JPH05111297A - Variable speed generator motor system and load interruption detecting method for variable speed generator motor - Google Patents

Abstract

PURPOSE:To provide a highly reliable interruption detector and detecting method for variable speed generator motor in order to suppress voltage rise of a generator motor upon interruption of primary system. CONSTITUTION:The system interruption detecting method for monitoring excessive difference between a secondary exciting current command Iref and an actual exciting current IFB comprises a filter 51 for damping a frequency component corresponding to the rotational speed in a detected value of the actual exciting current IFB in order to make a discrimination against disturbance at the time of system fault, and a comparator 52 for making a comparison with a set value 54.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable speed generator-motor system in which a secondary winding is AC-excited by using a frequency converter and is operated as a generator or an electric motor at a variable speed, and more particularly to a power system. The present invention relates to a detection method and device suitable for detecting interruption.

[0002]

2. Description of the Related Art An example of a generator / motor system is, for example, a generator / motor system for pumping or generating electricity. Conventionally, since a synchronous machine is generally used as a generator / motor of such pumped water or a power generation system, only operation at a constant rotation speed can be performed, so that the efficiency of the pump turbine depends on the amount of power generation, the amount of pumped water, and the head. There was a problem that the load was lowered and the load could not be adjusted during the pumping operation.

Therefore, there has been proposed a variable speed pumped storage power generation system which solves the above problems by making the rotational speed of a pump turbine variable. This system is a system in which a secondary winding of a variable speed generator motor (hereinafter referred to as a variable speed machine) including a large-capacity winding type AC excitation synchronous machine is secondarily excited, and the excitation frequency is adjusted. It realizes power generation and pumping operation at variable speed.

A major difference between such a variable speed machine and the above-mentioned synchronous machine is that, in the synchronous machine, a torque commensurate with the load torque (active power) is generated by changing the internal phase difference angle. However, in the variable speed machine, the exciting current does not contribute to the torque, whereas in the variable speed machine, the secondary exciting current is divided into the torque component (also called active power component or q-axis component) and the magnetic flux direction component ( Reactive power component, voltage component or d
It is also possible to control active power and reactive power independently of each other.

Due to these characteristics, each excitation control system 1) In the synchronous machine, the excitation voltage is controlled by the constant voltage control (hereinafter abbreviated as AVR) so as to keep the generator voltage constant.

2) In a variable speed machine, active power control for keeping active power constant as described above (hereinafter abbreviated as APR).
And an AVR for performing reactive power control, which determines a secondary excitation current command, and has a function of controlling the excitation current by constant current control (hereinafter abbreviated as ACR) so as to match the current command. As for the variable speed machine, there is, for example, one disclosed in JP-A-62-181698.

[0007]

However, in the above-mentioned variable speed machine, the following problems may occur due to its characteristics.

That is, the output voltage suddenly rises when the near-end or far-end of the power system, which is the primary side system, is cut off or when the load of the variable speed machine is cut off (hereinafter collectively referred to as "power system cutoff"). The phenomenon is to appear.

In the case of synchronization, when the load on the system disappears,
When the internal phase difference angle is returned to zero and the generator voltage rises ΔV, the excitation voltage is throttled by the AVR, so the generator voltage is held at the command value without increasing.

However, in the variable speed machine, when the load on the system disappears, the torque current component (q-axis component) also affects the magnetic flux direction component (d-axis component) applied to AVR-specifically, the q-axis component and the d-axis component. Vector composition of the components determines the generator voltage.
As a result, the generator voltage rises ΔV.

