Search Results (8)

The state of the energy-absorption branch MOV in the hybrid DC circuit breaker (DCCB) has a very important impact on the short fault breaking operation of the circuit breaker. Therefore, it is necessary to evaluate the state of the MOV, which is also called the “sleep component”. Due to DCCB being placed indoors, the aging is mainly caused by short-circuit impulse current. Therefore, this paper mainly focuses on the study of the short-circuit impulse aging characteristics of the energy-absorption branch MOV. The dynamic simulation system of a hybrid DCCB was built to investigate the impulse of short-circuit current on the MOV of the energy-absorption branch during the circuit breaking process. Then, an accelerated impulse aging test platform was built and the accelerated impulse aging tests of the MOV were conducted. The aging characteristics of the MOV were analyzed in detail and detailed analysis was conducted of the macroscopic parameters and microstructure changes. The results indicate that the nonlinear coefficient α could be emphasized as a basis for judging the “sleeping” component states and aging degree of the hybrid DC circuit breaker, and can be expected to be applicable to MOV condition monitoring of BCCB in the future. Full article

While traditional AC mechanical circuit breakers can protect AC circuits, many other DC power distribution technologies, such as DC microgrids (MGs), yield superior disruption performance, e.g., faster and more reliable switching speeds. However, novel DC circuit breaker (DCCB) designs are challenging due to the need to quickly break high currents within milliseconds, caused by the high fault current rise in DC grids compared to AC grids. In DC grids, the circuit breaker must not provide any current crossing and must absorb surges, since the arc is not naturally extinguished by the system. Additionally, the DC breaker must mitigate the magnetic energy stored in the system inductance and withstand residual overvoltages after current interruption. These challenges require a fundamentally different topology for DCCBs, which are typically made using solid-state semiconductor technology, metal oxide varistors (MOVs), and ultra-fast switches. This study aims to provide a comprehensive review of the development, design, and performance of DCCBs and an analysis of internal topology, the energy absorption path, and subcircuits in solid-state (SS)-based DCCBs. The research explores various novel designs that introduce different structures for an energy dissipation solution. The classification of these designs is based on the fundamental principles of surge mitigation and a detailed analysis of the techniques employed in DCCBs. In addition, our framework offers an advantageous reference point for the future evolution of SS circuit breakers in numerous developing power delivery systems. Full article

One of the technical challenges that needs to be addressed for the future of the multi-terminal high voltage direct current (M-HVDC) grid is DC fault isolation. In this regard, HVDC circuit breakers (DCCBs), particularly hybrid circuit breakers (H-DCCBs), are paramount. The H-DCCB, proposed by the ABB, has the potential to ensure a reliable and safer grid operation, mainly due to its millisecond-level current interruption capability and lower on-state losses as compared to electromechanical and solid-state based DCCBs. This paper aims to study and evaluate the operational parameters, e.g., electrical, and thermal stresses on the IGBT valves and energy absorbed by the surge arrestors within H-DCCB during different DC fault scenarios. A comprehensive set of modeling requirements matching with operational conditions are developed. A meshed four-terminal HVDC test bench consisting of twelve H-DCCBs is designed in PSCAD/EMTDC to study the impacts of the M-HVDC grid on the operational parameters of H-DCCB. Thus, the system under study is tested for different current interruption scenarios under a (i) low impedance fault current and (ii) high impedance fault current. Both grid-level and self-level protection strategies are implemented for each type of DC fault. Full article

DC circuit breaker (DCCB) systems with a DC reactor in series are normally equipped in the voltage-sourced-converter-based multi-terminal DC (VSC–MTDC) systems for DC fault clearance. However, it is revealed that the use of DC reactors could undermine the system damping and deteriorate the system stability. In this paper, a controller based on hybrid sensitivity is proposed to improve the stability of power system and realize the power symmetry of multi-terminal systems. Firstly, based on a generalized MTDC small-signal model, an eigenvalue analysis is performed to provide deep insight into the stability issue imposed by DC reactors. Furthermore, a local controller based on hybrid sensitivity was proposed, and on this basis, a global controller was designed to solve asymmetrical power flow. Finally, a four-terminal VSC–MTDC model was built in Simulink to evaluate the performance of DC-PSS. Simulation results verify the effectiveness of the proposed controller in stabilizing MTDC systems and symmetrizing of power flow. Full article

