JP5473699B2 - Transformer control device - Google Patents

Description

  The present invention relates to a transformer provided corresponding to a transformer in a power generation facility in which a generator controlled by a generator control device is connected to an electric power system through a transformer having a load tap switching mechanism. The present invention relates to a controller.

  The generator is connected to the power system through a transformer having a load tap switching mechanism, and the tap position of the load tap switching mechanism is switched (that is, by changing the system voltage of the transformer). There is a power generation facility that attempts to increase or decrease the system voltage of the power system. In such a power generation facility, the tap position of the on-load tap switching mechanism is automatically switched by the transformer control device. And when the specific area | region of the electric power system to which the generator is connected is made into a control object area | region, it becomes a role of a transformer control apparatus to maintain the system voltage of the control object area | region to a target voltage. For example, the system voltage of the control target region can be increased by switching the tap position of the on-load tap switching mechanism to increase the system voltage of the transformer. Or the system voltage of a control object area | region can be reduced by reducing the system side voltage of a transformer.

  Patent Document 1 discloses a transformer control device that automatically switches the tap position of the on-load tap switching mechanism in a power generation facility in which the generator is connected to the power system via a transformer having the on-load tap switching mechanism. Is described. This transformer control device has a voltage detection means and a tap control means. The voltage detection means detects the system voltage in the control target area of the power system. The tap control means outputs a tap position switching drive signal to the on-load tap switching mechanism according to the deviation of the system voltage in the control target area detected by the voltage detection means from the target voltage. At this time, the generator and the transformer play a role of adjusting the amount of reactive power supplied to the power system in addition to the role of adjusting the system voltage of the power system.

JP-A-5-227666

  Patent Document 1 describes control for switching the tap position of the on-load tap switching mechanism during normal operation of the generator, but the tap position of the on-load tap switching mechanism when the generator is disconnected from the power system. There is no description on how to perform control to switch between. Also, other prior art does not describe how to perform control for switching the tap position of the on-load tap switching mechanism when the generator is disconnected from the power system.

  In the first place, disconnecting the generator from the power system means that the generator that contributed to the maintenance of the system voltage suddenly falls off when viewed from the power system. The system voltage of the system may fluctuate greatly. The higher the generator's contribution to maintaining the grid voltage of the power system, the greater the reactive power output from the generator, and this causes a current to fill the voltage deviation between the generator and the power system. Yes. For this reason, it is considered preferable from the viewpoint of maintaining the system voltage of the power system that the generator is disconnected from the power system in consideration of the presence of reactive power output from the generator to the power system. .

  The present invention has been made in view of the above-mentioned problems, and its purpose is to control a transformer that can perform control such that fluctuations in the system voltage of the power system are reduced when the generator is disconnected from the power system. The point is to provide a device.

In order to achieve the above object, the characteristic configuration of the transformer control device according to the present invention is such that the generator controlled by the generator control device is connected to the power system via the transformer having the on-load tap switching mechanism. In a power generation facility, a transformer control device provided corresponding to the transformer,
Reactive power measuring means for measuring reactive power output by the generator;
Tap control means capable of outputting to the transformer a switching drive signal of the tap position of the on-load tap switching mechanism,
When the tap control unit detects that the operation control of the generator performed by the generator control device has entered the disconnection preparation operation from the power system, the reactive power measured by the reactive power measurement unit is The reactive power output suppression process is performed to output a tap position switching drive signal of the on-load tap switching mechanism to the transformer so as to be equal to or less than the reactive power at the time of setting disconnection.

According to the above characteristic configuration, when detecting that the operation control of the generator has entered the disconnection preparation operation from the power system, the tap control means reduces the reactive power output by the generator to be equal to or less than the set reactive power at the time of disconnection. Perform reactive power output suppression processing. That is, the tap control means reduces the reactive power output by the generator while the operation control of the generator is in the disconnection preparation operation. As a result, even if the generator is disconnected from the power system because the reactive power output by the generator is suppressed (that is, the contribution of the generator with respect to maintaining the system voltage of the power system is reduced). The system voltage of the power system will not fluctuate greatly.
Therefore, it is possible to provide a transformer control device capable of performing control such that fluctuations in the system voltage of the power system are reduced when the generator is disconnected from the power system.

