Power-system protection

About: Power-system protection is a research topic. Over the lifetime, 6353 publications have been published within this topic receiving 117961 citations.

Problems and solutions for microprocessor protection of series compensated lines

Abstract: Protection of systems with series compensated lines is considered to be one of the most difficult tasks for relay manufacturers and utility engineers. Protection and control of surrounding circuit elements, particularly transmission line protection, needs to be adapted to the variations introduced by these devices. Fixed series capacitors and thyristor controlled devices introduce harmonics and nonlinearities which adversely impact the protection function. To take full advantage of the series capacitor installation in a utility network, it is necessary to explore the impact of series capacitors on protection and implement appropriate schemes. This paper describes practical issues related to microprocessor based protection of power networks with fixed and controllable series compensating devices. Phenomena that affect the protection of a network with series compensated lines are explored. The paper also presents solutions and new concepts in protection and fault location for series compensated power networks.

A Positive-Sequence Directional Relaying Algorithm for Series-Compensated Line

Abstract: Series capacitor imposes problems to line protection and other online decisions. The directional relaying issues during voltage and current inversions in a series-compensated line are addressed in this paper. A conventional directional relaying algorithm uses fault voltage and current phasors to derive the decisions and, thus, finds its limitation at voltage or current inversion. This paper proposes a fault direction estimation technique for a series-compensated line using phase change in positive-sequence current and magnitude change in the positive-sequence voltage at fault. The technique is evaluated by using data simulated with EMTDC/PSCAD for a series-compensated line, and the dynamic performance of the algorithm is also studied.

High impedance fault detection on distribution systems

Abstract: The detection of high impedance faults on electrical distribution systems has been one of the most persistent and difficult problems facing the electric utility industry. Recent advances in digital technology have enabled practical solutions for the detection of a high percentage of these previously undetectable faults. This paper reviews several mechanical and electrical methods of detecting high impedance faults. The issues and application of this technology are also discussed.

Agent-based self-healing protection system

Abstract: This paper proposes an agent-based paradigm for self-healing protection systems. Numerical relays implemented with intelligent electronic devices are designed as a relay agent to perform a protective relaying function in cooperation with other relay agents. A graph-theory-based expert system, which can be integrated with supervisory control and a data acquisition system, has been developed to divide the power grid into primary and backup protection zones online and all relay agents are assigned to specific zones according to system topological configuration. In order to facilitate a more robust, less vulnerable protection system, predictive and corrective self-healing strategies are implemented as guideline regulations of the relay agent, and the relay agents within the same protection zone communicate and cooperate to detect, locate, and trip fault precisely with primary and backup protection. Performance of the proposed protection system has been simulated with cascading fault, failures in communication and protection units, and compared with a coordinated directional overcurrent protection system.