JP2009027802A - Surge absorber with measuring function, transformer for instrument, power facility, and protection method for power facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surge absorber with a measuring function improved in economic property and space property without installing an independent transformer for instrumentation when a transformer for instrumentation is required for monitoring or protection at a portion equipped with a surge absorber as a countermeasure against lightning discharge for power facilities. <P>SOLUTION: The surge absorber with the measuring function comprises a voltage dividing means 2 for dividing the AC voltage applied to the surge absorber by dividing the capacitance value of the surge absorber, a voltage dividing terminal 2a for taking out the divided voltage divided by the voltage dividing means 2, and a transformer 3 for an instrument connected to the voltage dividing terminal 2a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improved technique for a surge absorber that protects power equipment from lightning surges, and more particularly, a surge absorber with a measurement function that can monitor the voltage on the secondary side of a power transformer at low cost by using the surge absorber. The present invention relates to an instrument transformer, power equipment, and a method for protecting power equipment.

  In FIG. 7, the basic composition of the conventional electric power equipment 9 is shown. In this figure, a power supply 20 is connected to a power supply line (bus line) 10 via a circuit breaker 30. The power source 20 may be owned by the site or may be transmitted from another power generation / substation. The power facility 9 collects electrical data such as the power line 10, the circuit breaker 30, and the power source 20, the surge absorber 2X that is connected to the power line 10 and protects the facility from lightning, and the voltage of the power line. Instrument transformer 3X, a voltmeter 50 connected thereto, and various protective relays 41 and 42, and the like. The configuration of the power equipment is not limited to that shown in FIG. 7. For example, a capacitor-type surge absorber 2X and an instrument transformer (hereinafter abbreviated as PT) 3X of the power equipment are separately provided at necessary places.

  Here, since PT3X is relatively expensive and has a large size, the places to be equipped are limited. For this reason, as shown in FIG. 8, the secondary side circuit breaker 32 is inserted between the secondary winding B of the power transformer 60 in the distribution substation and the bus 10 of the distribution line, and the secondary side interruption is performed. In general, only the surge absorber 2X is installed between the voltage transformer 32 and the power transformer 60, and no PT is installed.

  In the equipment configuration of FIG. 8, for example, when a ground fault occurs in the bus 10, the ground fault overvoltage protection relays 41 and 42 via the PT 3 </ b> X installed in the bus 10 open the secondary circuit breaker 32. Since normality / abnormality cannot be determined between the 60 secondary winding B and the secondary circuit breaker 32, the primary circuit breaker 31 is tripped instead of the secondary circuit breaker 32 to avoid an accident. For this reason, the protective relay 41 or 42 causes a power failure to the circuit of the tertiary winding C of the transformer 60.

  In addition, as described above, it is impossible to identify a bus accident or an accident higher than the secondary circuit breaker 32, and the recovery work becomes complicated.

  As another example, in a two-bank type general distribution substation having two transformers 60a and 60b as shown in FIG. 9, there is a problem in the maintenance and inspection of the single transformer 60b. Is described below.

  First, as a preliminary work for maintaining and inspecting the transformer 60b, the bus 10b of the system to be inspected and connected is connected by turning on the bus 10a and the contact breaker 31c in order to continue operation without causing a power failure. Thereafter, in the one-system transformer 60b, the primary and secondary circuit breakers 31b and 32b are opened, and maintenance and inspection are performed. As a procedure at the time of restoration, first, after the primary side circuit breaker 31b is turned on, the voltage on the secondary side B of the transformer 60b after maintenance and inspection is matched with the voltage of the distribution buses 10a and 10b in operation. The side circuit breaker 32b is turned on. At this time, since there is no means for measuring the voltage on the secondary side B of the transformer 60b, the operator examines the tap value of the operational transformer 60a and adjusts the tap of the transformer 60b after the operation to match the voltage. After adjusting, the circuit breaker 32b is turned on.

  Thus, unless an instrument transformer is provided between the transformer 60a or 60b and the secondary circuit breaker 32a or 32b, the voltage at this point cannot be measured directly. There is a problem that a troublesome method such as checking the tap value on the transformer side and matching the tap of the transformer after maintenance to that value must be taken.

  Patent Document 1 proposes a technique for measuring a zero-phase voltage between the grounds of power facilities. This Patent Document 1 proposes a technique for measuring a zero-phase voltage using a cylindrical capacitor equivalent wound around a power line, a detection capacitor inserted in series for extracting a voltage, and an auxiliary transformer.

