JPS58189564A - Maximum value storage type converter - Google Patents

Abstract

PURPOSE:To measure and store the maximum value of a current or voltage gennerated at the time of an accident of a transmission and distribution line system, by integrating a current or voltage at the time of an accident alternately at every one cycle by two integrators, comparing and selecting its result, and updating an output. CONSTITUTION:A current or voltage at the time of an accident is integrated alternately at every one cycle by zero phase auxiliary current transformers 1A-1D of four banks, etc. of the same transmission and distribution line system having resistances 2A-2D of secondary winding being freely attachable and detachable, an impedance amplifier 4, a higher harmonic portion eliminating BPF6, and two integrators 10, 20. This integration result is compared by comparators 30, 40, a switch S5 turns on in accordance with a comparison result, and a measuring output beta is generated through a pulse counting circuit 50 and a D/A converting circuit 60. The output beta is used as a reference value of these comparators 30, 40, and the output beta is updated whenever it becomes larger than the immediately previous output beta. According to this constitution, it is possible to measure and store the maximum value of a current or voltage generated at the time of an accident of a transmission and distribution line system whose ground system, etc. are different.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring voltage or current occurring during a fault in a power transmission/distribution line system, and in particular to a device for measuring and storing the maximum value of voltage or current of a type. The present invention relates to a maximum value storage type converter for

Abnormal voltages caused by ground faults in power transmission and distribution systems are
If other healthy power equipment is subjected to sudden movements◆ and the accident continues for a long time, other equipment will be destroyed and the accident will spread. In order to prevent stiffness, the neutral point of power transmission and distribution lines is generally grounded to prevent abnormal voltage generation, and the zero-sequence voltage ■0 and zero-sequence current IO that occur in the event of a ground fault are detected and the accident is detected. Measures are being taken to prevent the accident from spreading by separating the parts.

The neutral point of power transmission lines is grounded in several ways for reasons such as preventing abnormal voltage in the event of a ground fault and ensuring reliable operation of protective relays. These grounding methods are mainly adopted depending on the feed pressure of 11 m, and representative ones include a direct grounding method, a resistance grounding method, and an arc extinguishing reactor grounding method.

Accidents in this type of system often occur when the fault current becomes a large value, and as a result, the connected equipment becomes severely damaged due to air pollution and mechanical damage, making it difficult to use 1=Qiφ again. are designed to be separated within a short period of time. Because of this, there is no such separation when it comes to measurements at the time of an accident.
+? There is a need for a device that can store data. As a device capable of performing such measurements at the open mountain and storing the measured values, the present applicant has proposed the following:
Voltage at the time of a transmission/distribution line fault as disclosed in Publication No. 711
Developed a flow measuring device. This measurement lid is preferable in that it can measure and store voltage or N1 current in a very short time, but it can only measure the average value of VIk voltage or 'Wi,m within a predetermined time, so it is not suitable for the following cannot adequately answer such needs.

In other words, the duration of a system fault will vary depending on the grounding method of the system, the detection and preservation relay system installed at the substation, the opening/closing speed of the breaker, etc. For example, in the case of a directly grounded type, the zero-phase W flow 1o at the time of the accident
The duration time of
The duration of the fault is approximately θ, OA seconds, and in the case of the arc-extinguishing reactor grounding type, the duration of the zero-sequence voltage Vo and zero-sequence current 10 at the time of the fault is approximately θ, OA seconds. in this way,
The duration of a system accident generally ranges over a wide range from approximately 60 milliseconds to more than 7 seconds, so it is impossible to completely determine the accident state by simply measuring the average value within a certain period of time from the occurrence of the accident. can't figure it out. Therefore,
In order to distinguish and understand the state of each accident by keeping the measurement conditions the same for any accident duration, K is the fault voltage or 11tk during the fault duration.

The purpose of the present invention is to measure and store the maximum value of voltage or current that will occur in the event of a fault in a power transmission/distribution line system, taking into consideration the above-mentioned needs. It is possible to convert the maximum flti storage type storage device for storage.

