Preset phase-control arc extinction control device based on counter calibration control phase angle

Abstract

The utility model discloses a pre-adjusting type phase-control arc extinction control device based on a counter calibration control phase angle, which comprises a phase-control arc extinction coil and a measurement and control device used for controlling the phase-control arc extinction coil to carry out arc extinction compensation, the phase control arc suppression coil comprises an arc suppression coil body, and a secondary filter circuit and a thyristor control circuit which are connected to the arc suppression coil body; the measurement and control device comprises a counter calibration unit and a logic control unit; the input end of the counter calibration unit is connected with the head end of the phase control arc suppression coil, the output end of the counter calibration unit is connected with the input end of the logic control unit, and the thyristor control circuit receives a trigger signal which is sent by the logic control unit and is calibrated according to information sent by the counter calibration unit. And the phase control arc suppression coil is adjusted according to the trigger signal to compensate the system. According to the utility model, the problem of control phase angle deviation caused when the synchronous voltage signal of the preset phase control arc suppression coil changes in a large range is solved, the method is simple and convenient, and the compensation process is reliable.

Description

Technical Field

[0001] The utility model relates to the technical field of power supply control, in particular to a pre-adjustable phase-controlled arc extinguishing control device. Background Art

[0002] With the rapid development of cities, a large number of cables are used in distribution networks, and the system capacitance current has increased dramatically, posing a hidden danger to the safe operation of the power grid, which has attracted more and more attention from management departments. The capacity of the new arc suppression coil should be able to change smoothly, and automatically track and measure the capacitance current. When single-phase grounding occurs, it should immediately act and fully compensate for the power frequency grounding current to quickly extinguish the arc. The phase-controlled arc suppression coil is a specially designed high-impedance transformer-type controllable reactor. It adjusts the short-circuit current in the secondary winding by adjusting the conduction angle of the thyristor, thereby achieving controllable adjustment of the reactance value. The adjustment range can reach 0-100%. It has good adaptability to large changes in capacitance current caused by substation expansion, operation mode adjustment, etc., and is significantly better than another widely used turn-type arc suppression coil in China.

[0003] However, at present, the arc extinguishing compensation of this type of phase-controlled arc extinguishing coil can only be adjusted on-the-fly, which has two major problems: first, the single-phase grounding transition resistance recognition sensitivity is insufficient, which can only reach about 500Ω, while the adjustable turn arc extinguishing system can reach 3kΩ or even above 5kΩ; second, after a single-phase grounding fault occurs in the system, multiple cycles are required to determine the grounding start compensation output, and the arc cannot be extinguished in time. It basically does not work for instantaneous grounding faults, which seriously limits the promotion and application of phase-controlled arc extinguishing coils.

[0004] In order to solve the above problems, the phase-controlled arc extinguishing coil usually adopts a pre-adjustment scheme. For example, the invention patent No. 202110357288.8 previously applied by the applicant discloses a pre-adjustment phase-controlled arc extinguishing control method, in which the pre-adjustment phase-controlled arc extinguishing control device includes a phase-controlled arc extinguishing coil XT, a measurement and control device, and a damping resistor R D and switching switch K, the phase-controlled arc extinguishing coil XT includes an arc extinguishing coil body and a filter circuit and a thyristor control circuit connected to the secondary of the arc extinguishing coil body, and a damping resistor R D Connected in parallel at both ends of the filter circuit or in series in the main circuit of the power grid system where the arc suppression coil body is located, the switching switch K realizes the damping resistor R under the control of the measurement and control device. DThe input end of the measurement and control device is connected to the output end of the current transformer and the voltage transformer respectively, and the output end of the measurement and control device is connected to the controlled end of the thyristor control circuit. When a single-phase grounding fault occurs in the system, the compensation phase angle obtained by the most recent measurement can be used to trigger the thyristor control circuit to perform compensation, thereby improving the measurement and calculation speed and the compensation output response speed of the phase-controlled arc suppression coil. However, this will face the problem of control phase angle deviation caused by a large range of changes in the synchronous voltage signal: when the synchronous voltage signal U0 is square-wave shaped, in order to avoid electromagnetic interference and jitter caused by harmonic components in the system, a certain hysteresis must be set for the zero-crossing comparison; at the same time, before grounding, the synchronous voltage signal U0 is less than 5V or even lower, and after grounding, it can reach a maximum of 100V. Such a large range of changes and the existence of zero-crossing hysteresis will inevitably cause the rising and falling edges of the shaped square wave signal to be offset from the actual zero-crossing point, and the offset value changes with the change of the synchronous voltage signal U0. If this deviation is not corrected, the output of the phase-controlled arc suppression coil will have a large deviation. Since the phase control angle resolution requirement is very high, at least 0.1°, and the shaping deviation follows a nonlinear change pattern, it is difficult and impractical to correct it by analog sampling and calculation. Utility Model Content

