JP2902826B2 - How to stop variable speed induction motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stopping a variable-speed induction machine that can be stopped without generating an overvoltage when the variable-speed induction machine is stopped in an emergency.

[0002]

2. Description of the Related Art A conventional method for stopping a variable speed induction motor will be described with reference to FIG.

A power generation system using a variable speed induction machine (hereinafter referred to as a generator) includes a generator 1, a primary device (a circuit breaker 2, a primary transformer 3, a power transmission system 4), and a pump turbine. Mechanical system device 5, secondary-side frequency converter 6 (hereinafter referred to as secondary exciter), transformer 7 for exciter, variable speed controller 8
(Hereinafter referred to as a control device) and a protection device 9.

The control device 8 includes a reference circuit 10 for setting a reference for active power and a reference for reactive power (Preff / Qreff), a detection circuit 11 for active power and reactive power (P / Q), an addition circuit 12, and a generator state. (P / Q) control circuit 13 for controlling a control state adapted to the system state, and secondary excitation device control circuit 1
4

[0005] In general, the generator 1 has active power (P) and reactive power (Q) of its primary side output having reference values Preref, Q, respectively.
After being calculated by the adder circuit 12 in the control device 8 so as to coincide with reff, it is controlled via the subsequent control circuits 13-14 and the secondary-side excitation device 6. Here, V1 and I1 in the figure indicate the voltage and current on the primary side of the generator, and V2 and I2 indicate the voltage and current on the secondary side of the generator. The output current of the secondary excitation device 6 is I2
Is supplied to the secondary coil of the generator 1, whereby the active power P and the reactive power Q of the generator output become controllable.

In such a generator system, when the protection device 9 is operated or a request to stop the generator is urgently issued, the generator circuit breaker 2 is quickly and safely opened. It is important to disconnect the generator 1 from the system. Hereinafter, a conventional emergency stop method of the generator will be described.

[0007] The first method is to open the circuit breaker 2 while the load is operating, and then to open the mechanical system 5 including the water system of the generator.
And the stopping operation of the generator secondary-side excitation device 6 is performed.

[0008] The second method is to wait for a series of actions of the mechanical system or in conjunction with the action procedure in order to minimize the impact on the mechanical system as in the case of a failure of the mechanical system device 5.
The active power reference / reactive power reference (Preff / Qreff) is gradually reduced to zero, and after the value of each PQ or the combined value is minimized, the circuit breaker 2 is opened, and then the mechanical system device 5 of the generator is opened. The final stop treatment and the stop treatment of the generator secondary-side excitation device 6 are performed (slow stop treatment).

The third method involves opening the circuit breaker 2 at the same time when the secondary excitation device 6 is stopped, such as when the secondary excitation device 6 of the generator fails, and then includes the water system of the generator. In some cases, stop processing of the mechanical system device 5 is performed.

[0010]

However, the above-mentioned conventional method has the following disadvantages.

That is, in the first method, since the circuit breaker 2 is opened while the load is in a load operating state, that is, a state in which a large current is supplied to the primary side of the generator and the circuit breaker 2, the power is generated when the current is cut off. There is a risk that a large overvoltage will be induced on the secondary side of the generator due to the operation of the primary and secondary transformers of the machine, and the secondary equipment will be damaged.

FIG. 9 shows an operation time chart of the first method. In FIG. 9, A is a stop command, B is a circuit breaker opening command,
D is the Preref / Qreff signal, I1 is the primary current of the generator, I2
Indicates the secondary side power supply output current, V2 indicates the generator secondary voltage, E indicates the point of time when the breaker opening is completed, F indicates the generator secondary side overvoltage, and G indicates the related device stop processing.

In the second method, as shown in an operation time chart of FIG. 10 with the same reference numerals as in FIG. 9, a mechanical system treatment is waited for or linked with a mechanical system treatment process. Therefore, it is necessary to intentionally delay the opening command of the circuit breaker 2, and it takes a long time to complete the opening of the circuit breaker, and as a result, the disconnection of the generator from the system is delayed.

Further, in the third method, as shown in the operation time chart of FIG.
Without waiting for the opening of the circuit breaker 2 to be completed, the secondary-side power supply stop signal shown in (c) causes the secondary-side exciter to be shut down, causing the generator to go into an uncontrolled state for a period of time. Circuit breaker 2
When an electrode is opened, an excessive current is cut off and an overvoltage is induced on the secondary side.

Accordingly, it is an object of the present invention to be able to quickly disconnect the generator from the system while preventing an overvoltage from occurring on the secondary side of the generator when the generator is stopped urgently. It is an object of the present invention to provide a method for stopping a shift induction machine.