Next, the present invention will be described in detail with regard to embodiments of the present invention based on the accompanying drawings.

The attached drawing is a schematic circuit diagram of a maximum storage type converter as an embodiment of the present invention.
The auxiliary current transformers IA, IB, IC, and 10 are configured to measure and store the maximum value of
It is connected to the device. These auxiliary current transformations stA, t
Resistor cages 2^, 2B, 2C and 2D are connected to the ends of the a-th windings of windings e, 1c and 10 in a detachable manner, respectively. These resistor packages 2^, 2
Since the current transformation ratio of the zero-phase current transformer in each bank is generally different, B, 2C, and 2D are resistance values according to the current transformation ratio of each corresponding zero-phase current transformer. 1!, which is proportional to the sum of the zero-sequence currents flowing through each bank. They are connected in series so that the output terminal 3 is outputted to the output terminal 3. These 9 resistors are designed to be plug-in types that can be attached and detached to the secondary winding end of the auxiliary current transformer, so each bank has one zero-phase current transformer with a different current transformation and ratio. If so, resistor with different resistance value depending on its current transformation ratio/? By replacing the pump with the pump, it is easy to provide the output terminal 3 with a composite voltage signal that is exactly proportional to the sum of the zero-sequence currents of each puncture.

The sum of the measurements given to output terminal 3 is 5! The alternating signal is passed through an impedance conversion amplifier 4 to a bandpass filter 5.
added to. The bandpass filter 5 removes the DC component and harmonic components at the time of a fault from the AC signal, and applies only the basic fault current or voltage component to the full-wave rectifier circuit 6. This signal is converted into DC by a full-wave rectifier circuit 6. In addition, the measured composite AC signal seen at the output terminal 3 is also input to the control unit 7 via the impedance conversion amplifier 4, and is compared with a reference value in the control unit 7 to determine whether or not an accident has occurred. When the control unit 7 confirms that an accident has occurred, it sends an instruction signal to the switches S/, S2, S3, and S+ to control their on/off states.

The seventh integrator 10 includes a capacitor 11 and an amplifier 12, and the second integrator 20 includes a capacitor 21 and an amplifier 22. These integrators 10
and 20, as will be described later, are used to alternately integrate the fault current or voltage over a period of 1tJh per cycle and obtain the average value of the fault signal during that period. Here, the reason why the integration period is set to /cycle is that if the period is shorter than this, it will depend on the phase at the time of the accident occurrence (repetitive stress difference will occur or the residual magnetic flux of the current transformer and the auxiliary current transformer will be affected by the residual magnetic flux i1). This is because the values differ in each cycle, leading to conversion feeding.Also, the reason why two integrator circuits are used is to eliminate the dead band time due to the discharge period of the integrator, which reduces the response time to the input of this converter. is the cocycle, that is, the input frequency!; OH
When z, it is IIO milliseconds, and the zero-sequence voltage and zero-sequence current at the time of a system fault with a duration of 0 milliJ seconds are also 1lII in total.
It becomes possible.

The control unit 7 controls the switch S/S when there is no accident.
, S3 are turned off, and switches S2 and s+ are turned on. By turning on the switches S2 and S4t, the capacitors 11 and 21 are placed in a discharged state. control s7
When an accident occurs, the first switch S/ and SII are turned on, the switches S2 and S3 are turned off, and the first
After a cycle period has elapsed since the occurrence of the accident, the switches S/ and SII are turned off, the switches S- and S3 are turned on, and the integrator 20 of the pen is set to perform an integral operation. Make sure to do the following. Then, the control unit 7 performs control such that such operations are alternately repeated while an accident occurs. This control state is summarized as shown in the following table.

