Current Breaking Test Research Articles

Transient Current Balancing of Parallel IGCTs in 10-kV/10-kA Hybrid DC Circuit Breaker

Integrated gate-commutated thyristor (IGCT) is an emerging alternative for hybrid DC breaker (HDCB) to achieve fault current clearance in DC systems. However, the maximum controllable current of present IGCT products cannot cope with high-capacity interruption and IGCTs often need to be paralleled. Unlike insulated-gate bipolar transistor (IGBT) whose parallel methods have been widely studied, there lacks intensive study on the transient current balancing and optimization methods for parallel IGCTs, especially in critical current breaking applications. This paper proposes a practical solution to the transient current balancing of parallel IGCTs in HDCB. Theoretical and mathematical analysis shows that current spike occurs due to anode voltage discrepancy. Although self balancing effect and delayed gate signals can help relieve the current spike, IGCT is still possible to exceed the safe operation area (SOA). An improved topology of parallel IGCTs with bypass capacitors is used to deal with this problem, which is verified by 10 kA turn-off experiment. Successful 10 kA current breaking tests of 10 kV HDCB prototype demonstrate the feasibility and validity of the improved parallel IGCT switch.

Synthetic test circuit with two‐level voltage source for HVDC circuit breakers

AbstractIn order to ensure the reliable interruption of high voltage direct current circuit breaker (HVDC CB), the breaking test of HVDC CB plays an important role in its performance verification. In this paper, the interruption process of the HVDC CB is analyzed, and the equivalent requirements for the breaking test of HVDC CB are summarized. In the breaking test of high voltage and high current, the transient interruption voltage (TIV) duration is short, which leads to insufficient voltage stress. A new synthetic test circuit for testing the interruption performance of HVDC CBs is proposed, which can solve the problem of insufficient TIV duration caused by insufficient test capacity. Subsequently, the working principle of the test circuit is introduced in detail and the design method of the circuit parameters is given. The short‐circuit current breaking test simulation of HVDC CB is carried out. The simulation results fit most well with the results of actual test cases, which verifies the universality of this test method. Finally, a test platform is built to verify the principle of the test circuit. TIV rose to 2.5 kV compared to the predetermined system voltage of 1.67 kV during the test, which means that the key stress provided by the test circuit can meet the expected requirements.

Reconfigurable Large-Current and High-Voltage Test Bench for HVDC Circuit Breaker Verification

This article presents a novel circuit configuration of a high-voltage direct current circuit breaker (HVdcCB) test bench that is based on a modified H-bridge modular multilevel cascaded converter (MMCC). The modified MMCC is composed of fewer H-bridge cells, and it can be reconfigured during operation to allow the proposed test bench to output large current or high voltage for the current breaking and dielectric withstand tests. Although simultaneous output of large current and high voltage is not possible, the maximum transient interrupt voltage (TIV) withstand test can be performed with reduced ratings. The controllable output allows generation of complex waveforms to simulate a wide range of fault conditions. Furthermore, the modified MMCC has some inherent safety features that can reduce the need for additional protective equipment in case of operational failure of the HVdcCB. In contrast, the conventional charged capacitor and inductor-based designs cannot generate arbitrary waveforms, are only suitable for current breaking tests, and require additional circuits to generate initial conditions for the HVdcCB. AC short-circuit generator-based designs offer one degree of freedom for control of the output waveforms and can sustain the maximum TIV withstand test. However, the ac output is unsuitable for the dielectric withstand test, and additional circuits are required to provide initial conditions for the HVdcCB. The proposed test bench circuit configuration is verified using a downscaled experimental test bench that consists of a total of nine H-bridge cells with an equivalent switching frequency of 92.5 kHz.

Dual-Circuit-Based Test Bench Design for HVDC Circuit Breaker Verification

High-voltage direct current (HVDC) circuit breaker development and deployment strongly depend on the testing process, which ensures that the HVDC circuit breakers will satisfy design requirements. This article presents an HVDC circuit breaker test bench circuit configuration that can provide controllable large output currents to simulate different fault conditions for the current breaking test and high output voltage for the dielectric withstand test. The current breaking test circuit is based on multiple cascaded power converters connected in parallel to provide the necessary output current capability. Each cascaded power converter is composed of multiple cells that are operated by a phase-shifted pulsewidth-modulated signal for greater controllability and higher quality of the output waveform. The dielectric withstand test circuit is a simple high-voltage source with a low power rating that can also be used to charge the test bench and the internal circuitry of the circuit breaker that is to be tested. The proposed test bench ensures that fault conditions can be replicated accurately and offers greater flexibility by being able to test mechanical, semiconductor-based, or hybrid HVDC circuit breakers with different current and voltage ratings on the same hardware without any changes. The idea and the operating principle of the proposed test bench are verified experimentally on a downscaled system that consists of three cascaded power converters connected in parallel with three cells per cascaded power converter and with a total equivalent switching frequency of 92.5 kHz.

