JP2009130952A - Bus-bar voltage adjusting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a bus-bar voltage from being controlled out of a specified value, and to prevent a loading switch tap from being controlled excessively largely or extremely insufficiently. <P>SOLUTION: It is determined whether a tap operation is in the fourth time in a step S1, processing is progressed to determination processing in a step S2 when the determination is "N", and in this step S2, it is determined whether a voltage deviates from "voltage adjustment relay 90+dead band" by the release of a branch reactor ShR. When the determination is "Y" in the step S2, the processing is progressed to determination processing in a step S3, it is determined whether the voltage deviates from "program control-dead band" when an LR tap is lowered in this step S3, the processing is progressed to processing in a step S4 when the determination is in "N", the "lowering" of an LRT tap is performed in a step S5 by resetting the relay 90 integration, and the processing is returned to the step S1. In the determination processing in the steps S1, S3, alarm output processing is performed when the determination is "Y", and in the determination processing in the step S2, a "phase modification operation" output is performed when the determination is "N". <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a bus voltage adjusting method in a substation.

As this type of bus voltage adjustment method, in order to supply a stable voltage, a load tap change transformer is installed in a substation having a phase adjusting facility on the bus, and the load tap change transformer is connected by a voltage adjustment relay. The tap is switched to adjust the output voltage of the transformer, that is, the bus voltage of the substation to be kept constant.

FIG. 3 is a conceptual diagram illustrating the bus voltage adjustment method in the substation, and the voltage adjustment method will be described with reference to FIG. In FIG. 3, 1 is a primary bus, 2 is a secondary bus, LRT ₁ and LRT ₂ are load tap switching transformers having a load tap switching mechanism, and these transformers LRT ₁ and LRT ₂ are The primary side is connected to the primary bus 1 via the circuit breaker CB, and the secondary side is connected to the secondary bus 2 via the circuit breaker CB. The voltage of the secondary bus 2 is the tap switching transformer LRT ₁ during loading. , LRT ₂ is adjusted by switching the tap.

Reference numeral 3 denotes an integral type voltage adjusting relay, which is an example of a digital type. The voltage of the secondary bus 2 is input via the instrument transformer PT and the input unit 4 and is compared with a set value in the relay to obtain a voltage deviation. When the voltage is over the specified value, an increase or decrease command is given to the tap switching mechanism of the on-load tap switching transformers LRT ₁ and LRT ₂ so that the deviation becomes small until the voltage deviation falls within the specified value. Repeatedly executed.

  In order to prevent hunting and eliminate harmful and useless switching operations, the integral voltage regulating relay 3 is set so that the upper and lower limits of the dead band are set to be equal to or higher than one tap voltage of the transformer. The operating time has an integral characteristic that is inversely proportional to the deviation from the settling reference voltage so that it does not respond to voltage fluctuations due to voltage fluctuations or voltage fluctuations due to temporary changes in the load. These characteristics are present in the digital voltage regulating relay described below, and the operation is processed in this relay.

  As shown in the conceptual configuration in FIG. 3, the digital voltage adjustment relay is composed of a calculation unit CPU, a memory PROM, a RAM, an input interface DI, an output interface DO, a clock unit, and the like, which are connected via a bus, The calculation unit CPU sequentially reads out the program written in the memory, and performs relay calculation and sequence calculation using information from the memory and the input interface DI according to the program.

6, 7, and 8 are phase adjusting equipments, which include a power capacitor SC and a shunt reactor ShR, and the phase adjusting equipments 6 and 7 are connected to the tertiary windings of the on-load tap switching transformers LRT ₁ and LTR ₂ , Further, the phase adjusting equipment 8 is connected to the secondary bus 2. In preparation for reactive power consumption of the load, these phase adjusting facilities 6 to 8 adjust the reactive power by turning on or opening the switches included in each power capacitor or shunt reactor.

  9 is a phase control device that selectively turns on and off the power capacitor SC or the shunt reactor ShR of one or both of the phase adjusting equipment 6, 7 or 8, and the amount set in advance for each time zone is controlled by program control. Or manually turn it on / off. In the case of program control, a timer is usually used.

When the power capacitor SC and the shunt reactor ShR of the phase adjusting equipment are turned on / off, the voltage of the secondary bus 2 fluctuates by the amount corresponding to the voltage of 1 tap or 2 taps. If the voltage change amount at that time is ΔV, ΔV can be expressed by the following equation. In the following equation, Tr _n % Z is the transformer's percent impedance, Tr _n capacity is the transformer capacity, and Σ1 / Z _n is the sum of the combined banks.

  Here, the primary impedance (hereinafter referred to as the primary Z) changes depending on the system configuration, and the voltage change amount ΔV also changes as the primary Z changes.