Further, in addition to the above-mentioned problems of the variable speed machine as a whole, there is a problem peculiar to the generator motor system having AVR and ACR. That is, the secondary excitation current that determines the generator voltage is in a minor loop A that is lower than the d-axis current command lowering operation of the AVR that operates with the increase of the generator voltage.
Since it is designed to have a quick CR response,
Since the CR increases the secondary excitation current up to the current command value obtained by the vector combination at high speed, the generator voltage rises quickly. That is, it can be said that the increase ΔV of the generator voltage is determined by the responsiveness of the ACR. In order to control the generator voltage rise ΔV, the ACR response is lowered to
It would be better to raise the response of VR. However,
AV of main loop rather than ACR which is minor loop
Increasing the response of R is problematic because it lacks control stability.

Therefore, when the power system cutoff occurs, it is essential to detect the power system faster than the response of the ACR in order to control the increase ΔV of the generator voltage.

As a conventional technique in consideration of this, Japanese Patent Application No.
There is a technique described in JP-A-288907. This measures the output voltage of a generator and detects load shedding. When it is determined that the load has been cut off, control is performed to set the active power component of the exciting current to 0. However, when a system accident such as a lightning strike occurs in the power system, disturbance due to distortion of the system voltage, etc. occurs, but it is necessary to distinguish between the load interruption and the system accident, and high-speed and highly reliable load interruption detection is possible. Required. However, in this prior art, no consideration was given to accidents in the electric power system.

An object of the present invention is to provide a variable speed generator / motor system that reliably detects the disconnection of the primary side system of the generator motor and controls the variable speed generator / motor.

[0015]

Means for Solving the Problems The above-mentioned problems are as follows: a generator motor, a frequency converter for outputting a secondary exciting current to a secondary winding of the generator motor, and a secondary exciting current command value for the frequency converter. In a variable-speed generator-motor system that has a control unit that outputs and performs a power generation operation or an electric operation at a variable speed, a secondary excitation current detection unit and a generator motor included in the detection value of the secondary excitation current. A filter for attenuating the rotational frequency component, a first detecting means for detecting a deviation between the secondary excitation current command value and the output of the filter, and a primary side system of the generator motor based on the deviation. It is achieved by correcting the secondary excitation current command value by the detection signal, and a first deviation detecting means for detecting the interruption of No. 1 and outputting a detection signal.

[0016]

Now, the operation of the present invention will be described.

A generator motor, a frequency converter that outputs a secondary excitation current to the secondary winding of the generator motor, and a controller that outputs a secondary excitation current command value to the frequency converter, are variable. In the variable speed generator-motor system that performs power generation operation or electric operation at speed, the secondary excitation current command value detection means detects the secondary excitation current command value output by the control unit. The secondary exciting current detecting means detects the secondary exciting current output from the frequency converter. The filter attenuates the rotational frequency component of the generator motor included in the detected value of the secondary excitation current. The first detecting means detects a deviation between the secondary excitation current command value and the output of the filter. The first deviation detecting means detects interruption of the primary side system of the generator motor based on the deviation and outputs a detection signal. The control unit corrects the secondary excitation current command value based on the detection signal.

[0018]

EXAMPLE An example of an electric power system having a variable speed generator-motor system according to the present invention will be described.

First, when the electric power system is cut off, the variable speed machine is released from the electric power system, so that the load of the variable speed machine instantly becomes zero. Along with this, the secondary excitation current (actual excitation current)
Is a combination of the torque current component Iq and the magnetic flux direction component Id, and the generator voltage increases. However, immediately after the interruption, a phenomenon occurs in which the actual exciting current is reduced by the armature reaction so as to keep the magnetic flux of the variable speed machine constant. After that, since the exciting current is increased up to the combined current command of Id and Iq by the ACR, the generator voltage of the variable speed machine sharply rises.

The detection of load cutoff by the secondary excitation current in the present invention is to detect the phenomenon that the actual excitation current is reduced as an excessive deviation from the excitation current command value, and to perform the load cutoff detection. However, an excessive deviation between the exciting current command and the actual exciting current occurs not only when the power system is cut off, but also when the power system accident occurs. The actual exciting current at this time is a current in which a pulsating current having a frequency corresponding to the rotation speed is superimposed.Therefore, by applying a filter that attenuates this pulsating component to the actual exciting current detection value, load cutoff detection is performed. Can be achieved.

