JPH05328612A - Noninterruption breaker in private power generation equipment with parallel input to utility distribution line - Google Patents

Abstract

PURPOSE:To give no influence of voltage fluctuation on any load in a private power generation side by shortening a system separation time at the time of an accident. CONSTITUTION:An utility side private distribution line (a) and a private power generation side distribution line (b) are connected by a GTO switch GS, to also measure power supplied from a private power generation side to the utility side private distribution line, and a reverse current detecting circuit 6, which outputs a gate off command of the GTO switch when this reverse current power exceeds a preset reference power value, is provided to make a line separation by turning off the GTO switch before the voltage of a generator drops when an utility side accident occurs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-instantaneous interruption selective cutoff device for a private power generation facility that is also installed in a general distribution line for protecting an important load from overload and voltage drop of the private power generation facility at the time of power failure of the system. Regarding

[0002]

2. Description of the Related Art Conventionally, the non-interruptive selective cut-off method of a private power generation facility that is also included in a general distribution line is, as shown in FIG. 5, a system connected to a distribution line A through a power receiving breaker CB _a. 3 between the local distribution line a and the private power generation side distribution line b connected to the generator G of the private power generation facility B via the circuit breaker CB _b
A vacuum breaker VCB for cycle breaking is provided.

However, under normal conditions, when the system power and the privately-generated power are supplied to the loads L ₁ and L ₂ connected to the distribution lines a and b, and the system power supply fails, a vacuum breaker for interconnection is provided. In order to prevent the private generator G from being overloaded by supplying power to all loads of the line interconnected from the private generator G via the VCB, the interconnecting vacuum breaker VCB is cut off. ..

This non-instantaneous interruption selection method takes about 2.5 seconds until the protection relay (not shown) operates and the interconnection vacuum breaker VCB shuts off (protection relay operation time about 0.2 seconds + interconnection). The circuit breaker operating time is 0.05 seconds), and during that time, the private generator G bears the full load of the interconnection line, and the voltage of the private generator G follows the locus shown by the curve A in FIG. , Unable to supply a stable voltage to important loads.

Therefore, the present applicant first used a thyristor switch as the interconnection breaker, and detected that the power supplied from the private power generation side to the grid side distribution line exceeded the reference power set value. We have proposed a non-instantaneous interruption selective cutoff device that is equipped with a backflow detection circuit that outputs a switch gate-off command and can disconnect the system within half a cycle after the backflow detection.
(Japanese Patent Application No. 3-4406) This non-instantaneous interruption selection interruption device will be described with reference to FIG.

In FIG. 6, SW _TH is an interconnection thyristor switch composed of an antiparallel circuit of a thyristor which interconnects the distribution line a on the system side and the distribution line b on the private power generation side, and 2 is connected in series with the thyristor switch TS. The backup circuit breaker, 3 is an interconnection backup circuit breaker that is connected in parallel with the thyristor switch TS, 4 is a system power supply voltage detection transformer, and 5 is a current detection current transformer that detects the current of the thyristor switch TS.

As shown in FIG. 7, reference numeral 6 denotes a power operation circuit for calculating the power P from the voltage and current of the transformer 4 and the current transformer 5 and the power P and the reference setting signal P _s are compared to output a gate-off command. Backflow detector consisting of a comparator circuit for

Reference numeral 9 denotes a thyristor gate circuit which controls the opening and closing of the thyristor switch TS in response to a gate-off command of the backflow detector 6 and a manual or distant on / off command.

However, the non-instantaneous interruption selection interruption device is
When the thyristor switch TS is on, an accident occurs on the grid side, the electric power P is supplied from the private generator G to all loads connected to the grid side distribution line on the grid side, and the electric power P exceeds the reference power equipment value P _s . Then, a gate-off command is issued from the backflow detector 6 to turn off the thyristor switch TS, and the system side from the power generation side distribution line b is solved.

[0010]

The non-instantaneous-interruption-selective interruption device using the thyristor switch does not turn off until the AC current crosses zero even if the gate is interrupted because the thyristor spontaneously extinguishes the gate.

For this reason, a system accident (blackout or momentary voltage drop)
If the detection takes about 10 ms including the confirmation time, the time from the occurrence of an accident until the thyristor switch turns off will be 20 ms (in the case of a 50 Hz system) in the worst case. In this case, the voltage of the private generator 4 passes through the locus indicated by the curve B in FIG. 4, so that if the important load to be protected is the power electronics application variable speed motor, the device will be stopped and other effects will occur. In order to eliminate the influence of the voltage drop on all loads, the moment of inertia GD ² of the engine that drives the generator must be increased.

The present invention has been made in view of the above problems of the prior art, and the purpose thereof is that the time from the occurrence of an accident to the disconnection of the system is almost the time required for the accident detection. Another object of the present invention is to provide a non-instantaneous-interruption-selective interruption device for a private power generation facility that is combined with a general distribution line and does not affect any load connected to the distribution line on the private power generation side.

[0013]

In order to achieve the above-mentioned object, a non-instantaneous interruption selective interruption device in a private power generation facility according to the present invention, which is included in a general distribution line, is a distribution line in a system side and a premises in a private generation side. In a private power generation facility interconnected with a distribution line by a grid breaker, the grid breaker is used as a GTO switch, and the power supplied from the private power generation side to the grid line is measured, and the power is measured. When the current exceeds the reference power set value, a backflow detection circuit for outputting a gate-off command for the GTO switch is provided.

The GTO switch is configured by connecting a plurality of anti-parallel circuits of the GTO having a reverse voltage blocking capability or an anti-parallel circuit of a GTO having no reverse voltage blocking capability and a forward diode in series, and providing a snubber circuit for each GTO. It is better to use the one that has been prepared.

