JPS60257798A - Excitation controller for synchronous generator - Google Patents

Abstract

PURPOSE:To always automatically follow up effectively a voltage setter during standby by automatically correcting the set value of a limiter during standby so that the output of the limiter during standby coincides with the output of the limiter during operation. CONSTITUTION:If the voltage of a power system decreases when a system A is operating and a system B is standing by, a voltage control system 11A outputs a magnetization increase command. When a field current increases from the value of a setter 113, a demagnetization signal is outputted from an overexcitation limiter 13B. A correcting unit 30B for the limiter applies a correction signal to an adder 132B of the limiter 13B so that the difference of the outputs of the limiters 13A, 13B due to the irregularity of the setters 113A, 113B of the systems A, B becomes zero. Accordingly, the setter 113B controlled by an automatic followup unit 50B is set to substantially the same value as the setter 113A of the system A.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an excitation control device for a synchronous generator, and in particular, a duplex system comprising two sets of excitation current limiting devices, one of which is suitable for use in a standby state. This invention relates to an excitation control device.

[Background of the invention]

The configuration of a conventional excitation control device for a synchronous generator is shown in FIG. In the figure, ] is a synchronous generator, 2 is a field winding of 1, and 3 is a synchronous generator.
is an excitation type FA transformer, 4 is a thyristor converter, 5 is a field breaker, 6, 7.9 is a CT, 8 is a PT, 10 is an automatic system that controls the terminal voltage of the generator at a constant level, 11 is a voltage Control system, 12 is a low excitation limiter, 13 is an overexcitation limiter, 40
6 is a manual system as a backup for the automatic system, and 60 is a switching device for switching between the automatic system and the manual system. The terminal voltage of the synchronous generator is detected by the second pin 8 and inputted to the voltage control system 1.

An adder 112 compares the PT secondary voltage converted into DC by the rectifier 11 and the set value of the voltage setter 113. The deviation signal from the set value is amplified by the amplifier 114, and the firing angle of the thyristor converter 4 is controlled by the output of the control device 115, thereby adjusting the field current of the synchronous generator and keeping the terminal voltage constant. Control.

The synchronous generator 1 is generally operated in parallel with the power system.

Depending on the conditions of the power system at this time, the terminal voltage of the synchronous generator 1 may be kept constant, and a field current exceeding a permissible value may flow through the field winding 2.

Therefore, the field current is detected by Cr2 and the detector 131 provided on the AC side of the thyristor converter, and if it becomes larger than the value of the setting device 133, it is passed through the adder 134 to the controller of the voltage control system 11. The field current is limited by applying a demagnetizing signal to the

This limiting device is used as an overexcitation limiting device 13. Conversely, if the field current drops too much, the synchronous generator will go into a low excitation state.
It may become impossible to operate in synchronization with the power grid.

In order to prevent this problem, the low excitation state of the synchronous generator is detected by the detector 121, and if the value falls below the value of the setting device 123, a magnetizing signal is given to the controller 115 of the voltage control system [1]. This limits the drop in field current. This limiting device is referred to as a low excitation limiting device 12. Although not shown in FIG. 1, there is a case where the automatic system 10 is equipped with a limiting device such as a V/I-1z limiting device that prevents low-frequency overexcitation that would otherwise cause a decrease in the rotational speed of the synchronous generator. There is.

Conventionally, a manual system 40 has been provided as a backup system in the event of a failure of the automatic system]0.

However, due to the recent increase in the single unit capacity of synchronous generators and the decrease in stability of the power system, operation using the manual system 40, which is a conventional bank-up system, cannot maintain synchronized operation when a system fault occurs, resulting in loss of synchronization. There are cases. Furthermore, in the case of operation using the manual system 40, an operator must constantly monitor load fluctuations and operate the setting device 403. Therefore, there has been an even stronger demand for improving operational reliability by duplicating the automatic system 10.

FIG. 2 shows a conventional example in which the self-weight system is duplicated.

If the conventional automatic system is simply duplicated, JP-A-55-
As described in detail in No. 29237, the automatic tracking of the voltage setter in the standby system may become abnormal.

