JP3475584B2 - Voltage adjustment method in substation - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage adjusting method in a substation, and more particularly to a bus voltage adjusting method by tap switching of a load tap change transformer in a substation having a phase adjusting facility on a bus.

[0002]

2. Description of the Related Art In order to supply a stable voltage, a load tap switching transformer is installed at a substation, and a tap of the load tap switching transformer is switched by a voltage adjusting relay to output the output voltage of the transformer, that is, The bus voltage of the substation is adjusted to keep it constant. FIG. 3 is a conceptual explanatory diagram of a voltage adjusting method in such a substation, and the conventional voltage adjusting method will be described with reference to FIG.

In FIG. 3, 1 is a primary busbar, 2 is a secondary busbar, and LRT ₁ and LRT ₂ are load tap switching transformers having a load tap switching mechanism, and each of these transformers LRT.
₁ , LRT ₂ has its primary side connected to the primary bus 1 via the circuit breaker CB and the secondary side to the secondary bus 2 via the circuit breaker CB, and the voltage of the secondary bus 2 is It is adjusted by switching the taps of the hour tap switching transformers LRT ₁ and LRT ₂ .

Reference numeral 3 denotes an integral type voltage adjusting relay, which is an example of a digital type and shows the voltage of the secondary bus 2 as an instrument transformer PT,
Input via the input unit 4, compare and calculate with the set value inside the relay, and if the voltage deviation is more than the specified value, tap switching of load transformers LR ₁ and LR ₂ to reduce the deviation. An up or down command is given to the mechanism, and the process is repeatedly executed until the voltage deviation is within the specified value.

In order to prevent hunting and prevent harmful and useless switching operation, the integral type voltage adjusting relay 3 has a dead band upper and lower limit width 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 will not respond to voltage fluctuations due to failure or voltage fluctuations due to temporary changes in load. These characteristics and operation commands are
In the case of a digital type voltage adjustment relay, as shown in FIG. 3, it is composed of an arithmetic unit CPU, a memory ROM, a RAM, an input interface DI, an output interface DO, a clock unit, etc., which are connected via a bus to perform arithmetic operations. The partial CPU sequentially reads the programs written in the memory, and performs relay calculation and sequence calculation using information from the memory and the input interface according to the program.

[0006] 6, 7 and 8 in the phase modifying equipment, power capacitor SC, consists of a shunt reactor S _h R, phase modifying equipment 6,
Reference numeral 7 is connected to the tertiary windings of the load tap switching transformers LRT ₁ and LRT ₂ , and the phasing equipment 8 is connected to the secondary bus 2. These phasing equipment prepares for reactive power consumption of the load,
The reactive power is adjusted by opening or closing the switch in each power capacitor or shunt reactor.

Reference numeral 9 is a phase control device for selectively turning on and off one or both of the power condensers or shunt reactors of the phase adjusting equipment 6, 7 or 9, which is a program control of a preset amount for each time zone. By or manually turn on / off. In the case of program control, a timer is usually used.

When the power capacitor and the shunt reactor of this phase adjusting equipment are turned on and off, the voltage of the secondary bus bar changes by an amount corresponding to the voltage of one tap or two taps.

[0009]

In the case of program control of the phasing equipment, it is carried out at a predetermined time regardless of the bus voltage, and the bus voltage fluctuates by this phasing operation.

On the other hand, the integral type voltage adjustment relay has a dead band width wider than the voltage fluctuation caused by one tap operation and has an integral characteristic which does not respond to a short-term voltage fluctuation.
Therefore, it takes a considerably long time to eliminate the voltage fluctuation due to the phasing operation and to operate the voltage adjustment relay to issue the tap switching command.

The voltage fluctuation range due to the opening and closing of the phase-adjusting equipment differs depending on the capacity of the phase-adjusting equipment, but it requires the operation of one or two taps. It takes longer time to reach the dead zone, and the dead zone is left for a long time, which adversely affects the device.

When the integral characteristic is expressed by the following equation and each variable is assumed as follows, the integral time t (s) is 20 sec.
Becomes

T = C ÷ {(ΔV-DV) ÷ DV} where C: integration time settling (s) = 20 (s) DV: dead zone settling (%) = 1 (%) ΔV: deviation | V _ref −V | / V _ref × 100 (%) = 2
(%) Further, in the voltage adjustment by the conventional integral type voltage adjustment relay, it may be impossible to adjust when the tap adjustment limit is reached.

In view of the above points, the present invention provides a voltage adjusting method in which the time during which the busbar voltage deviates from the dead zone during the phasing operation of the phasing equipment is shortened as much as possible and the adverse effects on the equipment connected to the busbar are reduced. The purpose is to

[0015]

Means for Solving the Problems In the invention of the present application, a means for solving the above problems is to adjust a bus voltage in a substation to a control target voltage by switching a tap of a load tap switching transformer. , Having a phasing equipment for consuming reactive power of the bus, and having a control means for turning on / off the phasing equipment, and the tap switching operation of the tap switching transformer under load is performed by an integral voltage adjusting relay. In the voltage adjusting method, the integral type voltage adjusting relay is
Input the signal for starting the phase adjusting operation by the control means of the phase adjusting equipment,
By inputting the signal, the change amount of the bus voltage that changes when the phasing equipment is operated , the transformer capacity, the phasing capacity and the transformer
Calculated using the value of the busbar state including the number of vessels ,
The bus voltage after the phasing operation is predicted, and it is judged whether or not the prediction result deviates from the dead zone. If not, an operation signal is sent to the control means of the phasing equipment and the If the operation is not performed and the prediction result deviates from the dead zone, a tap switching signal is output to the load tap switching transformer to adjust the bus voltage, and when the bus voltage is adjusted within the dead zone, the phase adjustment is performed. A phasing operation signal is sent to the control means of the equipment so that the phasing operation is performed by the control means.

