JPH07245996A - Method of controlling variable-speed generating system - Google Patents

Abstract

PURPOSE:To provide a method for stopping a variable-speed generating system when a trouble is found in a converter, the influence on the system being minimum, in the variable-speed generating system. CONSTITUTION:In a variable-speed generating system which consists of a winding-type induction machine whose primary winding is connected to a power system through a breaker, an inverter which controls a secondary current of the winding-type induction machine, a converter which converts a.c. current to d.c. power for supplying d.c. power to the inverter, and a capacitor for smoothing d.c. voltage, the output current of the inverter is so controlled that the current of the primary side of the winding-type induction machine may be nearly zero when the converter gets a trouble. After that, the winding-type induction machine and the system is separated by means of the breaker and then the inverter is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable speed power generation system for controlling a secondary current of a wire wound induction machine by a self-exciting inverter to perform a variable speed operation to transfer electric power to and from an electric power system. The present invention relates to a method of controlling a system in the event of an abnormality on the AC side of a converter that converts AC power into DC power for supplying DC current.

[0002]

2. Description of the Related Art FIG. 2 is a system configuration diagram of a variable speed power generation system. In the figure, 1 is a winding type induction machine, 2 is an inverter that controls the secondary current of the winding type induction machine 1, 3 is a converter that converts an AC power supply into a DC power supply for supplying a DC voltage to the inverter 2, and 4 is a power It is a system. The inverter 2 is, for example, a diode 6 to a bridge connection.
11 and GTOs 12 to 17, and a capacitor 18. In addition, the inverter 2 has current detectors 37, 38, for taking inflow current of the inverter 2 into its control device.
Including 39.

The converter 3 includes, for example, diodes 19 to 24 and GTO 25 to which are bridge-connected.
It is composed of 30 and a transformer 33. The converter 3 includes a discharge resistor 31 and a GTO 32, and when the DC voltage exceeds a rated value and reaches a predetermined value, the GTO 32 is turned on to allow a current to flow through the discharge resistor 31 so that the DC voltage does not become excessive. To protect. Furthermore, the converter 3 has a current detector 34 for taking inflow current of the converter 3 into its control device,
Including 35 and 36. Further, 38 is a circuit breaker.

FIG. 4 shows a case where the converter 3 is in an abnormal state in the system configuration shown in FIG. 2, for example, an overcurrent is generated in the converter 3 due to a short circuit of the transformer 33 connecting the converter 3 and the grid 4. 6 is a conventional control flowchart in FIG.

The control unit of the variable speed power generation system always controls the current flowing into the converter 3 by the current detector 34 shown in FIG.
35 and 36 are taken in and monitored, and when an overcurrent due to a short circuit of the transformer 33 is detected, the GTO of the converter 3 and the inverter 2 is turned off to protect the converter 3. At this time, since the inverter 2 is stopped, the winding-type induction machine 1 is not excited, so that a delayed reactive current determined by the exciting inductance of the winding-type induction machine 1 flows on the primary side of the winding-type induction machine 1.

[0006]

As described above, in the conventional control, when the failure of the converter 3 is detected and the system is stopped, when the breaker 38 is released, the exciting current of the winding induction machine 1 is released. Will flow to the secondary side, and this current will flow into the capacitor 18, increasing the voltage of the capacitor 18. As a result, the DC portion of the inverter 2 becomes an overvoltage, the GTO 32 is turned on, and the GTO 32 is consumed by the discharge resistor 31. The energy of the exciting inductance of the wire-wound induction machine 1 is very large, and this energy flows into the inverter 2 in a short time, so that the GTO 32 and the discharge resistor 31 become large. In addition, the reactive current determined by the exciting inductance is also large, and a large delayed reactive power is taken from the system, which causes fluctuations in the system.

Further, in the case where the operation of the converter 3 is temporarily stopped and the return of the converter 3 is awaited, for example, when the transformer 33 is demagnetized, the inverter 2 is simultaneously operated.
Since a large delay reactive current flows on the primary side of the wound-rotor induction machine 1, voltage fluctuations are applied to the system to cause fluctuations, which continues until operation is restored.