Current Breaking Test of the Superconducting Feeder on Tram-Train Running

To introduce the superconducting feeder cable for commercial operation of a railway system, it is required to establish technologies for safety and reliability. The behavior of the superconducting cable must be determined for the case in which the superconducting cable fails in the feeder system for railways. The superconducting cable can be introduced so that it is installed along with the existing feeder cable or so that only the superconducting cable is installed to be used as the feeder line. For this time, at first only, the superconducting cable was used to establish a circuit for feeder to the electric railcar without using the existing feeder circuit to conduct the power-transmission test and current breaking test. Then, the superconducting cable was installed along the existing feeder line to establish a circuit that is capable of feeder via both feeder lines to conduct the same tests. In both tests, it is confirmed that no problem occurs in the train and the superconducting cable system when it encounters the current breaking. For the parallel feeder system, it is found that the current path is transferred to the existing feeder line and the system is continuously capable of operating the train stably when the current is broken in the superconducting cable.

Effect of nozzle ablation amount on the generation amount of decomposition products for SF 6 circuit breaker

Non-uniform arc burning in the nozzle is a common latent fault of SF6 circuit breaker, which will affect its breaking performance. When arcing, PTFE in the nozzle is vaporized and involved in the formation reaction of SF6 decomposition products. Non-uniform arc burning leads to PTFE excessive vaporization and significantly affects the type and concentration of some SF6 decomposition products, which can provide a basis for the latent fault diagnosis. In this paper, 16 times of 31.5kA short-circuit current breaking tests were carried out by two 40.5kV SF6 circuit breakers respectively. The uniform and non-uniform ablation nozzles were obtained. It was found that the concentrations of SOF2, SO2 and SO2F2 were almost not affected by the amount of nozzle ablation. However, when the mass loss of excessive ablation nozzle is 1.8g more than the normal one, CF4, C2F6, CS2 and CO2 of excessive ablation nozzle are 807.5uL/L, 22.5uL/L, 9.0uL/L and 116.9uL/L more than the normal one, respectively. CF4, C2F6, CS2 and CO2 can be used as characteristic decomposition products to diagnose non-uniform arc burning in the nozzle. This study is of great significance for the latent fault diagnosis of SF6 circuit breakers based on decomposition product analysis.

Design and short‐circuit current breaking test verification of a 72.5 kV single‐break fast vacuum circuit breaker

Fast clearing of a short-circuit fault is vital to increase the transmission capacity of power grid transmission lines and improve the transient stability of a power system. A fast vacuum circuit breaker (FVCB) is a good candidate to realize quick elimination of a short-circuit fault. The original contribution of this paper is to present the design of a 72.5 kV single-break FVCB and its verification of short-circuit breaking performance. A specially designed 72.5 kV vacuum interrupter, with floating shields and reduced mass of moving components, was developed. An electromagnetic repulsion actuator was used to provide a high initial opening speed, V1, of 5 m/s over half of the full-contact gap and a relatively low average opening speed, V2, of 1.59 m/s in the full contact gap of 30 mm. The high-designed V1 and low-designed V2 were achieved with the aid of a deliberately designed oil buffer. The opening and closing time of the designed 72.5 kV FVCB was 1.2 ± 0.04 ms and 18 ± 0.20 ms respectively. The terminal fault test duty of T100s(b), carried out on the 72.5 kV FVCB, demonstrated both the 40 kArms and 80 kArms short-circuit current breaking performance. The short-circuit current breaking arcing time windows of FVCB, including the minimum arcing time, the maximum arcing time, and the middle arcing time, was verified to fulfill the requirement of the international standard, IEC 62271-100 2017, and the Chinese standard, GB/T 1984–2014, both for the 40 kArms and 80 kArms switching cases, respectively. Further development of the 72.5 kV single-break FVCB would benefit the development of ultra- or extra-high voltage FVCBs by reducing essential numbers of series-connected breaking units.

