JPH0226225A - Dc transmission controller - Google Patents

Abstract

PURPOSE:To suppress the twist of a shaft without deteriorating the characteristics of a constant-current control circuit by controlling a control signal of a shaft twist suppression control circuit in response to the amplitude of the detection signal of a shaft twist detector. CONSTITUTION:The output of a shaft twist detector 45 is '0' in a normal operating state. Thus, since an output control circuit 460 is OFF, an AC/DC converter 41 is controlled by a constant-current control circuit 410 of the basis control of a DC transmission. On the other hand, if the shaft twisting vibration of a generator 1 occurs due to a system accident or the like as a cause, the output of a shaft twist signal detector 450 becomes '1', and the control circuit 460 is turned ON. Accordingly, the output of a shaft twist suppression control circuit 430 is added to that of the control circuit 410, and it is so controlled on the basis of the signal that the DC power suppresses the shaft twist of the generator 1. When the shaft twist is suppressed, the output of the detector 450 becomes '0', and the converter 41 is controlled by the normal control circuit 410.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a DC power transmission control device, and in particular to a DC power transmission control device suitable for suppressing shaft twist of a generator due to interference between the generator and the DC power transmission. Regarding.

[Conventional technology]

In 1977, at a power plant located near the end of the forward conversion layer of the Scary Butte DC power transmission facility in the United States, a twist in the shaft of the generator occurred, causing interference between the generator and the DC power transmission. According to the results of the study so far, it is becoming clear that this phenomenon is caused by the control method of DC power transmission, but future studies will be needed to determine whether or not it occurs depending on the system status and the time course of the shaft twisting phenomenon. Regarding the shaft torsion suppression method, which many people are waiting for, please refer to the literature HUDCSYSTEM C0NT.
R0L FORDAMPING OF 5UBSYNC
HRONOO5oscillations (IEEE)
TRANS, Vol, PAS-101Nci7.1
982) One method is described in (7). The outline of this suppression device will be explained using FIG. 3. FIG. 3 shows a DC-only power transmission system in which the output of the generator, which is considered to be most susceptible to generator shaft torsional vibration, is transmitted only by DC power transmission. 1 is a generator, 2 is an AC transmission line, 31.32 is a transformer, 41.42 is an AC/DC converter that converts AC to DC or DC to AC, and 410 to 440 are control circuits for suppressing shaft torsion. A control device for an AC/DC converter 41 comprising:
410 is a constant current or constant power control circuit; 411 is an addition circuit that adds the output signal of a control circuit for suppressing shaft twisting, which will be described later; and the output of the constant current control circuit; 412 is a circuit that adds the output signal of the constant current control circuit; A control pulse for the above-mentioned AC/DC converter 41 is generated by a phase control circuit that outputs a pulse whose phase is controlled accordingly. Reference numeral 44 indicates a control device for the AC/DC converter at the power receiving end, but since it is not directly related to the present invention, the details will be omitted. 42
0 is a voltage transformer that detects the voltage at the AC/DC interconnection point, and 430 is a shaft twist suppression control that outputs a control angle command value (control signal) for suppressing the shaft twist of the generator from the voltage detection value of the voltage transformer 420. The circuit 6 is an AC system on the load side. Suppose that in such a system configuration, a generator shaft twist occurs due to a system accident. The shaft of the generator vibrates unstablely at the natural frequency of the shaft system, and therefore the amplitude, two phases, and frequency of the voltage at the AC/DC connection point oscillate. Shaft torsion suppression control circuit 4
At 30, a control signal for power control necessary to suppress shaft twisting is output from the voltage detection value at the AC/DC interconnection point.

This controls the DC power and suppresses unstable vibrations of the generator.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology has a configuration in which the control signal of the shaft torsion suppression circuit is always added to the output signal of the constant current control circuit, which is the basic control circuit of DC power transmission, so constant current control has the greatest effect on the operational performance of DC power transmission. It may deteriorate the characteristics of the circuit. This is because the response of the constant current control system operates in the frequency range of 10 to 50 Hz, whereas the shaft torsion frequency operates in the frequency range of 5 to 50 Hz.
This is because the control system of the shaft twist suppression circuit is configured to respond to this frequency.

An object of the present invention is to provide a control device for DC power transmission that can suppress shaft twisting without deteriorating the characteristics of a constant current control circuit, which is a basic control circuit for DC power transmission.

[Means for solving problems]

The above object is to provide a detection circuit for detecting shaft torsion in a DC power transmission control device equipped with a conventional shaft torsion suppression control circuit;
This is achieved by providing a circuit for controlling the output control signal of the shaft torsion suppression control circuit and controlling the control signal of the shaft torsion suppression control circuit in accordance with the magnitude of the detection signal of the shaft torsion detection circuit.