  Another characteristic configuration of the transformer control device according to the present invention is that the tap control means passes the confirmation time limit so that the tap position of the on-load tap switching mechanism is switched stepwise in the reactive power output suppression process. The switching drive signal is output to the transformer on the condition of

  According to the above characteristic configuration, suppression of the reactive power output output from the generator is performed stepwise for each confirmation time period. That is, since the tap switching operation is performed on the condition that the tap switching condition (that is, the reactive power measured by the reactive power measuring means is not yet equal to or less than the reactive power at the time of setting disconnection) continues for the confirmation time period, Unnecessary operation of the tap is suppressed. In addition, even if the system voltage decreases due to a decrease in the reactive power output from the generator, it may occur step by step for each set time. As a result, in the middle of the reduction of the system voltage, a time margin for the function of the system voltage maintenance function provided in the power system is created, so that the fluctuation of the system voltage is reduced.

Yet another characteristic configuration of the transformer control device according to the present invention is:
Comprising active power measuring means for measuring active power output by the generator;
The tap control means performs the operation control of the generator on the condition that the active power measured by the active power measuring means has decreased to a second setting threshold or less from a state where the active power is maintained to be a first setting threshold or more. The point is that it is determined that a disconnection preparation operation from the power system has been started.

  According to the above characteristic configuration, the tap control means monitors the active power measured by the active power measuring means, so that it is possible to quickly determine that the operation control of the generator has entered the disconnection preparation operation from the power system. . As a result, the reactive power output from the generator can be reduced before the generator is disconnected from the power system.

Yet another characteristic configuration of the transformer control device according to the present invention is:
The load drop start command information given to the generator control device for disconnecting the generator from the power system, and the generator control device that has received the load drop start command information Comprising information receiving means capable of receiving at least one of load drop start control information to be entered into the load drop start operation;
When the information accepting unit accepts at least one of the load drop start command information and the load drop start control information, the tap control unit causes the operation control of the generator to perform a disconnection preparation operation from the power system. It is in the point of judging that it entered.

  According to the above characteristic configuration, the tap control means monitors whether or not the load drop start command information and the load drop start control information are present, so that the generator operation control is a disconnection preparation operation from the power system. You can quickly determine that you have entered. As a result, the reactive power output from the generator can be reduced before the generator is disconnected from the power system.

It is a figure which shows the structure of the transformer control apparatus of this embodiment. It is a graph which shows transition of the system voltage of an electric power grid, the active power and reactive power of a generator, and the tap position of a load tap change mechanism. It is a figure which shows the structure of the transformer control apparatus of another embodiment.

A transformer control device according to the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of a transformer control device. As shown in FIG. 1, when the power generation facility 10A (10) is connected to the power system 1, the voltage (system voltage) of the power system 1 to which the power generation facility 10A is connected is maintained at the target voltage. It may be required for the facility 10A. For example, when the specific region of the power system 1 to which the power generation facility 10A is connected is set as the control target region 1a, the power generation facility 10A is required to maintain the system voltage of the control target region 1a at the target voltage. Therefore, in the present embodiment, the power generation facility 10A includes a prime mover 11a, a generator 11b, a generator control device 5, a transformer 12, and a transformer control device 20A (20). The generator 11b is driven by the prime mover 11a.

  The generator 11b is connected to the power system 1 via a transformer 12 having a load tap switching mechanism. When the tap position of the on-load tap switching mechanism is switched, the system side voltage of the transformer 12 changes, and accordingly, the system of the specific control target area 1a to which the generator 11b is connected in the power system 1. The voltage changes.

  The transformer control device 20 </ b> A includes power measurement means 17 and tap control means 16. Furthermore, the transformer control device 20 </ b> A includes voltage detection means 13. The voltage detection means 13 is provided so as to detect the system voltage of the specific control target region 1a to which the generator 11b is connected in the power system 1. The voltage detection means 13 includes a voltage detection transformer 14 and a converter 15. The voltage detection transformer 14 is connected to the electric power system 1 in the control target area 1a, and causes the internal circuit of the converter 15 to generate the system voltage (or voltage corresponding to the system voltage) at the connection portion. The converter 15 converts the voltage value generated in its own internal circuit by the voltage detection transformer 14 into a system voltage value in the control target area 1 a and outputs the system voltage value to the tap control means 16.