A Novel DC Circuit Breaker With Counter-Current Injection and IGCT Combined

The fast fault clearance in medium voltage direct current (MVDC) grids requires the DC circuit breakers (DCCBs) with high breaking capability and low cost. The traditional hybrid DCCB realizes large current interruption relying on several insulated gate bipolar transistors (IGBTs) in parallel, which results in difficulty of cost reduction. In this paper, a novel DC circuit breaker with counter-current injection and integrated gate-commutated thyristor (IGCT) combined is proposed and analyzed. By combining forced commutation and IGCT, the large current breaking capability can be realized and the low cost is guaranteed. The simulation of the proposed DCCB is performed to evaluate the fault current breaking capability and influence of circuit parameters consisting of stray parameters and pre-charged capacitors on current commutation processes. Furthermore, a prototype of the 10 kV MVDC circuit breaker with 20 kA breaking capability is developed, then the fault current breaking test is carried out to verify the validity of the proposed topology which can cut off current within 2.5 ms. 1

Development and Application of a 10 kV Mechanical DC Circuit Breaker

A DC circuit breaker is piece of core equipment for DC grid construction and can achieve fast isolation of DC faults in the grid. In this paper, based on the fault characteristics and protection requirements of an AC/DC hybrid distribution network, the technical parameters and topology structure of an inductance and capacitance (LC) resonant commutation-type mechanical DC breaker are proposed. Furthermore, an engineering prototype of the mechanical DC circuit breaker is developed, then a small current breaking test and a large current breaking test are carried out. The test results show that a 10 kA fault current can be interrupted within 10 ms by the engineering prototype. Finally, the engineering prototype of the mechanical DC circuit breaker is installed in the AC/DC hybrid distribution network project, and a current breaking test is carried out. The test results show that the mechanical DC circuit breaker has good running conditions, and the function and performance meet the engineering design and operation requirements.

Analysis of Dynamic Arc Parameters for Vacuum Circuit Breaker Under Short-Circuit Current Breaking

The vacuum circuit breaker (VCB) is an important vacuum switch widely used in generator protection systems and medium-voltage distribution power systems. For observing the vacuum arc behavior variation and analyzing the dielectric recovery characteristics and interrupting capability of VCBs, an experimental platform for a 40.5-kV/31.5-kA/2500-A VCB was established. Under the condition of typical short-circuit current breaking, the short-circuit current breaking test was carried out and the vacuum arc image was collected to obtain the curve of voltage versus current during the breaking process and the arc resistance distribution. By analyzing the variation trend of dynamic arc resistance, a physical and mathematical description of dynamic arc resistance was obtained by the curve fitting method. By comparing and analyzing the experimental data of arc resistance, it is shown that the physical and mathematical description can appropriately describe the spatiotemporal variation of arc resistance in the arcing interval.

Test circuit for verifying dielectric performance of phase-to-enclosure during capacitive current breaking

AbstractIn the case of Extra High Voltage and Ultra High Voltage circuit breaker, almost all of testing laboratories adopt the single-phase testing method for verifying the performance of capacitive breaking capability, based on IEC 62271-100 Annex O, due to the limitation of testing facilities. For dead-tank breaker, the tests for the insulating properties of phase-to-enclosure are recommended as a non-mandatory testing item. However, IEC MT36 has proposed the change of standard to specify as a mandatory in its next version planned in 2016. The peak of recovery voltages, occurring just after interrupting the some type of capacitive currents, arrives at different values on supply and load sides. With the technical background, the new capacitive current breaking test circuits are proposed to fulfill the next edition of IEC 62271-100 to be newly published. This paper illustrates the testing methods and simulation results for the single phase test circuits of capacitive current breaking, applicable to the ci...

Study on Static and Dynamic Voltage Distribution Characteristics and Voltage Sharing Design of a 126-kV Modular Triple-Break Vacuum Circuit Breaker

The static and dynamic voltage distribution characteristics and voltage sharing design of a 126-kV modular triple-break vacuum circuit breaker (VCB) was discussed in this paper. The finite-element method and power frequency tests were used to calculate and verify the static voltage distribution ratios and distributed capacitance parameters of multi-break VCBs, respectively. A model combining the post arc current model and equivalent capacitance model was proposed for simulations of dynamic transient recovery voltage (TRV) distribution characteristics of the triple-break VCB. The simulation results indicated that besides the stray capacitances, the TRV sharing design should take the influence of residual charge (RC) into account, and the influence of RC on the TRV distribution is relevant to the differences of RC parameters among the series interrupters. Therefore, the appropriate value of grading capacitors should meet the requirement of the worst case. Based on the investigation of this paper, a 126 kV U-shaped triple-break VCB prototype with 1000 pF grading capacitors has been produced, and the successful large current breaking tests indicate the good breaking capacity and suitable voltage sharing design of the triple-break VCB.

Investigation of DC hybrid circuit breaker based on high-speed switch and arc generator.