[Effect]

The shaft torsion detection circuit detects changes in the angular velocity of the generator from the voltage at the AC/DC interconnection point, further detects the shaft torsion frequency component via a filter circuit, and outputs a signal corresponding to the magnitude thereof. This detected value is guided to an output control circuit that controls a control signal output from the shaft twist suppression control circuit, and controls the magnitude of the output control signal from the shaft twist suppression control circuit in accordance with the thickness of the detected value. The controlled signal is added to the output of the basic control circuit for direct current power transmission to control the direct current transmitted power.

Here, the output for the input of the output control circuit changes according to the thickness of the detected value of the shaft torsion detection circuit described above, so it does not always have an adverse effect on the basic controllability of DC power transmission, and when shaft torsion occurs. This provides a DC power transmission control device that can suppress shaft torsion.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. Items with the same numbers as last time indicate the same items, so only the new and different items will be explained.

450 is a shaft torsion signal detection circuit that detects changes in the angular velocity of the generator from the output of the AC voltage transformer 420 and outputs a high level "1" signal when the shaft torsion frequency component becomes larger than a specified value. The detailed circuit is shown in Figure 2.
In the figure (a), 451 is an angular velocity change detection circuit that detects a change in the angular velocity of the generator from the AC voltage detection value of the AC voltage transformer 420, and 452 is an angular velocity change detection circuit that detects an unstable continuity of the generator from this angular velocity change detection value. Shaft torsion vibration frequency insert text on next page.

453 compares this detected value with a preset standard value Eo, and when the detected value is larger than the standard value, the high level is "1", otherwise the low level +iO
This is a comparator that outputs ff. 460 An output control circuit that operates to turn on the output of the shaft torsion suppression control circuit 430 according to the output signal of the shaft torsion signal detection circuit, when the output is at a high level "1", and is turned off when the output is at a low level "0". This detailed block diagram is shown in Figure 2 (
Shown in b). In the figure, AF is a band-pass active filter, and INC is an increase detection circuit that becomes high level rt 1 u when the output of the active filter increases, and at this time sets the flip-flop FF.

COM is a comparator and becomes high level "1" when the output of the active filter goes from a large value to below the reference value Po, and at this time resets the flip-flop FF. A
G is an analog gate circuit that turns on when the flip-flop is set and turns off when it is reset.

This circuit can detect the magnitude of the generator's persistently unstable shaft torsion frequency component. The output is the adder circuit 4
I am led to 11.

To explain the operation of this circuit, under normal operating conditions, the output of the shaft twist detection device 450 is it O11.

Therefore, since the output control circuit 460 is in the off state, the AC/DC converter 41 is controlled by the constant current control circuit which is the basic control of DC power transmission. On the other hand, grid accidents, etc. triggered
When shaft torsion vibration of the generator occurs, the output of the shaft torsion signal detection circuit 450 becomes R1#) and the output control circuit is turned on, so the output of the shaft torsion suppression control circuit 430 is added to the output of the constant current control circuit 410. Based on this signal, the DC power is controlled to suppress the shaft twist of the generator. When the shaft torsion is suppressed, the shaft torsion signal detection circuit 4
The output of 50 becomes #OI+, and the AC/DC converter is controlled by a normal constant current control circuit. Therefore, during normal operation, the shaft torsion suppression control circuit does not adversely affect the response of the constant current control circuit, which is the basic control of DC power transmission, and when shaft torsion occurs, the shaft torsion suppression control circuit operates to suppress shaft torsion. be done.

FIG. 4 shows another embodiment of the invention. In this embodiment, the shaft torsion suppression control circuit 440 generates a correction signal for the command value IP of the constant current control circuit, and the created signal is added to the current command value via an adder 490 to suppress shaft torsion. This figure shows a case in which the present invention is applied to a configuration in which:

In the absence of the circuit according to the embodiment of the present invention in FIG. 4, the shaft torsion suppression control circuit 430 in FIG. It is clear that the shaft torsion suppression control circuit shown in FIG. 4 is designed to obtain a correction signal for the command value Ip by considering the control characteristics of the constant current control circuit 410. The operation of the circuit is the same as that shown in Fig. 1, and when there is only normal shaft twist, the shaft twist suppression control circuit 440
The output of is set to the command value Ip by the operation of the output control circuit 460.
will not be added to, and will not be adversely affected. On the other hand, when shaft torsion occurs, the output of the shaft torsion suppression control signal is added as a correction value to the command value Ip of the constant current control circuit 410 by the operation of the output control circuit 460, and the DC power is controlled to suppress the shaft torsion. take action.