However, this technology is an improved technology for conventional zero-phase instrument transformers, zero-phase instrument capacitors, etc., and is used to measure the voltage between the secondary winding of the transformer and the secondary circuit breaker in distribution substations. Since it is not a technology related to protection, the above problem cannot be solved.
JP 2000-77247 A

  The present invention has been made in view of the above-mentioned circumstances, and when an instrument transformer for monitoring or protection is required at a place equipped with a surge absorber as a lightning countermeasure for electric power equipment, it is for an independent instrument. An object is to provide a surge absorber with a measuring function, an instrument transformer, electric power equipment, and a protection method for electric power equipment which are improved in economy and space without being equipped with a transformer.

  In order to achieve the above object, a surge absorber with a measuring function according to the present invention is a surge absorber for electric power equipment, and the AC voltage applied to the surge absorber is divided by dividing the capacitance of the surge absorber. And a voltage dividing terminal for extracting the divided voltage divided by the voltage dividing means.

  In the present invention, in addition to the function of the conventional surge absorber, the voltage applied to the surge absorber is measured by providing voltage dividing means for dividing the AC voltage applied to the surge absorber to a value suitable for measurement. To do.

  Preferably, an insulating means such as an insulating transformer that insulates and outputs the AC voltage divided by the voltage dividing means may be provided. Since this insulation means may be a low voltage insulation transformer having a rating for the divided voltage, it can be realized at a lower cost than an instrument transformer connected to a power line.

  In addition, this invention is not limited to the name, For example, it can also be grasped | ascertained as an instrument transformer which has a function of a surge absorber. In addition, the output voltage can be further adjusted as an instrument transformer to enable measurement in an appropriate voltage range as well as the insulation, thereby facilitating setting when connecting a device such as a voltmeter or a protective relay.

  The voltage dividing means of the surge absorber with a measuring function according to the present invention has one end connected to each phase of the power line, the other end connected in common, and the other end connected between the other end and the ground. A grounding capacitor, and the voltage across the grounding capacitor is extracted as a divided voltage.

  In the present invention, it is possible to measure the zero-phase voltage while maintaining the function of the surge absorber.

  Moreover, the surge absorber with a measuring function according to the present invention comprises three types of surge absorbers with a measuring function including the instrument transformer having secondary and tertiary windings, the primary side and the secondary side of the instrument transformer means. Either one of the means for connecting the one end of the power supply and outputting the positive phase voltage as a so-called Y connection and the means for connecting the tertiary winding of the instrument transformer means in series and outputting the zero phase voltage, or either It is characterized by having.

  In the present invention, even in a three-phase power facility, by providing a surge absorber with a measurement function for each phase, the function of the original surge absorber and the effect of measuring the positive phase voltage and the zero phase voltage can be obtained.

  A method of protecting a power facility according to the present invention includes a power transformer, a primary circuit breaker that interrupts a primary side of the transformer, and a secondary circuit breaker that interrupts a secondary side of the transformer. In the power facility, the surge absorber with a measuring function or the instrument transformer according to the present invention is connected between the secondary winding of the transformer and the secondary circuit breaker, and the voltage measuring means is connected to the voltage dividing terminal. Connect and measure the voltage on the secondary side, input the measured value to the ground fault overvoltage protection relay, and when the ground fault overvoltage protection relay detects the accident by monitoring the secondary side voltage, The secondary circuit breaker is cut off.

  In the present invention, the voltage between the secondary side of the transformer of the distribution substation and its circuit breaker, which was not generally equipped due to problems of economy and space, is measured, and the accident in that section is detected by the protective relay Therefore, it is possible to reduce power outage time and work time in the event of an accident.

  According to the present invention, it is possible to easily install in a power facility having a problem of economical efficiency and installation space by combining a surge absorber for lightning and a transformer for an instrument, thereby improving the quality of control and protection of the power facility. It can be improved.

  Embodiments of the present invention will be described below. FIG. 1 is a circuit diagram of a surge absorber with a measurement function according to the first embodiment of the present invention, and FIG. 4 is a circuit diagram of a general power facility using the surge absorber.

  In FIG. 1A, a surge absorber with a measurement function (hereinafter abbreviated as “measurement SA”) 1 is formed of a capacitor, and a surge absorber (voltage dividing means) 2 that can divide a capacitance, and divided electrostatics. A voltage dividing terminal 2 a for taking out an AC voltage divided by the capacitance and an insulating means 3 are configured. The insulating means 3 can be constituted by a voltage transformer for measuring voltage or a protective relay (hereinafter abbreviated as “PT”). The voltage dividing terminal 2a takes out a voltage from the middle of the surge absorber 2, that is, from a connection point of two sets of capacitors C1 and C2 equivalently connected in series as shown in FIG.

  The insulating means 3 has a primary side connected to the voltage dividing terminal 2a of the capacitor type surge absorber 2 and the ground E, and the secondary side is used as a measuring terminal K.

