High-voltage circuit breaker transient recovery voltage experiment device and method based on direct experiment method

Abstract

The invention discloses a high-voltage circuit breaker transient recovery voltage experiment device and method based on a direct experiment method. The device comprises a charging loop and an experiment loop. The charging loop comprises a main power supply module and an energy storage unit, a primary side of the main power supply module is connected with an AC power supply, and a secondary side is connected with a charging capacitor bank of the energy storage unit through diode rectification; an experiment module of the experiment loop is connected to two ends of a charging capacitor bank of the charging loop, the charging capacitor bank serves as a power supply capacitor of the experiment loop, and the experiment module comprises an LC resonance loop composed of a capacitor and an inductor and a tested circuit breaker. By means of the structure, in cooperation with an experimental method, parameter sensitivity analysis is carried out by inputting conditions such as an experimental mode, voltage and current levels and the like, parameter values of voltage needed by charging, power capacitance and inductance, frequency modulation capacitance and frequency modulation resistance are output, device building and parameter setting are facilitated, and actual parameters are verified.

Description

Technical Field

[0001] The present invention belongs to the technical field of power equipment testing, and in particular relates to a device and method for testing transient recovery voltage of a high-voltage circuit breaker based on a direct experimental method. Background Art

[0002] As an indispensable protective device in power systems, high-voltage circuit breakers' core function is to quickly and reliably interrupt fault currents, ensuring the safe and stable operation of the power grid. During the circuit breaker's interruption process, transient recovery voltage (TRV) is a key parameter for measuring the breaker's interrupting capability. Its amplitude, rise rate, and oscillation characteristics not only affect the successful interruption but also directly determine the insulation reliability and service life of the equipment. TRV is the transient voltage that appears between the circuit breaker contacts after the current passes through zero. Its amplitude, rise rate, and oscillation characteristics can cause dielectric reignition or insulation breakdown, posing significant challenges to circuit breaker design and testing. When a circuit breaker interrupts a fault current, the arc generated at the moment the contacts separate extinguishes when the current passes through zero. However, the energy released by inductive and capacitive components in the power grid can cause TRV to form. Therefore, accurately evaluating TRV characteristics and ensuring compliance with international standards (such as GB 1984-2024 "High-Voltage AC Circuit Breakers") are key aspects of circuit breaker research and development and engineering applications.

[0003] Typical characteristics of TRV include the initial peak voltage, the rate of rise of recovery voltage (RRRV) and the high-frequency oscillation component. These characteristics directly determine whether the dielectric recovery strength of the circuit breaker is sufficient to withstand transient voltage shocks. If the TRV exceeds the design threshold, it may cause arc reignition or insulation failure, leading to secondary faults or even equipment damage. Therefore, international standards (such as IEC 62271-100 and GB 1984-2024) have put forward clear requirements for the amplitude, time parameters and waveform envelope of TRV, and how to accurately reproduce and verify these characteristics through experimental means has become a core issue in circuit breaker research and development.

[0004] Traditionally, TRV testing and verification mainly uses the synthetic loop method. Although this method can more comprehensively simulate fault currents and TRVs by combining current sources and voltage sources, it is essentially a non-direct equivalence test, and its equivalence and operability have long been questioned. Taking the Weil-Dobke synthetic test loop as an example, although it can better ensure the equivalence of large current and steady-state recovery voltage stages, it has limited control over the dynamic process at the zero-crossing moment, and the loop structure is complex and the investment cost is high, which limits its applicability to high-voltage and large-capacity circuit breakers. In contrast, the direct test method directly generates TRVs through a single power source, which can directly reproduce the fault interruption process in the actual power grid. It has both simple structure and cost advantages, simplifies the test system, and reduces costs. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-voltage circuit breaker transient recovery voltage experimental device and method based on the direct experimental method. By combining the RLC series resonance principle, the circuit structure is simplified to a single power supply structure, the TRV during the high-voltage circuit breaker disconnection process is simulated, and the mathematical quantitative relationship between the loop parameters and the TRV characteristics is derived.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: a high-voltage circuit breaker transient recovery voltage test device based on a direct experimental method, comprising a charging circuit and an experimental circuit; the charging circuit comprises a main power module and an energy storage unit, the primary side of the main power module is connected to an AC power supply, and the secondary side is connected to a charging capacitor group of the energy storage unit through diode rectification; the experimental module of the experimental circuit is connected to both ends of the charging capacitor group of the charging circuit, the charging capacitor group serves as the power supply capacitor of the experimental circuit, and the experimental module comprises an LC resonant circuit composed of capacitors and inductors and a tested circuit breaker.

