JP2011050152A - System stabilizing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reliable system stabilizing system wherein a system can be properly and easily stabilized before the system frequency is deviated from a reduction tolerance limit. <P>SOLUTION: The system stabilizing system includes a means 101 for detecting continuous reduction in the effective power output PE of generators GA1, ..., GAn, and a means 102 for detecting continuous reduction in system frequency. When the effective power output PE of the generators and the system frequency F are both continuously reduced according to the detection by these means 101, 102, the system disconnects loads L1, L2, ..., Ln equivalent to the effective power output of the generators. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a system stabilization system that prevents a system frequency drop exceeding an allowable limit due to a power loss by performing a stabilization control by cutting off a load when a generator is disconnected (hereinafter referred to as a “power loss”). It is.

  As the prior art, there are the prior art 1 and the prior art 2 as described below.

Prior art 1
As a conventional system stabilizing system, for example, as described in Japanese Patent Laid-Open No. 8-322148 (Patent Document 1), the accommodation power and the frequency are detected, and the accommodation power is increased and the frequency is decreased. Some devices determine that the power supply on the power receiving side has been disconnected, and adjust or operate the voltage adjusting device or send a voltage drop command to each generator.
For example, when a failure or malfunction of the steam valve itself or its control system has occurred on the power plant side, the generator may drop off. However, in the conventional technique 1, a failure or malfunction has occurred on the power plant side. I can't identify the generator.

Prior art 2
There is also a method of detecting the power loss as a main detection element using the open signal of the circuit breaker attached to the generator main transformer, but the detection and system for power loss due to a failure or malfunction on the power plant side. There are cases where the start-up of the stabilization system is delayed and the system frequency deviates from the allowable lowering limit.

JP-A-8-322148- (FIG. 2 and its description)

  As described above, the conventional technique 1 has a problem that the generator on the power plant side, for example, the steam valve itself or a control system in which a failure or malfunction has occurred cannot be specified. There is a problem that the detection and the start of the system stabilization system are delayed with respect to power loss due to a failure or malfunction on the power plant side, and the system frequency may deviate from the allowable lowering limit.

  Further, protection / control signals on the power plant side, for example, signals such as pressure, temperature, flow rate, and many valve states in various places in boilers, turbines, etc. are extremely diverse, and all these signals are transmitted to the power plant side. It is extremely difficult to incorporate the signal into the system stabilization system as a detection signal for failure or malfunction of the system.

  Moreover, in the system stabilization control at the time of power disconnection in the prior art 2, etc., each load of the generator is shut off at once. However, if each load is shut off at once, there is a problem on the plant side. If it is eliminated and the generator does not fall off, over-control occurs and the system frequency increases.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a highly reliable system stabilization system.

  The system stabilization system according to the present invention includes means for detecting a continuous decrease in the active power output of the generator and means for detecting a continuous decrease in the system frequency, and the power generation based on detection of both means If both the active power of the machine and the system frequency are continuously reduced, the load corresponding to the active power output of the generator is cut off.

  The present invention comprises means for detecting a continuous decrease in the active power output of the generator and means for detecting a continuous decrease in the system frequency, and based on the detection of both means, the active power of the generator and the If both of the system frequencies decrease continuously, the load corresponding to the active power output of the generator will be cut off, so the system will be stabilized accurately and easily before the system frequency deviates from the allowable lowering limit. Therefore, it is possible to realize a highly reliable system stabilization system.