For example, when V = 77 (kV), phase adjusting equipment capacity = 40 (MVar), and Z = 0.3, the voltage change amount ΔV ₁ is given by the following equation.

When Z = 0.5 due to the change of the primary Z, the voltage change amount ΔV _{2 in} the following equation is obtained.

JP 09-028037 A

  The primary Z mentioned above needs to consider all the transmission lines connected to it, transformers of other substations, generators of the power plant, etc., so, for example, connected to 20 substations / power plants. If what has been increased to 25 locations by changing the system configuration, it is necessary to recalculate all of them. Therefore, there is a problem that the calculation for obtaining the primary Z becomes troublesome. For this reason, the primary Z is handled as a fixed value that is calculated and given in advance from the assumed system configuration. If the system configuration changes, there is a problem that ΔV cannot be calculated correctly unlike the actual system configuration.

  Therefore, in order to solve the above problems, it is predicted whether or not the bus voltage will deviate from the specified value (overvoltage or undervoltage) by operating the phase adjusting equipment. However, even in this device, the bus voltage is deviated from the specified value due to an erroneous result.

  In addition, there is a device that predicts the voltage change amount ΔV before operating the phase adjusting equipment and reduces the voltage shock applied to the system by controlling the tap of the load tap change transformer in advance by an amount corresponding to this ΔV. Even in this apparatus, the tap of the on-load tap switching transformer is switched or controlled excessively or too little due to an erroneous result.

  In any of the above cases, there is a problem in that it is troublesome to obtain the primary Z.

  In the above, the erroneous result is that the Z (impedance) calculated based on the primary Z obtained at a certain time and the Z calculated based on the current primary Z are doubled. That is, the voltage change ΔV is doubled even if the phase control equipment having the same capacity is controlled. That is, the voltage change amount ΔV at a certain point in time is 1000 V, but is now 2000 V. For example, the system state changes by 2000 V, but the calculation result of the device changes only by 1000 V. .

  The present invention has been made in view of the above circumstances, and calculates a bus voltage change amount ΔV when operating a small-capacity phase-adjusting facility whose capacity is known in advance from the primary impedance Z and the phase-adjusting capacity. It is an object of the present invention to provide a bus voltage adjustment method that prevents the bus voltage from being controlled outside the specified value and prevents the load switching tap from being excessively or excessively controlled. To do.

In order to achieve the above object, the present invention adjusts the bus voltage in the substation to the control target voltage by switching the tap of the on-load tap switching transformer, and also uses the reactive power of the bus. And a control means for turning on and off the phase adjusting equipment, wherein the tap switching operation of the on-load tap switching transformer is performed by an integral voltage regulating relay.
Operate a small-capacity phase-adjusting facility whose capacity is known in advance, calculate the primary impedance Z of the system configuration from the amount of change in bus voltage by the following formula, and calculate the primary impedance Z of the system configuration from the calculation result The value of is automatically changed.

  However, V is the bus voltage before the change, Σ / Zn is the sum of the combined bank, and the phase adjusting equipment capacity is MVar.

  According to the present invention, by operating a small-capacity phase-adjusting facility whose capacity is known in advance, whether or not the bus voltage is deviated from a specified value (overvoltage or undervoltage) is deviated. Has an advantage that in a device having a function of prohibiting operation, it is possible to prevent the bus voltage from being controlled out of a specified value due to an erroneous result.

  In addition, by operating the phase-adjusting equipment, the bus voltage change amount ΔV is predicted, and the tap of the on-load tap change transformer (LRT) is controlled in advance by an amount corresponding to this ΔV, and the voltage shock applied to the system is reduced. In the mitigating device, there is an advantage that it is possible to prevent the tap from being controlled excessively or excessively due to an erroneous result.

  Embodiments of the present invention will be described below with reference to the drawings. In the present invention, the bus voltage change amount ΔV that changes by operating (turning on / opening) the phase adjusting equipment is calculated from the primary Z and the phase adjusting capacity. This means that the primary Z can be calculated from the following equation by measuring the bus voltage change amount ΔV when the phase adjusting equipment is operated in advance and the phase adjusting equipment is operated. ing.

  However, V is the bus voltage before the change, Σ / Zn is the sum of the combined bank, and the phase adjusting equipment capacity is MVar.

  For this reason, in the present invention, by operating a small-capacity phase-adjusting facility whose capacity is known in advance, the device calculates the primary Z from the bus voltage change amount ΔV, and the apparatus has 1 from the obtained calculation result. If the value of the next Z is automatically changed, the next phase adjustment operation can be accurately controlled.

