JP3343711B2 - Static var compensator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static var compensator for controlling a power factor or a reactive power of a distribution line or a transmission line.

[0002]

2. Description of the Related Art In recent years, various types of electric equipment have been used, so that it has become increasingly important to improve the power factor of a distribution line or a transmission line.

Hereinafter, a conventional reactive power compensator will be described with reference to the drawings. FIG. 7 is a block diagram showing a configuration of a conventional reactive power compensation device. A static reactive power compensator is used to reduce the power loss of the distribution line or transmission line, and the reactive power output is controlled to reduce the power factor of the distribution line or transmission line to around 1 or to reduce the reactive power to around zero. It is controlled to keep. In FIG. 7, 1 is a distribution line or a transmission line, 2 is a plurality of reactors, a plurality of capacitors, and 1
A main circuit for generating a reactive power from a lead to a delay by controlling the conduction angle of the thyristor; And 4 is a second current transformer for detecting the current flowing in the distribution line or the transmission line 1 together with the phase, 5 is the target value of the power factor or reactive power of the distribution line or the transmission line 1 Is set by calculating the power factor or the reactive power of the distribution line or the transmission line 1 and controls the reactive power generated by the main circuit 2 so that the value becomes the target value. Control means.

In the above configuration, the control means 6 controls the distribution line or the transmission line 1 based on the output of the transformer 3 inserted into the distribution line or the transmission line 1 and the output of the second current transformer 4. By calculating the power factor or the reactive power and controlling the conduction angle of the thyristor so that the value becomes the target value setting means, the power factor of the distribution line or the transmission line 1 is kept close to 1,
The power loss of the distribution line or the transmission line 1 is suppressed.

[0005]

In such a conventional reactive power compensator, when the power flow direction is reversed in an actual distribution line or transmission line at the time of an accident, load interchange, or system change, etc. The rate or reactive power could not be controlled continuously.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a static var compensator capable of maintaining constant power factor or reactive power control even when the power flow direction changes.

[0007]

According to the present invention, there is provided a main circuit which is connected to a distribution line or a transmission line and generates reactive power from leading to delay, and detecting a voltage of the distribution line or the transmission line. A current transformer that detects an input current of the main circuit, and a second current transformer that is inserted into the distribution line or the transmission line closer to a power supply than a connection point of the main circuit. Comprising, based on the output of the second current transformer and the output of the transformer, detects the direction of the power flow of the distribution line or transmission line,
In the case of forward power flow, a power factor or reactive power is obtained from the output of the second current transformer and the output of the transformer, and in the case of reverse power flow, the output of the second current transformer is inverted. The power factor or reactive power is obtained from the output obtained by adding the output of the first current transformer to the output and the output of the transformer, and the main circuit is controlled so that the value becomes a target value. A static var compensator configured to constantly control the power factor or reactive power of the distribution line or the transmission line regardless of the power flow direction.

[0008] Thus, the power factor or the reactive power of the distribution line or the transmission line can be controlled to be constant regardless of the power flow direction. The present invention according to claim 2 is a main circuit that is connected to a distribution line or a transmission line and generates a reactive power delayed from a lead, a transformer that detects a voltage of the distribution line or the transmission line, and the main circuit. A first current transformer for detecting the input current of the second current transformer, and a second current transformer inserted into the distribution line or the transmission line on the load side of the connection point of the main circuit. The direction of the power flow of the distribution line or the transmission line is detected from the output of the current transformer and the output of the transformer, and in the case of the forward power flow, the first current transformer is output to the output of the second current transformer. The power factor or reactive power is obtained from the output obtained by adding the outputs of the above and the output of the transformer, and in the case of reverse power flow, the power is obtained by the inverted output of the output of the second current transformer and the output of the transformer. Rate or reactive power, and controlling the main circuit so that the value becomes a target value. Ri is a static var compensator in which the power factor or reactive power of the power distribution lines or transmission lines regardless of the flow direction so that constant control.

Thus, the power factor or the reactive power of the distribution line or the transmission line can be controlled to be constant regardless of the power flow direction.

[0010]

