (kV _ar ) increases with the rise of the bus voltage (greater than the bus voltage deviation ΔV).
Is large (greater than reactive power sharing deviation + ΔkV _ar )
In the case of a failure in which one is the failed generator and the generated voltage drops, the amount of shared reactive power (kV _ar ) is small due to the decrease in bus voltage (bus voltage deviation − less than ΔV) (reactive power sharing deviation − (Smaller than ΔkV _ar ) is judged to be the faulty generator and the output signal of the logical operation circuit 16a or 16b is output to the circuit breaker 3 _a1 or 3 _b1.
It is applied to the trip coil 3 _a2 or 3 _b2 of 1 to excite it.
As a result, the circuit breaker 3a or 3b operates to cut off and disconnects the failed generator 1a or 1b from the bus A.

Separately from this, a reactive power control device for an integrated power plant is disclosed in Japanese Patent Laid-Open No. 60-82033. This reactive power control device is designed to control part of the power generation axes of the combined cycle power plant by individual load control, control the other load generation axes collectively, and control the overall reactive power to the command value. Each addition circuit that calculates the actual reactive power value Q ₁ of the total axis and the actual reactive power value Q ₂ of the total control axis, and the subtraction circuit that calculates Q ^* -Q ₁ from the total reactive power command value Q ^* , And a distributor that compares Q ^* -Q ₁ and Q ₂ and distributes the difference only to the general control axis, and controls the reactive power of each general control axis according to the distributed difference. It is configured to

Further, a failure diagnostic device for an AC generator is disclosed in JP-A-62-16027.
It is shown in the publication. This fault diagnosis device is provided between each of the reactive load sharing device for issuing a reactive load sharing command commensurate with the capacity of each generator, and each of the automatic voltage adjusting device for fixing the output voltage of a plurality of AC generators. A plurality of limiters capable of externally limiting the invalid duty command and a failure based on the presence or absence of a change in the invalid duty share of the corresponding alternator when the invalid duty command is limited via any of the limiters. Failure detection means for making a judgment is provided.

Furthermore, apart from that, as something related to the present invention,
Japanese Patent Publication No. 45-17503 discloses a control device for a synchronous machine group.
Japanese Patent Publication No. 18498/45 discloses a comprehensive reactive power adjustment method.
Japanese Patent Publication No. 51-37422 discloses an AC generator protection device.
Japanese Patent Publication No. 56-19185 discloses a power failure detection device, which is disclosed in
-234833 discloses a faulty machine discrimination method for a parallel operation generator, JP-A-63-242126 discloses a generator failure detection device, and JP-A-51-96008 discloses a generator in parallel operation. And the simulation system of the field loss relay is disclosed in Japanese Patent Laid-Open No. 59-92718.

[Problems to be solved by the invention]

As described above, the conventional generator protection device is configured such that when the generators are operated in parallel, even if the generator voltage is increased or decreased due to an abnormality of the exciter or the like, the generator fails. , While the bus voltage control is operating, a healthy generator compensates for the rise or fall of the voltage of the failed generator, and apparently it is difficult for the bus voltage to change, and the determination of the failed generator is delayed and sound. There is a problem that overcurrent trip of various generators and a failed generator cannot be quickly determined.

Further, the reactive power control device for a complex plant disclosed in the above-mentioned JP-A-60-82033 has a function of
If one generator fails, even if the reactive power sharing control is performed, the failed generator cannot control the reactive power because the generator cannot control. In addition, there is a problem that the faulty generator cannot be identified.

In the failure diagnosis device disclosed in Japanese Patent Laid-Open No. 62-16027, the output of the generator changes rapidly when the automatic voltage regulator fails. Therefore, there is a problem in the quick response in the method in which the field current is slightly changed and the response is used for determination. Further, when the bus bar voltage is controlled to be constant, there is a problem that the rising and falling directions of the bus bar voltage cannot be effectively detected.

