Capacitive Current Switching Test Research Articles

Study on phase selection control characteristics of fast vacuum circuit breakers suitable for new power systems

Abstract With a high proportion of new energy access to the power system, the user side of the randomness and volatility of distributed photovoltaic large-capacity access to the 10 kV medium-voltage distribution grid operation results in more frequent fluctuations in the system voltage and more frequent switching of reactive compensation of the shunt capacitor bank on the 10 kV side of the conventional substation. Conventional reactive compensation switching circuit breakers adopt a spring mechanism whose mechanical stability is insufficient and the selection of the relevant fit capacitor bank accuracy is not enough. The 12 kV fast vacuum circuit breaker of small mechanical dispersion for selection related to the combination was proposed. First of all, based on the neutral grounded and ungrounded system of the capacitor bank, the strategy of capacitor bank phase selection closing was developed. For the action characteristics of the phase selection of the 12 kV fast vacuum circuit breaker, the variation laws of mechanical dispersion and the influence factors such as ambient temperature, capacitance voltage, capacitance degradation, mechanical wear, and conductive rod deformation were obtained by simulation and experiment. The results showed that the ambient temperature and capacitance voltage had a great influence on the switching time of the fast circuit breaker, while other factors had a small influence. Again, the pre-breakdown characteristics of the 12 kV fast vacuum circuit breaker were obtained by experiments. The results showed that the influence of contact opening distance and pre-breakdown voltage was a linear relationship, and the pre-breakdown slope was 30 kV/mm. According to the pre-breakdown closing characteristic curve, the pre-breakdown time of the fast circuit breaker was 0.45 ms at most. The feedforward compensation mechanism based on a neural network was proposed to compensate for the action characteristics of the fast circuit breaker and aimed to improve the phase selection accuracy. Finally, two rounds of capacitive current switching tests of 12 kV fast vacuum circuit breakers with C2 level were carried out in a third-party test station. The accuracy of phase closing is within the ±0.5 ms closing window, effectively preventing the occurrence of closing inrush current.

Improved Testing Method Using the Multi-Transformers Synthetic Circuit to Verify Capacitive Charging Current Switching Capability of High-Voltage Circuit Breakers

To perform a capacitive current switching test (CCT) at AC extra-high-voltage (EHV) and above level, this paper proposes a new multi-transformer synthetic circuit (MTSC) test method that replaces the general synthetic test method using capacitor banks. An MTSC method has a simpler circuit structure compared to other synthetic testing methods and has higher equivalence (especially recovery voltage and TRV) and validity. Using this method, CCTs for circuit breakers (CBs) of the AC 420 kV voltage class were performed as a field test using the IEC 62271-100 standard. To verify that the test method was valid, test results were analyzed and compared with the requirements of a standard. Consequently, the MTSC method completely covered the requirements of the standard.

Interpretation of NSDD and Restrike in Capacitive Current Switching Test on Medium Voltage Vacuum Circuit Breaker

Capacitor banks are installed in an increasing number to control power quality issues and improving the power factor tocounteract the reactive power in the transmission and distribution networks. Due to load fluctuations switching of capacitorbanks is a typical phenomenon. Capacitor bank is normally having concentrated capacitance in contrast with distributedcapacitance. It generally draws more current than unloaded cableor line in practical cases up to several hundred amperes.Hence, switching of capacitor bank causes a very high rate of rise of transient recovery voltage across circuit breakercontacts. This scenario can be simulated in testing laboratories by a voltage source connected to a circuit breaker whichagain is connected to a large capacitance in terms of IEC called capacitive current switching test. Non-sustained disruptivedischarge (NSDD) is a voltage breakdown after the vacuum circuit-breaker open the fault current which will not cause therecovery of power frequency current. Restrike is different from NSDD, the recovery of power frequency current betweenthe contacts will make the breaker failed. It’s not easy to show the distinction between NSDD and restrike during some typetests. The paper presents the study of performance evaluation of the circuit breaker during the capacitor current switchingduties. A statistical analysis of failure of circuit breaker during capacitor current switching tests are included in the paperto help the manufacturers & utilities, so that the care can be taken for trouble free services. The paper also discusses thechanges made in the IEC 62271 – 100, Amendment1:2012 for conducting the capacitive current switching tests.

Development and type test of ZW-126/D2000-40 vacuum circuit breaker with controlled switching technology