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 is a main circuit that is connected to a distribution line or a transmission line and generates reactive power from a lead to a delay, and detects a voltage of the distribution line or the transmission line. A transformer for detecting an input current of the main circuit;
Current transformer, a second current transformer inserted into the distribution line or the transmission line closer to a power source than a connection point of the main circuit, an output of the second current transformer, and an output of the transformer A power flow direction detecting means for detecting a power flow direction of the distribution line or the transmission line, a target value setting means for setting a power factor or a reactive power target value of the distribution line or the transmission line, The output of the current transformer and the output of the second current transformer are input, and the output of the second current transformer is output when the power flow direction is the forward direction, and the output of the second current transformer is output when the power flow direction is the reverse direction. Calculating means for calculating and outputting the sum of the inverted output of the polarity of the output of the second current transformer and the output of the first current transformer; and the output of the transformer and the output of the calculating means. Calculate the power factor or reactive power of the distribution line or transmission line, and the value matches the target value of the target value setting means. Control means for controlling the reactive power generated by the main circuit, the direction of the power flow is detected by the power flow direction detection means, and the control means controls the first current transformer in the case of a forward power flow. A power factor or reactive power is obtained from the output and the output of the transformer, and in the case of reverse power flow, an output obtained by adding the output of the first current transformer to the inverted output of the output of the second current transformer. And a power factor or reactive power obtained from the output of the transformer and controlling the main circuit so that the value becomes a target value set in the target value setting means. Alternatively, it is a static var compensator that controls the power factor or reactive power of the transmission line to a constant value. Also, the present invention according to claim 2 is a main circuit that is connected to a distribution line or a transmission line and generates a reactive power delayed from a lead, a transformer that detects a voltage of the distribution line or the transmission line, A first current transformer for detecting an input current of a circuit, a second current transformer inserted into the distribution line or the transmission line closer to a load than a connection point of the main circuit, and the second current transformer Direction detection means for detecting the direction of the power flow of the distribution line or transmission line based on the output of the transformer and the output of the transformer, and a target value for setting a target value of the power factor or reactive power of the distribution line or the transmission line Setting means for receiving an output of the first current transformer and an output of the second current transformer, wherein when the power flow direction is forward, the output of the second current transformer and the first And the output of the second current transformer is output when the power flow direction is the opposite direction. And a power factor or reactive power of the distribution line or the transmission line is calculated by the output of the transformer and the output of the calculation means, and the calculated value is the target of the target value setting means. Control means for controlling the reactive power generated by the main circuit so as to match the value, a direction of the power flow is detected by the power flow direction detection means, and the control means detects the second power flow in the case of a forward power flow. A power factor or reactive power is obtained from an output obtained by adding an output of the first current transformer to an output of the current transformer and an output of the transformer, and in the case of reverse power flow, the second current transformer The power factor or the reactive power is obtained from the inverted output of the output of the transformer and the output of the transformer, and the main circuit is controlled so that the value becomes the target value set in the target value setting means. Regardless of the power of the distribution line or transmission line Or static var compensator for constant control of the reactive power.

Hereinafter, embodiments of the present invention will be described. (Embodiment 1) An embodiment of a static var compensator according to the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing the configuration of the present embodiment. The same components as those in the conventional example shown in FIG. 7 are given the same numbers.

In the figure, 1 is a distribution line or a transmission line, 2
Is a main circuit consisting of a capacitor, a reactor, and a thyristor.When the thyristor is off, advanced reactive power by the capacitor is output, and as the conduction angle of the thyristor increases, the advanced reactive power decreases. Delay reactive power corresponding to the difference from the capacitor capacity is generated, and by controlling the conduction angle of the thyristor, the reactive power from advance to delay is continuously controlled. Reference numeral 7 denotes a first current transformer for detecting an input current of the static var compensator, 8 denotes a power flow direction detecting means, and a voltage and a current obtained from the second current transformer 4 and the transformer 3 To detect the power flow direction in the distribution line or transmission line 1. As a method of detecting the power flow direction, for example, the active power is calculated, and when the value is positive, it can be determined that the power flow is in the forward direction, and when the value is negative, it can be determined that the power flow is in the reverse direction, and the phase difference between the phase voltage and the current is ± 90
If it is within ± °, it can be determined that the current is in the forward direction. The power flow direction may be detected by another method. Numeral 9 denotes a calculating means, which outputs the signal of the second current transformer 4 installed in the distribution line or the transmission line 1 to the control means 6 as it is when the tide is in the forward direction, and outputs the signal to the control means 6 in the reverse direction. In this case, the sum of the inverted signal of the second current transformer 4 and the signal of the first current transformer 7 is calculated and output to the control means 6.

In the above configuration, the power flow direction detecting means 8 detects whether the power flow direction is the forward direction or the reverse direction, and instructs the calculating means 9 and the control means 6. When the power flow direction is the forward direction, the arithmetic means 9 gives the output of the second current transformer 4 to the control means 6 as it is, so that the control means 6 The power factor or reactive power in the distribution line or the transmission line 1 is obtained from the output of the transformer 3 and the output of the transformer 3, and the main circuit 2 is controlled so that the power factor or the reactive power becomes the target value set in the target value setting means 5. When the power flow direction is reverse, the calculating means 9 adds the inverted output of the second current transformer 4 and the output of the first current transformer 7 to obtain the current on the power supply side during the reverse power flow. The control unit 6 outputs the power factor or the reactive power at the time of reverse power flow, and determines the power factor or the reactive power of the main circuit 2 so as to reach the target value of the power factor or the reactive power set by the target value setting unit 5. Control the thyristor.