By such an operation, the integrators 10 and 20 continuously obtain a cycle-by-cycle average value signal of the fault current while the fault continues. The average value signal from the integrator 10 (total integrated !5lll signal) is sent to the first comparator 3
0, the average value signal from the integrator 20 is applied to one input of the second comparator 40, and the comparators 30 and 40 combine the average value signal and the pulse signal. A comparison is made with the stored value stored in the counting circuit 50. The average value signal from the integrator 10 is α4, and the average value signal from the integrator 20 is α/'P. When the converted analog roughness value is β, the comparator 30
Alternatively, 40 inputs an instruction signal to the OR circuit 70, and the OR circuit 70 outputs a signal to turn on the switch 15 in response. Conversely, when α, <β or α2×β, the comparator 30 or 40 turns off the switch S5 via the OR circuit 70.

When the switch S5 is in the on state, the base pulse counting circuit 50
counts the reference pulses sent from the reference pulse generator 80 through the switch 3.3-, and continues counting until α,=β or α22β.

When α, = β or α2 = β, the comparator 3° or 40 turns off the switch s, 1 via the OR circuit 70, and stops the counting of the pulse counting circuit 500. As a result of this operation, the maximum value of the average value measurement signals for each cycle of the fault current over the entire period from the occurrence of the accident to the time the accident continues is stored in the arm count counting port 5o.

The shrimp average value measurement number stored in the pulse counting circuit 50 is converted into an analog quantity by the digital-to-analog conversion circuit 6o, and is outputted as the maximum average value measurement output signal during the accident via the output amplifier 90. Alternatively, the base pulse counting circuit 50 may also be directly transmitted as a digital quantity.

Furthermore, the resolution of this measurement value is determined by the oscillation frequency of the reference pulse generator 80 and the comparison ability of the comparators 30 and 40, and by appropriately selecting them, it is possible to obtain a resolution much higher than K. be able to. Furthermore, in the initial state before the accident, the notarus counting circuit 50 is reset (
It is obtained by counting OII (reduction).

Since the maximum value storage type converter of the present invention has the above-described configuration, even if the fault duration varies widely, the fault current per cycle from the occurrence of the fault to the duration of the fault can be reduced. Since the maximum value of the average signal is measured and stored, it is possible to provide data that allows a more complete understanding of the actual state.

In the above-mentioned embodiment, the case where the auxiliary current transformers IA to 10 are connected to the zero-phase current transformer was explained to measure the fault current, but when measuring the fault voltage, these auxiliary current transformers The current transformer may be converted into an auxiliary transformer and connected to a voltage transformer that picks up the fault voltage (the present invention also includes such a case).

[Brief explanation of drawings]

Attached page 1 is an analytical circuit diagram of a maximum value storage type converter as an embodiment of the present invention. 1^, 1B, IC, ID...Auxiliary current transformer, 2^
, 2B, 2C, 2D...m anti)mother cage,
3... Output terminal, 4... Impedance conversion amplifier, 5... Pantone motherboard filter, 6... Full wave rectifier circuit, 7...・
・・Control unit, lO・・・・Hana/integrator, 20
・・・・・・Second integrator, 30・・・・・・First
Comparator, 40...Second comparator, 50...
...Pulse counting circuit, 60...Digital-to-analog conversion circuit, 70...OR circuit,
80...Reference/9 pulse generator, 90...
...output amplifier, S/, S, 2, S3, slI, s,
t...Switch.

Claims (1)

[Scope of Claims] Fault current or voltage signal generation means for picking up fault current or fault voltage occurring in a power transmission and distribution line system and generating a fault current or voltage signal proportional to the fault current or fault voltage, and from the fault current or voltage signal generation means. first and first integrators for integrating a fault current or voltage signal of the fault current or voltage; a control section for alternately starting and stopping the integrated values for each predetermined cycle, a storage section for storing the integrated values from the seventh and first integrators, and a new integrated value from the first integrator. a first comparator that compares the integral value with the integral value stored in the storage unit and generates a predetermined output when the new integral value is larger; a first comparator that compares the integral value with the integral value stored in the storage unit and generates a predetermined output when the new integral value is thicker; and means for updating the Kikusen of the Eph constant to the new integral value in response to the output of the previous Eph constant or the predetermined output from the second comparator. Value code [memory converter.