JPH01148026A - Voltage controller in power station - Google Patents

Abstract

PURPOSE:To improve operating property, by controlling main transformer transmission-system side voltage according to switching the tap of a main transformer, interlocked with the control of generator voltage. CONSTITUTION:A generator 11 is connected to a transmission system 13 via a main step-up transformer 12. In this case, the generator 11 is provided with a field winding 14, and the main transformer 12 is provided with a tap switching device 15 at the time of loading. In the meantime, to a controller 16, transmission system side voltage, reactive power, or the like as control command 17 is applied, and the transmission system side voltage of the main transformer 12 as detection input 18 is applied. Besides, to the tap switching device 15 at the time of loading, tap switching command is applied, and to a voltage setting unit 19, the setting command of generator voltage is applied. The controller 16 is composed of an arithmetic controlling means 161 and an execution controlling means 162, and by said command 17 and the like, arithmetic is performed on the generator voltage, and the output of the tap switching command is generated. Then, based on a reference value with an automatic voltage regulator 20 for the generator, DC voltage to the field winding 14 is determined.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention relates to voltage control in a power plant where a generator is connected to the power grid through a main transformer having on-load tap switching means. Regarding a control device.

(Prior Art) In an electric power system, stable operation of the system allows electrical equipment to function normally, and for this reason, stable voltage control without voltage fluctuations is required.

By the way, it is thought that voltage fluctuations in such power systems are due to the influence of active power and due to the influence of reactive power, and here, the sending end voltage of the power transmission system is
(constant), the receiving end voltage is Vr, the impedance between them is z = r + jx, active power is P, and reactive power is Q. When these active power P and reactive power Q change slightly, the relationship between them is as follows. It can be expressed by the formula.

Then, taking the ratio of these ■■ expressions, we get: In this case, in formula 0, Vr2/z)P, Q, x)
Since r, z is illusory

Therefore, control to suppress fluctuations in reactive power Q is effective for stabilizing the power system, but as mentioned above, reactive power Q is uniquely correlated with voltage.
In the end, the power plant has decided to deal with the problem through voltage control.

Conventionally, the voltage control system for this type of power plant includes a generator voltage control system using an automatic voltage regulator for the generator, and an on-load tap switching system for the main transformer interposed between the generator and the power transmission system. Some systems also use voltage control on the power transmission system side of the main transformer.

FIG. 5 shows an example of such a control device, in which a generator 1 is connected to a power transmission system 3 via a main transformer 2 having an on-load tap changer 9 . and,
A control command C1 containing the reference value of reactive power and a detection input C2 of the generator voltage Vg and generator current Ig are input manually or from the central power dispatch center to the generator reactive power adjustment device 4, where the voltage is set. The value is calculated and given to the voltage setting device 5. Further, the output of the voltage setting device 5 is given as a reference value to the generator automatic voltage regulator 6, and the DC voltage of the generator field winding 8^ is controlled by the control of the excitation power supply device 7 based on this reference value. , the generator voltage is now controlled, and on the other hand, a command C3 containing a pre-programmed setting value is sent to the on-load tap changer 9 for the main transformer manually, from the central dispatch center or the power plant central control room. entered,
The on-load tap switching device 9 controls switching of the taps, and the voltage on the power transmission system side of the main transformer 2 is controlled.

(Problems to be Solved by the Invention) With this configuration, generator voltage control is performed by an automatic generator voltage regulator, and power transmission system side voltage control of the main transformer is performed by a load tap switching device of the main transformer. For example, if the generator voltage exceeds a certain range due to generator voltage control using an automatic generator voltage regulator, an alarm will alert the operator to Measures are taken to change the taps of the main transformer by means of a tap changer. Therefore, if there are large fluctuations in the voltage of one generator, frequent operations by the operator will be required.
This has the disadvantage of poor operability, such as requiring a great deal of effort. Also, if the generator voltage exceeds a certain range, but the operator does not change the main transformer tap.

During this time, the power generation Ia voltage remains at an overvoltage or a low voltage, resulting in a lack of quick resolution and reliability in voltage control, and there is also a risk that stable operation of the power system will be disturbed.

Therefore, an object of the present invention is to be able to perform voltage control on the power transmission system side of the main transformer by switching taps on the main transformer in conjunction with generator voltage control, thereby improving operability and providing voltage control. It is an object of the present invention to provide a voltage control device for a power plant that can ensure quick dissolution and reliability, and can also be expected to ensure stable operation of the power system.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention is as follows.

In other words, in a power plant where a generator is connected to the power transmission system via a main transformer having on-load tap switching means, the generator voltage within a predetermined permissible fluctuation range is calculated based on the control command, and the system is adapted to the generator voltage. an arithmetic control means for determining the tap position of the main transformer, which detects the power transmission system side voltage of the main transformer, and sets the generator voltage so that the power transmission system side voltage is equal to the content of the control command; The apparatus includes execution control means for giving a tap switching command to the on-load tap switching means so that the set generator voltage falls within a predetermined allowable range.