  The power measuring means 17 receives the information related to the output current of the generator 11b detected by the current transformer 3 and the information related to the output voltage of the generator 11b detected by the voltage detection transformer 4, and outputs the information output from the generator 11b. Deriving power and reactive power. That is, the power measuring unit 17 functions as an active power measuring unit 17A that measures the active power output by the generator 11b, and functions as a reactive power measuring unit 17B that measures the reactive power output by the generator 11b. The measurement result of the power measuring means 17 (information about active power and reactive power) is transmitted to the tap control means 16 as needed. Therefore, the tap control means 16 can determine the operating state of the generator 11b at any time based on the measurement result of the power measurement means 17.

  The tap control means 16 can output a tap position switching drive signal to the transformer 12 (load tap switching mechanism). In the present embodiment, the on-load tap switching mechanism is configured to be able to switch the tap position in 17 stages. Table 1 is a table illustrating the relationship between the tap position and the tap voltage of the transformer 12.

Below, the tap position control at the time of the normal driving | operation of the generator 11b is demonstrated.
The tap control means 16 of the transformer control device 20A detects whether the system voltage of the control target area 1a detected by the voltage detection means 13 is equal to or higher than a set value with respect to the target voltage, or is detected by the voltage detection means 13. The system voltage in the control target area 1a is less than or equal to the set value with respect to the target voltage, or the system voltage in the control target area 1a detected by the voltage detecting means 13 is within a range of a value smaller than the set value from the target voltage. Determine if there is. For example, the target voltage is V [kV] and the allowable deviation is ± α [kV].

  The system voltage in the control target area 1a is equal to or higher than a set value with respect to the target voltage (in this embodiment, the system voltage is V + α [kV] or more), and the state is a confirmation time limit (70 seconds in this embodiment). When continuing as described above, the power generation facility 10 </ b> A needs to operate so as to lower the system voltage of the power system 1. Specifically, it is necessary to lower the system side voltage of the transformer 12. Therefore, the tap control means 16 outputs a switching drive signal for the tap position of the on-load tap switching mechanism so as to lower the system side voltage of the transformer 12 to the on-load tap switching mechanism.

  Alternatively, the system voltage in the control target area 1a is less than or equal to the set value with respect to the target voltage (in this embodiment, the system voltage is V−α [kV] or less), and the state is the confirmation time limit (in this embodiment). , 70 seconds), the power generation facility 10A needs to operate so as to increase the system voltage of the power system 1. Specifically, it is necessary to increase the system side voltage of the transformer 12. Therefore, the tap control means 16 outputs a switching drive signal for the tap position of the on-load tap switching mechanism so as to increase the system voltage of the transformer 12 to the on-load tap switching mechanism.

  Alternatively, when the system voltage in the control target area 1a is within a range of values smaller than the allowable deviation with respect to the target voltage (in this embodiment, the system voltage is larger than V−α [kV] and smaller than V + α [kV]. Since the system voltage of the power system 1 is properly maintained, the tap control means 16 maintains the tap position of the on-load tap switching mechanism as it is.

[Generator operation control]
The operations of the prime mover 11a and the generator 11b are controlled by the generator control device 5. In the following description, it will be described that the generator control device 5 adjusts the output of the generator 11b, but actually, the generator control device 5 also adjusts the output of the prime mover 11a as necessary.
The administrator of the power generation facility 10 </ b> A can input various command information such as a command for starting the generator 11 b, a command for stopping the power generator 11 b, and a command for operating with the set output to the generator control device 5. When the generator control device 5 receives various command information as described above, the generator control device 5 gives appropriate control information to the generator 11b. The generator 11b operates according to the control information received from the generator control device 5.
The transformer control device 20A can know that the generator 11b has entered the load increasing operation based on the measurement result of the power measuring means 17. For example, the tap control means 16 of the transformer control device 20 </ b> A indicates that the output of the generator 11 b has risen based on the information about the active power and the reactive power output from the power generator 11 b transmitted from the power measuring means 17. Is recognized, it is determined that the generator 11b has entered the load increasing operation.