In this paper, direct current (DC) fault current limiting and interrupting operation of hybrid DC circuit breaker (DCCB) using double quench, which consists of DCCB, a series resonance circuit, power electronic switch, surge arrestor, two separated current limiting reactor/resistor, and two superconducting elements, were suggested. The suggested hybrid DCCB can perform the interrupting operation after twice or once DC fault current limiting operation according to DC fault current amplitude. To verify the effective operation of the suggested hybrid DCCB, the modeling for the components of DCCB, the surge arrestor, and the SCE was carried out and its DC operational characteristics were analyzed. Through the analysis of the modeling results for the suggested hybrid DCCB, the advantages of hybrid DCCB were discussed. Full article

With the increasing demand for renewable energy power generation systems, high-power DC transmission technology is drawing considerable attention. As a result, stability issues associated with high power DC transmission have been highlighted. One of these problems is the fault current that appears when a fault occurs in the transmission line. If the fault current flows in the transmission line, it has a serious adverse effect on the rectifier stage, inverter stage and transmission line load. This makes the transmission technology less reliable and can lead to secondary problems such as fire. Therefore, fault current must be managed safely. DC circuit breaker technology has been proposed to solve this problem. However, conventional technologies generally do not take into account the effects of fault current on the transmission line, and their efficiency is relatively low. The purpose of this study is to introduce an improved DC circuit breaker that uses a blocking inductor to minimize the effect of fault current on the transmission line. It also uses a ground inductor to efficiently manage the LC resonant current and dissipate residual current. DC circuit breakers minimize adverse effects on external elements and transmission lines because the use of elements placed on each is distinct. All of these processes are precisely verified by conducting simulation under 200 MVA (±100 kV) conditions based on the VSC-based HVDC transmission link. In addition, the mechanism was explained by analyzing the simulation results to increase the reliability of the circuit in this paper. Full article

Voltage source converter-based (VSC-based) DC systems play an important role in connecting large-scale renewable energy and distributed energy, but they are vulnerable to DC short-circuit fault and lacks mature protection devices and appropriate protection strategies. Therefore, a hybrid type DC superconducting fault current limiter (H-SFCL) is proposed and the current limiting mechanism of the SFCL is analyzed. According to the requirements and strategies for protection, several different effective parameter matching and optimization methods of the H-SFCL are proposed by combining optimization algorithms and two short-circuit transient calculation models of VSC-based DC systems. The optimization methods proposed in this paper are compared and analyzed in terms of convergence, running time, calculation range and stability of optimization results, revealing their respective calculation characteristics. Finally, the effectiveness of parameter matching and optimization methods are well validated by comparison and analysis of simulation. The proposed methods can select a good parameter matching scheme of the H-SFCL to deal with different requirements. Full article

The half bridge (HB) modular multilevel converter (MMC) technology is considered a breakthrough to mitigate the shortcomings of the conventional voltage source converter (VSC) in high-voltage direct-current (HVDC) grid application. However, interruption of the DC fault is still a challenge due to fast di/dt and extremely high levels of DC fault current. The fault interruption using a DC circuit breaker (DCCB) causes enormous energy dissipation and voltage stress across the DCCB. Therefore, the use of a fault current limiter is essential, and the superconducting fault current limiter (SFCL) is the most promising choice. Past literature has focused on the operating characteristics of DCCB or limiting characteristics of the SFCL. However, there is little understanding about the fault interruption and system recovery characteristics considering both DCCB and SFCL. In this paper, we have presented a comparative study on fault interruption and system recovery characteristics considering three types of fault limiting devices in combination with circuit breaker. The transient analyses of AC and DC system have been performed, to suggest the most preferable protection scheme. It has been concluded that, amongst the three fault limiting devices, the Hybrid SFCL in combination with circuit breaker, delivers the most desirable performance in terms of interruption time, recovery time, energy dissipation and voltage transients. Full article