In the above embodiment, the generator shaft torsion was detected using the signal detected from the voltage at the AC/DC interconnection point, but the generator shaft torsion signal was detected using the voltage/current of the AC system and the voltage of the DC system.・It can be performed in the same manner as described in the above embodiment by changing the current, the control angle of the AC/DC converter, etc. Naturally, it is also possible to detect a shaft torsion signal directly from the shaft of the generator/turbine. This embodiment is shown in FIG. The ones with the same numbers as the previous one indicate the same ones, so to explain the new ones, 11 is the turbine connected to the generator shaft 12, 47
0 is a torque sensor that detects the shaft torque (stress) of the shaft 12, 480 is a torque sensor that compares the output of the torque sensor with a preset reference value To, and when the former is greater than the latter, it becomes a high level "1". , low level “0” when small
It is clear that the same effect as the above-mentioned embodiment can be obtained with this configuration as well.

In the above embodiment, the output control circuit 460 that controls the output of the shaft torsion suppression control circuit operates on and off in response to the detection signal of the shaft torsion signal detection circuit 450, but the input/output characteristics of the output control circuit It is obvious that the filter may have a characteristic in which the input/output gain changes depending on the detected value of the detection signal. FIG. 6 shows an example of this case.

An output control circuit 510 comprised of a shaft torsion signal detection circuit 500 and a multiplier is different from that in FIG. Details of the shaft torsion signal detection circuit 500 are shown in FIG.

451 is the above-mentioned angular velocity change detection circuit, 452 is the above-mentioned bandpass filter, and 454 is a sensor that responds to the magnitude of the persistent unstable shaft torsion frequency component contained in the angular velocity change signal detected by the bandpass filter. This is a gain conversion circuit that outputs a signal with a weighted value, and this output is connected to the multiplier of the output control circuit. Here, the input/output characteristics of the gain conversion circuit 454 are expressed as, for example, when the output of the bandpass filter 452 is smaller than a certain reference value, 'I
”, and when this is exceeded, set it to “1” to obtain the characteristics shown in FIG. Alternatively, when the output of the bandpass filter 452 exceeds a certain reference value, the output can be proportional to the input.In the latter method, when the output of the bandpass filter 452 exceeds a certain reference value, the output is proportional to the difference between the reference value and the input. If the shaft torsion suppression control circuit operates when shaft torsion occurs, the shaft torsion suppression signal can be gradually activated, so the output control circuit described above is configured with an on/off switch. The feature is that it can prevent problems such as disturbances to the system during operation, such as in cases where the system is in operation.

In any of the above cases, normally only constant current control, which is the basic control of DC power transmission, operates when shaft torsion does not occur.
When shaft torsion occurs, the shaft torsion suppression control circuit operates to suppress the shaft torsion, and unlike conventional systems, the shaft torsion suppression control circuit does not adversely affect the basic control characteristics of DC power transmission.

〔Effect of the invention〕

According to the present invention, by adding a simple circuit to a conventional DC power transmission control device, it is possible to suppress the shaft twist of the generator without deteriorating the normal control characteristics of DC power transmission.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a DC power transmission control device for suppressing shaft torsion according to an embodiment of the present invention, FIG. 2 is a detailed block diagram of the shaft torsion signal detection circuit of FIG. 1, and FIG. 3 is a diagram of the present invention. FIG. 4, FIG. 5, and FIG. 6 are diagrams showing a DC power transmission control device for suppressing shaft torsion according to other embodiments of the present invention, FIG. 7 is a diagram showing details of the shaft torsion signal detection circuit of FIG. 6. 1... Generator, 2... AC transmission line, 5... DC transmission line, 6... Load AC system, 31.32... Conversion transformer. 41.42... AC/DC converter, 410... Constant current control circuit, 411, 490... Adder, 412... Phase control circuit, 420... AC voltage transformer, 430, 44
0... Shaft torsion suppression control circuit, 450... Shaft torsion signal detection circuit, 453, 480... Comparator, 460...
...Output control circuit, 470...Torque sensor.

Claims (1)

[Claims] 1. A shaft torsion signal for detecting shaft torsion of the generator in a DC power transmission control device comprising a generator and a control circuit for suppressing shaft torsion of the generator due to interference between the DC system. A DC power transmission control device comprising: a detection circuit; and an output control circuit that controls an output signal of the shaft twist suppression control circuit in accordance with an output signal of the signal detection circuit. 2. In claim 1, the shaft torsion signal detection circuit detects a signal corresponding to a change in the angular velocity of the generator from the voltage/current of the system, the shaft torque of the turbine generator, etc. A DC power transmission control device characterized in that detection is performed from an unstable shaft torsion vibration frequency component of a detected value.