  In FIG. 4, the power equipment 9 includes a power source 20 connected to the bus 10 via the circuit breaker 30, and the bus 10 is equipped with a measurement SA 1, to which a voltmeter 50 and protective relays 41 and 42 are connected. Yes.

  Next, the effect | action of measurement SA1 which has said structure is demonstrated using FIG.1 (b). The AC voltage V2x divided by the voltage dividing terminal 2a of the surge absorber 2 is V2x = (C1 / (C1 + C2)) · V1 with respect to the AC voltage V1 applied to both ends of the surge absorber 2, and is a voltage proportional to V1. Appears at V2x. The voltage V2x is insulated by the insulation means 3, and the measurement voltage V2 is output to the secondary measurement terminal K.

  Thus, by providing the terminal 2a capable of dividing the voltage from the conventional capacitor type surge absorber, the voltage applied to the terminal 2a is reduced and outputted, and the voltage transformer terminal 2a is used as an insulating means 3 as an instrument transformer. Etc. can be used as a general instrument transformer.

Next, a second embodiment will be described.
FIG. 2 is a circuit diagram of the measurement SA1 for three-phase AC voltage according to the present embodiment. In this figure, the measurement SA1 is provided with three sets of the surge absorber 2 of the first embodiment each composed of C1 □, C2 □ (□: r, s, t), and further includes a primary winding 3a and a secondary winding. It is composed of a three-phase PT3 having up to a line 3b or a tertiary winding 3c. Each of the three types of surge absorbers 2 is mounted between R, S, T of each phase and the ground E, and is Y-connected to the primary winding 3a of the three-phase PT 3 via a voltage dividing terminal 2a at the intermediate point. . The secondary winding 3b of PT3 is also Y-connected, and outputs the positive phase voltages Vr2, Vs2, and Vt2. The tertiary winding 3c is connected in an open delta manner and outputs a zero-phase voltage V02 that flows to the ground.

  As an effect | action of measurement SA1 in this Embodiment, the divided voltage of each phase appears from the surge absorber 2 by the principle similar to 1st Embodiment. Since the three-phase PT3 is Y-connected to the primary winding 3a and the secondary winding 3b is also Y-connected, the divided voltage of each phase is output to each terminal of the positive phase voltages Vr2, Vs2, and Vt2. Further, the zero-phase voltage can be measured by measuring the voltage at both ends by connecting the tertiary winding 3c to the open delta connection.

  By connecting three types of single-phase measurement SA1 equivalents to a three-phase power facility, and connecting the PT3 in the Y-connection and Δ-connection in the same way as above, a general instrument transformer The same positive phase voltage and zero phase voltage as the function can be measured simultaneously.

Next, a third embodiment will be described.
FIG. 3 is a circuit diagram of the measurement SA1 according to this embodiment. In this figure, in measurement SA1, three types of capacitors C1r, C1s, and C1t connected to three-phase R, S, and T are connected to ground E through one set of common capacitor C2o. The voltage between C2o is connected to the single-phase insulating transformer 3 to obtain a measurement output V02.

  With this circuit configuration, it is possible to measure the zero-phase voltage V02 generated between the grounds when the balance of each phase is lost such as during a ground fault.

  According to the present embodiment, when only the function of the surge absorber and the zero-phase voltage are measured, the number of components can be reduced from the measurement SA1 of the second embodiment.

Next, a fourth embodiment will be described.
5 and 6 are usage examples of the configuration diagram of the control protection circuit in the power facility of the measurement SA1. FIG. 5 is a configuration diagram of a protection circuit using the measurement SA1 according to the second or third embodiment. In this figure, the primary side circuit breaker 31 of the power transformer 60 is provided on the primary side of the distribution substation, and the secondary side circuit breaker 32 is provided on the secondary side, and the secondary side circuit breaker 32 is connected to the distribution line. No. 10 bus 10 is provided. A measurement SA1 is provided between the secondary side B of the transformer 60 and the secondary side circuit breaker 32, and a voltmeter 50 and a ground fault overvoltage relay 40 are connected to the measurement SA1. The bus 10 is generally equipped with two types of ground fault overvoltage relays 41, 42, etc. in the instrument transformer 3X.

In this configuration, when a ground fault or the like occurs in the bus 10, as shown in FIG. 5 (a), the ground fault overvoltage relay 41 or 42 via the instrument transformer 3X installed in the bus 10 is An accident is detected, and the secondary circuit breaker 32 of the transformer 60 that supplies electricity to the bus 10 is opened to avoid the accident. Further, when a ground fault occurs between the transformer 60 and the secondary circuit breaker 32, as shown in FIG. 5 (b), the ground fault overvoltage relay 40 via the instrument SA1 installed therebetween, and the bus The ground fault overvoltage relay 41 or 42 connected to 10 detects an accident, and the secondary circuit breaker 32 is first opened by the protective relay 41 or 42 of the bus 10. However, the protective relay 40 installed in the accident section detects that the accident is still continuing and trips the primary circuit breaker 31 of the transformer 60. Accidents are avoided by this two-stage operation.
Thereby, it can be set as the appropriate power failure range according to an accident location.