[0016]

[0017]

In order to achieve the above object, the present invention provides a circuit breaker provided between a primary winding of a variable speed induction machine and a power system, and a secondary winding of the variable speed induction machine. A variable voltage variable frequency excitation power, and a secondary converter comprising a frequency converter for adjusting the current on the primary side of the variable speed induction machine; and a current reference corresponding to the power reference signal. A variable speed induction machine comprising a control device that controls the signal in accordance with a deviation signal between a signal and a current feedback signal detected from a primary winding side of the variable speed induction machine. Means for rapidly shifting the current reference signal to near zero in response to a stop command, and when opening the circuit breaker, after the current on the primary side of the variable speed induction machine is reduced to zero or minimum, The variable speed induction motor is stopped. A method of stopping the variable speed induction machine characterized in that shifting to.

[0018]

With the above-described configuration, the response time of the secondary excitation device and the control device for controlling the same is sufficiently faster than the operation time of the circuit breaker. At the same time, or during the time difference from the circuit breaker opening command to the completion of circuit breaker opening, the primary current of the variable speed induction machine can be reduced to zero or minimized. Does not occur.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment will be described with reference to FIGS. In this embodiment, the control circuit 8 serves as a means for minimizing the primary current of the generator 1 to zero or minimum.
The real power and the reactive power are set to zero at the same time as the stop command, and the real power and the reactive power of the output of the generator 1 are controlled to zero values. A Pro / Qro reference circuit 15 is provided for setting the zero reference, and the switching circuit 16 is operated by a stop command signal, and the power reference value is changed from the Preref / Qreff reference circuit 10 to Pro / Qro at this stage.
Switch to reference circuit 15. Next, the switching circuit 16 and P
The operation of the present invention having the ro / Qro reference circuit 15 will now be described with reference to FIG.
This will be described with reference to the time chart of FIG.

When a stop command (i) is issued to the system that has been in a steady operation state by the Preref / Qreff reference circuit 10, the stop command (i) is issued simultaneously with the circuit breaker opening command (b) for the generator circuit breaker 2 and the switching circuit 16 is transmitted. At this stage, the power reference value is determined by the output signal C of the switching circuit 16 as Pre.
The ff / Qreff reference circuit 10 is switched to the Pro / Qro reference circuit 15. As a result, the primary output of the generator is rapidly controlled toward zero in both the active and reactive powers. Since the control response of the secondary-side excitation device 6 is sufficiently faster than the operating speed of the circuit breaker 2, the primary-side current I1 reaches zero or the minimum value by the time when the opening of the circuit breaker 2 is completed. Because
Since the overvoltage does not occur on the primary side of the generator 1 even when the circuit breaker 2 opens, the generator 1 is disconnected from the system without overvoltage occurring on the secondary side of the generator 1 due to the action of the transformer. It is possible to do. Then, the process may be shifted to the stop processing of the related device.

FIG. 3 is a block diagram showing a second embodiment of the present invention, in which a so-called vector control technique is applied to the control of a generator. This embodiment is characterized in that, instead of controlling the active power and the reactive power, the current on the primary side of the generator 1 is directly controlled, and a target means is provided at an intermediate position in the entire control system.

Id^* , Ido^* , Id are used in vector control.
Iq^* , Iqo^* , Iq is the imaginary axis current component
Active current corresponding to the active power on the primary side of the generator
Reactive current components corresponding to minute and reactive power
Control signal. That is, these signals must be handled.
Thus, it is possible to directly control the primary side current.
You.

The deviation value signal calculated by the addition circuit 12 is
The vector is converted by the PQ control circuit 13, and Id ^* , I
q ^* Are output as a real axis current reference and an imaginary axis current reference. Similarly, the generator primary-side current I1 is vector-converted by the Id / Iq detection circuit 18 and is output as real-axis current detection and imaginary-axis current detection signals Id and Iq.

In the steady state, the difference between the two signals is calculated by the adder circuit 19, and the primary current of the generator is changed to Preref / Qreff via the exciting device control circuit 14 including the vector inversion circuit and the secondary exciting device 6. Control is performed so as to match the set power value of the reference circuit 10. Ido ^* / Iqo ^* The reference circuit 17 is a zero-setting reference circuit for controlling the detected values of Id and Iq to be zero, that is, the primary current value I1 of the generator to be zero.

If a stop command is issued at the same time as the opening command of the circuit breaker 2, the switching circuit 20 operates in response to the stop command, and the real axis current reference and the imaginary axis current reference are Id ^*. , Iq ^*
From the value Ido ^* , Iqo ^* Value is changed to Id, Iq
The detected value becomes zero, that is, the primary current value of the generator immediately becomes zero. As a result, it is possible to prevent the occurrence of overvoltage when the circuit breaker is opened.