  When the administrator of the power generation facility 10A gives load drop start command information for starting the load drop of the generator 11b to the generator control device 5, the generator control device 5 controls the load drop start with respect to the generator 11b. Give information. When the generator 11b receives the load drop start control information from the generator control device 5, the generator 11b enters a disconnection preparation operation that starts to reduce the output. When the generator 11b starts to decrease the output, the effective power output from the generator 11b starts to decrease. The generator control device 5 gradually decreases the output of the generator 11b, and then opens the circuit breaker 2 when the generator active power output becomes sufficiently small.

  The transformer control device 20A can know that the generator 11b has entered the disconnection preparation operation based on the detection result of the power measuring means 17. In other words, the tap control unit 16 controls the operation of the generator 11b on the condition that the active power measured by the active power measuring unit 17A has decreased from the state maintained at the first set threshold or more to the second set threshold or less. Is determined to have entered into a disconnection preparation operation from the power system 1. In the present embodiment, the tap control means 16 of the transformer control device 20A receives the active power output from the generator 11b based on the information about the active power output from the power generator 11b and transmitted from the power measurement means 17. From the state maintained above the first setting threshold (for example, 14% of the rated output), it subsequently decreases to a second setting threshold (for example, 12% of the rated output) that is smaller than the first setting threshold. When it is recognized that the generator 11b has started (ie, the output has been reduced after the generator 11b has been started once), it is determined that the generator 11b has entered the disconnection preparation operation.

[Reactive power output suppression processing when the generator is disconnected]
Hereinafter, referring to FIG. 2, when the operation control of the generator 11b performed by the generator control device 5 enters the disconnection preparation operation from the power system 1, the reactive power output suppression process performed by the tap control means 16 Will be described. FIG. 2 is a graph showing changes in the system voltage of the power system, the active power and reactive power of the generator, and the tap position of the on-load tap switching mechanism.

  In the present embodiment, when the tap control means 16 of the transformer control device 20A detects that the operation control of the generator 11b performed by the generator control device 5 has entered the disconnection preparation operation from the power system 1, Transforms the drive signal for switching the tap position of the on-load tap switching mechanism so that the reactive power measured by the reactive power measuring means 17B is less than or equal to the reactive power at the time of disconnection before the machine 11b is disconnected from the power system 1. Reactive power output suppression processing to be output to the unit 12 is performed. In this embodiment, the reactive power at the time of setting disconnection is set to 25 MVar in view of the fact that the reactive power change caused by one stage operation of the tap of the transformer 12 is approximately 20 Mvar. That is, when the reactive power of the generator 11b measured by the power measuring unit 17 is larger than 25 MVar, the tap control unit 16 gives a switching drive signal to lower the tap position to the on-load tap switching mechanism.

  As shown in FIG. 2, at the time before time t1, the tap control means 16 of the transformer control device 20A holds the tap position of the on-load tap switching mechanism at the 12th stage. Moreover, the generator control device 5 is starting to lower the output of the generator 11b. The tap control means 16 can recognize that the output of the generator 11b tends to decrease based on the measurement result of the power measurement means 17. Note that the reactive power output by the generator 11b remains at a substantially constant value.