Next, a fifth embodiment will be described.
FIG. 6 is a voltage adjustment circuit configuration diagram using the measurement SA1 of the second embodiment.
In a so-called two-bank type distribution substation composed of two transformers 60a and 60b, the circuit configuration around each transformer 60a or 60b is the same as that in the third embodiment, and the secondary of each transformer 60a and 60b. Voltmeters 50a and 50b are provided between the winding B and the secondary circuit breakers 32a and 32b via measurement SA1a and 1b. Voltmeters 51a and 51b are also provided in the instrument transformers 3Xa and 3Xb of the buses 10a and 10b, and a communication breaker 31c is provided between the buses 10a and 10b.

  With this configuration, when performing maintenance work on the single-system transformer 60b, first, after the connection circuit breaker 31c connecting both buses 10a and 10b is turned on, the primary circuit breaker 31b and the secondary circuit breaker 32b are opened. Is done. Maintenance work is performed in this state, and at the time of recovery, the primary circuit breaker 31b is first turned on, and both voltages are measured by the voltmeters 50b and 51b to match the voltage on the secondary side and the voltage on the bus 10b. The tap of the device 60b is adjusted to match both voltages.

  In this adjustment, since the voltage can be measured by the measurement SA1, this voltage is transmitted to the control station that monitors and controls this substation via the remote monitoring and control device, and the tap of the transformer 60b is adjusted and controlled from this distance by this value. You can also

  As described above, according to the fourth and fifth embodiments, since the level of measurement and protection can be improved, it is possible to limit the range of power outage at the time of an accident and to shorten the time and to maintain the transformer. Fine voltage adjustment and remote monitoring control are possible even during work.

  The present invention can be used for voltage measurement and protection in a power system.

FIG. 1A is a circuit diagram of a surge absorber with a measurement function according to the first embodiment of the present invention, and FIG. 1B is an equivalent circuit diagram of FIG. It is a circuit diagram of the surge absorber with a measurement function by the 2nd Embodiment of this invention. It is a circuit diagram of the surge absorber with a measurement function by the 3rd Embodiment of this invention. It is a basic circuit example of the surge absorber with a measurement function of the present invention. It is a block diagram of the protection circuit using the surge absorber with a measurement function by the 4th Embodiment of this invention. It is a block diagram of the protection circuit using the surge absorber with a measurement function by the 5th Embodiment of this invention. It is a circuit block diagram of the conventional basic power equipment. It is a block diagram of the protection circuit of the conventional distribution substation (the 1). It is a block diagram of the protection circuit of the conventional distribution substation (the 2).

Explanation of symbols

1, 1a, 1b Surge absorber 2 Voltage dividing means 2a Voltage dividing terminal 3, 3X, 3Xa, 3Xb Insulating means (instrument transformer, PT)
9 Electric power equipment 10, 10, 10a, 10b Busbar 30, 31, 31a, 31b, 32, 32a, 32b Breaker 40, 41, ... Protection relay 50, 50a, 50b, 51a, 51b Voltmeter 60, 60a, 60b transformer

Claims (5)

A surge absorber for electric power equipment,
Voltage dividing means for dividing the alternating voltage applied to the surge absorber by dividing the electrostatic capacity of the surge absorber;
A voltage dividing terminal for taking out a divided voltage divided by the voltage dividing means;
Surge absorber with measuring function, characterized by having   The voltage dividing means includes a capacitor having one end connected to each phase of the power line and the other end connected in common, and a ground capacitor connected between the other end and the ground. 2. The surge absorber with a measuring function according to claim 1, wherein the voltage across the capacitor is taken out as a divided voltage.   3. An instrument transformer comprising an insulating means for insulating and outputting an alternating voltage divided by a surge absorber with a measuring function according to claim 1. A power facility of a substation having a power transformer, a primary circuit breaker that interrupts a primary side of the transformer, and a secondary circuit breaker that interrupts a secondary side of the transformer,
3. A power characterized by connecting a surge absorber with a measuring function according to claim 1 or a measuring instrument transformer according to claim 3 between a secondary winding of the transformer and the secondary circuit breaker. Facility. A method for protecting a power facility according to claim 4,
Connect the voltage measuring means to the voltage dividing terminal to measure the secondary voltage,
When the measured value is input to the ground fault overvoltage protection relay and the ground fault overvoltage protection relay detects an accident by monitoring the secondary side voltage, the secondary side circuit breaker is shut off. A method for protecting electric power equipment.

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