[0007] The experimental circuit is composed of power supply capacitor C h 、Circuit breaker QF h 、Inductor L h , FM capacitor C oa 、Tested circuit breaker QF s The direct experimental circuit is composed of the power supply capacitor C h 、Circuit breaker QF h 、Inductor L h , FM capacitor C oa Series, tested circuit breaker QF s and the FM capacitor C oa in parallel.

[0008] The charging circuit is composed of transformer TM, resistor R, rectifier D, charging circuit breaker QF c , power supply capacitor C h A circuit composed of connections.

[0009] The power supply capacitor C h Charging is complete, open the charging circuit breaker QF c When the circuit breaker QFs is closed, the frequency modulation capacitor C oa Provides transient recovery voltage for experiments.

[0010] A method for conducting an experiment using the high-voltage circuit breaker transient recovery voltage experimental device based on the direct experimental method:

[0011] a) Close the charging circuit breaker QF c For power supply capacitor C h Charge to the preset voltage;

[0012] b) Open the charging circuit breaker QF c And close the circuit breaker DF h and the tested circuit breaker QF s , FM capacitor C oa Output target short-circuit current;

[0013] c) The voltage path outputs a compliant TRV when the current crosses zero;

[0014] d) Optimize loop parameters based on the simulation model to ensure that the TRV waveform meets national standards: Use MATLAB / Simulink to design a parameter calculation system, combine it with the experimental device to form a system device, input the experimental method, voltage and current level conditions, perform parameter sensitivity analysis, output the parameter values ​​of the charging voltage, power supply capacitance and inductance, FM capacitor, and FM resistor, and verify the actual parameters.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] This invention provides an efficient and economical technical means for evaluating the interrupting capacity of high-voltage circuit breakers through a device and method for transient recovery voltage testing of high-voltage circuit breakers based on a direct testing method. The direct testing method offers significant advantages in terms of structural simplicity and cost-effectiveness. The single power supply design not only reduces equipment complexity and cost, but also allows parameter adjustment to accommodate circuit breaker testing requirements at different voltage levels. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the circuit diagram of the direct experimental method experimental circuit;

[0018] Figure 2 This is the schematic diagram of the direct loop experimental method;

[0019] Figure 3 is the equivalent circuit diagram of the circuit breaker under test being disconnected;

[0020] Figure 4 It is a Simulink simulation diagram. DETAILED DESCRIPTION

[0021] A high-voltage circuit breaker transient recovery voltage test device based on a direct test method includes a charging circuit and an experimental circuit; the charging circuit includes a main power module and an energy storage unit, the primary side of the main power module is connected to an AC power supply, and the secondary side is connected to a charging capacitor group of the energy storage unit through diode rectification; the experimental module of the experimental circuit is connected to both ends of the charging capacitor group of the charging circuit, and the charging capacitor group serves as the power supply capacitor of the experimental circuit. The experimental module includes an LC resonant circuit composed of capacitors and inductors and a tested circuit breaker.

[0022] The experimental circuit is composed of power supply capacitor C h 、Circuit breaker QF h 、Inductor L h , FM capacitor C oa 、Tested circuit breaker QF s The direct experimental circuit is composed of the power supply capacitor C h 、Circuit breaker QF h 、Inductor L h , FM capacitor C oa Series, tested circuit breaker QF s and the FM capacitor C oa in parallel.

[0023] The charging circuit consists of a transformer TM, a resistor R, a rectifier D, and a charging circuit breaker QF. c , power supply capacitor C h The circuit is connected through the power supply capacitor C h Charging is complete, open the charging circuit breaker QF c And close the circuit breaker QF under test s In this state, the frequency modulation capacitor C oa Provides transient recovery voltage for experiments.