This patent application fixes a standby limiter, for example, an overexcitation limiter 1.313, to an adder 132B with a relay contact so that the operating point of the overexcitation limiter 1313 is outside the operating range of 13A of the overexcitation limiter during operation. Adding signals.

By the way, with this proposal, there is a possibility that the following problem may occur. In other words, consider the operating state in which system A is in operation and system B is on standby.

When the voltage of the power system decreases, in an attempt to keep the terminal voltage of the synchronous generator constant, a magnetization command is issued from the voltage control system A, and the output of the thyristor converter 4, that is, the field current also increases. When the field current reaches 33A, a demagnetization signal is output from the overexcitation limiting device 1.3A, and the field current finally reaches a value close to that of the setting device 133A. On the other hand, the operating point of the B-system overexcitation limiting device 13B is determined by the setting device 13.
Since it is the sum of 3B and V 2B, overexcitation limiter 1
The output of 3B is zero.

Although the output of the overexcitation limiter 13A of the A system is output, the output of the overexcitation limiter 1.3B of the system 3 is zero, so the automatic system 1 of the B system], B It is thought that the output of is sending out a large signal to the magnetizing side.

Therefore, even though the voltage setting device 1]3A in operation is at the rated value, that is, equivalent to 100% voltage, the voltage setting device 113B in standby is connected to the generator currently in operation due to the operation of the automatic follow-up device 50B. Terminal voltage value (for example 95
% voltage). In this state, if the conditions of the power system are restored to their original state, and furthermore, if the operating system A breaks down and is switched to the standby system, it is conceivable that the generator terminal voltage will drop abnormally.

[Purpose of the invention] It is an object of the present invention to ensure that the restriction device operates at all times.

An object of the present invention is to provide a redundant excitation control device that reliably automatically follows a voltage setting device during standby.

[Summary of the invention]

The key point of the present invention is to compare the output of the limiter in operation with the output of the limiter in standby, and to adjust the output of the limiter in standby so that the output of the limiter in standby matches the output of the limiter in operation. The reason is that the setting values are automatically corrected.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4. FIG. 3 shows an overall configuration diagram of the present invention.

It is assumed that the A system is currently in operation and the B system is on standby. It is assumed that the value of the setter 113B of the overexcitation limiter iR1, 3B is slightly lower than the value of the setter 1]3A of the A system due to product variations or the like. When the power system voltage drops, the synchronous generator tries to keep the terminal voltage constant, so the voltage control system! 1. A
When the magnetization command is issued and the field current increases beyond the value of the setter 1.3B, a demagnetization signal is output from the overexcitation limiter 1.3B to prevent field overcurrent. On the other hand, since the value of setting device 1 of system A] 3A is higher than that of system B, the output of system A's overexcitation limiter] 3A is the output of system B's overexcitation limiter], 3B's A value lower than the output or zero output. The overexcitation limiter correction device 30B detects the output deviation of each overexcitation limiter, and supplies a correction signal to the adder 132B of the B-system overexcitation limiter [3B] until the deviation disappears. As a result, the overexcitation limiting device between system A and system B] 3A.

Even if there is a setting variation in 13B, the same signal is output. Therefore, the setting of the voltage setter 113B controlled by the automatic follow-up 50B becomes approximately the same value as the voltage setter 113A of the A system, which is convenient. On the other hand, the setting device 1.33 of the overexcitation control device 13B has the value of A system]
It is assumed that the value is slightly lower than the value of 33A due to product variations. When the voltage of the power system decreases, the voltage control system 11A issues a magnetization command to keep the terminal voltage of the synchronous generator constant, and when the field current increases beyond the value of the setting device 113A, the overexcitation limiting device 13A A demagnetization signal is outputted, and the field current is limited to the value of setter 1] 3A. Therefore, since the field current is within the limit operation of the B-system overexcitation limiting device 13B, the output signal remains zero. The overexcitation limiter correction device 30B detects the deviation in the output voltage of each overexcitation limiter, and supplies a correction signal to the adder 132B of the B-system overexcitation limiter 13B until the deviation disappears.

