JP2000139028A - Controlling reactive power compensating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably respond to a surge voltage without relying on the increase of the dimensions of a reactive power compensating device. SOLUTION: As a method for controlling a reactive power compensating device 3 connected to an electric power system provided with an automatic voltage regulator 1, the range that can be outputted of the reactive power compensating device 3 is divided into fixed and fluctuating ranges in advance, and the output is reduced to the fixed range gradually after the control of keeping the voltage constant is performed instantaneously in the fluctuating range for a surge that cannot be responded in the fixed range. Also, the upper and lower limit values of the system voltage are preset. When the system voltage is within the range not exceeding the limits, keeping the voltage constant is controlled by the automatic voltage regulator 1. If the system voltage exceeds the limits, keeping the voltage constant is controlled by the reactive power compensating device 3, too.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for a reactive power compensator connected to a power system.

[0002]

2. Description of the Related Art The voltage of a power system such as a power distribution system is constantly fluctuating due to a sudden change in load, and the situation is particularly long when a quarry or ski slope is located near a terminal of a track. It is. Such a load fluctuation causes an instantaneous voltage drop and flicker. In addition, precision and high-sensitivity equipment using electronics is easily affected by voltage fluctuations, and in the market, stabilization of the voltage of the power system is strongly desired. Therefore, conventionally, SVR (Static Voltage Regulat
or SVC (Static Var)
The system voltage is stabilized by a reactive power compensator called a compensator.

As shown in FIG. 10, an automatic voltage regulator (S
VR) 1 is used by being connected in series to an electric power system, and is a device that automatically switches taps of a transformer 2 according to a change in system voltage to change the system voltage on the load side. By this tap switching, the system voltage on the load side with respect to the automatic voltage regulator 1 is adjusted with a fixed step width, and constant voltage control is performed. However, since the operation of the automatic voltage regulator 1 is performed by operating the mechanical contacts, it takes a long time of about 60 to 120 seconds from the detection of the fluctuation of the system voltage to the completion of the operation, and the instantaneous voltage There was a problem that it could not cope with fluctuations.

On the other hand, a reactive power compensator (SVG) 3 has an inverter 4 and a capacitor 5 connected in parallel to a power system via a transformer 6 as shown in FIG. By flowing the output current through the power system, the reactive power is compensated to prevent voltage fluctuation of the entire system. The reactive power compensator 3 adjusts the output so that the control circuit 7 that detects the state of the power system injects output power according to the difference between the system voltage and the set voltage into the system, and performs constant voltage control. Is going.

Since the reactive power compensator 3 has no contact, it can be operated in a short time of about 20 msec.
Therefore, as shown in FIG. 1, the automatic voltage regulator 1 and the reactive power compensator 3 are conventionally combined, and the automatic voltage regulator 1 responds to daily gradual voltage fluctuations. A steep voltage change that cannot be achieved is devised by the reactive power compensator 3.

However, in the conventional control method, even in a state where there is no sharp voltage fluctuation, the reactive power compensator 3 operates constantly in accordance with the difference between the system voltage and the set voltage and suppresses the steady and gradual voltage fluctuation. are doing. For this reason, if the reactive power compensator 3 operates under the condition that the output possible range is fully used to compensate for the steady voltage fluctuation, and the voltage varies more steeply, the reactive power compensator 3
Has no margin and cannot compensate for sharp voltage fluctuations.

FIG. 12 is a graph showing the situation.
Even if the system voltage suddenly drops at this point, the output of the reactive power compensator (SVG) has already reached the limit and there is no margin, so that the constant voltage control by tap switching of the automatic voltage regulator (SVR) is completed. It shows that the state where the system voltage is lower than the set voltage continues for several minutes up to the time. It should be noted that this problem can be alleviated to some extent by increasing the capacity of the reactive power compensator, but there is a practical limit because the device becomes larger.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides a reactive power compensator capable of reliably responding to a steep voltage fluctuation without depending on an increase in the size of a reactive power compensator. The purpose of the present invention is to provide a method of controlling the apparatus.