[0005] The technical problem to be solved by the utility model is to provide a pre-adjustable phase-controlled arc extinguishing control device based on counter calibration control phase angle, which can improve the compensation accuracy on the basis of improving the compensation response speed of the phase-controlled arc extinguishing coil without the need for high-speed analog quantity sampling and calculation.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present utility model are as follows.

[0007] A pre-adjustable phase-controlled arc extinguishing control device based on counter calibration to control phase angle includes a phase-controlled arc extinguishing coil connected to the neutral point of the system and a measurement and control device for controlling the phase-controlled arc extinguishing coil to perform arc extinguishing compensation. The phase-controlled arc extinguishing coil includes an arc extinguishing coil body and a filter circuit and a thyristor control circuit connected to the secondary of the arc extinguishing coil body. The measurement and control device includes a counter calibration unit and a logic control unit; the input end of the counter calibration unit is connected to the head end of the phase-controlled arc extinguishing coil, and the output end of the counter calibration unit is connected to the input end of the logic control unit. The thyristor control circuit receives a trigger signal sent by the logic control unit that is calibrated according to the information sent by the counter calibration unit, and adjusts the phase-controlled arc extinguishing coil according to the trigger signal to compensate the system.

[0008] Preferably, the counter calibration unit comprises a Schmidt square wave shaping circuit, a zero-crossing comparator circuit, a continuous counter and an accumulative counter, the input ends of the Schmidt square wave shaping circuit and the zero-crossing comparator circuit are respectively connected to the system neutral point, the count control end of the continuous counter is connected to the output end of the Schmidt square wave shaping circuit, the two count control ends of the accumulative counter are respectively connected to the output ends of the Schmidt square wave shaping circuit and the zero-crossing comparator circuit, the input end of the logic control unit is respectively connected to the output ends of the Schmidt square wave shaping circuit, the continuous counter and the accumulative counter, and the output end of the logic control unit is connected to the controlled end of the thyristor control circuit.

[0009] Preferably, the counter calibration unit further comprises a clock circuit, and the clock input ends of the continuous counter and the cumulative counter are connected to the output end of the clock circuit.

[0010] The utility model is suitable for 6-66kV power supply systems. It adopts the constructed hardware circuit to realize the calibration of the synchronous reference. It does not require high-speed analog sampling and calculation. It can improve the compensation accuracy of the phase-controlled arc suppression coil on the basis of improving the compensation response speed of the phase-controlled arc suppression coil. It solves the problem of control phase angle deviation caused by the pre-adjusted phase-controlled arc suppression coil when the synchronous voltage signal changes over a large range. The method is simple and the compensation process is reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The electrical schematic diagram of Example 1;

[0012] Figure 2 This is the electrical schematic diagram of Example 2.

[0013] Among them: XT. Phase-controlled arc suppression coil, SSR. Thyristor control circuit, C1. Schmidt square wave shaping circuit, C2. Zero-crossing comparator circuit, T1. Continuous counter, T2. Accumulative counter, CPU. Logic control unit, CT. Voltage transformer, PT. Current transformer. DETAILED DESCRIPTION

[0014] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0015] Example 1

[0016] A pre-adjustable phase-controlled arc extinguishing control device based on counter calibration control phase angle, the pre-adjustable phase-controlled arc extinguishing control device includes a phase-controlled arc extinguishing coil XT, a damping resistor R D , switching switch K, voltage transformer PT, current transformer CT and measurement and control device.