  At time t1, the tap control unit 16 generates power on the condition that the active power measured by the active power measuring unit 17A has decreased from the state where the active power measured by the active power measurement unit 17A is maintained above the first set threshold value to the second set threshold value or less. It is determined that the operation control of the generator 11b performed by the machine control device 5 has entered the disconnection preparation operation from the power system 1. In this embodiment, the tap control means 16 is based on the measurement result of the power measurement means 17, and the active power output by the generator 11b is the first set threshold: 44.1 MW (in this embodiment, 14% of the rated output). ) From the state maintained above, the active power has subsequently decreased and has become equal to or lower than the second setting threshold value: 37.8 MW (12% of the rated output in this embodiment), which is smaller than the first setting threshold value. Is recognized (time t1), it is determined that the generator 11b has entered the disconnection preparation operation. Then, the tap control means 16 sets the tap position of the on-load tap switching mechanism in the direction of decreasing the reactive power on the condition that the disengagement preparation operation determination continues for a predetermined time or longer (that is, the elapse of the confirmation time limit). A switching drive signal for switching is output to the transformer 12. As a result, the tap position of the on-load tap switching mechanism is switched from the 12th stage to the 11th stage. As shown in FIG. 2, when the tap position is switched from the 12th stage to the 11th stage at time t1, the reactive power output from the generator 11b decreases.

  In the present embodiment, the tap control unit 16 performs a load tap switching mechanism in the reactive power output suppression process that switches the tap position so that the reactive power measured by the reactive power measuring unit 17B is equal to or less than the reactive power at the time of set disconnection. In order to switch the tap position in stages for each predetermined confirmation time period and to avoid the hunting operation of the tap position, a switching drive signal is output to the transformer on condition that the predetermined confirmation time period has passed. That is, the tap control means 16 does not continuously switch the tap positions in a plurality of stages, and the tap switching condition is satisfied (that is, the reactive power measured by the reactive power measuring means is still the reactive power at the time of setting disconnection). A control for lowering the tap position by one step is performed on the condition that the state that is not below continues for the confirmation time limit. Specifically, in the present embodiment, the tap control means 16 commands a tap position switching operation on condition that the tap switching condition is satisfied for 70 seconds. In this way, since the suppression of the reactive power output from the generator 11b is performed in a stepwise manner on the condition that the confirmation time limit elapses, unnecessary tap operation due to the generator output fluctuation is avoided. Further, even if a system voltage drop occurs due to suppression of reactive power output from the generator 11b, it may occur step by step for each confirmation time period. As a result, in the middle of the drop of the system voltage, a time margin for the function of the system voltage maintenance function provided in the power system 1 is created, so that the fluctuation of the system voltage is reduced.

  Subsequently, the tap control unit 16 determines whether or not the reactive power of the generator 11b is equal to or lower than the set parallel disconnecting reactive power (25 MVar in the present embodiment) based on the measurement result of the power measuring unit 17. As a result of the determination, if the tap switching condition is satisfied, the tap control means 16 performs the operation at time t2 on the condition that the establishment has continued from time t1 to t2 (after 70 seconds in the present embodiment). The tap switching drive signal is output to the transformer 12 so that the tap position is further lowered by one step. In the example shown in FIG. 2, the reactive power immediately before time t2 is about 37 MVar (> reactive power at the time of setting disconnection), but when the tap position is switched from the 11th stage to the 10th stage at time t2, The reactive power output from the machine 11b is reduced to about 17 MVar.

  Even after the tap position has been switched to the tenth stage at time t2, the tap control means 16 determines that the reactive power of the generator 11b is equal to or less than the set reactive power (25 MVar) based on the measurement result of the power measurement means 17. Continue to determine whether or not. In the example illustrated in FIG. 2, the reactive power at time t3 is approximately 17 MVar (<reactive power at setting disconnection). Accordingly, the tap control means 16 determines that the reactive power generated by the generator, which is measured by the reactive power measuring means 17B, has become equal to or less than the reactive power at the time of setting disconnection, and the tap position of the on-load tap switching mechanism is left as it is. Hold. Thereafter, the generator 11b is disconnected from the power system 1, and the active power output and reactive power output of the generator 11b become zero (time t4).

  As can be seen from FIG. 2, between the system voltage at time t1 when the reactive power output suppression process is started and the system voltage at time t4 after the generator 11b is disconnected from the power system 1, There is a large voltage difference. That is, this voltage difference corresponds to the degree to which the generator 11 b contributes to maintaining the system voltage of the power system 1. In other words, if the reactive power output suppression process of the present embodiment is not performed, the potential difference should be instantaneously reduced in the system voltage. However, by performing the reactive power output suppression process, the time from time t1 is reduced. It can be said that the system voltage could be gradually decreased over time between t4. Therefore, when the generator 11b is disconnected from the power system 1, it is possible to perform control such that the fluctuation of the system voltage of the power system 1 is reduced.