[0009]

A first invention for solving the above-mentioned problem is a method of controlling a reactive power compensator connected to a power system having an automatic voltage regulator, the method comprising: The output possible range of the power compensator is divided into a fixed area and a variable area, and normal voltage constant control is performed for fluctuations that can be handled in the fixed area. On the other hand, the constant voltage control is performed instantaneously in the fluctuation region, and thereafter, the output of the reactive power compensator is gradually reduced to the fixed region.

[0010] The second is made to solve the same problem.
The present invention is a method for controlling a reactive power compensator connected to a power system including an automatic voltage regulator, wherein a system voltage is set with a voltage upper limit value and a voltage lower limit value, and When the voltage is within a range not exceeding, the voltage constant control by the automatic voltage regulator is performed, and when the system voltage deviates from this range, the reactive power compensator also performs the voltage constant control. .

[0011] A third problem has been made to solve the same problem.
The present invention is a method for controlling a reactive power compensator connected to a power system including an automatic voltage regulator, wherein a system voltage is set with a voltage upper limit value and a voltage lower limit value, and If the voltage does not exceed the range, normal voltage constant control by the reactive power compensator is performed, and if the system voltage deviates from this range, the set voltage of the reactive power compensator is The voltage is changed to a voltage closer to the voltage, and the reactive power compensator performs voltage constant control.

A fourth solution has been made to solve the same problem.
The invention is a method of controlling a reactive power compensator connected to a power system including an automatic voltage regulator, while changing the set voltage stepwise according to the average value of the output of the reactive power compensator, It is characterized by causing the reactive power compensator to perform constant voltage control.

In each of the first to fourth aspects of the present invention, there is room for handling steep voltage fluctuations by operating the reactive power compensator with an allowance for the output. In addition, by coordinating with the function of the automatic voltage regulator, steady and gradual voltage fluctuation can be suppressed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, each invention will be described in detail according to embodiments. Each invention described below relates to a control method of a reactive power compensator (SVG) 3 connected to a power system including an automatic voltage regulator (SVR) 1 as shown in FIG. The automatic voltage regulator 1 performs the constant voltage control by automatically switching the taps so that the system voltage is maintained at the set voltage, as in the related art, but the operation takes about 60 to 120 seconds as described above. Is required.

(Embodiment of the First Invention) FIG. 2 is a block diagram showing an operation flow of the first invention, and FIG. 3 is a graph showing an outline of the operation. In the first invention, the output possible range (rated output range) of the reactive power compensator 3 is divided into a fixed region and a variable region. The fluctuating region is a portion extending from the fixed region to the output limit. As shown in FIG. 2, the reactive power compensator 3 is caused to perform constant voltage control so that the system voltage is maintained at the set voltage as in the related art. Then, it is constantly monitored whether or not the output of the reactive power compensator 3 is within the fixed region. If the output is within the fixed region, the constant voltage control is directly performed.

However, when a steep change that cannot be handled in the fixed range occurs in the system voltage, the output of the reactive power compensator 3 is out of the fixed range. At this time, the deviation (detection deviation) between the detected system voltage and the set voltage is compared with the set deviation. If the detected deviation is smaller than or equal to the set deviation, the output of the reactive power compensator 3 is set to the maximum value of the fixed region. The constant voltage control is performed while maintaining the voltage. In this state, since the output of the reactive power compensator 3 still has a margin corresponding to the fluctuation region, it is possible to cope with a steep voltage fluctuation.

However, if there is a sharp voltage change in this state, the detection deviation exceeds the set deviation. In this case, the constant voltage control is instantaneously performed using the fluctuation region of the reactive power compensator 3. However, when the reactive power compensator 3 is operated in the fluctuation region, its output has a small margin, so that it is not preferable to continue the operation as it is. Therefore, after entering the variable region, the output of the reactive power compensator 3 is gradually reduced to the fixed region.

