Short-circuit Current Limitation Research Articles

Short-Circuit Current Limitation Through 2G YBCO Resistive-Type SFCL Devices: A Model for Technical and Economic Comparison With Traditional Air-Core Reactors

Short-Circuit Current Limitation Through 2G YBCO Resistive-Type SFCL Devices: A Model for Technical and Economic Comparison With Traditional Air-Core Reactors

Overview of permanent-magnet fault-tolerant machines: Topology and design

Permanent-magnet (PM) machines have attracted a lot of interest in various applications since they have the merits of high torque density, high power density and high efficiency. However, issue of poor fault tolerance of the conventional PM machines restricts their practical applications in the field of safety-critical applications, e.g. aerospace, electric vehicle, electrical propulsion and wind power generator applications. An enormous amount of work has been done to improve the fault-tolerant capability of PM machines. This paper will review research work on PM fault-tolerant machines up-to-date, including modular design, short-circuit current limitation design, redundant design, ease of thermal dissipation of PM design, and torque enhancement design techniques. The work of this paper can provide some references for future studies and engineering applications of PM fault-tolerant machines for safety-critical applications.

Operation Modes and Combination Control for Urban Multivoltage-Level DC Grid

With the development of urban economy and the growing integration of renewable energy, there are increasing challenges on the urban power grid. Due to the transmission stress and short-circuit current limitation, the traditional urban power grid cannot satisfy the new requirements. Multivoltage-level dc grid (MDCG) is an alternative approach to the urban power grid upgrade. This paper presents an MDCG topology, which can be used in a future urban power grid. Three operation modes of an urban MDCG are proposed: auto operation mode, power-limited operation mode, and stand-alone operation mode. The auto operation mode is the normal one for urban MDCG. The power-limited operation mode is designed to keep the capability to support urban high voltage ac transmission grid in emergencies. The stand-alone operation mode is used to keep stability in case the dc–dc converter system outage occurs. The combination control of three operation modes is put forward to enhance the reliability of urban MDCG in various operating conditions. The simulation results show that the proposed operation modes and combination control are effective and have good performance.

A Method to Control the Interphase Power Controller with Common DC Bus

Increasing number of interconnections at a power system network raises the short circuit current levels and may cause to replace part of protecting equipment. The interphase power controller (IPC) is capable to control the power flow and to limit the short circuit current. This paper presents a control method for the IPC with common DC bus which is an alternative to phase-shifting transformers. The model of a common DC bus IPC is developed in d-q frame and based on it a control system is proposed to regulate the active power flow. The utilized structure has more flexibility in controlling the power system compared to previously proposed IPCs which are based on static synchronous series compensator. An experimental setup based on cascaded H-bridge converters has also been implemented to verify the proposed control method. Both the simulation and experimental results confirm the ability of common DC bus IPC with the proposed control method in power flow control and short circuit current limitation.

ANALYSIS OF THE OPERATION PECULIARITIES OF THE SUPERCONDUCTING INDUCTIVE CURRENT LIMITER WITH ADDITIONAL SUPERCONDUCTING SCREEN

Purpose. The inductances of magnetic system of a current limiter for the nominal operating mode were determined. The aspects of functioning and a design of a superconducting short-circuit current limiter of inductive type with a superconductive main and additional screens, and superconductive winding, which are placed in a general cryostat on a ferromagnetic core, which ensures an improvement of magnetic field dissipation and in energy efficiency are observed. Methodology. The analysis of distribution of magnetic field of the short-circuit current limiter of inductive type with superconducting high-temperature coil and superconducting main and additional screens, using mathematical modeling by the finite element method in math software package FEMM for different modes of operation is carried out. Results. The calculations of magnetic field dissipation in operational modes are carried out. Originality. The investigations aimed to analyze the influence of distribution of the magnetic field in inductive short-circuit current limiter with superconducting additional screen on its operation modes. First calculation of the distribution of magnetic fields in different modes of operation for the short-circuit current limiter in the area between high-temperature superconducting screens. Practical value. The advantage of additional screen of superconducting short-circuit current limiter is to improve screening from dissipation of the magnetic fields of the magnetic system and reducing the power losses at nominal mode. Using the proposed methodology will identify options acceptable to the current limiter mode of operation.