In this embodiment, FIG. 1 shows the case of a single-phase AC distribution line. However, in a three-phase AC distribution line or a transmission line, the power factor or the reactive power is controlled by using the same configuration for each phase. It goes without saying that it can be controlled. FIG.
As shown in (1), the main circuit 2 may include a reactor in series with a parallel circuit of a capacitor circuit and a thyristor circuit. Further, a photocurrent sensor may be used as a current transformer attached to the distribution line or the transmission line 1. The use of a photocurrent sensor is very advantageous in terms of the construction method because it is not necessary to cut the electric wire.

An embodiment of the static var compensator according to the present invention will be described below with reference to FIG. The same components as those in FIG. 1 are denoted by the same reference numerals , and description thereof will be omitted. The present invention according to claim 1 is different from the present invention in that the second current transformer 4 of the distribution line or the transmission line 1 is installed on the load side, and the calculating means 9 uses the second current transformer when the power flow is in the forward direction. And outputs the sum of the signal of the current transformer 4 and the signal of the first current transformer 7 for detecting the input current of the static reactive power compensator to the control means 6, and in the case of reverse power flow, the second current transformer 4 Is output to the control means 6. In this case, the output of the second current transformer 4 is based on the output polarity at the time of forward power flow.

In the above configuration, the power flow direction detecting means 8
Detects the direction of the tidal current as in the first embodiment, and instructs the calculating means 9 and the control means 6. In the case of a forward power flow, the calculating means 9 calculates the sum of the output of the second current transformer 4 and the output of the first current transformer 7 to thereby supply the current during the forward power flow to the control means 6. Then, the control means 6 obtains a power factor or a reactive power from the voltage output of the transformer 3 and the current, and controls the thyristor of the main circuit 2 so as to reach the target value set in the target setting means 5. In the case of a reverse power flow, the calculating means 9 outputs the current at the time of the reverse power flow to the control means 6 based on the inverted signal of the second current transformer 4. The control means 6 determines the power factor or the reactive power based on the current and the voltage output of the transformer 3, and controls the thyristor of the main circuit 2 so as to reach the target value of the power factor or the reactive power set in the target value setting means 5. Control.

In this embodiment, FIG. 2 shows a case of a single-phase AC distribution line, but in a three-phase AC distribution line or a transmission line, a power factor or a reactive power It goes without saying that it can be controlled. FIG.
As shown in (1), the main circuit 2 may include a reactor in series with a parallel circuit of a capacitor circuit and a thyristor circuit. Further, a photocurrent sensor may be used as a current transformer attached to the distribution line or the transmission line 1.

Reference Example Hereinafter, a reference example of the static var compensator according to the present invention will be described with reference to the drawings. FIG. 3 is a block diagram showing the configuration of the present reference example . 1 and 2
The same reference numerals are given to the same components as those described above, and the description is omitted. This reference example is different from the first and second embodiments in that the distribution line or the transmission line 1 is provided with the second current transformer 4 on the power supply side and the first current transformer 7 on the load side. Static reactive power
It is not installed on the input line of the compensator , and the calculating means 9 outputs the signal of the second current transformer 4 on the power supply side to the control means 6 when the power flow is in the forward direction, and outputs the load when the power flow is in the reverse direction. Since the signal of the first current transformer 7 on the side is output to the control means 6, only the output switching operation of the second current transformer 4 and the first current transformer 7 is performed.

In the above configuration, the power flow direction detecting means 8
Detects the direction of the tidal current and instructs the arithmetic means 9 and the control means 6 as in the first embodiment. The control means 6 controls the output of the second current transformer 4 and the output of the transformer 3 in the case of forward power flow, and the first current transformer 7 in the case of reverse power flow.
The power factor or the reactive power is obtained from the output of the transformer 3 and the power factor or the reactive power, respectively, and the thyristor of the main circuit 2 is controlled so that the target value of the power factor or the reactive power set by the target value setting means 5 is obtained.

In this embodiment , FIG. 3 shows the case of a single-phase AC distribution line, but in the case of a three-phase AC distribution line or a transmission line, the power factor or the reactive power It goes without saying that it can be controlled. Further, as shown in FIG. 6, the main circuit 2 may include a reactor in series with a parallel circuit of a capacitor circuit and a thyristor circuit. Further, a photocurrent sensor may be used as a current transformer attached to the distribution line or the transmission line 1.