As a result, the system voltage may deviate from the set voltage again, but after an operation time of about 60 to 120 seconds elapses, the tap of the automatic voltage regulator 1 is switched, and the system voltage returns to the set voltage. At the same time, the output of the reactive power compensator 3 returns to the fixed region and returns to the first steady state.

As described above, the first invention divides the output possible range of the reactive power compensator 3 into a fixed region and a variable region,
Since the operation in the fluctuation range is limited to a short time, the reactive power compensator 3 has room for a steep voltage fluctuation. When the constant voltage control is performed only by the automatic voltage regulator 1 without the reactive power compensator 3, the system voltage greatly fluctuates as shown by a broken line in FIG.

(Embodiment of the Second Invention) FIG. 4 is a block diagram showing an operation flow of the second invention, and FIG. 5 is a graph showing an outline of the operation. In the second invention, an upper voltage limit and a lower voltage limit are set for the system voltage. For example, if the set voltage of the system is 6600V, the voltage upper limit value is 6700V
And the lower voltage limit is determined to be 6500V. In the second invention, the output of the reactive power compensator 3 is always set to 0, and when the system voltage is within a range not exceeding the upper voltage limit and the lower voltage limit, the constant voltage control only by the automatic voltage regulator 1 is performed. Let it do. As described above, the reactive power compensator 3 is not operated at all times, leaving room for steep voltage fluctuation.

Only when the system voltage deviates from this range, the reactive power compensator 3 is also caused to perform the constant voltage control. In this case, in order to allow the reactive power compensator 3 to have a margin as much as possible, it is preferable to set the set voltage to the voltage upper limit and the voltage lower limit closer to the system voltage.
As shown in FIG. 5, the system voltage may not return to the range between the voltage upper limit value and the voltage lower limit value even when the reactive power compensator 3 is operated at the output limit, but it may take 60 to 120 seconds.
After a certain operating time, the tap of the automatic voltage regulator 1 is switched, and the system voltage approaches the set voltage. Accordingly, the output of the reactive power compensator 3 is returned to 0 and the initial steady state is restored.

(Embodiment of the Third Invention) FIG. 6 is a block diagram showing an operation flow of the third invention, and FIG. 7 is a graph showing an outline of the operation. In the third invention as well, similarly to the second invention, a voltage upper limit value and a voltage lower limit value are set for the system voltage. When the system voltage is within the range not exceeding the voltage upper limit value and the voltage lower limit value, the normal voltage constant control is performed by the reactive power compensator 3 as in the related art. However, when the system voltage exceeds the voltage upper limit or the voltage lower limit, the set voltage of the reactive power compensator 3 is changed to the voltage upper limit and the voltage lower limit closer to the system voltage, and the reactive power compensator 3 The constant voltage control is performed.

That is, when the system voltage exceeds the voltage upper limit, the set voltage of the reactive power compensator 3 is changed to the voltage upper limit, and when the system voltage becomes lower than the voltage lower limit, After the set voltage is changed to the lower voltage limit, the reactive power compensator 3 is caused to perform constant voltage control. As a result, a margin of output is generated in the reactive power compensator 3, and it becomes possible to cope with a steep voltage fluctuation. After the operation time of about 60 to 120 seconds elapses, the tap of the automatic voltage regulator 1 is switched, and the system voltage approaches the initial set voltage, so that the reactive power compensator 3 has more tolerance.

(Embodiment of the Fourth Invention) FIG. 8 is a block diagram showing an operation flow of the fourth invention, and FIG. 9 is a graph showing an outline of the operation. In the fourth invention, the average value of the output of the reactive power compensator 3 within the sampling time is calculated while causing the reactive power compensator 3 to perform the normal voltage constant control. In this example, when the average value of the output of the reactive power compensator 3 exceeds 100 kVar, the set voltage (control voltage value) is increased stepwise by 50 V, and conversely, the average of the output of the reactive power compensator 3 If the value exceeds -100 kVar,
The set voltage (control voltage value) is reduced stepwise by 50 V, and the reactive power compensator 3 is caused to perform constant voltage control.