Separate Poles Mode for Large-Capacity HVDC System

This paper proposes a novel connection mode, separate poles mode (SPM), for large-capacity HVDC systems. The proposed mode focuses on the core issues of HVDC connection in interconnected power grids and principally aims at increasing effective electric distance between poles, which helps to mitigate the interaction problems between AC system and DC system. Receiving end of bipolar HVDC has been divided into different inverter stations under the mode, and thus significantly alleviates difficulties in power transmission and consumption of receiving-end AC grids. By investigating the changes of multi-feed short-circuit ratio (MISCR), finding that HVDC with SPM shows critical impacts upon itself and other HVDC systems with conventional connection mode, which demonstrates that SPM can make balance between MISCR increase and short-circuit current limit.

Power-Flow Control and Short-Circuit Current Limitation of Wind Farms Using Unified Interphase Power Controller

This paper presents analytical and simulation studies of wind farms (WFs) connected to power system through a unified interphase power controller (UIPC), which should control power flow and the short-circuit contribution of WF. The UIPC is based on an interphase power controller (IPC) in which the phase-shifting transforms are replaced by two series converters (SECs). In this paper, the UIPC model is developed based on phase angles of injected SEC voltage and a control scheme is proposed to control power flow and limit the short-circuit contribution of WF. The WF model is based on an equivalent aggregated variable-speed double-fed induction generator. The PSCAD/EMTDC simulation results show that the UIPC is an effective and novel solution for power-flow control and limitation of short-circuit contribution of WF in power systems.

A hybrid-excited flux-switching machine for fault short-circuit current limitation in embedded DC alternator applications

A hybrid-excited flux-switching machine for fault short-circuit current limitation in embedded DC alternator applications

Analysis of energy efficiency of a superconducting short circuit current limiter

The work deals with theoretical and experimental studies, aimed at increasing operational indicators of high-temperature superconducting short circuit current limiter of inductive type. We designed a high-temperature superconducting current limiter of inductive type with a superconductive screen, a superconductive winding and a core, which are placed in a general cryostat, which ensures an improvement in energy efficiency. The inductances of magnetic system of a current limiter were determined for the nominal and emergency operating modes. A special feature of the proposed procedure for the calculation of power losses in a current limiter, as well as the magnitude of heat flows to a cryostat, is the fact that the developed procedure considers design parameters of magnetic system with complete cryogenic cooling. Based on the developed procedure, we carried out analysis of the power losses of a superconducting current limiter of inductive type and heat tides to the cryostat for the nominal regime, which demonstrated that the effect of cryogenic cooling of magnetic circuit on the power of heat release of a current limiter is insignificant and amounts to less than one percent. We simulated the work of experimental model of the magnetic system of a current limiter of inductive type during cryogenic cooling with liquid nitrogen. The calculation procedure proposed makes it possible to analyze energy efficiency while determining necessary critical parameters of a superconducting current limiter. It was experimentally explored that the power losses under the nominal mode in the magnetic circuit of a superconductive current limiter of inductive type are insignificant, which corresponds to the previous theoretical calculations. The conducted experimental research confirmed theoretical positions and developed mathematical models.

Optimization of SMES-FCL for Augmenting FRT Performance and Smoothing Output Power of Grid-Connected DFIG Wind Turbine

Fault-ride-through (FRT) performance and output power variation are crucial issues of the grid-connected wind turbine with the doubly fed induction generator (DFIG). To overcome these problems, the optimal parameters tuning of the superconducting magnetic energy storage and the fault-current limiter (SMES-FCL) with the common part of the superconducting coil (SC) is proposed. In addition to the alleviation of the DFIG output power, the SC behaves as the short-circuit current limiter to enhance the FRT capability. The tuning of the SC inductance and the controller parameters of converters is optimally conducted, so that the DFIG terminal voltage deviation and the power fluctuation during faults are at their minimum. By simulation study, the utilized power and energy of the SC for the grid stabilization are curtailed, whereas the dynamic performance of the SMES-FCL is higher than a single SMES unit.

A Fault Current Limiter Circuit to Improve Transient Stability in Power System

Short circuit current limitation in distribution system utilities can be an operational approach to improve power quality, since the estimated voltage sag amplitude during faults may be intensely reduced. The application of superconducting fault current limiter (SFCL) is projected here to limit the fault current that occurs in power system. SFCL utilizes superconductors to instantaneously decrease the unanticipated electrical surges that happen on utility distribution and power transmission networks. SFCL considerably decrease the economic burden on the utilities by reducing the wear on circuit breakers and protecting other expensive equipment. The designed SFCL model is used for determining an impedance level of SFCL according to the fault current limitation necessities of different types of the smart grid system. The representation of this paper about to see the optimum resistive value of SFCL for enhancing the transient stability of a power system. The assessment of optimal resistive value of the SFCL connected in series in a transmission line with a conductor throughout a short circuit fault is consistently determined by applying the equal-area criterion supported by power-angle curves. A Simulink based primary model is developed and additionally the simulation results for the projected model are achieved by using MATLAB.