It is a figure which shows Embodiment 1 of this invention, and is a figure which shows the example of a system | strain stabilization system and its application. It is a figure which shows Embodiment 1 of this invention, and is a figure which shows the example of the functional block diagram of the power-off detection in a system | strain stabilization system. It is a figure which shows Embodiment 1 of this invention, and is a figure which shows the example of the change state of the active power output of a generator at the time of the power-off and the system frequency at the time of the power supply for demonstrating operation | movement of FIG. 1 and FIG. It is a figure which shows Embodiment 2 of this invention, and is a flowchart which shows the example in the case of performing the function of a system | strain stabilization system by S / W. It is a figure which shows Embodiment 3 of this invention, and is a block diagram which shows the example in the case of implement | achieving the function of a system | strain stabilization system by H / W on a board | substrate. In the figure which shows Embodiment 4 of this invention, when a generator stop command and a generator output fall (load fall) command can be utilized for each generator individually, these are used to prevent unnecessary generator dropout detection. It is a flowchart which shows the example at the time of adding to S / W of a system stabilization system as a means. In the figure which shows Embodiment 5 of this invention, when a generator stop command and a generator output fall (load fall) command can be utilized for each generator individually, these are used to prevent unnecessary generator dropout detection. It is a block diagram which shows the example at the time of adding to the H / W board | substrate of a system | strain stabilization system as an element.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to FIGS. An example of application to a 60 Hz system is shown here. 1 is a diagram showing an example of a system stabilization system and its application, FIG. 2 is a diagram showing an example of a functional block diagram for detecting a generator loss (hereinafter also referred to as “power loss”) in the system stabilization system, and FIG. It is a figure which shows the example of the change state of the active power output of a generator at the time of the power-off and the system frequency at the time of the power supply disconnection for describing operation | movement of FIG. 1 and FIG.

  In FIG. 1, power is supplied to a power system 2 from a certain A power plant and its substation 1 through a power plant substation bus BA and a power transmission line F. The illustrated power system 2 is a non-connected example that does not receive interchanged power from other power systems via a connection line. Further, when there are a plurality of power plants and their substations in the power system 2, it is assumed that an accident detection terminal device having the same configuration as that of the first embodiment is installed in all the power plant substations.

  A power plant 1 is provided with a plurality of generators GA1,... GAn whose output is individually controlled by the corresponding plant control device. In other words, the generator GA1 is output-controlled by the GA1 plant controller GA1C, and the generator GAn is output-controlled by the GAn plant controller GAnC.

  The output ends of the generators GA1,... GAn are connected to the power station-added substation bus BA via corresponding main transformers (step-up transformers) and corresponding main variable circuit breakers, respectively. That is, the output terminal of the generator GA1 is connected to the power station substation bus BA via the corresponding main transformer (step-up transformer) MTr1 and the corresponding main variable circuit breaker CB1, and the output terminal of the generator GAn corresponds to the generator GA1. It is connected to the power station side substation bus BA via the main transformer (step-up transformer) MTrn and the corresponding main variable circuit breaker CBn.

  A plurality of loads L1, L2,... Ln are connected to the power system 2, and each load is controlled to be connected to or disconnected from the power system 2 by a corresponding load control terminal device. That is, the load L1 is controlled by the L1 load control terminal device 21, the load L2 is controlled by the L2 load control terminal device 22, and the load Ln is controlled by the Ln load control terminal device 2n.

A current transformer for measuring current is provided at the power transmission end of the corresponding main transformer of each of the generators GA1,. That is, a current transformer CT1 for measuring the power transmission end output current of the generator GA1 is provided at the power transmission end of the corresponding main transformer MTr1 of the generator GA1, and the power transmission end of the corresponding main transformer MTrn of the generator GAn. Is provided with a current transformer CTn for measuring the power transmission end output current of the generator GAn. Further, a power transformer substation bus BA is provided with an instrument transformer PT for measuring the bus voltage. These are general instrument configurations in a power station substation, but the active power output obtained by this configuration does not include the active power of the on-site load of the generator. Therefore, when it is necessary to consider the effective power of the on-site load, correction is performed by multiplying the effective power output measured at the power transmission end of the generator by a predetermined coefficient.

  An accident detection terminal device 10 is provided on the side of the auxiliary substation in the A power plant and its substation 1, and each output of the instrument current transformers CT1, ... CTn is provided in the accident detection terminal device 10. And the output of the instrument transformer PT are individually inputted, and the interruption command for the main variable breakers CB1,... CBn is individually outputted.

  In the first embodiment, an abnormal state on the plant control device side such as a failure of a boiler, a turbine, a large number of valves, etc. in the plant control device and abnormal pressure, temperature, and flow rate at each place is called an “accident”. Detecting the accident or predicting an accident on the plant control apparatus side is referred to as “accident detection”, and the terminal device that performs the accident detection is referred to as “accident detection terminal apparatus”.