Further, since the pulsating current component superposed on the actual exciting current which is the output of each frequency converter satisfies the AC condition and the vector composition becomes zero, the amplitude of the actual exciting current is calculated. By performing the comparison with the amplitude of the secondary excitation current command, it can be discriminated whether there is a power system load cutoff or a system failure, so that load cutoff detection can be achieved.

Further, since the voltage waveforms before and after the circuit breaker greatly differ before and after the load is cut off, load cutoff detection can be achieved by comparing the two voltage waveforms.

The present invention will be described below based on examples.

FIG. 3 shows the overall construction of an embodiment of a variable speed pumped storage generation system which is a variable speed generator / motor system according to the present invention.

In FIG. 3, the variable speed pumped storage power generation system is connected to a power system 5 via a main transformer 4.
That is, the primary terminal of the variable speed machine 2 connected to the pump turbine 1 is connected to the power system 5 via the circuit breakers 3 and 8 and the main transformer 4.

The variable speed pumped storage system is a pump turbine 1
, A variable speed generator 2 which is a variable speed generator motor, a circuit breaker 3,
8, frequency converters 6A to 6C, and excitation transformer 7A to
7C, active power / voltage control device 15, excitation current control devices 14A, 14B, 14C, and current command calculator 22
A constant current calculator 23, a pulse generator 24, a phase detector 12, a reference signal generator 13, load cutoff detection devices 50A and 50B, a breaker control device 30, and an active power / voltage detector. 11 and 11. Further, the actual exciting current detectors 29A, 29B, 29 which are means for detecting the secondary exciting current.
Has C. Active power / voltage control device 15, exciting current control devices 14A, 14B, 14C, and current command calculator 2
2, the constant current calculator 23, the pulse generator 24, the phase detector 12, the reference signal generator 13, and the circuit breaker controller 30 constitute a controller.

The secondary winding of the variable speed machine 2 includes a frequency converter 6
Three-phase AC excitation is performed from A to 6C. Frequency converter 6A-
6C is connected to the main transformer 4 via the excitation transformers 7A to 7C and the circuit breaker 8. Generator active power PL, voltage VG
Is controlled by the active power / voltage controller 15 by using the active power command PO, the voltage command VO, and the active power / voltage detector 1.
1 (current is detected by the current detector 10, and the transformer 9A to
9B to detect the voltage and obtain active power / voltage)
Torque current component I from active power PL and voltage VG from
This is performed by obtaining q and the magnetic flux current component Id and outputting them to the excitation current control devices 14A to 14C. The excitation current controller 14 has reference signals 131A to 13A obtained from the Iq and Id, the phase detector 12, and the reference signal generator 13.
1C, a current command calculator 22 for calculating an AC exciting current command Iref, a current control 23 and a pulse generator 24 which operate so as to match the actual exciting current detections 29A to 29C and the current command Iref.

Each circuit breaker 3, 8, 16A, 16B is output from the circuit breaker controller 30 with a closing / closing command. The load cutoff detection device according to the present invention has a load cutoff detection device 50A that monitors the secondary excitation current and a load cutoff detection device 50B that monitors the voltage waveform of the circuit breaker.

FIG. 4 shows the phenomena at the time of load shedding and at the time of system fault only for one phase. In this figure, the excitation current command Ire
f with a solid line, the steady state actual exciting current TFB IFB1 (mm), load shedding during IFB ₂ (dashed line ...) indicated by the time a system fault IFB3 (dashed ...). During normal operation, the current command Iref and the actual current IFB are A
It agrees by CR. Actual current IFB2 due to load cutoff
Is reduced by the armature reaction, but is returned to the current command by the ACR. Actual excitation current IFB3 in case of system failure
Is superimposed on IFB1 with a pulsating current having a frequency corresponding to the rotational speed.