Further, in Japanese Patent Publication Nos. 45-17503 and 45-18498, when one generator fails during parallel operation, even if the reactive power sharing control is performed, the failed generator Since the control side cannot control, reactive power cannot be shared. In addition, there is no function to identify a faulty generator.

The devices disclosed in Japanese Patent Publication Nos. 51-37422 and 56-19185 have a sudden change in the output of the generator when the automatic voltage regulator, the exciter or the like fails. If the field current is slightly changed and the faulty generator is identified based on the response, quick response cannot be obtained. Further, when the bus voltage is controlled to be constant, it is not possible to effectively detect the rising and falling directions of the bus voltage.

The devices disclosed in JP-A-63-234833 and JP-A-63-242126 cannot effectively detect the rising and falling directions of the bus voltage when the bus voltage is controlled to be constant.

The one disclosed in Japanese Patent Laid-Open No. 51-96008 does not have a function of discriminating a failed generator.

According to Japanese Patent Laid-Open No. 59-92718, only field loss can be detected, and field overcurrent, disconnection inside the generator, failure of the generator due to short circuit, etc. cannot be detected.

In view of the above-mentioned problems, it is an object of the present invention to provide a generator protection device that can quickly and accurately determine a failed generator regardless of bus voltage control.

[Means for solving problems]

The generator protection device according to the present invention includes a voltage of each generator,
A first input section for applying a current and a voltage of a bus bar, and a second input section for inputting an operation signal of an auxiliary contact interlocking with the main contact of the circuit breaker.
Input section, the signals given to both of these input sections are used to discriminate whether or not parallel operation is being performed, and in the parallel operation state, the reactive power is calculated, and the total reactive power of the generator and the preset generator A means for calculating the reference reactive power per generator from the rated capacity ratio, a means for obtaining the reactive power deviation between the reference reactive power and the reactive power that the generator bears, and when the voltage control of the generator is being performed. Confirms the rise and fall states of the bus voltage by the output state of the voltage control signal and the voltage change state before a predetermined time while the generator voltage control is stopped. When the judgment is made, a means for logically operating the direction of the deviation of the reactive power and the rising and falling states of the voltage to judge the faulty generator is provided.

[Action]

The voltage and current of the generator are applied to the first input section. An operation signal of an auxiliary contact that works with the main contact of the circuit breaker is applied to the second input section. From the operation signal of the auxiliary contact, it is judged whether or not the generator is in parallel operation. When the generator is in parallel operation, the voltage of the generator,
The reactive power of each generator is calculated from the current, and the reference reactive power per generator is calculated from the total of the reactive power of the generator and the preset rated capacity ratio of the generator to obtain the reference reactive power. Calculate the reactive power deviation from the reactive power that the generator bears. When the voltage control of the generator is in progress, the bus voltage rises due to the output state of the voltage control signal, and when the voltage control of the generator is stopped, due to the change state of the voltage from a predetermined time before,
When the falling state is confirmed and it is judged that the deviation of the reactive power is more than a predetermined value, the direction of the deviation of the reactive power and the increase of the voltage,
The down state is logically operated to determine the faulty generator.

As a result, the failed generator can be determined regardless of the control operation of the bus voltage.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing its embodiments. FIG. 1 is a single line connection diagram of a power supply system to which a generator protection device according to the present invention is applied. Each of the generators 1a and 1b operated in parallel has a characteristic that the voltage decreases with a delayed reactive current and increases with a reactive current as a cross current compensation.

The generated voltage of the generators 1a and 1b is applied to the bus A via the circuit breakers _3a1 and _3b1, and to the load 6 via the bus A.

In addition, the generated voltage and current of the generator 1a are passed through the transformer 4a and the current transformer 5a, and the generated voltage and current of the generator 1b are passed through the transformer 4b.
And the current input to the analog input section 8 of the failure determination section 11 including the digital input section 7, the analog input section 8, the calculation section 9 and the output section 10 via the current transformer 5b. The voltage of the bus A is applied to the analog input section 8 via the transformer 4c. Breaker 3 _a1 auxiliary contact 3 _a3 switching signal and breaker
The opening / closing operation signal of the auxiliary contact 3 _b3 of 3 _b1 is given to the digital input section 7. The output signals of the digital input section 7 and the analog input section 8 are given to the arithmetic section 9, and the output signal of the result of the arithmetic operation by the arithmetic section 9 is given to the output section 10.