A first object of the present invention is to solve the above-mentioned drawbacks of the conventional control method of the variable speed power generation system, and after the abnormality of the converter is detected, the variable speed power generation system has a minimum influence on the system. To provide a way to stop.

A second purpose is, in the case where a primary abnormality of the converter 3 occurs, for example, when the transformer 33 is demagnetized, a period from the occurrence of the abnormality of the converter 3 until the normal state is restored. It is an object of the present invention to provide a control method for a variable speed power generation system, which puts the variable speed power generation system in a standby state with a minimum adverse effect on the system and quickly returns to normal operation.

[0010]

In order to achieve the first object of the present invention, according to the invention of claim 1, when a failure on the converter 3 side is detected, the current on the primary side of the winding type induction machine 1 is The inverter 2 which controls the secondary side current of the wire-wound induction machine 1 is controlled so as to shift to almost 0, and the circuit breaker 38 connecting the system and the wire-wound induction machine 1 is connected after the current becomes almost 0. After releasing, the inverter is stopped to control the variable speed power generation system.

In order to achieve the second object of the present invention, the invention of claim 2 temporarily stops the converter 3 and restores it, for example, when the transformer on the converter side is demagnetized. In order to wait until the current is reached, the inverter 2 which controls the primary side current of the winding type induction machine 1 is controlled so that the primary side current of the winding type induction machine 1 shifts to almost 0, and this state is maintained. After the control unit 3 returns to the normal state, the control of the converter 3 and the inverter 2 is returned to the normal operation state again, and the primary side current of the wound-rotor induction machine 1 is set to the normal state to control the system again.

[0012]

According to the invention of claim 1, when a failure occurs on the converter 3 side during the normal operation of the variable speed power generation system, the converter 3 is quickly stopped and the primary side of the winding type induction machine 1 is provided. The inverter 2 which controls the secondary side current of the wire wound induction machine 1 is controlled so that the current shifts to almost zero. Since the breaker 38 separates the winding-type induction machine 1 from the system 4 after the primary current becomes almost 0,
It is possible to stop the system with minimal influence on the grid.

According to the second aspect of the invention, in addition to the effect of the first aspect of the invention, the converter 3 is temporarily stopped and restored, for example, in the case where the transformer on the converter 3 side is demagnetized. When waiting for, the winding-type induction machine 1 is moved to a no-load excited state as in claim 2, and this state is maintained, so that the system is kept in a standby state while minimizing the influence on the system, and the converter 3 operates normally. As a result, the system can gradually return to normal operation quickly.

[0014]

FIG. 1 is a system control flowchart showing an embodiment of the present invention. In this example, the device name is shown based on FIG. 2, which is a configuration diagram of the variable speed power generation system described in the conventional example. In FIG. 1, the current detectors 33 to 39 shown in FIG. 2 are used to detect the operating conditions of the converter 3 and the inverter 2.

During normal operation, when the inverter 2 is normal but the converter 3 side is in an abnormal state, in state 1, the control system detects this. In state 2, converter 3 is stopped. Next, in the state 3, the inverter 2 controlling the secondary side current of the winding type induction machine 1 is controlled so that the primary side current of the winding type induction machine 1 shifts from the value in the normal operation state to 0. To do. In the state 4, the wire wound induction machine 1 and the system 4 are separated by the breaker 38, the inverter in the state 5 is stopped, and the variable speed power generation system in the state 6 is stopped.

According to this embodiment, after the occurrence of a failure on the converter 3 side, the breaker 38 is released with the primary current of the wound-rotor induction machine 1 being 0, so that the energy of the exciting inductance of the wound-rotor induction machine 1 is reduced. Will not flow into the secondary side in a short time. After releasing the circuit breaker 38, the inverter 2 is controlled to gradually absorb the energy of the exciting inductance in the capacitor 38, and the GTO 32 and the discharge resistor 31 gradually consume the energy.
It suffices to stop the inverter 2. Therefore, it is possible to prevent the GTO 32 and the discharge resistor 31 from increasing in size. Further, since the inverter 2 controls the primary current of the wire wound induction machine 1 to 0, the delay current is not taken from the system 4 and the influence on the system 4 is very small.