  The accident detection terminal device 10 includes an accident detection terminal side arithmetic device 10C. The accident detection terminal side arithmetic device 10C includes the outputs of the instrument current transformers CT1, ... CTn and the instrument transformer. From the output of PT, the increase / decrease of the active power output PE and the effective power output PE of each of the generators GA1,... GAn is derived, and the system frequency F and the increase / decrease of the system frequency F from the output of the instrument transformer PT , And determining that both the active power output PE and the system frequency F are continuously decreased for each of the generators GA1,. Detected before the system frequency deviates from the permissible lowering limit (in other words, predicts power loss), and signals to that effect (referred to as “PF lowering activation establishment signal” in this embodiment) and P A load equivalent to the active power output PE of the generator at the time when the reduced activation is established (hereinafter referred to as “corresponding load”) is output to the remote central controller 3 via the signal path S1-3, and this output is output. In the received central controller 3, the central controller 3C selects a load corresponding to the corresponding load amount from among the loads L1, L2,... Ln on the basis of preset priorities. A load cutoff signal is output to the corresponding load control terminal devices 21, 22,... 2n via the corresponding signal paths S3-L1, S3-L2,. To do. By cutting off the selected load, the system frequency is maintained at a predetermined frequency even when the power is turned off. That is, system stabilization is performed.

  In the PF decrease start establishment signal, “PF” means the generator output P and the system frequency F, and “PF decrease start establishment” means that both the above-mentioned active power PE and system frequency F continuously decrease. This is a state in which it is detected that the generator has dropped out and a signal to that effect is output. Further, the effective power output of the generator at the time when the PF lowering activation is established, that is, the corresponding load amount, is expressed as “PEC” in the first embodiment.

  The system stabilization system according to the first embodiment includes an accident detection terminal device 10, a central control device 3, load control terminal devices 21, 22,... 2n, and signal paths S1-3, S3 that function as described above. -L1, S3-L2, ... S3-Ln.

  GA1 plant controller GA1C, ... GAn plant controller GAnC on the plant side, when the system frequency is healthy, increases the output of the corresponding generator GA1, ... GAn, and responds if the system frequency increases. The input amount of the corresponding generator GA1,... GAn is controlled in the direction of decreasing the output of the generator GA1,.

  The power plant central control room 4 individually sends a generator stop command, a generator output drop (load) during normal operation and periodic inspections to the plant controller of each generator of the A power plant and its substation 1 Descent) command. When these commands or signals indicating the presence / absence of the commands can be used, they are also sent to the accident detection terminal device 10 via the signal path S4-1. When these instructions are given, the accident detection terminal device 10 operates so that the PF lowering activation establishment is not performed or the generator dropout is not detected. Specific examples of the logic that operates so as not to establish the PF lowering activation and the logic that operates so that the generator dropout is not detected will be described in the fourth and fifth embodiments.

  Next, the function of the generator dropout detection in the system stabilization system, in particular, the function of the accident detection terminal side arithmetic device 10C of the accident detection terminal device 10 will be described with reference to FIG.

  The accident detection terminal side arithmetic unit 10C includes a generator output power increase / decrease detection unit 101, a generator output frequency increase / decrease detection unit 102, an AND unit 103, and a generator dropout detection element 104 for each of the generators GA1,. Has each function.

The generator output power increase / decrease detection unit 101 receives the current I, which is the output of the current transformer CT at the power transmission end of the corresponding generator, and the voltage V, which is the output of the instrument transformer PT of the power station substation bus BA. The active power detection unit 1011 for deriving the active power output of the corresponding generator from the current I and the voltage V, the current active power output from the active power detection unit 1011 and the active power reference set in the reference value setting unit 1013 The active power increase / decrease detecting unit 1012 that detects the increase / decrease in the active power output of the corresponding generator by comparing with the value, and the timer unit 1014 for determining that the increase / decrease in the active power output of the corresponding generator continues for a predetermined time. It has each function. Here, as the reference value of the active power, a moving average value of the active power from the present time to a predetermined time before is used.
The generator output power increase / decrease detection unit 101 is means for detecting a continuous decrease in the active power output PE of the generators GA1,.