[0024] A method for conducting an experiment using a high-voltage circuit breaker transient recovery voltage experimental device based on a direct experimental method:

[0025] a) Close the charging circuit breaker QF c For power supply capacitor C h Charge to the preset voltage;

[0026] b) Open the charging circuit breaker QF c And close the circuit breaker DF h and the tested circuit breaker QF s , FM capacitor C oa Output target short-circuit current;

[0027] c) The voltage path outputs a compliant TRV when the current crosses zero;

[0028] d) Based on the simulation model to optimize the loop parameters, ensure that the TRV waveform in line with national standards: the use of MATLAB / Simulink design parameter calculation system, combined with experimental device constitutes a system device, input experimental way, voltage and current level conditions, parameter sensitivity analysis, output charging voltage, power capacitor and inductance, frequency modulation capacitor, frequency modulation resistance parameter value, and the actual parameters are verified.

[0029] The above experimental device is safer in laboratory environment, especially suitable for studying the breaking mechanism of circuit breakers under specific fault conditions; significantly reduces the requirements for experimental sites, suitable for small and medium-sized laboratories or rapid construction of temporary test platforms; saves large power equipment and complex grid connection, compact structure, laboratory construction and debugging are more convenient; reduces the experimental cost, suitable for scientific research institutions or enterprises to carry out high-frequency and small-scale circuit breaker characteristic research; by adjusting the capacitance value C and inductance value L, the frequency and attenuation characteristics of the oscillation current can be changed, the parameter adjustment is flexible, and different frequency currents (such as power frequency, high frequency or near fault frequency) can be simulated quickly to meet diversified testing needs; the LC resonance circuit generates a single frequency decaying current, which is controllable and has good repeatability; by accurately controlling the capacitor charging voltage and LC parameters, a high-repeatability decaying oscillation waveform can be generated, with high control accuracy; convenient operation, short test cycle, suitable for laboratory environment, and does not affect the actual power grid; has the advantages of simple structure, low cost and high safety.

[0030] The principle of the test of the direct experimental circuit is to charge a pulse capacitor bank in parallel for a long time, store energy, and then discharge through an inductor and a tested circuit breaker to generate an oscillating current of a certain frequency, so as to obtain a short-circuit current in a short time for circuit breaker breaking capacity test. The oscillation loop capacitance and inductance value should be appropriately selected, that is, the appropriate current waveform can be obtained. When the power capacitor in the loop is fully charged, the stored energy is released through the inductor element, thereby forming a short-circuit current path. This process can be described by a typical passive second-order series RLC circuit model, and the response waveform is determined by the parameters of resistance, inductance and capacitance.

[0031] In the direct experiment circuit test process, the sinusoidal current of 50Hz can be obtained in the discharge circuit by selecting the inductance and capacitance appropriately. And the sinusoidal current i in the circuit lags behind the voltage uc on the capacitor by 90° phase angle. Therefore, the current broken by the tested circuit breaker in the oscillation circuit is equivalent to the pure inductive current in the power grid. When the current is zero, the voltage uc on the power capacitor Ch is the maximum value Ucm, which is equivalent to the value of the power frequency recovery voltage at the breaking moment. The size of the frequency modulation capacitor can be adjusted to change the transient recovery voltage frequency when the tested circuit breaker is broken. If the amplitude of the transient recovery voltage needs to be adjusted, a frequency modulation resistance can be connected in parallel or in series with the frequency modulation capacitor. The value of the frequency modulation resistance can be adjusted to change the amplitude of the recovery voltage.

[0032] The circuit is shown in Figure 1 The charging circuit breaker QF c is closed first, and the AC output by the transformer TM is rectified by the rectifier device D to charge the power capacitor C h in the main circuit. When the voltage of the capacitor rises to the predetermined value U0, the charging circuit breaker QF c is opened and the closing circuit breaker QF h is closed. At this time, the power capacitor C h charges the circuit composed of the tested circuit breaker QF s through the inductor L, and the oscillation discharge is performed. The appropriate TRV is generated by the frequency modulation capacitor C oa , so that the breaking capacity test is realized. In the test system, the power frequency power supply is used as the basic energy input, the LC series resonant circuit effectively simulates the equivalent impedance characteristics of the power grid, and the damping resistance is introduced to suppress the high-frequency oscillation component of the TRV. During the test process, when the circuit breaker is opened at the current zero, the electromagnetic energy stored in the inductor and the capacitor is released and converted to each other, and then the transient recovery voltage (TRV) is generated at the breaking point, and the waveform characteristics are determined by the main parameters of the circuit.

[0033] The present application can perform parameter sensitivity analysis by inputting experimental methods, voltage and current levels and other conditions, and outputting the parameter values of the required charging voltage, power capacitor and inductor, frequency modulation capacitor and frequency modulation resistance, which is convenient for the construction of the device and the setting of the parameters, and the actual parameters can be verified.