<Another embodiment>
In the above-described embodiment, the tap control unit 16 has the condition that the active power measured by the active power measuring unit 17A has decreased from the state where the active power is maintained at the first set threshold or more to the second set threshold or less. Although the example in the case where it is determined that the operation control has entered the disconnection preparation operation from the power system 1 has been described, the tap control unit 16 determines that the operation control of the generator 11b is the solution from the power system 1 based on other criteria. It can also be modified to determine that a column preparation operation has been entered. The transformer control device 20B (20) according to another embodiment will be described below, but the description of the same configuration as that of the transformer control device 20A according to the above embodiment will be omitted.

  Drawing 3 is a figure showing the composition of the transformer control device of another embodiment. The transformer control device 20B receives the load drop start command information and the load drop start command information given to the generator control device 5 in order to disconnect the generator 11b from the power system. Is provided with information receiving means 18 capable of receiving at least one of the load drop start control information for causing the generator 11b to enter the above-mentioned disassembly preparation operation. When the information receiving unit 18 receives at least one of the load drop start command information and the load drop start control information, the tap control unit 16 performs operation control of the generator 11b to prepare for disconnection from the power system 1. It is determined that the operation has started.

  Alternatively, the tap control unit 16 monitors both the active power measured by the active power measuring unit 17A and the information received by the information receiving unit 18, and the information receiving unit 18 detects the load drop start command information and the load drop. When at least one of the start control information is accepted, or on the condition that the active power measured by the active power measuring unit 17A has decreased from the state maintained at the first setting threshold or more to the second setting threshold or less, It may be determined that the operation control of the generator 11b has entered the disconnection preparation operation from the power system 1.

  INDUSTRIAL APPLICABILITY The present invention can be used for a transformer control device that can perform control such that fluctuations in the system voltage of the power system are reduced when the generator is disconnected from the power system.

DESCRIPTION OF SYMBOLS 1 Electric power system 1a Control object area | region 5 Generator control apparatus 11 Generator 12 Transformer 16 Tap control means 17 Power measurement means 17A Active power measurement means 17B Reactive power measurement means 18 Information reception means 20 (20A, 20B) Transformer control apparatus

Claims (4)

In a power generation facility in which a power generator controlled by a power generator control device is connected to a power system via a transformer having a load-time tap switching mechanism, the transformer control device provided corresponding to the transformer Because
Reactive power measuring means for measuring reactive power output by the generator;
Tap control means capable of outputting to the transformer a switching drive signal of the tap position of the on-load tap switching mechanism,
When the tap control unit detects that the operation control of the generator performed by the generator control device has entered the disconnection preparation operation from the power system, the reactive power measured by the reactive power measurement unit is The transformer control apparatus which performs the reactive power output suppression process which outputs the switching drive signal of the tap position of the said on-load tap switching mechanism with respect to the said transformer so that it may become below reactive power at the time of setting disconnection.   In the reactive power output suppression process, the tap control means outputs the switching drive signal to the transformer on the condition that the confirmation time limit elapses so that the tap position of the on-load tap switching mechanism is switched stepwise. The transformer control device according to claim 1. Comprising active power measuring means for measuring active power output by the generator;
The tap control means performs the operation control of the generator on the condition that the active power measured by the active power measuring means has decreased to a second setting threshold or less from a state where the active power is maintained to be a first setting threshold or more. The transformer control device according to claim 1, wherein it is determined that the operation for preparing the disconnection from the power system has been started. The load drop start command information given to the generator control device for disconnecting the generator from the power system, and the generator control device that has received the load drop start command information Comprising information receiving means capable of receiving at least one of load drop start control information to be entered into the load drop start operation;
When the information accepting unit accepts at least one of the load drop start command information and the load drop start control information, the tap control unit causes the operation control of the generator to perform a disconnection preparation operation from the power system. The transformer control device according to any one of claims 1 to 3, which is determined to have entered.

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