A ZW-126/D2000-40 type single-break vacuum circuit breaker(VCB) with controlled switching technology is designed and produced in this paper. The results of type test based on IEC and GB standards are presented. A 126 kV single-break vacuum interrupter (VI) with 3/4 coil axial magnetic field (AMF) contacts is used in the VCB, which can interrupt short current of 40 kA. The external insulation of the VI is provided by SF6 at 0.1 MPa. In order to match the 126kV single-break VI and controlled switching device, a long-stroke electro-magnetic force actuator (EMFA) with 16kN closing holding force and 3.5 m/s average opening speed is designed. Moreover, a position tracking controlled switching device based on closed-loop control by the technology of fuzzy control algorithm and pules width modulation is applied to the controlled switching device. This device is applied to control the coil current of EMFA and the electromagnetic force, so as to control the EMFA to follow the ideal position curve. The type tests of 126kV VCB are all passed according to the IEC62271-100 and GB1984-2014, including dielectric tests, basic short-circuit tests, short-line fault test, out-of-phase test, etc. The strong capacitive current breaking capacity and mechanical strength of the VCB are proved by the capacitive current switching test of class C2, electrical endurance test of class E2 and mechanical endurance test of class M2. The electromagnetic compatibility (EMC) tests are passed according to the IEC61000-4. The controlled switching test of capacitive current was successful according to IEC62271-302 and GB/T30846-2014, and the controlled switching accuracy is less than ±0.5 ms. The test results showed that the VCB has excellent performance, which has broad application prospects in special occasions at 126 kV voltage level, such as switching capacitor and no-load transformer, etc.

Development and Type Test of a Single-Break 126-kV/40-kA–2500-A Vacuum Circuit Breaker

The objective of this paper is to present a 126-kV/40-kA–2500-A single-break vacuum circuit breaker (VCB) and its type test results based on the IEC 62271-100: 2006 and GB1984-2003 standards. A single-break 126-kV vacuum interrupter (VI), with a pair of 2/3 coil-type contacts, is used in the 126-kV VCB. The external insulation of the VI is provided by ${\rm SF}_{6}$ at 0.1 MPa. A spring-type operating mechanism is used to provide a closing velocity of 1.15 m/s, which is an average velocity for 4 mm before the moving contact mates with the stationary contact. The opening velocity within 20 mm, which is 1/3 of a full contact stroke of 60 mm, is 3.5 m/s. Two kinds of test circuits are used in the type tests to verify the making and breaking capabilities of this 126-kV VCB prototype. One is a direct test circuit for test duty cycles, such as out-of-phase making and breaking test duties, that is, OP1 and OP2; capacitive current switching test of class C1, that is, CC1/LC1 and CC2/LC2. The other is a synthetic circuit, used for tests, such as the terminal fault test, the short-line fault test, the double earth fault test, and the electrical endurance test of class E2. The dielectric tests of a 230-kV/1 min power frequency voltage withstand test and a 550-kV lightning impulse voltage withstand test were used to verify the dielectric withstand performance of the VCB. Experiment results presented in this paper showed that the 126-kV/40 kA–2500 A single-break VCB passed the type tests according to IEC 62271-100 and GB1984-2003.

HVDC시스템에서 AC 필터 차단기의 TRV해석

The circuit breaker in an electric power system is not operated when the voltage in the circuit breaker is higher than the rated transient recovery voltage (TRV). The TRV of a circuit breaker is characterized by re-ignition of the arc between two poles and determined by the value of connecting impedance. In this study, we simulated the peak value of TRV in the AC filter of the circuit breaker. The suitability of TRV is assessed by capacitive current switching test conditions defined by the international guide IEC62271-100.

Development of Single Break 420 kV GCB

420 kV-63 kA single break gas circuit breaker (GCB) has been developed(1). The authors show the steps to develop new interrupting chamber and circuit breaker by using various techniques. At first two interrupting chamber models are considered and investigated conducting electric field calculation and pressure measurement at the top of fixed arc contact, and capacitive current switching test is conducted especially with short arcing times. According to the test results, basic dimensions of interrupting chamber for development is determined. Pre-series CBs are manufactured, then it is confirmed that the breaker can produce the pressure rise in puffer cylinder (ΔP) as the predicted value by calculation and can interrupt short line fault (SLF) current. The driving energy is confirmed to be sufficient by conducting asymmetrical 100% breaker terminal fault (T100a) current interruption tests. All the type tests according to IEC are successfully conducted at the international neutral test station for the breakers for commercial use reflected the above results. The GIS layout with the above mentioned single break GCB can reduce the installation area in half comparing the case with the existing two break GCB.

Comparing direct and synthetic tests for interruption of line-charging capacitive current

Using a validated arc model, this paper analyzes current distortion and voltage waveforms during both direct and synthetic tests for interruption of line-charging capacitive current by power circuit breakers. Although the voltage of the electric arc drawn between breaker contacts may produce significant current distortion, it is demonstrated that the most significant parameter affecting the breaking capacity of power circuit breakers in capacitive-current switching tests is the voltage jump appearing across breaker contacts immediately after current interruption. It is essential to correctly define the supply circuit impedances and the associated voltage jump so as not to reduce or increase this test severity unduly.

Recent Experience with Synthetic Circuits for Capacitive Current Switching Tests on HV Circuit-Breakers

The phenomena related to capacitive current switching are briefly summarized and the resulting requirements for such tests carried out by synthetic methods are discussed.

Recent Experience with Synthetic Circuits for Capacitive Current Switching Tests on HV Circuit Breakers

Recent Experience with Synthetic Circuits for Capacitive Current Switching Tests on HV Circuit Breakers