[0034] The present invention uses the above-mentioned device to design a high-voltage circuit breaker TRV calculation method based on the direct experimental method to study the transient recovery voltage characteristics of the circuit breaker. In combination with the RLC series resonance principle, an equivalent circuit model of the direct test circuit is established, and the mathematical quantitative relationship between the circuit parameters and the TRV characteristics is derived. The equivalent circuit model uses an industrial frequency power supply as the basic energy input, and the LC series resonant circuit effectively simulates the equivalent impedance characteristics of the power grid. The damping resistor is introduced to suppress the high-frequency oscillation component of the TRV. During the test, when the circuit breaker opens when the current passes through zero, the electromagnetic energy stored in the inductance and capacitance in the circuit is released and converted to each other, thereby generating a transient recovery voltage (TRV) at the break. Its waveform characteristics are determined by the main parameters of the circuit; the mathematical quantitative relationship between the deduced loop parameters and the TRV characteristics is derived. According to the circuit principle, the circuit is listed and the differential equation is deduced to obtain the energy storage element parameter expression. According to the experimental requirements, the numerical value is entered to calculate the element parameters to achieve the appropriate TRV.

[0035] The circuit of this method is mainly composed of the energy storage capacitor C h , tuning inductor L h 、Tested circuit breaker QF s , loop inherent resistance R eq , and the FM capacitor C oa and frequency modulation resistor R oa The simplified topological structure is as follows Figure 2 The steps are as follows:

[0036] Step 1. Determine the energy storage capacitor and tuning inductor. Discharging the energy storage element creates a short-circuit current. When the current passes through zero, the voltage carried by the tuning capacitor and resistor provides the transient recovery voltage. This circuit satisfies Equation (1), so the circuit operates in an underdamped state, outputting an oscillating wave. The circuit exhibits an oscillating attenuation characteristic, and the output current amplitude is an exponentially decaying sinusoidal waveform, which can be expressed mathematically as Equation (2).

[0037]

[0038] Where: R is the inherent resistance in the circuit, U is the initial energy storage voltage of the capacitor, U r is the rated voltage of the circuit breaker, σ is the attenuation coefficient, and ω is the damped oscillation angular frequency.

[0039] From formula (1), we can get L h / C h >R 2 / 4, in order to keep TRV oscillation lasting, the resistance R is minimized, so L h / C h ? R 2 / 4, so i1(t) satisfies formula (7), and its peak value I m It is formula (8).

[0040] Therefore, ω can be simplified to the following form

[0041]

[0042]

[0043] Therefore, the oscillation frequency f1 in the circuit is:

[0044]

[0045] From formula (7), it can be seen that the exponential decay characteristic only depends on the resistance R and the inductance L. h Parameters, and the loop capacitance C h It is independent of the charging voltage U. Specifically, the attenuation coefficient σ determines the oscillation frequency of the current source loop current. Its physical mechanism is derived from the periodic alternating conversion between the electric field energy stored in the capacitor and the magnetic field energy stored in the inductor. At the same time, the resistance element gradually dissipates the system energy through heat dissipation, eventually causing the current to gradually decay to zero. Due to the oscillation frequency I m It is highly sensitive to the resistance in the loop, so controlling the total loop resistance, especially the equivalent resistance in the inductor, plays an important role in optimizing system performance.

[0046] During the loop oscillation discharge process, if the influence of the loop resistance is ignored, the effective value of the AC current can be expressed as:

[0047]

[0048] The specific expressions of capacitance and inductance required for the test can be derived:

[0049]

[0050] Step 2. Selection of frequency modulation circuit parameters. The charging capacitor Ch in the circuit not only needs to provide short-circuit current through the inductor Lh, but also needs to provide transient recovery voltage through Roa and Coa. Therefore, the required capacitance and inductance are relatively large. When the circuit breaker is separated and the short-circuit current passes through zero, Lh, Ch, Roa, and Coa form an attenuated oscillation circuit, and the voltage borne by Roa and Coa provides the transient recovery voltage. When the circuit breaker under test is disconnected, the equivalent circuit of the circuit is as follows: Figure 3 shown.