The system frequency increase / decrease detection unit 102 detects an increase / decrease in the system frequency. The frequency detection unit 1021 receives the voltage V, which is the output of the instrument transformer PT, and detects the system frequency based on the voltage V. A frequency increase / decrease detection unit 1022 that detects the increase / decrease of the system frequency by comparing the current system frequency that is the output of the frequency detection unit 1021 and the system frequency reference value set in the reference value setting unit 1023, and the increase / decrease of the system frequency Each function of the timer unit 1024 for determining that it has continued for a predetermined time is provided. Here, as the reference value of the frequency, a moving average value of the frequency from the present time to a predetermined time before is used.
The system frequency increase / decrease detecting unit 102 is means for detecting a continuous decrease in the system frequency.

  The AND unit 103 performs an AND operation on the outputs of the timer units 1014 and 1024, and the generator dropout detection element 104 to which the output of the AND unit 103 is input has both the active power output of the corresponding generator and the system frequency. If it continuously decreases, it is determined that the generator has been dropped, and the PF decrease start establishment signal is output. The PF decrease activation establishment signal and the corresponding load amount at the time of PF decrease activation establishment are output from the accident detection terminal device 10 (see FIG. 1) to the central control device 3 (see FIG. 1) as described above. The central controller 3 cuts off the load corresponding to the corresponding load amount, and the system is stabilized.

Here, the GA1 plant control device GA1C,... GAn plant control device GAnC on the plant side increases the output of the corresponding generators GA1,. If so, the input amount of the corresponding generator GA1,... GAn is controlled in the direction of decreasing the output of the corresponding generator GA1,. If both the power output and the system frequency at the output end of the generator continuously decrease, it is detected for each generator that an accident such as a failure or malfunction has occurred in the plant controller of the generator. It can be done. In addition, in this plant control device, the detection (prediction) of the generator dropout due to the occurrence of an accident is detected by an instrumental current transformer CT installed at the power transmission end of each generator and an instrumental transformer installed at the power station substation bus BA. This can be done using the output of the device PT. Accordingly, the system can be stabilized accurately and easily before the system frequency deviates from the allowable lowering limit.

  Next, the active power output of the generator and the change state of the system frequency when the power is turned off, and the change state of the system frequency due to the above-described function of the system stabilization system of the first embodiment will be described with reference to FIG.

FIG. 3A illustrates a change state of the active power output of the generator when the power supply is cut off, and FIG. 3B illustrates a change state of the system frequency at the generator output end when the power supply is cut off and the state of the first embodiment. The change state of the system frequency by the above-mentioned function of the system stabilization system is illustrated.
3 (a) and 3 (b), the horizontal axis is time t, the vertical axis of FIG. 3 (a) is the generator active power output PE (t) (unit pu), and the vertical axis of FIG. 3 (b) is the power generation. System frequency F (t) (unit: Hz) at the machine output end.

As illustrated in FIGS. 3A and 3B, when both the active power output PE of the generator and the system frequency F at the generator output end are continuously decreased, the system frequency F is set to the activation determination level F. _{SET1 (eg} 59.8Hz) to assume that the PF decrease start if reduction is satisfied, the total target value of the load cut off the load corresponding to the active power output PEC of the generator at that time.

Grid frequency F is decreased further, the control execution determination level _{F SET2} (e.g. 59.5Hz) frequency decrease detecting unit 1022 at the time when decreased to (see FIG. 2) is output _from the time the drops to _{F SET2 F SET2} following When the state continues for T time (set time of the timer unit 1024 (see FIG. 2)), the central controller 3 (see FIG. 1) executes the first load cut-off based on the priority.

The load shedding embodiment of the first time, exceeds the system frequency F is _{F SET2,} then if again decreases to _{F SET2,} as in the case of load shedding in the first _{round, F SET2} or less from the time when decreased to _{F SET2} When this state continues for T time, the central control device 3 executes the second load blocking (load blocking different from the load blocked by the first load blocking execution) based on the priority.