[0022]

As is apparent from the above description, the power factor or the reactive power control can be continuously controlled even if the direction of the power flow in the distribution line or the transmission line changes. Also,
If the current transformer is realized by a photocurrent sensor, there is no need to cut the electric wire, which is very advantageous in terms of the construction method.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of an embodiment of a static var compensator of the present invention according to claim 1;

FIG. 2 is a circuit diagram showing a configuration of an embodiment of a static var compensator of the present invention according to claim 2;

FIG. 3 is a reference relating to the static var compensator of the present invention .
Circuit diagram showing example configuration

FIG. 4 is a circuit diagram showing the configuration of another embodiment of the static var compensator of the present invention according to claim 1;

FIG. 5 is a circuit diagram showing the configuration of another embodiment of the static var compensator of the present invention according to claim 2;

FIG. 6 is a reference relating to the static var compensator of the present invention .
Circuit diagram showing another configuration of the example

FIG. 7 is a circuit diagram showing a configuration of a conventional static var compensator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Distribution line or transmission line 2 Main circuit 3 Transformer 4 Second current transformer 5 Target value setting means 6 Control means 7 First current transformer 8 Power flow direction detecting means 9 Computing means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02J 3/00-5/00 G05F 1/70

Claims (5)

(57) [Claims] 1. A main circuit that is connected to a distribution line or a transmission line and generates reactive power from leading to lag, a transformer that detects a voltage of the distribution line or a transmission line, and detects an input current of the main circuit. And a second current transformer inserted into the distribution line or the transmission line closer to a power source than a connection point of the main circuit.
Current transformer, power flow direction detecting means for detecting the direction of the power flow in the distribution line or the transmission line based on the output of the second current transformer and the output of the transformer, and the power of the distribution line or the transmission line. A target value setting means for setting a target value of a rate or a reactive power; inputting an output of the first current transformer and an output of the second current transformer; Outputting the output of the second current transformer, and calculating the sum of the inverted output of the polarity of the output of the second current transformer and the output of the first current transformer when the power flow direction is reverse. And calculating the power factor or reactive power of the distribution line or the transmission line based on the output of the transformer and the output of the calculation means, and the value matches the target value of the target value setting means. Control means for controlling the reactive power generated by the main circuit, the power flow direction detecting means More detecting the direction of power flow, control means, in the case of forward power flow determined power factor or reactive power by the output of the transformer and the output of the second current transformer,
In the case of reverse power flow, a power factor or reactive power is obtained from an output obtained by adding the output of the first current transformer to an inverted output of the output of the second current transformer and the output of the transformer, and By controlling the main circuit so that the value becomes a target value set in the target value setting means, a static reactive type that constantly controls the power factor or reactive power of the distribution line or the transmission line regardless of the power flow direction. Power compensator. 2. A main circuit which is connected to a distribution line or a transmission line and generates a reactive power from a lead to a delay, a transformer which detects a voltage of the distribution line or a transmission line, and which detects an input current of the main circuit. A first current transformer, and a second current transformer inserted into the distribution line or the transmission line on a load side of a connection point of the main circuit.
Current transformer, power flow direction detecting means for detecting the direction of the power flow in the distribution line or the transmission line based on the output of the second current transformer and the output of the transformer, and the power of the distribution line or the transmission line. A target value setting means for setting a target value of a rate or a reactive power; inputting an output of the first current transformer and an output of the second current transformer; Outputting the sum of the output of the second current transformer and the output of the first current transformer, and outputting an inverted signal of the polarity of the output of the second current transformer when the power flow direction is the opposite direction; Calculating means, and the power factor or reactive power of the distribution line or the transmission line is calculated by the output of the transformer and the output of the calculating means, so that the value matches the target value of the target value setting means. Control means for controlling the reactive power generated by the main circuit; Detecting the direction and control means,
In the case of a forward power flow, a power factor or reactive power is obtained from an output obtained by adding an output of the first current transformer to an output of the second current transformer and an output of the transformer, and obtains a power factor or reactive power by the output of the transformer and the inverted output of the output of the second current transformer when the main so that the target value the value is set to the target value setting means A static var compensator that controls a circuit to constantly control the power factor or the reactive power of the distribution line or the transmission line regardless of the power flow direction. 3. The first reactor and the first capacitor
Series circuit and one or more second reactors
Parallel the second series circuit with the anti-parallel circuit of the thyristors in the row
Connected to each other, and by controlling the conduction angle of the thyristor.
Equipped with a main circuit that generates reactive power from advance to delay
The static var compensator according to claim 1 or claim 2 . 4. A method according to claim 3, wherein the third reactor and the second capacitor
A third series circuit comprising the fourth reactor and one or more
Consists of an anti-parallel circuit of a plurality of thyristors in series.
The fifth reactor is connected in series to the parallel circuit with the series circuit.
From the advance due to the conduction angle of the thyristor.
And a main circuit for generating the reactive power up to that time.
A static var compensator according to claim 2 . 5. A first current transformer and a second current transformer by a photocurrent sensor.
Contractors that constitute one or both of the current transformers
The static var compensator according to any one of claims 1 to 4 .