As described above, by changing the set voltage (control voltage value) in small increments according to the average value of the output of the reactive power compensating device 3, the output of the reactive power compensating device 3 has a margin, and the steep voltage It can respond to fluctuations. Also in the fourth invention, the tap of the automatic voltage regulator 1 is switched after the operation time of about 60 to 120 seconds elapses, and the system voltage approaches the initial set voltage as in the other inventions.

[0026]

As described above, according to these inventions, the operating characteristics of the automatic voltage regulator and the operating characteristics of the reactive power compensator are skillfully combined so that the reactive power is always maintained even when the system voltage fluctuates. The compensator can be provided with a margin of output to cope with a steep voltage fluctuation. For this reason, the conventional problem that the output of the reactive power compensator has no margin for compensating for the steady voltage fluctuation and the steep voltage fluctuation cannot be compensated without increasing the size of the reactive power compensator. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a power system including an automatic voltage regulator and a reactive power compensator.

FIG. 2 is a block diagram showing an operation flow of the first invention.

FIG. 3 is a graph showing an outline of the operation of the first invention.

FIG. 4 is a block diagram showing an operation flow of the second invention.

FIG. 5 is a graph showing an operation outline of the second invention.

FIG. 6 is a block diagram showing an operation flow of the third invention.

FIG. 7 is a graph showing an outline of the operation of the third invention.

FIG. 8 is a block diagram showing an operation flow of the fourth invention.

FIG. 9 is a graph showing an outline of the operation of the fourth invention.

FIG. 10 is a circuit configuration diagram of an automatic voltage regulator.

FIG. 11 is a circuit configuration diagram of a reactive power compensator.

FIG. 12 is a graph showing an outline of a conventional operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Automatic voltage regulator (SVR) 2 Transformer 3 Reactive power compensator (SVG) 4 Inverter 5 Capacitor 6 Transformer 7 Control circuit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasutomi Toyoda 2-56, Suda-cho, Mizuho-ku, Nagoya-shi, Aichi Japan Inside Nihon Insulators Co., Ltd. (72) Inventor Yuji Sasaki 4-23-6, Fukui, Nishi-ku, Sapporo, Hokkaido (72) Inventor Takahiko Yoshida 2-6-12-302 Atsubetsu-minami, Atsetsu-ku, Sapporo, Hokkaido F-term (reference) 5G066 DA04 DA08 FA01 FB13 FC11 5H420 BB02 BB12 BB13 BB16 CC04 DD03 EA10 EA27 EA30 FF03 LL01 NB04 NE13

Claims (4)

[Claims] 1. A method for controlling a reactive power compensator connected to a power system including an automatic voltage regulator, wherein a range in which the reactive power compensator can output is divided into a fixed region and a variable region, Normal voltage constant control is performed for fluctuations that can be handled in the fixed area, and voltage constant control is performed instantaneously in the fluctuation area for steep changes that cannot be handled in the fixed area, and thereafter disabled. A control method for a reactive power compensator, wherein the output of the power compensator is gradually reduced to a fixed region. 2. A control method for a reactive power compensator connected to a power system having an automatic voltage regulator, wherein a system voltage is set to a voltage upper limit value and a voltage lower limit value. When the voltage is outside the range, the voltage is controlled by the automatic voltage regulator, and when the system voltage deviates from this range, the reactive power compensator also performs the voltage constant control. A control method for the compensator. 3. A method of controlling a reactive power compensator connected to a power system having an automatic voltage regulator, wherein a system voltage is set to a voltage upper limit value and a voltage lower limit value, and When the system voltage is out of this range, the set voltage of the reactive power compensator is changed from the upper voltage limit to the lower voltage limit. A method for controlling a reactive power compensator, wherein the method is changed to a side closer to the system voltage to cause the reactive power compensator to perform constant voltage control. 4. A method for controlling a reactive power compensator connected to a power system having an automatic voltage regulator, wherein a set voltage is changed stepwise according to an average value of an output of the reactive power compensator. And controlling the reactive power compensator to perform constant voltage control.