A new design of DC hybrid circuit breaker based on high-speed switch (HSS) and arc generator (AG), which can drastically profit from low heat loss in normal state and fast current breaking under fault state, is presented and analyzed in this paper. AG is designed according to the magnetic pinch effect of liquid metal. By utilizing the arc voltage generated across AG, the fault current is rapidly commutated from HSS into parallel connected branch. As a consequence, the arcless open of HSS is achieved. The post-arc conducting resume time (Δ tc) of AG and the commutation original voltage (Uc), two key factors in the commutation process, are investigated experimentally. Particularly, influences of the liquid metal channel diameter (Φ) of AG, fault current rate of rise (di/dt) and Uc on Δ tc are focused on. Furthermore, a suitable Uc is determined during the current commutation process, aiming at the reliable arcless open of HSS and short breaking time. Finally, the fault current breaking test is carried out for the current peak value of 11.8 kA, and the validity of the design is confirmed by the experimental results.

Research on a novel two-stage direct current hybrid circuit breaker.

The DC hybrid circuit breaker based on high-speed switch (HSS) and parallel connected capacitor has been widely applied in the fault current breaking of DC system. However, when the current is commutated from HSS to the capacitor according to single-stage operation, the capacitor has to absorb a large amount of energy stored in the system inductance within very short time. Meanwhile, a high over-voltage rate of rise is especially prone to be produced between the contacts of HSS, which will lead to a failed breaking. As a result, a novel DC hybrid circuit breaker based on the two-stage operation is proposed and analyzed in this paper. By controlling the thyristors in the commutation branches, the fault current is fast commutated into the capacitor, which can not only realize the arcless open of HSS, but also decrease the over-voltage rate of rise significantly in comparison to the traditional single-stage operation. The simulation model of fault current breaking under different conditions in 10 kV medium voltage DC system is constructed. The simulated over-voltages of single-stage and two-stage operations in the case of fault current breaking are compared and analyzed. Finally, the fault current breaking test in the two-stage operation is investigated experimentally, which validates the feasibility and effectiveness of the simulation model well.

７２ｋＶ低圧力ドライエア絶縁Ｃ－ＧＩＳにおけるドライエア中および真空中での絶縁技術

A new 72kV rated low pressured dry air insulated switchgear applying electromagnetic actuation and function that supports CBM has been developed. First, dielectric characteristics in dry air under lightning impulse application has been investigated at bare and insulator covered electrodes. Dependence of the breakdown electric field strength on the effective area has been clarified to apply the configuration design of the insulation mold for the vacuum interrupter. In addition, moisture volume dependence on surface resistance has been clarified to decide moisture volume in gas pressure tank. Next, a new vacuum circuit breaker (VCB) has been designed. To keep dimensions from former 72kV SF6 gas insulated switchgear, distance between contacts in vacuum interrupter is needed to be shorter than that of former switchgear. Voltage withstand capability between electrodes practically designed for vacuum interrupter has been investigated under dc voltage application simulated the small capacitive current breaking test. Gap configuration including contacts and slits has been optimized and distance has been shortened 11% from former switchgear.As a result, the new low pressured dry air insulated switchgear has been designed comparably in outer size to former SF6 gas insulated switchgear. Using dry air as an insulation medium with low pressure has been able to reduce the environmental burden.

Johnson(-like)–Noise–Kirchhoff-loop based secure classical communicator characteristics, for ranges of two to two thousand kilometers, via model-line

A pair of Kirchhoff-loop–Johnson(-like)–Noise communicators, which is able to work over variable ranges, was designed and built. Tests have been carried out on a model-line performance characteristics were obtained for ranges beyond the ranges of any known direct quantum communication channel and they indicate unrivalled signal fidelity and security performance of the exchanged raw key bits. This simple device has single-wire secure key generation and sharing rates of 0.1, 1, 10, and 100 bit/second for corresponding copper wire diameters/ranges of 21 mm/2000 km, 7 mm/200 km, 2.3 mm/20 km, and 0.7 mm/2 km, respectively and it performs with 0.02% raw-bit error rate (99.98% fidelity). The raw-bit security of this practical system significantly outperforms raw-bit quantum security. Current injection breaking tests show zero bit eavesdropping ability without triggering the alarm signal, therefore no multiple measurements are needed to build an error statistics to detect the eavesdropping as in quantum communication. Wire resistance based breaking tests of Bergou–Scheuer–Yariv type give an upper limit of eavesdropped raw-bit ratio of 0.19% and this limit is inversely proportional to the sixth power of cable diameter. Hao's breaking method yields zero (below measurement resolution) eavesdropping information.

DC breaking tests up to 55 kA in a single vacuum interrupter

DC current breaking tests were carried out on several vacuum circuit-breakers during the design of the energy transfer units for the RFX fusion experiment. The tests were performed with a synthetic circuit able to reproduce the expected stresses on the switching element during the breaking phase. The performance of a prototype for a medium-voltage AC switch with a self-produced axial magnetic field is discussed. The interrupter was found capable of breaking currents up to 55 kA with a recovery voltage greater than 35 kV and high values of di/dt in a large range of arcing times. >