Tests of the 15-kV Class Coreless Superconducting Fault Current Limiter

This paper presents the design and tests of a superconducting fault current limiter (SFCL) for medium voltage as a device allowing for a more effective use of the existing power network infrastructure. The limitation of short-circuit currents by the SFCL to safe levels will result in the network elements being susceptible to smaller electrodynamic and thermal overloads. The application of an SFCL leads to an increase of the allowable short-circuit power at the point of connection of new power generating sources, which is determined by the short-circuit parameters of the power network. This, in turn, will result in an increase of the capability of the power network for connecting distributed generation energy sources based on renewable energy sources. Light and compact construction of the coreless SFCL consists of three magnetically coupled windings cooled in liquid nitrogen: primary and secondary windings, made of HTS 2G tape, and a parallelly connected primary copper winding. A high magnetic coupling between the superconducting primary and secondary windings gives a low voltage drop on the limiter at a nominal current. The presented solution reduces the size and the weight of the device. Tests performed at a high-power test facility show the limiting performance of the coreless inductive SFCL.

Optimal Transmission Switching With Short-Circuit Current Limitation Constraints

With the expansion and enhancement of the power transmission network, short-circuit current (SCC) has become a major concern in grid operations. While transmission switching is one effective solution to reduce the SCC without investing in additional equipment, switching lines could threaten system N-1 security. To find an efficient, and secure, yet economic switching solution, this paper proposes an optimal transmission switching model with SCC limitation and N-1 reliability. As the relationship between SCC and integer variables associated with the line states is coupled, nonlinear and difficult to explicitly express, an effective linearization method is proposed. Theoretical analysis of the linearization error is performed using an illustrative example. Case studies have shown that the linearization error is generally small and decreases rapidly with the increase of electrical distance. Based on the linearized expression for SCC, a transmission switching model with SCC limitation and N-1 reliability constraints is proposed. Furthermore, to assure the calculation accuracy for the SCC, an iterative algorithm is designed to compensate for the linearization error. Case studies on the modified IEEE 30-bus, 118-bus and practically-sized 300-bus systems validate the effectiveness of the proposed model and algorithm. The solving efficiency of the model is investigated and discussed as well.

Increasing of Switching Abilities of High Voltage Circuit Breakers

The most effective way of increasing switching abilities of high voltage circuit breakers in energy transmission systems is to influence around zero degree to short circuit currents (Maljkovic Z et al 2000; Gashimov, A.M et al. 2001; Antipov, K.M et al. 1985; Gashimov A.M 1991). For this reason, transformers neutral points should be grounded variously for limitation of asymmetric short circuit currents. But another way for this limitation is grounded of transformers neutral points over non-linear reactor. The non-linear reactor effects around zero degree to short circuit current. Therefore, the main purpose of non-linear reactor is to increase the switching abilities of the high voltage circuit breakers. This kind reactor does not necessitate the isolation exchange of transformer neutral points. Non-linear reactors effect around zero degree to asymmetric short circuit current at the networks, which their neutral point, have been grounded with non-linear reactors. In addition, it also effects to changing speed of temporary recover of voltage, which occurred, between contacts of high voltage circuit breakers after removing of short circuit. So increasing switching abilities of the high voltage circuit breakers will be provided by these two ways. Therefore, switching abilities of transformers neutral point the networks with 220 kV or higher can be increased by grounding over non-linear reactor.

Study of short-circuit robustness of SiC MOSFETs, analysis of the failure modes and comparison with BJTs

This paper presents experimental robustness tests made on Silicon Carbide (SiC) MOSFETs and SiC Bipolar Junction Transistors (BJTs) submitted to short-circuit operations (SC) or current limitation modes. For SiC MOSFETs, a gate leakage current is detected before failure without being responsible for the immediate failure. Nevertheless this gate leakage current is not without effect on the integrity of the SiC MOSFETs. Based on several robustness tests performed on SiC MOSFETs and on the comparison with experimental results obtained with SiC BJTs, the paper points out two main failure modes for SiC MOSFETs. The first one results in a simultaneously short circuit between drain and gate and drain and source and the second one in a degradation of the insulation between gate and source leading to a short circuit between gate and source. For some tested devices, the failure appears in a very interesting open state mode between drain and source after physical short-circuit between gate and source with a mode of failure very similar to those observed for SiC BJT.