The load shedding embodiment of this second round, than the system frequency F is _{F SET2,} then if again decreases to _{F SET2,} as in the case of load shedding in the first _{round, F SET2} or less from the time when decreased to _{F SET2} If this state continues for T time, the central control device 3 performs the third load cutoff (load cutoff different from the load cut off by the first and second load cutoff executions) based on the priority order. To do.

If the system frequency F exceeds F _SET2 by the third load interruption and the state continues, the central controller 3 does not perform the subsequent load interruption.

  As described above, the load limit amount (load cutoff amount) per time is PEC / n (arbitrary natural number), and the load cutoff is performed step by step in a plurality of times. Further, a plurality of n is provided according to the required control amount and the output reduction speed. For example, the central controller 3 selects an n value corresponding to the output decrease rate so that a small value n is selected if the output decrease rate is fast and a large value n is selected if the output decrease rate is slow. To suppress over- and under-control of load shedding.

  If the load for the total target value of load interruption is cut off at once, if the accident in the plant control device on the plant side is resolved and the turbine trip or main circuit breaker is not opened, the system frequency becomes over-controlled. Although F may rise abnormally, if the load limit amount (load cutoff amount) per time is set to PEC / n, and the load cutoff is performed in stages in a plurality of times, Even when the accident in the plant-side plant control device is resolved and the turbine trip or main variable circuit breaker is not opened, it is possible to prevent the system frequency F from rising abnormally without being over-controlled. On the other hand, when the decrease in the effective power output of the generator is abrupt, it may be difficult to prevent the system frequency from being lowered by stepwise load interruption. As a countermeasure for this, when the active power output of the generator falls below a certain level when PF lowering activation is established, load interruption for PEC is performed once. That is, n = 1 is set. This determination is also performed by the generator output power increase / decrease detection unit 101 in FIG.

Embodiment 2. FIG.
The second embodiment of the present invention is a case where the function of the system stabilization system described above is executed by S / W, and an example thereof is illustrated in FIG.

The accident detection terminal device 10 (see FIG. 1) performs the process shown in FIG. 4 on all operating generators belonging to the A power plant and its substation 1. Hereinafter, the processing shown in FIG. 4 will be described by taking as an example a generator in operation belonging to the A power plant and its substation 1.
In FIG. 4, first effective power output PE of the generator, to collect the values of grid frequency F (step ST1), then determine system frequency F is lower than the activation determination level _{F SET1} (eg 59.8Hz) If this condition is not established, the process returns to step ST1.
If the condition of step ST2 is satisfied, it is determined whether the active power output PE and the system frequency F of the generator are continuously decreasing (step ST3). If this condition is not satisfied, step Return to ST1.
If the condition of step ST3 is satisfied, it is determined that the PF reduced activation is satisfied (step ST4), the effective power output PE of the generator, the output determination coefficient to the rated output PE _S of the generator K _GD ( For example, it is determined whether or not the value multiplied by 0.1) is exceeded (step ST5). If this condition is not satisfied, the load interruption count n is set to 1 (step ST10), and the process proceeds to step ST7.
When the condition of step ST5 is satisfied, the load interruption count n is set according to the PE decrease rate (step ST6), and the system frequency F is F as the total target load amount (corresponding load amount) PEC to be interrupted. The active power output PE of the generator at the time of becoming _SET1 is set (step ST7).
Next, a signal indicating that the “PF lowering activation” is established, the total target load amount PEC to be interrupted, and the load interrupting frequency n are sent to the central controller 3 (see FIG. 1) (step ST8).

When the central control device 3 receives from the accident detection terminal device 10 the signal indicating that the “PF lowering activation” has been established, the total target load amount PEC to be shut off, and the load shut-off frequency n from the accident detection terminal device 10 in step ST8, the system frequency F is controlled. Each time it falls below the execution determination level F _SET2 (for example, 59.5 Hz), a load cutoff command for PEC / n is sent to the load control terminal device of the corresponding load based on the priority order (step ST9).
If the condition of PE ≧ K _GD · PE _S is not satisfied in step ST5, load interruption corresponding to general power loss can be executed instead of shifting to step ST10. In this case, the accident detection terminal device 10 immediately instructs the central control device 3 to execute load shedding corresponding to a general power-off, a prior active power output of the generator (for example, from the present time to a predetermined time before (Moving average value). The central control unit 3 calculates a target load amount to be cut off based on the transmitted advance active power output of the generator, a control target frequency (setting value), a frequency characteristic constant (setting value), and the like, and the system frequency F is calculated. On condition that the control execution determination level F _SET2 (for example, 59.5 Hz) has been reached, a load cutoff command corresponding to the target load amount to be shut off is sent to the load control terminal device of the corresponding load based on the priority order.