[0051] When the circuit breaker is disconnected, the circuit can be equivalent to a decaying oscillation circuit composed of Lh, Ch, Coa, and Roa. Writing the differential equation for the circuit gives

[0052]

[0053]

[0054] Combining (13), (14), and (15) we can get

[0055]

[0056] The initial conditions are

[0057]

[0058] From (21) and (22), we can get

[0059]

[0060] in Then calculate

[0061]

[0062] Because the system is underdamped and So u(t) can be simplified to

[0063]

[0064] The oscillation frequency of the transient recovery voltage is

[0065]

[0066] in But because C oa Usually less than C eq ≈C oa Therefore, in order to make the waveform meet the requirements of the national standard, the corresponding values ​​in the national standard are substituted, and then according to the definition of the natural oscillation frequency:

[0067]

[0068] In the formula, f0 is the natural frequency of TRV measured without connecting the FM capacitor and inductor. From this, the value of the FM capacitor can be obtained as

[0069]

[0070] The amplitude coefficient of the frequency modulation parameter is specified in the national standard as

[0071]

[0072] U hfm is the peak value of the recovery voltage of the circuit breaker under test, U m is the maximum amplitude of u(t), km is a constant, usually ranging from 1.4 to 1.6. Substituting tm into u(t), we get

[0073]

[0074] From (26), (27), and (28), we can get

[0075] R oa =-4f0L h ln(k m -1) (29)

[0076] Example 1:

[0077] The preset current level is 63kA, and the first-pole coefficient kpp is 1.5.

[0078] According to formulas (11), (12), (25), and (29), the component parameters are calculated for different voltage levels and experimental conditions, as shown in Table 1:

[0079] Table 1 Circuit parameters for different voltage levels at 63kA current

[0080]

[0081]

[0082] Based on the above parameters, a simulink simulation model is built. The model topology is as follows Figure 4 shown.

Claims

1. A high-voltage circuit breaker transient recovery voltage test device based on a direct test method, characterized by: It includes a charging circuit and an experimental circuit; the charging circuit includes a main power module and an energy storage unit, the primary side of the main power module is connected to the AC power supply, and the secondary side is connected to the charging capacitor group of the energy storage unit through diode rectification; the experimental module of the experimental circuit is connected to both ends of the charging capacitor group of the charging circuit, and the charging capacitor group serves as the power supply capacitor of the experimental circuit. The experimental module includes an LC resonant circuit composed of capacitors and inductors and a tested circuit breaker.

2. A high-voltage circuit breaker transient recovery voltage test device based on a direct test method according to claim 1, characterized in that: The experimental circuit is composed of power supply capacitor C h , closing circuit breaker QF h 、Inductor L h , FM capacitor C oa 、Tested circuit breaker QF s The direct experimental circuit is composed of the power supply capacitor C h , closing circuit breaker QF h 、Inductor L h , FM capacitor C oa Series, tested circuit breaker QF s and the FM capacitor C oa in parallel.

3. A high-voltage circuit breaker transient recovery voltage test device based on a direct test method according to claim 2, characterized in that: The charging circuit is composed of a transformer TM, a resistor R, a rectifier D, and a charging circuit breaker QF. c , power supply capacitor C h A circuit composed of connections.

4. A high-voltage circuit breaker transient recovery voltage test device based on a direct test method according to claim 2, characterized in that: The power supply capacitor C h Charging is complete, open the charging circuit breaker QF c And close the circuit breaker QF under test s In this state, the frequency modulation capacitor C oa Provides transient recovery voltage for experiments.

5. A method for conducting an experiment using a high-voltage circuit breaker transient recovery voltage test device based on a direct test method according to any one of claims 1 to 4, characterized in that: a) Close the charging circuit breaker QF c For power supply capacitor C h Charge to the preset voltage; b) Open the charging circuit breaker QF c And close the circuit breaker DF h and the tested circuit breaker QF s , FM capacitor C oa Output target short-circuit current; c) The voltage path outputs a compliant TRV when the current crosses zero; d) Optimize loop parameters based on the simulation model to ensure that the TRV waveform meets national standards.

6. The experimental method according to claim 5, characterized in that: In step d), a parameter calculation system is designed using MATLAB / Simulink and combined with the experimental device to form a system device. The experimental mode, voltage and current level conditions are input to perform parameter sensitivity analysis, output the parameter values ​​of the charging voltage, power supply capacitance and inductance, frequency modulation capacitor, and frequency modulation resistor, and the actual parameters are verified.

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