In the above description, in response to the stop command, the switching circuit changes from Pref / Qreff to Pro / Qro or Id ^*. /
Iq ^* From Ido ^* / Iqo ^* I'm trying to switch to
In response to the switching command, Preref / Qreff or Id ^* / Iq
^* May be rapidly shifted to zero.

The present invention is not limited to the apparatus shown in FIGS. 1 and 3, but includes a secondary excitation device on the secondary side of the induction machine 21 as shown in the block diagram of FIG. The present invention can also be applied to a variable speed pumping power generation system that can control both the pumping direction and the power generation direction using the variable speed induction machine 21. In the figure,
22 is a frequency converter, 23 is a control / protection device, 24 is a circuit breaker, 25 is a power system, and 26 is a pump turbine.

As shown in the block diagram of FIG. 5, the variable speed induction machine 21 and the flywheel 27 are directly connected to each other,
The present invention can also be applied to a flywheel power generation system that uses the inertial energy of 7 to cope with power fluctuations and frequency fluctuations in the system.

Further, as shown in the block diagram of FIG. 6, a reactive power control function is added to the variable speed induction machine 21 to provide a rotary reactive power compensator for coping with fluctuations in system voltage and reactive power of the power system. Applicable.

Further, as shown in the block diagram of FIG. 7, the synchronous machine 28 and the variable speed induction machine 21 are mechanically directly connected to each other and connected to different power systems. The present invention can also be applied to a rotary frequency converter for providing power to the system 29 via a mechanical system.

[0031]

As described above, according to the method for stopping a variable speed induction machine of the present invention, the opening command of the circuit breaker is not intentionally delayed at the time of an emergency stop procedure, and the generator The generator can be disconnected from the system without inducing an overvoltage in the next circuit.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of FIG. 1;

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a block diagram of a variable speed pumped storage power generation system to which the present invention can be applied.

FIG. 5 is a block diagram of a flywheel power generation system to which the present invention can be applied.

FIG. 6 is a block diagram of a rotary reactive power compensator to which the present invention can be applied.

FIG. 7 is a block diagram of a rotary frequency converter to which the present invention can be applied.

FIG. 8 is a block diagram of a conventional device.

FIG. 9 is a time chart for explaining the operation of the conventional device.
Figure.

FIG. 10 is a time chart for explaining the operation of the conventional device.

FIG. 11 is a time chart for explaining the operation of the conventional device.

[Explanation of symbols]

1: generator, 2: circuit breaker for generator, 3: primary side transformer,
4 power transmission system, 5 mechanical device, 6 secondary excitation device
7 ... Transformer for excitation device, 8 ... Control device, 9 ... Protection device,
Reference numeral 10: Preref / Qreff reference circuit, 11: P / Q detection circuit, 12: Addition circuit 13: P / Q control circuit, 14 exciter control circuit, 15: Pro / Qro reference circuit, 16: Switching circuit, 17: Ido ^* / Iqo ^* Reference circuit, 18 ... Id / Iq
A detection circuit, 19 an addition circuit, and 20 a switching circuit.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hirokazu Kaneko 1-3-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Inside Tokyo Electric Power Company (72) Ryoichi Narukawa 1st Toshiba-cho, Fuchu-shi, Tokyo Inside plant (72) Inventor Takahisa Kageyama 1 Toshiba-cho, Fuchu-shi, Fuchu-shi, Tokyo Inside the Toshiba Fuchu plant, Co., Ltd. Literature JP-A-4-38198 (JP, A) Japanese Utility Model Showa 50-43217 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02P 3/00 H02P 9/00

Claims (1)

(57) [Claims] A circuit breaker provided between a primary winding of a variable speed induction machine and a power system; and an exciting power of a variable voltage and variable frequency supplied to a secondary winding of the variable speed induction machine, A secondary exciter comprising a frequency converter for adjusting the current on the primary side of the variable speed induction machine, a current reference signal corresponding to the power exciter, and a secondary exciter from the primary winding side of the variable speed induction machine; In a variable speed induction machine comprising a control device that controls according to a deviation signal from a detected current feedback signal, the current reference signal is rapidly reduced to zero in response to an emergency stop command of the variable speed induction machine to the control device. Providing means for shifting to the vicinity, when opening the circuit breaker, after reducing the current on the primary side of the variable speed induction machine to zero or minimum, opening the circuit breaker and stopping the variable speed induction machine Stop of variable speed induction machine characterized by shifting Stop method.