  By the processing in the above-described steps ST1 to ST9, the same function as the system stabilization system in the first embodiment is exhibited.

Embodiment 3 FIG.
Embodiment 3 of the present invention is an example in which the function of the system stabilization system described above is realized by H / W on a substrate, and an example thereof is illustrated in FIG.

5, the effective power output PE of the generator, the output judging the rated output PE _S of the generator coefficient K _{GD (e.g.} 0.1) element determines exceeds a value obtained by multiplying the 101A and the generator The element 101B that determines whether or not the effective power output PE continues to decrease corresponds to the generator output power increase / decrease detection unit 101 of FIG. Each element has a predetermined timer, and outputs each output when the determination condition is satisfied for each set time or longer.
Moreover, determining element 102B deterioration continuation system frequency F is activation determination level _{F SET1} (eg 59.8Hz) determining element or is below 102A and grid frequency F is shown in FIG. 2 in the first embodiment described above This corresponds to the system frequency increase / decrease detection unit 102. Each element has a predetermined timer, and outputs each output when the determination condition is satisfied for each set time or longer.
Reference numeral 103 denotes an AND circuit. The generator dropout detecting element 104A corresponding to the multiple load cut-off (n ≧ 2) and the generator dropout detecting element 104B corresponding to the single load cut-off (n = 1) are the generator dropout shown in FIG. This corresponds to the detection unit 104.
The element 101A has the same function as the function of step ST5 of the second embodiment, the element 101B has the same function as the function of step ST3 of the second embodiment, and the element 102A has the function described above. The element 102B has the same function as the function of step ST2 of the second embodiment, and the element 102B has the same function as the function of step ST3 of the aforementioned second embodiment.
Reference numeral 5 denotes a lock switch which is opened by the OFF operation means 6 at the time of generator inspection or the like so that the system dropout system does not detect an unnecessary generator dropout at the time of generator inspection or the like.

In the system stabilization system the third embodiment, whether active power output PE of the generator exceeds the value obtained by multiplying the output determination coefficient to the rated output PE _S of the generator K _{GD (for} example, 0.1) determining element 101A, the generator determines element 101B deterioration continuation of the active power output PE, grid frequency F is activation determination level _{F SET1} (eg 59.8Hz) determining element 102A whether the below, grid frequency F 102B, AND circuit 103, generator dropout detection element 104A corresponding to multiple load cut-off (n ≧ 2), generator dropout detection element 104B compatible with single load cut-off (n = 1) and lock The switch 5 is configured as a circuit on the substrate and exhibits a function equivalent to that of the first and second embodiments.

Embodiment 4.
Embodiment 4 of the present invention provides a means for preventing unnecessary generator dropout detection when a generator stop command and a generator output drop (load drop) command can be used individually for each generator. This is an example of the case where the system is added to the S / W of the system stabilization system described above, and an example thereof is illustrated in FIG.