Further, when the predicted result of the bus voltage after the phasing operation deviates from the dead zone, it is judged whether or not the tap change limit of the tap changer is reached. The display signal is output.

As described above, the phasing operation is performed immediately after the taps of the load tap switching transformer are switched and the bus voltage becomes the specified voltage. Therefore, the time when the bus voltage deviates from the dead zone is used for the phasing operation. It is shortened to the required time (about 0.1 sec).

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a processing flow for explaining a voltage adjusting method in a substation of the present invention. The use of the integral type voltage adjustment relay and the phase control device is the same as that in FIG. 3, but the integral type voltage adjustment relay (hereinafter, abbreviated as a relay) is a load tap switching transformer capacity, a percent impedance ( % Z), the phase-modulating capacity, and the primary-side impedance can be set, and signals can be transferred to and from the phase-modulating controller.

FIG. 1 shows an embodiment of a processing flow when a power capacitor (hereinafter abbreviated as SC) of a phase-adjusting facility is turned on, and when the SC is about to be turned on, the SC starts to be turned on to a relay. A signal is input (step S
1). When this signal is input to the relay, the amount of change in how much the bus voltage changes due to the phasing operation △
V is calculated and obtained, and the bus voltage after the phasing operation is predicted in consideration of the current bus voltage (step S2).

Next, it is judged whether or not the prediction result deviates from the dead zone (steps S3 and S4).

When the result of this judgment does not deviate from the dead zone, a phase-tunable signal is transmitted (step S5), and the phase-adjustment control device immediately performs a phase-adjustment operation.

When the above judgment deviates from the dead zone,
It is judged whether or not the number of taps for tap switching is the limit (step S
6) If there is a limit, a signal indicating that the phase adjustment operation is impossible and an alarm / display signal are output (step S7). Within limits
If the voltage rises when the capacitor is turned on, a tap down command is output (step S8), it is determined whether the voltage has dropped (step S9), and if it does not drop, a command is issued until it drops, and the voltage drops. If step S3
When the dead zone is no longer returned to, the phase-adjustment enabling signal is sent to perform the phase-adjustment operation.

The voltage fluctuation due to the phasing operation is obtained by the following equation.

Z _n = (T _γn % Z) / (T _γn capacity) Z = {1 / (Σ1 / Z _n )} + Z ₁ where T _γn % Z is the percent impedance T _γn capacity of the transformer. , The transformer capacity Z _1st is the primary side impedance Σ1 / Z _n is the sum voltage fluctuation width of the combined bank ΔV is ΔV = (V _S × Z / 100) × phasing capacity where V _S is the secondary bus Rated voltage.

As for the phase-modulating capacitance, the power capacitor is (+) and the shunt reactor is (-). At the time of opening operation, the sign of ΔV in the above formula is inverted.

[0027]

As described above, according to the present invention, the voltage is adjusted by the tap switching of the load tap switching transformer before the phasing operation, and the phasing operation is performed after the voltage adjustment. The time during which the dead zone is deviated is shortened to 0.1 seconds as shown in FIG.

That is, FIG. 2B shows the case of the conventional method, assuming that tap switching under load takes 5 seconds and phase adjustment operation takes 0.1 seconds, the integration time calculated by the above-mentioned hypothetical variable. When the time is 20 seconds, the time during which the dead zone is deviated is 25 seconds.

On the other hand, according to the present invention, as shown in FIG. 7A, the time required for the phase adjustment operation is only 0.1 seconds.
In FIG. 2A, point A is a voltage change point due to tap switching (lowering) and a point where a phase adjustment operation is possible, and point A is a voltage change point due to the phase adjustment operation. The point C in Fig. 2 (b) is
The time point of the phase adjusting operation and the point D indicate the time point of the tap switching (lowering) command.

[Brief description of drawings]

FIG. 1 is a flow chart for explaining a voltage adjusting method of the present invention.

FIG. 2 is an explanatory diagram of voltage adjustment times of the present invention and a conventional example.

FIG. 3 is an explanatory diagram of a voltage adjusting method in a conventional substation.

[Explanation of symbols]

1 ... primary bus 2 ... Secondary bus 3 ... Integral type voltage adjustment relay 4 ... Input section 5 ... Output section 6, 7, 8 ... Phase adjusting equipment 9 ... Phase control device

Claims (2)

(57) [Claims] 1. A phase adjusting facility for adjusting a bus voltage in a substation to a control target voltage by switching a tap of a load tap switching transformer and consuming reactive power of the bus. In the voltage adjustment method, which is provided with a control means for turning on / off, the tap switching operation of the tap switching transformer under load is performed by an integral voltage adjusting relay, wherein the integral voltage adjusting relay is By inputting a phasing operation start signal by the control means, and by inputting the signal, the change amount of the bus voltage that changes when the phasing equipment is operated ,
Of bus state including transformer capacity, phasing capacity and number of transformers
Calculated using the value, predict the bus voltage after the phasing operation, judge whether this prediction result deviates from the dead zone, and if not, send an operation signal to the control means of the phasing equipment. If the predicted result deviates from the dead zone by sending the signal and performing the phase adjustment operation by the control means, a tap switching signal is output to the tap switching transformer at load to adjust the bus voltage, and the bus voltage is in the dead zone. A voltage adjusting method in a substation, characterized in that a phase adjusting operation signal is sent to a controlling means of a phase adjusting facility when adjusted in the inside so that the phase adjusting operation is performed by the controlling means. 2. If the prediction result of the bus voltage after the phase adjusting operation deviates from the dead zone, it is judged whether the tap changer has a tap variable limit or not. The voltage adjusting method in a substation according to claim 1, wherein a display signal is output.