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Aiming at the problem of short-circuit protection, a novel bridge-type topology of fault current limiting (FCL) is established based on resonant characteristics. It is equivalent to a piece of wire during the normal operating state. When short-circuit fault occurs, the dc limiting reactor inserts automatically and rapidly under the joint action of the capacitor, limiting the increasing speed and amplitude...
This work presents a comparative study of Least Squares Filter, Kalman Filter and Unscented Kalman Filter for estimating the secondary current phasor distorted due to saturation of Current Transformers (CTs). Several distorted current signals were generated in a Real Time Digital Simulator (RTDS) and embedded in noise. Then, these signals were segmented in two kinds of regions, named saturated and...
This paper describes hands-on solid modeling experience of the safe optimal ground grid design (less copper) for a large Extra High Voltage (EHV) substation. The optimized ground grid meets the IEEE-80 standards for safety without compromising on step or touch potential thresholds. The ground grid has been designed in CDEGS using fault current flow concepts, and multiple injection points simulate...
In this paper, a communication-assisted protection scheme is proposed for medium voltage dc (MVDC) distribution networks. MVDC grids are applicable for connection between microgrids, upgrading the transmission capacity of ac lines by the conversion to dc, and integration of renewable energy systems to the distribution grids. However, protection issues are one of the main challenges in the development...
Protection scheme for AC transmission systems are well understood and matured. On the other hand, DC system is still facing a challenge in developing proper protection scheme because of its natural characteristics. A protection scheme, which utilizes some of the developed techniques for AC system, and modified to suit the DC system characteristics, is proposed in this paper. The scheme is based on...
Direct current transmission based on Voltage Source Converters (VSC-HVDC) has a number of advantages compared with traditional HVDC systems. However, VSC-HVDC systems are subjected to high short circuit currents due to faults in the DC line, which may contribute negatively to the dissemination and advances of this technology. In this context, this paper analyzes the impact of superconducting fault...
This paper studies the methodologies for developing dc fault tolerant and highly efficient VSC converter. Building on a recently proposed LCL-VSC converter, which suffers from low efficiency at partial load, an operating strategy of switchable capacitor banks instead of fixed central capacitor is proposed to improve the efficiency. A theoretical framework is presented to enable LCL-VSC to achieve...
The application of Superconducting Fault Current Limiters (SFCLs) in electrical power system has recently attracted increasing attentions, which is encouraged by the pronounced progress of High Temperature Superconducting (HTS) technology. Many topologies of SFCL have been developed and yet to be put into practice. In this paper, the resistive type and flux-lock type of SFCL are firstly introduced...
This paper presents basic guidelines on design considerations for large utility-scale photovoltaic (PV) solar power plant (SPP) substation and collector grounding systems for safety aspects. While SPP grounding design is similar to both traditional power plants and substations, it's much larger scale allows and requires design optimization for an economical approach. This paper highlights items unique...
The traditional distribution network is primarily composed of radial feeders, designed for unidirectional power flow. Therefore, many operation regulation, protection and control system, in distribution network, are based on the radial distribution systems assumption. The integration of decentralized renewable sources will create a multidirectional power flow condition in the distribution grid which...
Segregated phase comparison technique is a special form of current differential protection. It takes into account the difference of phase angle of currents entering at one terminal and current leaving out of other terminal of transmission line. Line charging current causes significant change in phase angle of two end currents of a transmission line. This paper presents novel phase comparison technique...
This research exploits the Superconducting Fault Current Controller (SFCC) to effectively regulate fault current contribution of a Wind Power Plant (WPP) comprising different types of wind turbines. Different types of wind turbines commercially available exhibiting different Short Circuit Contributions (SCC) to the fault current level may change for different fault types under varying operating conditions...
This paper presents a novel fault current management (FCM) technique for radial distribution systems with embedded inverter-based distributed generators (IB-DGs). At the point of connection to a power system, many distributed generators (DGs) require power electronic (PE) interfaces, which are normally idle during faults. The proposed FCM method employs these PE interfaces for control of the fault...
The increase of Distributed Generators (DG) has encouraged the operation of these generators in islanded mode or intentional islanding. Such operation mode can increase the system reliability, once in the event of network failure the supply of critical consumers will be maintained by the DGs. However, it is necessary to consider that the fault current is considerably reduced when the system is in...
The implementation of high-reliability microgrids requires proper protection schemes that effectively function in both grid-connected and island modes. This paper presents a communication-assisted four-level hierarchical protection strategy for high-reliability microgrids, and tests the proposed protection strategy based on a loop structured microgrid. The simulation results demonstrate the proposed...
Directional elements need to be able to differentiate between load current and fault current when two sources are present in the distribution network (closed-loop). When the fault current is about two- or three-times the load current, this is easy to accomplish. But when the directional element is used in a relay that is protecting a distributed generator (DG) the fault and load current may be within...
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