The backflow detector is a power calculation circuit for calculating power from the voltage signal of the distribution line on the system side and the signal of the current flowing from the GTO switch to the distribution line on the system side, and an output signal of this power calculation circuit and a reference. It is preferable to use a comparison circuit that compares the set power value.

[0016]

[Function] When the GTO switch connects the grid distribution line on the system side and the distribution line on the private power generation side, the system power and private power are supplied to the load on the site.

In this state, if a power failure or an instantaneous voltage drop occurs on the grid side, the privately generated power is supplied to the grid side. The backflow detector constantly measures the electric power supplied to this system side, and when this electric power exceeds the reference power setting value, it outputs a gate-off command and shuts off the GTO switch instantaneously (several 10 μs).

Therefore, the time required to disconnect the system is only the operating time (about 10 ms) of the backflow detector, and the private generator can bear the load of the interconnected line when the system power fails or the voltage drops. Since it disappears, a stable voltage can be supplied to the important load connected to the private power generation side distribution line.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the circuit of a non-instantaneous interruption selection interruption device.
The same components as those shown in FIG. 6 of the related art are designated by the same reference numerals, and the duplicate description thereof will be omitted.

Referring to FIG. 1, this embodiment uses a GTO switch GS in place of the thyristor switch TS in the conventional device of FIG. As shown in FIG. 2, the GTO switch GS connects N anti-parallel circuits of GTO having reverse voltage blocking capability in series according to the circuit voltage, and connects a diode SD and a resistor R in parallel to each GTO. Capacitor C
In this example, a snubber circuit 11 formed by connecting in series is used.

When a GTO having no reverse blocking capability is used as the GTO, a forward diode D is connected in series with the GTO as shown in FIG. In addition,
2 and 3, GT indicates a gate circuit and TF indicates a gate transformer.

The GTO switch GS can cut off the current within several tens of μs by the reverse bias by the gate-off signal. Therefore, the time from the occurrence of an accident in the system to the disconnection of the system by the GTO switch GS is the reverse current detection circuit required for the accident detection. This is possible in 10 ms, which is approximately equal to the operating time of 6. Therefore, the voltage locus of the private power generator G can be guaranteed without affecting the voltage drop on all loads as shown by the curve C in FIG.

[0023]

Since the present invention is configured as described above, it has the following effects.

(1) Since the GTO switch can cut off the current within several tens of microseconds by the reverse bias by the gate-off signal, the time from the occurrence of an accident such as a power failure of the system to the disconnection of the system by the GTO switch is detected by the backflow detector. It is possible in 10 ms which is almost equal to the time.

(2) Therefore, the voltage locus at the time of system disconnection of the private generator does not affect the voltage drop to all loads. Therefore, it is no longer necessary to increase the moment of inertia of the engine that drives the generator, which was conventionally required to supply a stable voltage to the important load.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a non-instantaneous interruption selection interruption device according to an embodiment.

FIG. 2 is a circuit diagram showing a GTO switch.

FIG. 3 is a circuit diagram showing another GTO switch.

FIG. 4 is an explanatory diagram showing an example of influence of a momentary voltage drop of a load device.

FIG. 5 is a block circuit diagram showing a conventional hitless selective interruption device.

FIG. 6 is a block circuit diagram showing another conventional hitless selection device.

FIG. 7 is a block circuit diagram showing a backflow detector.

[Explanation of symbols]

GS ... GTO switch, TS ... thyristor switch, G
T, 9 ... Gate circuit, 2, 3 ... Backup switch, 4 ... Voltage detection transformer, 5 ... Current detection current transformer, 6
... Backflow detection circuit, 7 ... Power calculation circuit, 8 ... Comparison circuit, 1
1 ... Snubber circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Kataoka 2-1-117 Osaki, Shinagawa-ku, Tokyo Stock company inside the company Meidensha (72) Inventor Yasunobu Yanagisawa 2-1-117 Osaki, Shinagawa-ku Tokyo Shameidensha (72) Inventor Toshiyuki Furuguchi 2-17 Osaki, Shinagawa-ku, Tokyo Stock company Shameidensha

Claims (4)

[Claims] Claim: What is claimed is: 1. In a private power generation facility in which a grid side distribution line and a private power generation side distribution line are interconnected by a grid breaker, the grid breaker is a GTO switch, and the grid is connected from the private power generation side. Measure the power supplied to the side distribution line,
A backflow detection circuit that outputs a gate-off command for the GTO switch when the power exceeds a reference power setting value is provided.
A non-instantaneous interruption selective interruption device in a private power generation facility that is inserted into a general distribution line, characterized in that the interconnection is instantaneously interrupted by an output signal of the backflow detection circuit. 2. A GTO switch, wherein a plurality of GTO antiparallel circuits having a reverse voltage blocking capability are connected in series, and each GTO switch is provided.
A non-instantaneous interruption selective interruption device in a private power generation facility that is inserted into a general distribution line according to claim 1, characterized in that a snubber circuit is provided in the TO. 3. A GTO switch, wherein a plurality of GTOs having no reverse voltage blocking capability and an anti-parallel circuit of a series circuit of a forward diode are connected in series, and a snubber circuit is provided in each GTO. A non-instantaneous interruption selective interruption device in a private power generation facility that is also included in the general distribution line according to Item 1. 4. A power calculation circuit for a backflow detector to calculate power from a voltage signal of a distribution line on the system side and a signal of a current flowing from a GTO switch to a distribution line on the system side, an output signal of the power calculation circuit and a reference setting. A non-instantaneous interruption selective interruption device in a private power generation facility, which is also included in a general distribution line according to any one of claims 1 to 3, comprising a comparison circuit for comparing the electric power value.