In the present invention, the current IFB2 when the load is cut off is
It is considered to discriminate the current IFB3 at the time of system fault.

1 and 5 show a load cutoff detecting device for monitoring the exciting current and its operation. FIG. 1 shows a load cutoff detection device that suppresses a pulsating current at the time of a system fault by providing a filter 51 that attenuates a frequency component generated at the time of a system fault. The load cutoff detecting device 50A is a first deviation detecting means 53 and a comparator 52 which is a first detecting means for comparing deviations of the exciting current designations IrefA to IrefC and the actual exciting currents IFBA to IFBC with a set value 54. And detecting that the deviation is larger than the set value, the load cutoff detection signal OUT is output. The active power / voltage control device 15 receives the load cutoff detection signal OUT and sets the command value of the active power to 0 to prevent the voltage from rising. This can be carried out, for example, by the method described in Japanese Patent Application No. 1-288907.

6 and 7 show the construction and operation of the load cutoff detecting device 50A for monitoring the voltage waveforms before and after the circuit breaker for cutting the load on the variable speed machine 2. As shown in FIG. Load shedding detection device 5
The 0A has a third deviation detecting means 53 and a comparator 52 ″ which is the third detecting means. Deviation detecting means 53 ″
Calculates the deviation between the voltage on the input side and the voltage on the output side of the circuit breaker 16A. As shown in FIG. 7, the circuit on the power system side and the circuit on the variable speed machine side are disconnected due to the interruption, so that the amplitude or phase of the voltage waveform becomes different. From this, the apparatus shown in FIG. 6 detects the voltage waveforms on the electric power system side and the variable speed machine side, and detects an excessive deviation between both voltages. Deviations are similarly obtained for the voltage on the input side and the output side of the circuit breaker 3 and for the voltage on the input side and the output side of the circuit breaker 8.

Furthermore, the active power / voltage control device 15 sends a signal to the circuit breaker break commands 301, 302, 303 output from the circuit breaker control device 30 of FIG. 304, and the command value of active power is set to 0.

FIG. 2 shows a load cutoff detecting device for monitoring an exciting current according to a second embodiment. The configuration is the same as that of the first embodiment except for the load cutoff detection device. Load cutoff detection device 50A
′ Is a first synthesizing means 55, a second synthesizing means 56,
The second detecting means 53 and the comparator 5 which is the second detecting means.
2'and. The vector combining operation is performed on the amplitude | IFB | of the current commands IrefA to IrefC and the amplitude | IFB | of the actual exciting currents IFBA to IFBC, which are the three phases combined from each frequency converter. Amplitude of actual excitation current at system fault | I
FB | can be expressed as | IFB | = | IFB1 | + | IFB3 | ... (1) by using the symbols IFB1 to IFB3 in FIG. 4, so the deviation Δ | Ir from the excitation current designation | Iref |
The following formula holds for ef |.

Δ | Iref | = | Iref | − | IFB | ≦ 0 (2) Therefore, unlike the phenomenon that IFB decreases when the load is cut off, discrimination is possible. At the time of detection of load shedding, as in FIG.
It is the time when the excessive deviation is detected.

As another load cutoff detection method, a load cutoff detection device having high reliability against malfunction can be configured by combining the above-described cutoff detection methods. For example, if the breaker's cutoff command is load cutoff detection, there is a possibility that the load will be cut off before the actual cutoff due to the operating time of the breaker. The recognition rate can be reduced and accurate detection can be performed. Furthermore, during steady operation, the current command I
When a deviation between ref and the actual current IFB occurs, if a breaker breaker command is not issued, this becomes an interlock to prevent malfunction. In the above embodiment, as a load shedding detection method, a plurality of methods are carried out at the same time, but the present invention is not limited to this. The object of the invention can be achieved.

