JPH0224711A - System voltage/invalid power control device - Google Patents

Abstract

PURPOSE:To prevent a system from being abnormally dropped at its voltage by monitoring the time change values of the system voltage and a delay invalid current and turning on a capacitor under a prescribed condition. CONSTITUTION:A system voltage/invalid power control device (AVQC) 10 operates invalid power from a system voltage/current detected through a voltage detecting transformer (PT) 8 and a current detecting current transformer (CT) 9, operates a deviation between the voltage and the current and applies a prescribed control output to a tap switching device (LRT) control part 12 of the transformer and a capacitor (SC)/reactor (SR) control part 13 to execute the tap switching control of the transformer or the opening/closing control of the SC 4 and SR 8. A correction control device 11 operates the time change value of a delay invalid current from the system voltage/current detected through the PT 8 and the CT 9, and when the system voltage is dropped and the time change value of the delay invalid current is increased more than a prescribed value, the opening/closing control of the SC 4 and the SR 8 or the tap switching control of the transformer is executed prior to control based upon the operating characteristics of the AVQC 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a system voltage/reactive power control device for controlling voltage and reactive power of a power system, and particularly to improvements thereof.

[Conventional technology]

Conventionally, this type of system voltage/reactive power control device (hereinafter referred to as A
Also called VQC. ) detects fluctuations in the load reactive power of substations and distribution stations and the resulting voltage fluctuations, and controls two taps using the transformer's tap changer (LRT) or the condenser? (SC).

[Problem to be solved by the invention]

By the way, such AVQR is designed to handle randomly fluctuating voltage or reactive power, mainly from the viewpoint of lifespan.
In order to suppress the number of times T, SC or SR is controlled as much as possible, and to avoid unnecessary operations during short-term fluctuations, the voltage and reactive power fluctuation detection section is equipped with inverse timing characteristics as shown in Figure 2 (a) and (b). It is normal to have . Note that FIG. 10A shows the characteristics with respect to the voltage deviation Δ■, and FIG. 11B shows the characteristics with respect to the reactive power deviation ΔQ.

In addition, the operating characteristics of AVQC are based on standard 1 at its installation point.
For direct Vs'QS, it is set as shown in FIG. Note that VS'Q8 is normally variable according to daily fluctuation patterns.

For this reason, when the delayed reactive power increases due to a sudden increase in load, the grid voltage suddenly drops. At this time, tap raising or SR open/SC close control is executed with the operating characteristics shown in Figure 2. In this case, the reactive power generated by the induction motor connected to the grid increases, causing the grid voltage to drop at an accelerating rate, which may lead to an abnormal situation.

Therefore, this invention prevents abnormal drops in grid voltage,
The purpose is to ensure stable operation.

[Means to solve the problem]

Monitors temporal changes in grid voltage and delayed reactive current,
When the system voltage drops by a predetermined value from the reference 1st shift and the amount of change over time in the delayed reactive current exceeds a set value, at least one or more capacitors are turned on.

In addition to the amount of time change in grid voltage and delayed reactive current, the ratio of the amount of time change in delayed reactive current to the amount of time change in active current, temperature, temperature change over time, humidity, and humidity It may also be possible to monitor at least one of the temporal changes and add as a condition that it satisfies a predetermined relationship.

[Effect]

By doing the above, the system voltage is prevented from decreasing at an accelerated rate, and an abnormal situation is prevented.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the invention.

In the figure, 1 is the primary system, 2 is the main transformer with tap changer, 3 is the secondary system, 4 is the capacitor (SC), 5 is the SC switchgear, 6 is the reactor (SR), and 7 is the SR switchgear. 8 is a voltage detection transformer (PT), and 9 is a current detection current transformer (CT).

10 calculates reactive power Q from the system voltage and current detected via PT8 and CT9, and calculates the deviations ΔV and Δ with respect to each setting value vs'QS of voltage V and reactive power Q.
Calculate Q, and then perform dead zone calculations as shown in Figures 2 and 6.
The resulting inverse time characteristic is calculated and a predetermined control output is given to the LRT control section 12.5C-8R sub-control 15 to perform tap switching control of the transformer or opening/closing control of the SC and SR.

