JP5084645B2 - Phase control switchgear - Google Patents

Description

  The present invention provides a circuit breaker switching operation that is severe for a power transmission and transformation device connected to an AC power system when power is supplied to a phased load circuit such as an unloaded transmission line via a circuit breaker. The present invention relates to a phase control switching device that performs control so as to suppress a transient voltage and current associated with.

  Conventionally, when power is applied to a three-phase unloaded transmission line, the voltage on the bus side of each phase of the circuit breaker provided between the bus line connected to the power source and the transmission line is measured, Phase control that suppresses transient voltage and current by detecting the zero point of the voltage on the bus side for each phase and individually turning on the breaker for each phase near the zero point of the voltage on the bus side There is a switchgear.

No. 00/004564 (Pages 29-30, FIG. 1, FIG. 2, FIG. 3)

  When a phase advance load circuit such as an unloaded transmission line (hereinafter referred to as an unloaded transmission line) is interrupted, a DC voltage with a polarity corresponding to the phase of the voltage on the bus side of the circuit breaker at the moment of interruption is transmitted. By remaining in the electric wire (hereinafter referred to as “residual voltage”), a voltage waveform is generated between the AC voltage supplied from the power source and the DC residual voltage of the transmission line between the breaker poles. This residual voltage is discharged with a decay time constant of several seconds to several hundred seconds determined by the ground capacitance of the transmission line and the leakage resistance of the transmission line support insulator. For this reason, when the time from when the no-load transmission line is cut off until the next turn-on is sufficiently long, this residual voltage becomes almost zero, and the turning-on of the breaker is controlled by focusing only on the voltage on the conventional bus side. Transient voltage and current could be suppressed even with the phase control switchgear.

  However, in the circuit breaker connected to the power transmission line, there is a case where the time interval from the time of breaking to the next turning-on is performed at a high speed switching operation as short as, for example, about 0.3 seconds, and only the voltage on the conventional bus side is used. In the phase control switchgear that controls the closing phase of the circuit breaker by paying attention, the absolute value of the residual voltage on the transmission line side is high immediately after the absolute value of the AC voltage supplied from the power supply is opened in a high phase. When the circuit breaker is turned on in a state, there is a problem that the transient voltage and current generated by the potential difference between the poles of the circuit breaker cannot be suppressed.

  The present invention has been made in view of the above, and is a phase control open / close control that effectively suppresses transient voltage and current associated with power-on of a phased load circuit such as a no-load transmission line An object is to provide an apparatus.

  In order to solve the above-described problems and achieve the object, a phase control switchgear according to the present invention closes a three-phase switchgear connected between a no-load transmission line and a bus to which power from a power source is supplied. In the phase control device for controlling the pole phase, an inter-electrode capacitor connected in parallel to both ends of each contactor constituting the three-phase switchgear and a current measurement for measuring the current flowing through the inter-electrode capacitor for each phase Unit, a circuit breaker electrode voltage calculation unit for obtaining a circuit breaker electrode voltage for each phase by integrating the current measured by the current measuring unit, and a circuit breaker obtained by the circuit breaker electrode voltage calculation unit Obtain the time constant of the DC component of the breaker pole voltage from the breaker pole voltage to predict the breaker pole voltage waveform for each phase at the previous time. At each period, the voltage waveform between the circuit breakers and the circuit breaker overload The time at which the dielectric strength change rate characteristic line at the point of time intersects at the lowest voltage after a predetermined input time and a predetermined closing time elapses in response to the input command. And a control unit that calculates and controls the insertion of the circuit breaker for each phase.

  According to the phase control switchgear according to the present invention, the interelectrode capacitor current flowing in the interelectrode capacitor connected in parallel with the circuit breaker is measured, and the circuit breaker interelectrode voltage obtained by time integration of the interelectrode capacitor current is measured. Then, by calculating the decay time constant of the DC component of the breaker pole voltage, the breaker pole voltage waveform after opening the breaker is predicted, and the breaker closure is Since the time at which the inter-layer dielectric strength change rate characteristic line in the pole process intersects at the lowest voltage is calculated and the circuit breaker is always turned on when the voltage between the circuit breakers is low, no load transmission is performed. There is an effect that it becomes possible to suppress a transient voltage and current when the circuit breaker is turned on in the high-speed switching operation of the electric wire.

  Preferred embodiments of a phase control switch according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the following embodiments.