The accident detection terminal device 10 (see FIG. 1) performs the process shown in FIG. 6 on all operating generators belonging to the A power plant and its substation 1. In the following, the process shown in FIG. 6 will be described by taking as an example an operating generator belonging to the A power plant and its substation 1.
6, first active power output PE of the generator, to collect the values of grid frequency F (step ST1), then determine system frequency F is lower than the activation determination level _{F SET1} (eg 59.8Hz) If this condition is not established, the process returns to step ST1.
If the condition of step ST2 is satisfied, it is determined whether the active power output PE and the system frequency F of the generator are continuously decreasing (step ST3). If this condition is not satisfied, step Return to ST1.
If the condition of step ST3 is satisfied, it is determined whether there is a stop command for the generator (step ST10). If this condition is not satisfied, the PF lowering activation within a predetermined time is locked (step ST12). .
If the condition of step ST10 is satisfied, it is determined whether there is an output decrease command for the generator (step ST11). If this condition is not satisfied, the PF decrease activation within a predetermined time is locked (step ST12). ).
If the condition of step ST11 is satisfied, it is determined that the PF reduced activation is satisfied (step ST4), the effective power output PE of the generator, the output determination coefficient to the rated output PE _S of the generator K _GD ( For example, it is determined whether or not the value multiplied by 0.1) is exceeded (step ST5). If this condition is not satisfied, the load interruption count n is set to 1 (step ST10), and the process proceeds to step ST7.
When the condition of step ST5 is satisfied, the load interruption count n corresponding to the rate of decrease of PE is set (step ST6), and the system frequency F is F as the total target load amount (corresponding load amount) PEC to be interrupted. The active power output PE of the generator at the time of becoming _SET1 is set (step ST7).
Next, a signal indicating that the “PF lowering activation” is established, the total target load amount PEC to be interrupted, and the load interrupting frequency n are sent to the central controller 3 (see FIG. 1) (step ST8).

When the central control device 3 receives from the accident detection terminal device 10 the signal indicating that the “PF lowering activation” has been established, the total target load amount PEC to be shut off, and the load shut-off frequency n from the accident detection terminal device 10 in step ST8, the system frequency F is controlled. Each time it falls below the execution determination level F _SET2 (for example, 59.5 Hz), a load cutoff command for PEC / n is sent to the load control terminal device of the corresponding load based on the priority order (step ST9).
If the condition of PE ≧ K _GD · PE _S is not satisfied in step ST5, load interruption corresponding to general power loss can be executed instead of shifting to step ST10. In this case, the accident detection terminal device 10 immediately instructs the central control device 3 to execute load shedding corresponding to a general power-off, a prior active power output of the generator (for example, from the present time to a predetermined time before (Moving average value). The central control unit 3 calculates a target load amount to be cut off based on the transmitted advance active power output of the generator, a control target frequency (setting value), a frequency characteristic constant (setting value), and the like, and the system frequency F is calculated. On condition that the control execution determination level F _SET2 (for example, 59.5 Hz) has been reached, a load cutoff command corresponding to the target load amount to be shut off is sent to the load control terminal device of the corresponding load based on the priority order.

  In the grid stabilization system of the fourth embodiment, the means for determining the presence / absence of a generator stop command (step ST10) and the presence / absence of a generator output reduction (load drop) command are determined in the flowchart of the second embodiment. By adding means (step ST11), when any one of the commands is present, the PF lowering activation is locked for a predetermined time to prevent the detection of an unnecessary generator dropout.

Embodiment 5.
Embodiment 5 of the present invention, when a generator stop command and a generator output reduction (load drop) command can be used individually for each generator, these are used as elements for preventing unnecessary generator dropout detection. FIG. 7 illustrates an example of the case where the above system stabilization system is added to the H / W substrate.

7, the active power output PE of the generator, the output judging the rated output PE _S of the generator coefficient K _{GD (e.g.} 0.1) element determines exceeds a value obtained by multiplying the 101A and the generator The element 101B that determines whether or not the effective power output PE continues to decrease corresponds to the generator output power increase / decrease detection unit 101 of FIG. Each element has a predetermined timer, and outputs each output when the determination condition is satisfied for each set time or longer.
Moreover, determining element 102B deterioration continuation system frequency F is activation determination level _{F SET1} (eg 59.8Hz) determining element or is below 102A and grid frequency F is shown in FIG. 2 in the first embodiment described above This corresponds to the system frequency increase / decrease detection unit 102. Each element has a predetermined timer, and outputs each output when the determination condition is satisfied for each set time or longer.
Reference numeral 103 denotes an AND circuit. The generator dropout detecting element 104A corresponding to the multiple load cut-off (n ≧ 2) and the generator dropout detecting element 104B corresponding to the single load cut-off (n = 1) are the generator dropout shown in FIG. This corresponds to the detection unit 104.
7 is an element for determining whether or not there is a generator stop command for the generator, and 8 is an element for determining whether or not there is a generator output reduction (load drop) command for the generator. Output to.
The element 101A has the same function as the function of step ST5 of the above-described fourth embodiment, the element 101B has the same function as the function of step ST3 of the aforementioned fourth embodiment, and the element 102A has the function described above. The element 102B has the same function as the function of step ST3 of the fourth embodiment, and the element 7 has the same function as the function of step ST2 of the fourth embodiment. The element 8 has the same function as that of ST10, and the element 8 has the same function as the function of step ST11 of the above-described fourth embodiment.
Reference numeral 5 denotes a lock switch which is opened by the OFF operation means 6 at the time of generator inspection or the like so that the system dropout system does not detect an unnecessary generator dropout at the time of generator inspection or the like.