  Here, the reason why the phase adjusting equipment has a small capacity is that if the capacity is small, the bus voltage fluctuation is also small. In addition, when the above formula is used, an appropriate value can be obtained without performing complicated calculations for the primary Z.

[Embodiment 1]
By operating the phase adjusting equipment from the above formula, it is predicted whether or not the bus voltage will deviate from the specified value (overvoltage or undervoltage). It is possible to prevent the bus voltage from being controlled out of the specified value due to an erroneous result.

[Embodiment 2]
In the same way as above, the voltage change amount ΔV is predicted before operating the phase adjusting equipment, and the LR tap is controlled in advance by an amount corresponding to the voltage change amount ΔV to reduce the voltage shock applied to the system. Therefore, it is possible to prevent the LR tap from being controlled excessively or excessively.

  Next, the voltage adjustment method according to the first embodiment of the present invention will be described with reference to the flowchart in FIG.

  In FIG. 1, when attempting to open the shunt reactor ShR, which is a small-capacity phase-adjusting facility, first, in step S1, it is determined whether the tap operation is the fourth time. If “N”, the determination process in step S2 is performed. In step S2, the shunt reactor ShR is opened, and it is determined whether or not the voltage deviates from the “voltage regulating relay 90 + dead zone” shown in FIG.

  In addition, the voltage adjustment relay sets the reference voltage, ± dead band width, integration time in advance, and if the input voltage from the system deviates from the dead band width with respect to the reference voltage, the amount corresponding to the deviated voltage value Is a relay that issues a tap “rising” or “falling” command to the LRT tap when it expires.

  If “Y” in step S2, the process proceeds to the determination process in step S3. When the LR tap is lowered in step S3, it is determined whether the voltage deviates from “program control (procedure) —dead zone” shown in FIG. If “N”, the process proceeds to step S4, 90 relay integration is reset, the LRT tap “decrease” is performed in step S5, and the process returns to step S1. In addition, the process controller commands the opening / closing control of the phase adjusting equipment according to the time.

  If “Y” in the determination process of steps S1 and S3, an alarm output process is performed. If “N” in the determination process of step S2, “phase adjustment operation” is output.

  FIG. 2 is an operation explanatory diagram in the above, (1) is the shunt reactor ShR is opened, (2) is after one tap “lower”, and the shunt reactor ShR is opened, (3) is after two taps “lower”, Open shunt reactor ShR, (4) does not operate alarm output (does not operate when tap control deviates from pro-con dead zone, does not operate when phase deviation operation deviates from 90 dead zone), (5) Indicates that the alarm output is not operated.

  In FIG. 2, # 59 is an overvoltage relay, which sets an operating voltage in advance, and issues an operating signal when the input voltage from the system exceeds this.

  # 27 is a shortage relay. This relay sets an operating voltage in advance, and issues an operating signal when the input voltage from the system falls below this.

Operation when the shunt reactor ShR is opened (1) If the shunt reactor ShR connecting the transformer LRT to the secondary bus is opened, the secondary bus voltage is increased to the capacity and the primary Z of the system. The voltage increases by a corresponding voltage change amount ΔV.

  (2) Here, if the calculation result that the primary Z of the set system is different from the actual system due to the system change and does not deviate from “90+ dead zone” is obtained, the shunt reactor ShR Is output.

  (3) The above is “the bus voltage is controlled to be out of the specified value due to an erroneous result”, and the fact that the correct primary Z can be obtained can be prevented.

The flowchart of the voltage adjustment method which shows embodiment of this invention. Operation | movement explanatory drawing in embodiment. The conceptual structure explanatory drawing of the bus voltage adjustment method in a substation.

Explanation of symbols

ShR ... Shunt reactor SC ... Electric power capacitor LRT ... Load tap change transformer 90 ... Voltage regulator relay # 59 ... Overvoltage relay # 27 ... Undervoltage relay

Claims (1)

The bus voltage in the substation is adjusted to the control target voltage by switching the tap of the on-load tap switching transformer, and has a phase adjusting equipment that consumes reactive power of the bus, and the phase adjusting equipment is turned on / off. A voltage adjusting method comprising a control means, wherein the tap switching operation of the on-load tap switching transformer is performed by an integral voltage adjusting relay;
Operate a small-capacity phase-adjusting facility whose capacity is known in advance, calculate the primary impedance Z of the system configuration from the bus voltage change ΔV by the following formula, and calculate the primary impedance of the system configuration from the calculation result A bus voltage adjusting method, wherein the value of Z is automatically changed.

However, V is the bus voltage before the change, Σ / Zn is the sum of the combined bank, and the phase adjusting equipment capacity is MVar.

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