Next, another embodiment of the present invention described in claim 2 will be described. FIG. 3 is a flowchart of the embodiment of claim 2 according to the present invention. The states 1 to 3 are the same as those of the embodiment shown in FIG. For example, transformer 33
When it is determined to wait for the converter 3 to recover, as in the case where a temporary abnormality of the converter 3 side occurs such as when the magnetic field is demagnetized, the state moves to state 4 and the winding type induction machine 1 The next current is set to 0 and the no-load excitation state is maintained to wait for the converter 3 to recover. Next, when the recovery of the converter 3 is detected as shown in the state 5, the converter 3 in the state 6 is detected.
And the inverter 2 is returned to the normal operation state,
It becomes the normal operation of state 7.

According to the present invention, when a temporary failure of the converter 3 occurs, for example, when the transformer 33 is demagnetized, the system is operated for a period from the occurrence of the failure of the converter 3 until the normal state is restored. It is possible to bring the variable speed power generation system into a standby state and quickly return to normal operation without adversely affecting.

In the above embodiments, both the converter 3 and the inverter 2 are self-excited converters using GTO, but other switching elements capable of self-extinguishing may be used. The converter may be a separately excited converter. Also, the inverter may be of a multiple type,
A multilevel inverter may be used. Furthermore, although the output of the inverter is three-phase in the embodiment, it may be single-phase or other multi-phase output. Further, the converter may be multi-type, single phase and other multi-phase converters.
Furthermore, in the embodiment, the converter state is detected by the converter input, and the inverter state is detected by the inverter output current. However, the detection in other parts may be used.

[0020]

As described above, according to the present invention, when the converter fails during operation of the variable speed power generation system, the influence on the system is minimized and the variable speed power generation system is stopped. In addition, the chopper of the inverter does not need to consume the exciting current of the wire-wound induction machine in a short time, and need not have a large capacity.

In addition to the above-mentioned effects, when the converter recovers if the converter is stopped for a certain period in the case of a temporary abnormality of the converter, the variable speed power generation system is in the standby state without adversely affecting the system. Since the converter can be restored to normal operation quickly after the converter returns,
Since it is possible to return from the protection operation to the normal operation in a short time, the influence on the system is small and the effect is remarkable.

[Brief description of drawings]

FIG. 1 is a flowchart of system control showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing an example of a variable speed power generation system.

FIG. 3 is a flowchart of system control showing another embodiment of the present invention.

FIG. 4 is a flowchart of system control when a converter is abnormal in a conventional variable speed power generation system.

[Explanation of symbols]

1 ... Winding type induction machine 2
… Inverter 3… Converter 4
... Power system 6-11 ... Diodes 12-17
… GTO 18… Capacitors 19-24
… Diodes 25 to 30… GTO 31
... Discharge resistor 32 ... GTO 33 ... Transformers 34 to 37 ... Current detector 38
… Circuit breaker

Claims (2)

[Claims] 1. A winding type induction machine having a primary winding connected to a power system via a circuit breaker, an inverter for controlling a secondary current of the winding type induction machine, and a DC power supply to the inverter. In the variable speed power generation system including a converter for converting an alternating current into a direct current power and a capacitor for smoothing the direct current voltage, when the fault occurs on the converter side, the output current of the inverter is the winding type induction. The variable speed control means is such that the primary side current of the machine is controlled to be substantially zero, and after that, the winding type induction machine and the system are separated by the circuit breaker and then the inverter is stopped. Power generation system control method. 2. A winding type induction machine having a primary winding connected to a power system via a circuit breaker, an inverter for controlling a secondary current of the winding type induction machine, and a DC power supply to the inverter. In the variable speed power generation system including a converter for converting an alternating current into a direct current power and a capacitor for smoothing the direct current voltage, when the fault occurs on the converter side, the output current of the inverter is the winding type induction. The current on the primary side of the machine is controlled to be substantially zero, and then the inverter is stopped after disconnecting the wire wound induction machine and the system by the circuit breaker, and a temporary failure occurs on the converter side. When generated, the output of the inverter is controlled so that the current on the primary side of the wound-rotor induction machine becomes almost zero, and when the converter side returns to a normal state, the converter Is restarted, and the control is returned so that the output of the inverter is in a normal state.