Embodiment (main part of the present invention)
An object of this invention is to provide the phase control switchgear which can suppress the transient voltage and electric current by throwing in the circuit breaker of a no-load power transmission line. In the circuit breaker closing process, the dielectric strength between the electrodes decreases as the distance between the contacts decreases.When this dielectric strength falls below the electric field value due to the system voltage applied between the contacts, Thus, a leading arc is generated due to a dielectric breakdown between the contacts of the contact and is turned on electrically. Since the change in the contact distance between contacts is determined by the switching pole operating time of the circuit breaker, it is evaluated by a mechanical property test, and the dielectric strength between the contact poles is determined by the voltage applied between the contact poles and the contact It is determined by the electrical characteristic test because it is determined by the distance between the electrodes. From these mechanical characteristic test and electrical characteristic test, the inter-dielectric strength change rate characteristic line specific to each breaker in the closing process of the breaker is obtained. The main part of the present invention is to control the circuit breaker closing operation from the inter-layer dielectric strength change rate characteristic line in the circuit closing process of the circuit breaker and the voltage waveform between circuit breakers after circuit breaker opening. The circuit breaker can always be turned on when the voltage across the circuit breaker is low.

(Device configuration)
FIG. 1 is a block diagram for explaining a preferred embodiment of a phase control switching apparatus according to the present invention. In FIG. 1, a circuit breaker 1 that is a three-phase switchgear includes a power supply side circuit shown on the left side of the figure and a phase-advancing load 1R, 1S, 1T such as an unloaded transmission line shown on the right side of the figure. Connected between and. The circuit breaker 1 includes contacts 2R, 2S, and 2T that can be opened and closed independently for each phase. Capacitors 3R, 3S, and 3T are connected in parallel to the contacts 2R, 2S, and 2T, respectively. Current measuring units 4R, 4S, and 4T that continuously measure are provided.

  Moreover, the circuit breaker pole voltage calculation part 5 which integrates the measured value of current measuring part 4R, 4S, 4T and calculates | requires the pole voltage of the contacts 2R, 2S, 2T of the circuit breaker 1, and circuit breaker pole voltage calculation Based on the output of the unit 5, the decay time constant of the DC component of the breaker pole voltage is obtained, and the voltage waveform between the breaker poles after the previous time, that is, after the breaker is opened, is predicted. And a control unit 6 for calculating a time at which the voltage waveform and the inter-dielectric strength change rate characteristic line in the closing process of the circuit breaker intersect at the lowest voltage and turning on the circuit breaker. The circuit breaker pole voltage calculation part 5 and the control part 6 can be comprised by a control processor, a computer, etc., for example.

(Device operation)
Next, the operation of the phase control switch shown in FIG. 1 will be described with reference to FIG. Here, FIG. 2 is a waveform diagram for explaining the operation of the phase control switching device. In the following description of the operation, first, the waveform diagrams shown in FIG. 2 will be described, and then the operation of the control unit 6 for determining the closing phase will be described based on the waveform diagrams of FIG. In addition, although the actual operation is performed for each phase, for simplification of description, only the operation for one phase (R phase) is described, and the description of the operation of the other phase is omitted.

  2 (a) to 2 (e) are diagrams showing examples of waveforms of the respective parts when the breaker 1 breaks current at a breaker current breaking point indicated by a broken line part. FIG. 2 (a) is a more detailed explanation. Is the power supply side voltage waveform, FIG. 2B is the transmission line side voltage waveform, and the residual voltage of the DC component after the circuit breaker is opened depends on, for example, the ground capacitance of the transmission line and the leakage resistance of the transmission line support insulator Discharging is performed with a decay time constant of several seconds to several hundred seconds determined. FIG. 2 (c) shows the circuit breaker current waveform flowing through the contact 2R of the circuit breaker 1, and FIG. 2 (d) shows the inter-electrode capacitor current flowing through the inter-electrode capacitor 3R output from the current measuring unit 4R. It is a waveform.

  FIG. 2 (e) is a waveform showing the absolute value of the voltage appearing between the electrodes after the circuit breaker 1 is interrupted, and the interelectrode capacitor current measured by the current measuring unit 4 </ b> R is used as the circuit breaker interelectrode voltage calculation unit. 5 is a voltage waveform between circuit breaker electrodes obtained by time integration in FIG. This inter-breaker voltage waveform indicates the absolute value of the difference between the AC voltage supplied from the power supply (see FIG. 2A) and the DC residual voltage of the transmission line (see FIG. 2B). ing. If the decay time constant of the residual voltage is obtained by the control unit 6, the voltage waveform between the circuit breakers at the previous time can be predicted.

  In the present embodiment, the voltage waveform between circuit breakers predicted by the control unit 6 and the dielectric strength change rate characteristic line between the circuit breakers in the closing process of the circuit breaker 1 are crossed at a single point within the same period. The operation of calculating the time at which the voltage crosses at the lowest voltage and performing the control as the target phase for closing the circuit breaker will be described.

  T1 to t8 shown on the waveform of FIG. 2 (e) are mechanical closing times at which the contact 2R of the circuit breaker 1 mechanically contacts. Further, straight lines 11 to 18 that extend from t1 to t8 in the upper left direction are inter-layer dielectric strength change rate characteristic lines in the closing process of the circuit breaker 1. That is, the inter-layer dielectric strength change rate characteristic line in the closing process of the circuit breaker 1 when the circuit breaker 1 is operated so as to be mechanically closed at t1 to t8, respectively. Therefore, A to H at which each of these straight lines intersects with the breaker pole voltage waveform is an electrical turn-on time for electrical contact before mechanical closing.