Live Grid Field-Testing Final Results of the First Italian Superconducting Fault Current Limiter and Severe 3-Phase Fault Experience

The first Italian Superconducting Fault Current Limiter 9 kV/3.4 MVA was developed and lab tested by Ricerca sul Sistema Energetico S.p.A. and then installed in the Milan distribution grid belonging to A2A Reti Elettriche S.p.A. This resistive-type SFCL device was operational since March 2012 and hence has been field tested for more than two years, providing a large amount of experimental data with a significant experience gaining. Some preliminary results were already presented; however, this paper reports on the main outcomes of the field testing activity including the effective short-circuit current limitation provided by this SFCL prototype during a severe real three-phase short-circuit event in the Milan distribution grid. The SFCL device showed to behave as expected, promptly limiting the short-circuit current by a factor of about 2. This is the first SFCL limiting action in Italy and one of the very first worldwide. Further to this first successful installation, the hosting utility A2A agreed to install in the same substation a new SFCL device protecting four different feeders, therefore implying a SFCL upgrading up to 15.6 MVA. Therefore, this paper also anticipates the key steps towards the development of the upgraded SFCL prototype to be commissioned in early 2015.

An Analysis of the Measures for Limiting Short-Circuit Currents in the Moscow Power System

At the end of the 2000s the companies of the electric power system of the Russian Federation attempted to make a systematic estimate of the various measures for limiting short-circuit currents in the Moscow power system. The result of this assessment was a number of publications by different scientific-research institutes, including a conceptual investigation, carried out by the JSC “Institute “Energosetproject” and with the participation of specialists of JSC “Systems Operator of the United Power System,” on the development of strategic ways of developing the Moscow Power System, taking into account the increase in the level of short-circuit currents. From the results of these investigations, possible ways of developing the Moscow Power System were determined depending on the problems involved in limiting short-circuit currents, by taking the necessary measures and determining the points where current-limiting devices should be connected. This paper reflects the practical conclusions reached by companies of the electric power industry, operating in the Moscow Region, regarding the results of these investigations, namely, the measures used during 2011 – 2014 are analyzed, as well as promising measures for limiting short-circuit currents, together with further possible ways of achieving short-circuit current limitation in the Moscow Power System.

A New Method of Short-Current Limiting

This research proposes a new parallel-type short-circuit current limit adjustment device. A unified power quality control strategy is provided to solve the typical issues of the power system. Meantime，when short-circuit fault occurs in the load side，short-circuit current can be limited to minimal range. The parallel-type short-circuit current limit adjustment device simulation model is established based on PSCAD/EMTDC simulation software. By doing some experiments on the parallel short-circuit current limit adjustment device, the correctness and validity of the proposed main circuit topology and control strategy is validated.

Zero Magnetic Flux Short-circuit Current Limiter Based on Passivity Control

According to the basic principle of zero flux short-circuit current limiter, the control method of the space vector control was applied to the inverter to generate a tracking current which is to compensate the magnetic flux. Based on the theory of passivity control, the energy formation and damping injection method was used into designing the control part. In the environment of MATLAB/SIMULINK, a simulation model was established for short-circuit current limiter and passivity control. Compared with the traditional control method, short-circuit current limiter under passivity control showed a better steady state response. DOI : http://dx.doi.org/10.11591/telkomnika.v12i4.3874

A Method of Online Topology Adjustment Decision Support for Short-Circuit Current Limitation

With the growing scale of power systems in China, short-circuit current levels of power systems have been significantly increasing. Appropriate grid topology adjustment is an effective method for short-circuit current limitation. The specific measures include transmission line outage, transformer outage, etc. In this paper, a practical optimization algorithm of grid topology adjustment is put forward. A weighted comprehensive sensitivity index is adopted to speed up the procedure of adjustment strategy searching. The detailed calculation method of this index for different measure types is presented. And a security & economy assessment is implemented to ensure the feasibility of potential adjustment strategies. Moreover, the framework of an online topology adjustment decision support software based on this optimization algorithm is proposed. The effectiveness of the presented method is demonstrated by the test on a large-scale power system.