11 is a correction control device specially added according to the present invention;
Calculate the amount of time change ΔIQ/Δt of the delayed reactive current from the system voltage and current detected via PT8 and CT9, and perform the following calculation based on this information to calculate the AVQC.
Prior to the control based on the operating characteristics of No. 10, opening/closing control of the SC and SR or tap switching control of the transformer is performed.

v8-α<VL<VB...
(1) ∆ engineering. /Δt>kl...
...(2) Note that VL is the current grid voltage line (detection section), v
s indicates the standard value, α indicates the voltage drop at the time of a short-circuit accident, and kl indicates the set value.

Therefore, equation (1) is used to confirm that there is no short-circuit accident, and when conditions such as equation (2) are established in such a situation, the transformer tap-up control and the SR opening or The SC closing control will be performed immediately after the noise filter table confirmation time (1 second or less). Note that the number of taps to be switched in the transformer or the number (amount) of opening and closing of SR and SC can be determined in advance, but ΔI,
It is also possible to change it depending on the amount of /Δt.

In the above, the amount of change over time in the system voltage and delayed reactive current is monitored, but in addition to this, the ratio ΔI of the amount of time change in delayed reactive current to the amount of time change in active current, /Δt2 ．．
Furthermore, the temperature T, its temporal change ΔT/Δt, and the humidity H
2. Also monitor the temporal change amount ΔH/Δ, etc., and at least one of them is ΔIQ/ΔIP〉k2 ・
...(3) T>Ts
・・・・・・(4)ΔT/Δt〉k3
・・・・・・(5)H>H8・・・・・・(
6) ΔH/Δt〉k4...
- In addition to the condition that the relationship (7) is satisfied, the tap switching of the transformer or the opening/closing control of the SR and SC may be performed. Note that 4 indicates the set value for k2~, T8 indicates the temperature-based saliva, and ■ indicates the humidity-based taste. Additionally, it is desirable to measure temperature, humidity, etc. at multiple locations and take the average value.

〔Effect of the invention〕

According to this invention, when the system voltage decreases, if the amount of change over time in the delayed reactive current exceeds the set value,
At least I tried to put the capacitor in immediately, so
This prevents the grid voltage from dropping at an accelerated rate, allowing for stable operation.

In addition to the above temporal changes in system voltage and lagged reactive current, the ratio of the temporal change in lagged reactive current to the temporal change in active current, temperature, temporal change in temperature, humidity, By monitoring at least one amount of change over time and adding as a condition that it satisfies a predetermined relationship, more accurate measures can be taken.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a graph showing the hardness characteristics of voltage deviation and reactive current deviation, and the third factor is a characteristic showing the control characteristics of the system voltage/reactive power control device. It is a diagram. Code explanation 1...Primary system, 2...Main transformer, 3
... Song secondary system, 4... Capacitor (SC),
5...SC switchgear, 6...Reactor (SR), 7...SR switchgear, 8...
...Transformer (PT), 9...Current transformer (CT),
10...System voltage/reactive power control device (AVQ)
C), 11... Correction control device, 12...
-LRT control unit, 13...SC-SR control unit.

Claims (1)

[Scope of Claims] 1) In a system voltage/reactive power control device in which a power system is provided with a capacitor and a reactor, a transformer is provided with a tap switching device, and the capacitor and the reactor are controlled to open and close, and the tap switching control of the transformer is performed. , monitor the amount of time change in grid voltage and delayed reactive current,
When the system voltage decreases by a predetermined value from the reference value and the amount of change in delayed reactive current over time exceeds the set value,
A system voltage/reactive power control device characterized by introducing at least one or more capacitors. 2) In addition to the amount of change over time in the system voltage and delayed reactive current, the ratio of the amount of change over time in delayed reactive current to the amount of time change in active current, the temperature, the amount of change in temperature over time, humidity, humidity. 1. A system voltage/reactive power control device, characterized in that it monitors at least one amount of change over time, and adds as a condition that it satisfies a predetermined relationship.