In system stabilization system of the fifth embodiment, a valid power output PE of the generator exceeds the value obtained by multiplying the output determination coefficient to the rated output PE _S of the generator K _{GD (for} example, 0.1) determining element 101A, the generator determines element 101B deterioration continuation of the active power output PE, grid frequency F is activation determination level _{F SET1} (eg 59.8Hz) determining element 102A whether the below, grid frequency F 102B, AND circuit 103, generator drop detection element 104A corresponding to multiple load interruption (n ≧ 2), generator drop detection element 104B, 7 corresponding to one load interruption (n = 1) Is an element that determines whether there is a generator stop command to the generator, 8 is an element that determines whether there is a generator output reduction (load drop) command to the generator, and a lock switch. 5 is configured as a circuit on a substrate, Teisu the same function as the fourth embodiment described above.

    1 to 7, the same or corresponding parts are denoted by the same reference numerals.

DESCRIPTION OF SYMBOLS 1 A power station and its substation, 10 Accident detection terminal device 10C Accident detection terminal side arithmetic unit, 2 Power system,
21, 22,... 2n load control terminal device,
3 Central control unit, 3C Central control unit side arithmetic unit,
4 Power plant central control room, 5 Lock switch,
6 OFF operation means during generator inspection, 7 Determining element without generator stop command,
8 Determining element without generator output reduction command,
101 generator output power increase / decrease detection unit, 1011 active power detection unit,
1012 active power increase / decrease detection unit, 1013 reference value setting unit,
1014 timer unit, 102 system frequency increase / decrease detection unit,
1021 Frequency detector, 1022 Frequency increase / decrease detector,
1023 Reference value setting unit, 1024 timer unit,
103 AND section, 104 Generator dropout detection element,
BA power station substation bus, CT1, CTn current transformer,
CB1, CBn circuit breaker, F transmission line,
GA1, ... GAn generator,
GA1C, ... GAnC plant control device,
L1, L2, ... Ln load, MTr1, ... MTrn main transformer,
PE generator active power output,
Generator active power output at PEC frequency 59.8Hz,
PT1, PTn current transformer,
S1-3, S3-L1, S3-L2,... S3-Ln, S4-1, S4-2 Signal path.

Claims (6)

  Means for detecting a continuous decrease in the active power output of the generator, and means for detecting a continuous decrease in the system frequency, and based on detection of both means, the active power output of the generator and the system frequency A system stabilization system that shuts off the load corresponding to the active power output of the generator if both are continuously reduced.   The system stabilization system of Claim 1 WHEREIN: The said load interruption | blocking is performed in steps divided into multiple times, The system stabilization system characterized by the above-mentioned.   3. The system stabilization system according to claim 2, wherein the number of stepwise interruptions of the load is increased in a case where it is slower than a case where the effective power output reduction speed of the generator is high. 4. .   4. The system stabilization system according to claim 2 or 3, wherein when the active power output of the generator falls below a certain level, it is regarded as equivalent to a power loss and a load interruption corresponding to the power loss is performed. System stabilization system.   4. The system stabilization system according to claim 2 or 3, wherein when the active power output of the generator falls below a certain level, it is regarded as equivalent to a power loss, and the load interruption is performed once instead of divided into a plurality of times. System stabilization system characterized by   In the system stabilization system according to any one of claims 1 to 5, if there is at least one of a stop command for the generator and a load drop command for the generator, a load cutoff corresponding to the active power output of the generator is performed. System stabilization system characterized by locking.

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