Further, the present invention is not limited to the load cutoff detection of the generator motor, but can be applied to the load cutoff detection of the generator which is variable speed or the load cutoff detection of the electric motor which is variable speed.

The means relating to the present invention can also be realized by a microcomputer.

As described above, according to the present invention, when the power system is cut off, it is possible to instantly detect the cutoff. Further, the system fault and the load shedding are discriminated from each other, and the reliability of the load shedding detection is very high.

Further, since the method and apparatus configuration of load cutoff detection and the function thereof can be realized by a very simple one, there is an effect that the generator voltage rise ΔV at the time of load cutoff of the variable speed machine can be suppressed.

[0041]

As described above, according to the present invention, it is possible to provide a variable-speed generator-motor system that reliably detects the interruption of the primary side system of the generator-motor and controls the variable-speed generator-motor. ..

[Brief description of drawings]

FIG. 1 is a block diagram of a load shedding detection device.

FIG. 2 is a block diagram of another embodiment of the load shedding detection device.

FIG. 3 is an overall configuration diagram of a variable speed pumped storage power generation system.

FIG. 4 is an explanatory diagram of the behavior of the secondary excitation current at the time of load shedding and a system fault.

5 is an operation time chart in the embodiment of FIGS. 1 and 2. FIG.

FIG. 6 is a block diagram of another embodiment of the load shedding detection device.

7 is an operation time chart in the embodiment of FIG.

[Explanation of symbols]

1 ... Pump turbine, 2 ... Variable speed machine, 3, 8, 16A, 16
B ... Circuit breaker, 6A-6C ... Frequency converter, 7A-7C ...
Excitation transformer, 12 ... Reference signal generator, 13 ... Phase detector, 14 ... Excitation current control device, 15 ... Active power / voltage control device, 22 ... Current command calculator, 23 ... Constant current calculator, 24 ... Pulse generator, 30 ... Circuit breaker control device, 50
A, 50B ... Load cutoff detection device, 51 ... Filter-5
2 ... comparator.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Akio Ito 5-2-1 Omika-cho, Hitachi-city, Ibaraki Hitachi Ltd. Omika factory (72) Inventor Yoshinori Nishi 3-chome Nakanoshima, Kita-ku, Osaka-shi, Osaka 3-22 No. 22 in Kansai Electric Power Co., Inc. (72) Inventor ▲ Scrap Satoshi Saka No. 3-22 Nakanoshima 3-chome, Kita-ku, Osaka City, Osaka Prefecture (72) In Kansai Electric Power Co., Inc. (72) Hiroto Nakagawa North, Osaka City, Osaka Prefecture Kansai Electric Power Co., Inc.

Claims (8)