[0017] The phase-controlled arc suppression coil XT is connected between the system neutral point and the ground, and includes an arc suppression coil body and a filter circuit and a thyristor control circuit SSR connected to the secondary side of the arc suppression coil body. The filter circuit includes two filter branches connected in parallel, one filter branch is a third harmonic filter branch composed of an inductor L3 and a capacitor C3 connected in series, and the other filter branch is a fifth harmonic filter branch composed of an inductor L5 and a capacitor C5 connected in series.

[0018] The damping resistor RD is connected in series in the main circuit of the power grid system where the arc suppression coil is located. Figure 1 As shown, the switching switch K realizes the switching of the damping resistor RD under the control of the measurement and control device.

[0019] The voltage transformer PT is connected between the measurement and control device and the system neutral point to measure the voltage signal of the phase-controlled arc suppression coil; the current transformer CT is connected between the phase-controlled arc suppression coil XT and the ground to measure the current signal of the phase-controlled arc suppression coil.

[0020] The measurement and control device is used to control the phase-controlled arc suppression coil XT to perform arc suppression compensation, and the measurement and control device includes a counter calibration unit and a logic control unit CPU. The output ends of the counter calibration unit, the voltage transformer PT, and the current transformer CT are respectively connected to the input end of the logic control unit CPU, and the output end of the logic control unit CPU is connected to the controlled end of the thyristor control circuit SSR.

[0021] The counter calibration unit comprises a Schmidt square wave shaping circuit C1, a zero-crossing comparator circuit C2, a continuous counter T1, an accumulative counter T2 and a clock circuit CLK, wherein the clock input terminals of the continuous counter T1 and the accumulative counter T2 are connected to the output terminal of the clock circuit CLK.

[0022] The input ends of the Schmidt square wave shaping circuit C1 and the zero-crossing comparator circuit C2 are respectively connected to the system neutral point, the counting control end EP of the continuous counter T1 is connected to the output end of the Schmidt square wave shaping circuit C1, and the two counting control ends of the accumulative counter T2 are respectively connected to the output ends of the Schmidt square wave shaping circuit C1 and the zero-crossing comparator circuit C2, that is, the ET counting control end of the accumulative counter T2 is connected to the output end of the Schmidt square wave shaping circuit C1, and the EP counting control end of the accumulative counter T2 is connected to the output end of the zero-crossing comparator circuit C2; the input end of the logic control unit CPU is respectively connected to the output ends of the Schmidt square wave shaping circuit C1, the continuous counter T1 and the accumulative counter T2.

[0023] In the present invention, in order to ensure the calibration accuracy, the frequency of the clock circuit CLK is generally greater than or equal to 180kHz; the counter is not less than 12 bits. The number of counting bits N of the continuous counter T1 and the cumulative counter T2 Q The clock frequency f of the clock circuit CLK CMeet the following requirements:

[0024] N Q >log2(f C ).

[0025] The arc extinguishing control method using the utility model specifically includes the following steps.

[0026] S1. The logic control unit calculates the system capacitor current and the corresponding initial control phase angle θ according to the voltage and current signals of the phase-controlled arc suppression coil.

[0027] S2. The counter calibration unit tracks the system synchronization reference voltage signal U0 and calculates the correction value Δθ of the control phase angle according to the change of the synchronization reference voltage signal U0.

[0028] The specific method of this step is as follows.

[0029] S21. The Schmidt square wave shaping circuit C1 and the zero-crossing comparator circuit C2 output signals of different levels according to the change of the synchronous voltage signal U0.

[0030] S22. When the output level of the Schmidt square wave shaping circuit C1 is reversed, the logic control unit CPU reads the count value CNT_T1 of the continuous counter T1 and the count value CNT_T2 of the cumulative counter T2; and resets the continuous counter T1 and the cumulative counter T2 to restart counting.