The voltage control signal output from the output unit 10 is the excitation device 2a, 2b.
The output of the exciter 2a to the generator 1a
The output of 2b is given to the generator 1b. Also, the signal output from the output unit 10 for tripping the circuit breaker is the circuit breaker 3 _a1 , 3
It has been given to the trip coil 3 _a2, 3 _b2 of _b1.

Next, the determination procedure of the failure determination unit will be described with reference to the flowchart shown in FIG. 2 and the subroutine shown in FIG. Calculation unit 9 first checks the digital input section 7 (S1), the breaker 3 _a1, 3 _b1 auxiliary contact 3 _a3, 3 _b3 generator 1a from the opening and closing operation signal, 1b determines whether concurrent operation (S2). In the parallel operation state, the calculation unit 9 takes in the generated voltage and current of each of the generators 1a and 1b from the analog input unit 8 and calculates the reactive power of each of the generators 1a and 1b (S3). Further, the calculation unit 9 adds the calculated reactive powers of the generators 1a and 1b, and the rated reactive power of each generator preset in the calculation unit 9 to the generators 1a and 1b. Calculate the standard reactive power that each unit should bear. Then, the standard reactive power of each generator is compared with the reactive power that the generator actually bears to obtain the reactive power deviation, and if the actual reactive power is large, the generator Output section to lower the voltage
A signal is output from 10 to the exciter 2a or 2b. On the contrary, when the reactive power actually burdened is small, the output unit 10 outputs a signal to the exciter 2a or 2b in order to increase the voltage of the generator. As a result, the reactive power that is actually borne is distributed to the capacity ratio of each generator. In addition, the bus voltage is checked (S4), and if the bus voltage is decreasing or rising, the reactive power sharing control described above is temporarily interrupted,
From the output unit 10 to the excitation devices 2a, 2b in order to keep the bus voltage constant.
It outputs a signal to raise or lower the voltage. by the way,
If the generator voltage rises or falls due to abnormal operation of the exciter of the generators 1a, 1b during parallel operation and the generator 1a or 1b fails, check the rise and fall of the bus voltage. In the subroutine of FIG. 3, it is determined whether or not the voltage control state is set (S5). If the voltage is being controlled, it is judged whether or not the "rising" signal for raising the bus voltage is being output (S6), and if it is the "rising" signal, the flag that the voltage is regarded as "falling" is set (S7). , If the "falling" signal is being output, the flag that the voltage is considered to "rise" is set (S8). If it is not in the voltage control state in step (S5), it is determined whether or not the bus voltage has changed by the bus voltage deviation ΔV or more from the predetermined time t ₁ second before (S9). Then, (S10), if the actual bus voltage rises, the flag that regards the voltage as "increase" is set (S7), and if it decreases, the flag that regards the voltage as "fall" is set (S7).
8). When the bus voltage deviation ΔV is not changed by the step (S9), both the voltage rising / falling flags are reset (S11). After the completion of such a subroutine, if the voltage “up” flag or the “down” flag is subsequently set (S12), that is, if the bus voltage is rising or falling, the reactive power (kV _ar ) It is determined whether the sharing is unbalanced (inappropriate) (S13). If the sharing is unbalanced, it is judged whether or not it has increased compared to t ₁ seconds before (S1
4) If it is rising, it is judged whether or not the rising amount is equal to or more than a predetermined value (S15). If the amount of increase is equal to or greater than the predetermined value, then the faulty generator is determined (S17). If the amount of increase is less than or equal to the predetermined value, it is determined whether the increase state has passed a predetermined time t ₂ seconds (same as or slightly longer than t ₁ ) (S16). Then, when the amount of rise is equal to or greater than a predetermined value or when the rise state has passed t ₂ seconds, the faulty generator is determined (S18). Then, the determination of the generator to be in failure is made by the calculation table shown in Table 2 below.