(Function) In this invention, when a control command (main transformer power transmission side voltage) is given, the generator voltage is calculated based on the contents of the control command, and the generator electrical voltage at this time is kept within an allowable range. At the same time as determining the tap position of the main transformer, if tap switching is necessary, set the generator voltage so that it is close to the control finger during tap switching. Then, the main transformer power transmission side voltage obtained in this way is detected, and the main transformer power transmission side voltage is adjusted so that the generator voltage, which makes the main transformer power transmission side voltage equal to the above control command, falls within a predetermined allowable fluctuation range. Controls transformer tap switching. This makes it possible to perform main transformer power transmission system side voltage control by switching taps of the main transformer in conjunction with generator voltage control.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the circuit configuration of the same embodiment.

In the figure, 11 is a generator, and this generator 11 is connected to a power transmission system 13 via a main transformer 12 for boosting the voltage. In this case, the generator 11 is provided with a field winding 14,
In addition, the main transformer 12 is equipped with an on-load tap changer (MTr,
LTC) 15 is provided.

On the other hand, 16 is a main controller, and this controller 16 outputs a power transmission system side voltage Vl as a control command 17.

Alternatively, reactive power VAR or transmission system side voltage and reactive power increase/lower commands are given, and on the other hand.

The power transmission system side voltage v1 of the main transformer 12 is detected as the human power 18.
, generator voltage Vg, generator current Ig, or reactive power. In addition, a tap switching command is given to the on-load tap switching device 15, and the voltage setting device (9
0R) Give a generator voltage setting command to 19.

In this case, the main controller 16 consists of an arithmetic control means 161 and an execution control means 162, as shown in FIG. Here, the calculation control means 161 calculates the generator voltage in the generator 11 based on the control command 17 and the grid side voltage based on the current main transformer tap position, and also causes the generator voltage to fall within a predetermined allowable fluctuation range. A tap switching command is output to the load tap switching device 5 so that the tap switching command is corrected. Further, the execution control means 162 determines that the power transmission system side voltage Vl is determined by the control command 17 based on the power transmission system side voltage 1 of the main transformer 12 given as the detection input 18.
In addition to giving a setting command for the generator voltage to the voltage setting device 19 so that the content is equal to the contents of A tap switching command is output to the device 5.

The voltage setter 19 sets a reference value according to a setting command from the main controller 16, and provides this set value to a generator automatic adjustment control device (Gen AVR) 20. Then, the DC voltage to the generator field winding 14 is determined by controlling the excitation power supply device 21 based on the reference value in the generator automatic voltage regulator 20, and the generator voltage Vg of the generator 11 is controlled. It has become.

Next, the operation of the embodiment configured as described above will be explained according to the flowchart of FIG.

Note that this embodiment shows a case where the power transmission system side voltage Vlo is used as the control command 17.

Now, in step Al in FIG. 3, when the power transmission system side voltage Vlo is input as the control command 17, in step A2, the power transmission system side voltage Vlo at this time is changed to the current power transmission system side voltage of the main transformer 12. It is determined whether there is a change in Vl.

Here, if a change is recognized, the process proceeds to step A3, where the current tap position of the main transformer 12 is detected.

Then, the process advances to step A4.

In step A4, the current power transmission system voltage v1 of the main transformer 12 is determined from the tap position of the main transformer 12, and this power transmission system voltage Vl and the control command 17 (power transmission system voltage Vlo) are made equal. The generator voltage V
go is calculated. Then, the process advances to step A5.

In this step A5, the generator voltage Vg.

It is determined whether or not the value falls within a predetermined allowable variation range. In this case, the upper limit of the allowable variation range is Vgh, and the lower limit is Vgl. Here, if the variation is not within the allowable variation range, the process proceeds to step 86.

In this step A6, the generator voltage Vgo is set to the lower limit Vgl.
If it is smaller, a command to increase the tap is output to the on-load tap switching device 15;

If the generator voltage Vgo is higher than the upper limit Vgh, a command to lower the tap is output to the on-load tap switching device 15. Generally, the switching time of the on-load tap switching device w15 is longer than the settling time of the automatic voltage regulator 20 for one generator, so even during the switching of the on-load tap switching device, the voltage control command Vlo on the power transmission system side can be kept as close as possible. Considering that,
In parallel with the tap switching command, if the generator voltage Vgo is smaller than the lower limit Vgl, a command is given to the voltage setting device 19 to set the generator voltage to the lower limit Vgl, while if the generator voltage Vgo is larger than the upper limit Vgh , a command is given to the voltage setting device 19 to set the generator voltage to the upper limit Vgh. Then, in step A7, the above-mentioned generator voltage Vgl
or a reference value necessary for Vgh setting is set, while in step 8 tap switching of the main transformer 12 is performed,
Return to Step 3 again.

Thereafter, as a result of repeating similar operations, when it is determined in step A5 that the generator voltage Vgo falls within a predetermined allowable fluctuation range (of course, in steps A6 and A7
The generator voltage Vgo suddenly changes without going through the operation of
The same applies when the value falls within a predetermined allowable variation range. )
, proceed to step 88.