[Claims] 1. A generator motor, a frequency converter that outputs a secondary excitation current to a secondary winding of the generator motor, and a control unit that outputs a secondary excitation current command value to the frequency converter. In a variable-speed generator-motor system that performs a power generation operation or an electric operation at a variable speed, a secondary excitation current detection means and a filter for attenuating a rotation frequency frequency component of the generation motor included in the detection value of the secondary excitation current. A first detection means for detecting a deviation between the secondary excitation current command value and the output of the filter; and a detection signal for detecting a disconnection of the primary side system of the generator motor based on the deviation. And a first deviation detecting means for outputting, and the control unit corrects the secondary excitation current command value by the detection signal. 2. A generator motor, a frequency converter that outputs a secondary exciting current to a secondary winding of the generator motor, and a control unit that outputs a secondary exciting current command value to the frequency converter. In a variable-speed generator-motor system that performs a power generation operation or an electric operation at a variable speed, first combining means for vector-combining secondary excitation current commands, secondary excitation current detection means, and detected secondary excitation current Second combining means for performing vector combination, second detecting means for detecting a deviation between the output of the first combining means and the output of the second combining means, and the deviation of the generator motor And a second deviation detecting means for detecting the interruption of the primary side system and outputting a detection signal, wherein the control section corrects the secondary excitation current command value by the detection signal. Variable speed generator motor system. 3. A generator motor, a frequency converter that outputs a secondary exciting current to a secondary winding of the generator motor, a controller that outputs a secondary exciting current command value to the frequency converter, and the power generator. A variable speed generator-motor system having a circuit breaker for breaking the primary side system of an electric motor and performing a power generation operation or an electric operation at a variable speed, wherein the voltage on the input side of the circuit breaker and the output side of the circuit breaker. The third deviation detecting means for detecting the deviation of the voltage of the above, and the third detecting means for detecting the interruption of the primary side system of the generator motor based on the deviation and outputting the detection signal, The control unit corrects the secondary excitation current command value according to the detection signal, which is a variable speed generator-motor system. 4. A generator motor, a frequency converter that outputs a secondary exciting current to a secondary winding of the generator motor, a controller that outputs a secondary exciting current command value to the frequency converter, and the power generator. A variable-speed generator-motor system that has a circuit breaker for breaking the primary side system of an electric motor and a circuit breaker control device that outputs a breaking command to the circuit breaker, and performs a power generation operation or an electric operation at a variable speed, The control unit corrects the secondary excitation current command value according to the breaking command of the circuit breaker, wherein the variable speed generator-motor system is characterized. 5. A generator motor, a frequency converter that outputs a secondary exciting current to a secondary winding of the generator motor, and a controller that outputs a secondary exciting current command value to the frequency converter. A method for detecting a load cutoff of a variable speed generator-motor system that performs a power generation operation or an electric operation at a variable speed, wherein a secondary excitation current is detected, and the rotational frequency of the generator motor is detected from the detected value of the secondary excitation current. Attenuating the component, detecting the deviation between the secondary excitation current command value and the output of the filter, detecting the disconnection of the primary side system of the generator motor based on the deviation, and outputting a detection signal. A method for detecting load shedding in a variable-speed generator-motor system, comprising: outputting, and correcting the secondary excitation current command value by the detection signal. 6. A generator motor, a frequency converter that outputs a secondary exciting current to a secondary winding of the generator motor, and a controller that outputs a secondary exciting current command value to the frequency converter. A load shedding method for a variable speed generator-motor system that performs a power generation operation or an electric operation at a variable speed, wherein the secondary excitation current command is vector-synthesized, the secondary excitation current is detected, and the detected secondary excitation current is detected. Vector detection, detecting a deviation between the two combined results, detecting a disconnection of the primary side system of the generator motor based on the deviation, and outputting a detection signal; A load shedding method for a variable speed generator-motor system, characterized in that the method comprises modifying a secondary excitation current command value. 7. A generator motor, a frequency converter that outputs a secondary exciting current to a secondary winding of the generator motor, a controller that outputs a secondary exciting current command value to the frequency converter, and the power generator. A load breaking method for a variable speed generator-motor system having a circuit breaker for breaking a primary side system of an electric motor and performing a power generation operation or an electric operation at a variable speed, comprising: a voltage on an input side of the circuit breaker; Detecting a deviation from the voltage on the output side of the circuit breaker, detecting the interruption of the primary side system of the generator motor based on the deviation, and outputting a detection signal; A load shedding method for a variable speed generator-motor system, characterized by comprising modifying a next current command value. 8. A generator motor, a frequency converter that outputs a secondary exciting current to a secondary winding of the generator motor, a controller that outputs a secondary exciting current command value to the frequency converter, and the power generator. A load breaker for a variable-speed generator-motor system having a circuit breaker for breaking the primary side system of the electric motor and a circuit breaker control device for outputting a breaking command to the circuit breaker, and performing a power generation operation or an electric operation at a variable speed. A load breaking method for a variable speed generator-motor system, characterized in that a secondary excitation current command value is corrected by a breaking command of the circuit breaker.