That is, in the voltage “fall” flag set, the reactive power deviation ΔkV _ar is in the (−) direction, that is, the reactive power sharing is small,
Alternatively, the one in which the reactive power sharing shows a decreasing direction (-) for time t ₂ seconds is regarded as the faulty generator. Also, when the voltage “rising” flag is set, the reactive power deviation ΔkV _ar is (+)
The direction, that is, the direction in which the reactive power sharing is large or the direction in which the reactive power sharing is increasing (+) for time t ₂ seconds is determined as the faulty generator.

When the faulty generator is determined in this way, the output unit 10 gives a signal to the trip coil of the circuit breaker connecting the faulty generator to the busbar A to cause the tripping operation, thereby causing the fault. Separate the generator from the bus A (S19) and protect it. Then, the load 6 is continuously supplied with power by a sound generator. If the voltage rising / falling flag is reset in step (S11), that is, if the bus voltage deviation ΔV or less, it is determined that the generator is normal and the determinations in step (S13) and thereafter are not performed.

In this way, when determining a faulty generator, after confirming that the bus voltage is in a rising or falling state, it is determined whether the actual reactive power sharing state of each generator is appropriate. Therefore, even when the bus voltage is being controlled, it is possible to quickly determine the failed generator without making an erroneous determination. Further, since the reactive power of the generator is directly calculated by the voltage and the current of the generator, a separate power converter is not required and the reactive power can be obtained quickly and with high accuracy.

As described above in detail, according to the present invention, the generator operating in parallel has a failure such that the voltage rises or falls due to the abnormal operation of the excitation system, and the bus voltage is controlled at that time. However, it is possible to quickly and accurately determine the failed generator. Therefore, the present invention has an excellent effect of improving the reliability of the power supply system that operates a plurality of generators in parallel.

[Brief description of drawings]

FIG. 1 is a single line connection diagram of a power supply system to which the generator protection device of the present invention is applied, and FIG. 2 is a flowchart showing the determination contents of a failure determination unit. FIG. 3 is a subroutine for checking rise / fall of the bus voltage, and FIG. 4 is a single wire connection diagram of a conventional power supply system. 1a, 1b ...... generator, 2a, 2b ...... exciter, 3 _a1, 3 _b1 ...... breaker, 3 _a3, 3 _b3 ...... auxiliary contacts, 6 ...... load, 7 ...... digital input, 8 ... … Analog input section, 9 …… Calculation section, 10
...... Output section, 11 ...... Fault determination section In the drawings, the same reference numerals indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-51-96008 (JP, A) JP-A-59-92718 (JP, A) JP-A-60-82033 (JP, A) JP-A-62- 16027 (JP, A) JP 63-234833 (JP, A) JP 63-242126 (JP, A) JP 45-17503 (JP, B1) JP 45-18498 (JP, B1) JP-B-51-37422 (JP, B1) JP-B-56-19185 (JP, B2)

Claims (1)

[Claims] 1. A generator protection device, which is connected to a busbar through a circuit breaker and determines a generator when a plurality of generators operating in parallel have an excitation system failure, First to give voltage and current of each generator and voltage of said busbar
Input section, a second input section for giving an operation signal of an auxiliary contact interlocking with the main contact of the circuit breaker, and a parallel operation state by discriminating whether or not the parallel operation is performed by the signals given to these both input sections. And a means for calculating the reactive current and calculating the reference reactive power per generator from the total of the reactive power of the generator and the preset rated capacity ratio of the generator. Means to obtain the reactive power deviation from the reactive power that is being carried and the output state of the voltage control signal when the generator voltage control is in progress, and the change state of the voltage before the specified time when the generator voltage control is stopped. If the deviation of the reactive power is judged to be more than a predetermined value by checking the rise and fall state of the bus voltage, the direction of the deviation of the reactive power and the rising and falling states of the voltage are logically operated to determine the faulty generator. Have the means to Generator protection device comprising and.