In this step A9, the power transmission system side voltage v1 of the main transformer 12 at this point in time is detected. And step AI
Proceed to O, and the power transmission system side voltage Vl and control command 17 at this time
A generator voltage setting command is given to the voltage setter 19 so that the (transmission system side voltage Vlo) becomes equal. and,
As shown in step All, a reference value necessary for setting the generator voltage Vg number is set in the voltage setter 19.

Next, the process proceeds to step A12. In step A12, the current generator voltage Vg of the generator 11 is detected. Then, the process advances to step A13.

In step A13, the generator voltage V at this time is
It is determined whether g falls within a predetermined allowable variation range.

In this case, the upper limit of the allowable fluctuation range is Vgh, and the lower limit is Vgl.
It becomes. Here, if it does not fall within the allowable variation range, the process proceeds to step A14.

In this step A14, as in step 6, if the generator voltage %Igo is smaller than the lower limit Vgl, a command to raise the tap is output to the on-load tap changer [15], and at the same time the generator voltage is set to the lower limit Vgl. On the other hand, if the generator voltage Vgo is greater than the upper limit Vgh, a command to lower the tap is output to the on-load tap changer 15, and at the same time the generator voltage is set to the upper limit. A command is given to the voltage setting device 19 to set the voltage to Vgl. Then, in step A15, a reference value necessary for the above-mentioned generator voltage Vgl or Vgh is set,
On the other hand, tap switching of the main transformer 12 is performed in step A16, and the process returns to step A9 again.

Thereafter, as a result of repeating the same operation, when it is determined in step A13 that the generator voltage Vg falls within the predetermined allowable fluctuation range (of course, in step A14 and step A
The generator voltage V suddenly changes without going through the operations in step 15.
The same applies when go falls within a predetermined allowable variation range. ), the process returns to step AAI and waits for the first control command 17.

According to control according to such a flowchart,
The relationship between the generator voltage Vg and the change in the tap position of the main transformer 12 is as shown in FIG.

In this way, when a control command (main transformer power transmission side voltage) is given, the generator voltage is calculated from the control command and the current main transformer tap position, and the generator voltage at this time is set to a predetermined value. The tap switching of the main transformer is controlled to stay within the permissible fluctuation range, and at the same time, if tap switching is to be performed, the generator voltage is set so that the output approaches the control command during tap switching, and then this The main transformer power transmission side voltage obtained in this way is detected, and the generator voltage of the generator is set so that the main transformer power transmission side voltage is equal to the control command, and the generator voltage based on this setting is set. The tap switching of the main transformer is controlled to stay within a predetermined allowable fluctuation range, and as a result, main transformer transmission side voltage control is performed by switching the main transformer tap in conjunction with generator voltage control. can be done. As a result,
Compared to the conventional system where an operator had to operate the tap switching at the main transformer every time there was an alarm, this type of troublesome operation can be omitted, resulting in a significant improvement in operability. Moreover, tap switching at the main transformer is controlled so that the generator voltage always stays within the allowable fluctuation range, so the generator voltage does not remain at overvoltage or undervoltage as in the past. Immediate response and reliability of voltage control can be ensured, and stable operation of the power system can be expected.

Furthermore, although the case where the power transmission system side voltage is used as the control command 17 has been described above, reactive power VAR may be used as the control command. In this case, when the reactive power VAR is input as a control command, the main controller 16 calculates the generator voltage Vgo, and adjusts the generator voltage automatic voltage regulator W20 so that this value is equal to the actual generator voltage Vg. Becomes in control.

〔Effect of the invention〕

According to the present invention, it is possible to control the main transformer power transmission system side voltage by switching the taps of the main transformer in conjunction with the generator voltage control, so that the operability of such voltage control can be improved, and moreover, the voltage control In addition to ensuring connectivity and reliability, stable operation of the power system can be expected.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a configuration diagram showing a main controller used in the embodiment,
Fig. 3 is a flowchart for explaining the same embodiment, Fig. 4 is an explanatory diagram for explaining the relationship between generator voltage and main transformer tap position in the same embodiment, and Fig. 5 is a diagram for explaining the relationship between the generator voltage and the main transformer tap position in the same embodiment. FIG. 2 is a circuit diagram showing an example of a voltage control device. 11... Generator 12... Main transformer 1
3... Power transmission system 15... On-load tap switching device 16... Main controller 161...
Arithmetic control means 162...Execution control means 17...
・Control command 18...Detection input 19...
Voltage setting device 20... Generator voltage automatic voltage regulator agent Patent attorney Nori Chika Ken Yudo Daishimaru Kendai 1 1 f7 Tsui Dai 2 Figure

Claims (1)

[Claims] In a power plant where a generator is connected to the power transmission system via a main transformer with on-load tap switching means, the generator voltage within a predetermined permissible fluctuation range is calculated based on a control command, and the main power generator corresponding to the generator voltage is an arithmetic control means for determining the tap position of the transformer, a power transmission system side voltage detected from the power transmission system side of the main transformer, and the control command to set the generator voltage of the generator, and generate power based on the setting. 1. A voltage control device for a power plant, comprising execution control means for giving a tap switching command to the on-load tap switching means so that the machine voltage falls within a predetermined allowable range.