[0031] The synchronous reference voltage signal U0 passes through the Schmidt square wave shaping circuit C1 and the zero-crossing comparator circuit C2 at the same time; the rising and falling edges of the square wave output by the Schmidt square wave shaping circuit C1 are the synchronous reference for the phase angle of the phase-controlled arc suppression coil, and the width of the square wave output by the Schmidt square wave shaping circuit C1 is the counting cycle control signal of the continuous counter T1 and the accumulative counter T2, that is, when the output of the Schmidt square wave shaping circuit C1 is reversed between high and low levels, the counting cycle ends.

[0032] When the output of Schmidt square wave shaping circuit C1 maintains high level and low level, continuous counter T1 and cumulative counter T2 count the CLK pulse signal output by clock circuit CLK at the same time. Among them, continuous counter T1 counts continuously, and cumulative counter T2 counts cumulatively when the output of zero-crossing comparator circuit C2 is high level, and stops counting when the output of zero-crossing comparator circuit C2 is low level.

[0033] S23. According to the count values ​​of the continuous counter T1 and the cumulative counter T2 obtained in step S22, the correction value Δθ of the control phase angle is calculated according to the following formula:

[0034]

[0035] S3. The logic control unit calculates and obtains the calibrated phase control phase angle θ′ according to steps S1 and S2.

[0036] θ′=θ+Δθ

[0037] S4. The logic control unit sends a trigger instruction KG to the thyristor control circuit SSR according to the phase-controlled control phase angle θ′ calculated in step S4 to compensate the system.

[0038] The utility model adopts a counter calibration unit set in the measurement and control device to realize the calibration of the synchronous reference. It has a pure circuit structure control, is easy to implement, and does not require high-speed analog quantity sampling and calculation. It can further improve the compensation accuracy of the phase-controlled arc suppression coil on the basis of improving the compensation response speed of the phase-controlled arc suppression coil.

[0039] Example 2

[0040] The difference between this embodiment and embodiment 1 is that the damping resistor RD is connected in parallel at both ends of the filter circuit. Figure 2 shown.

Claims

1. A pre-adjustable phase-controlled arc-extinguishing control device based on counter calibration control phase angle, comprising a phase-controlled arc-extinguishing coil (XT) connected to the neutral point of the system and a measurement and control device for controlling the phase-controlled arc-extinguishing coil (XT) for arc-extinguishing compensation, wherein the phase-controlled arc-extinguishing coil (XT) comprises an arc-extinguishing coil body and a filter circuit and a thyristor control circuit (SSR) connected to the secondary of the arc-extinguishing coil body, characterized in that: The measurement and control device includes a counter calibration unit and a logic control unit; the input end of the counter calibration unit is connected to the head end of the phase-controlled arc suppression coil (XT), the output end of the counter calibration unit is connected to the input end of the logic control unit, the thyristor control circuit (SSR) receives a trigger signal sent by the logic control unit and calibrated according to the information sent by the counter calibration unit, and adjusts the phase-controlled arc suppression coil (XT) according to the trigger signal to compensate the system.

2. The pre-adjustable phase-controlled arc extinguishing control device based on counter calibration and phase angle control according to claim 1 is characterized in that: The counter calibration unit comprises a Schmidt square wave shaping circuit (C1), a zero-crossing comparator circuit (C2), a continuous counter (T1) and an accumulative counter (T2); the input ends of the Schmidt square wave shaping circuit (C1) and the zero-crossing comparator circuit (C2) are respectively connected to the system neutral point; the count control end of the continuous counter (T1) is connected to the output end of the Schmidt square wave shaping circuit (C1); the two count control ends of the accumulative counter (T2) are respectively connected to the output ends of the Schmidt square wave shaping circuit (C1) and the zero-crossing comparator circuit (C2); the input end of the logic control unit (CPU) is respectively connected to the output ends of the Schmidt square wave shaping circuit (C1), the continuous counter (T1) and the accumulative counter (T2); and the output end of the logic control unit (CPU) is connected to the controlled end of the thyristor control circuit (SSR).

3. The pre-adjustable phase-controlled arc extinguishing control device based on counter calibration and phase angle control according to claim 2 is characterized in that: The counter calibration unit further comprises a clock circuit (CLK), and the clock input ends of the continuous counter (T1) and the cumulative counter (T2) are connected to the output end of the clock circuit (CLK).

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