  In A to H, which are electrical turn-on times, the time on each horizontal axis indicates the time of the make-up phase when the contact 2R of the circuit breaker 1 is electrically closed, and the value on the vertical axis is It shows the magnitude of the applied voltage between the electrodes at which the insulation between the electrodes is broken. Since the magnitude of the voltage applied between the electrodes is an initial value of a transient phenomenon that is started by turning on the contact 2R of the circuit breaker 1, the larger the voltage between the electrodes, the greater the influence on the power system. Therefore, as shown in FIG. 2 (e), the voltage waveform between the breaker poles and the inter-layer dielectric strength change rate characteristic line in the closing process of the breaker 1 are crossed at a single point within the same period. Therefore, if the A to H crossing at the lowest voltage are set to the target phase for turning on the circuit breaker 1, the transient voltage and current when the circuit breaker 1 is turned on can be suppressed.

  It should be noted that a predetermined charging time is required from when the control unit 6 instructs to close the contact 2R of the circuit breaker 1 until the contact 2R is actually electrically turned on. A predetermined closing time is required until the contact 2R is actually mechanically closed after the contact 2R of the device 1 is instructed to close. For this reason, it is necessary for the control unit 6 to instruct the closing of the contact 2R of the circuit breaker 1 in consideration of the predetermined charging time and the predetermined closing time.

  In this way, the control unit 6 predicts the absolute value waveform of the voltage between the circuit breakers after the circuit breaker is opened, and shows the voltage characteristic between the circuit breaker electrodes and the rate of change in dielectric strength between the electrodes in the circuit breaker closing process. Of the circuit breaker 1 at the timing at which the circuit breaker 1 intersects at the lowest voltage after the passage of the predetermined closing time and the predetermined closing time in response to the breaker closing command from the timing of crossing at a single point within the same period. Control is performed so that the contact 2R is electrically charged. By performing such control, it becomes possible to always turn on the circuit breaker 1 at a timing when the voltage across the circuit breaker is low, so that the effect of suppressing transient voltage and current when the circuit breaker is turned on is obtained. It is done.

  As described above, according to the phase control switching device of this embodiment, the inter-capacitor capacitor current flowing in the inter-capacitor capacitor connected in parallel with the circuit breaker is measured, and the inter-capacitor capacitor current is obtained by time integration. By calculating the decay time constant of the DC component of the breaker pole voltage from the breaker pole voltage, the breaker pole voltage waveform after opening the breaker is predicted, and one cycle of the breaker pole voltage waveform Every time, it calculates the time when it intersects the dielectric strength change rate characteristic curve between the circuit breakers at the lowest voltage in the closing process of the circuit breaker, and always controls the circuit breaker to be turned on when the voltage between the circuit breakers is low. Therefore, it is possible to suppress transient voltage and current when the circuit breaker is turned on in the high-speed switching operation of the no-load transmission line.

  As described above, the phase control switchgear according to the present invention is useful as an invention that can effectively suppress a transient voltage and current associated with power-on of a phase-advancing load circuit such as a no-load transmission line. is there.

It is a block diagram for describing a preferred embodiment of a phase control switching device according to the present invention. It is a wave form diagram for demonstrating operation | movement of the phase control apparatus shown in FIG.

Explanation of symbols

1R, 1S, 1T Phase advance load 1 Circuit breaker 2R, 2S, 2T Contactor 3R, 3S, 3T Capacitor 4R, 4S, 4T Current measurement unit 5 Circuit breaker voltage calculation unit 6 Control unit

Claims (2)

In the phase control switchgear that controls the closing phase of the three-phase switchgear connected between the no-load power transmission line and the bus supplied with power from the power source,
An inter-electrode capacitor connected in parallel to both ends of each contactor constituting the three-phase switchgear,
A current measuring unit for measuring the current flowing through the inter-electrode capacitor for each phase;
A circuit breaker inter-electrode voltage calculation unit for integrating the current measured by the current measuring unit over time to obtain a circuit breaker inter-electrode voltage for each phase;
From the circuit breaker electrode voltage obtained by the circuit breaker electrode voltage calculation unit, the circuit breaker electrode voltage waveform for each phase at the previous time is predicted, and one cycle of the circuit breaker electrode voltage waveform for each phase Each time, the voltage waveform between the circuit breakers and the characteristic line of change in dielectric strength in the circuit breaker closing process intersect at a single point within the same period. And a control unit that calculates the time of crossing at the lowest voltage after a predetermined closing time has elapsed and controls the insertion of the circuit breaker for each phase;
A phase control switchgear characterized by comprising: The phase-controlled switchgear according to claim 1, wherein the breaker-pole voltage waveform is predicted based on a decay time constant of a DC component of the breaker-pole voltage.

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