As a result, as in the case described above, the value of the B-system voltage setter 113B is automatically tracked to almost the same value as the A-system voltage setter 13A by the automatic tracking device [, 50B], which is convenient. In this way, the system in operation (system A in the above example)
The output of the overexcitation limiter of the standby system (system B in the following example) is automatically corrected at all times so that the output of the overexcitation limiter of the system is equal to the output of the overexcitation limiter of the standby system. If the generator is automatically tracked, even if the operating system is switched to the standby system due to a failure, etc., the operating state of the synchronous generator can be maintained in the state before the failure occurred.

FIG. 4 shows a detailed example of the correction circuit 40B. The output of the A-system overexcitation limiting device 13A in operation and the output of the B-system overexcitation limiting device 1.3B in standby are input to the adder 31, and the deviation between them is detected. The detected deviation signal is sent to the B system overexcitation limiting device 1.3 through the arithmetic unit 36 (used as an integrator or simple amplifier) under the condition that the A system is in operation.
2B as a correction signal.

The maximum value of this correction signal is determined by the detector] 31B in the overexcitation limiting device 13B of the A system, the setting device 133B, and the rj+ device 134.
Minimum necessary to compensate for product variations between B and A series. In this way, by selecting the maximum value of the correction signal, the correction signal is added to the adder 132B of the overexcitation limiter 1.3B only when some kind of failure occurs in the standby overexcitation limiter 13B. However, the B system overexcitation limiting device 1.
The output of 3B is not equal to the output of the overexcitation limiter 1.3A during operation. If the output of the adder 31 in FIG. 4 is added to the comparator 32, and the timer 33 detects that the comparator 32 has operated for a certain period of time or more under the condition that the A system is in operation, the overexcitation limiter is in standby mode. It is possible to detect that something is abnormal. It goes without saying that the same principle of operation can also be used for limiting devices such as low excitation limiting devices.

Although the present invention has been explained by taking an analog type excitation control device as an example, the present invention can also be used as is in the case of a digital type.

In the figure, 122 is an adder, 124 is an adder, ]32
is an adder, 401 is a detector, 402 is an adder, 40-4
is a controller, 51 A, +51 B is an AND circuit, 34
is an AND circuit, 35 is a switch, 36 is an arithmetic unit, 2OA
, 20B is a correction device for low excitation limiting device, 30A, 30
B is a correction device for the overexcitation limiting device.

〔Effect of the invention〕

According to the present invention, it is possible to prevent the voltage setter from automatically following an abnormality while on standby under any power system condition, and to automatically detect an abnormality of each limiting device during standby.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional general excitation control device for a synchronous generator, Fig. 2 is a block diagram of a conventional duplex excitation control device for a synchronous generator, and Fig. 3 is a block diagram of an excitation control device for a conventional dual synchronous generator. FIG. 4 is a block diagram of a duplexed excitation control device for a synchronous generator, and FIG. 4 is a functional block diagram of a correction device for an overexcitation limiting device according to an embodiment of the invention. 20.. Correction device for low excitation limiting device; 30.. Correction device for overexcitation limiting device; 50.. Automatic tracking device. Hanging 1 figure 1 ('l also 3

Claims (1)

[Scope of Claims] 1. A plurality of automatic systems that control the excitation current of the synchronous generator and keep the terminal voltage constant; and a plurality of limiting devices that limit the excitation current; when one is in operation, the other In the excitation control device of the synchronous generator, which automatically or manually switches to the standby system when an abnormality occurs in the operating system, the output of the limiting device in the operating state and the standby state are controlled. Synchronization characterized by comprising means for comparing the outputs of a certain limiting device, and means for automatically correcting the set value of the limiting device in a standby state so as to eliminate the deviation when a deviation occurs between the two. Excitation control device for generator. 2. An excitation control device for a synchronous generator according to claim 1, characterized in that the excitation control device for a synchronous generator is provided with an alarm means for determining that the limiting device in the standby system is abnormal due to the continuation of the automatic correction signal in the standby system. .