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.

VSC-HVDC system protection: A review of current methods

Abstract: Currently classical thyristor-based high voltage direct current (HVDC) systems hold the market in bulk power transmission. However, recent advances in semiconductor technology have led to voltage source converter based HVDC (VSC-HVDC) systems becoming a viable competitor. Not only is VSC-HVDC a competitor for transmission but it can also be used in multi-terminal systems, which have become an attractive option for renewable energy applications or for distribution in large cities. As more and more VSC-HVDC systems are installed, the protection of these systems must be taken into account. This paper explores different options and ideas for VSC system protection.

Anatomy of power system blackouts: preventive relaying strategies

Abstract: Major blackouts of electric power systems in which many customers are left without power are rare events. However, the effects of blackouts, for instance, can be catastrophic. It has been observed that protective system failures are a contributing factor in a large proportion of these blackouts. The most troublesome protection system failures are hidden failures, which remain dormant during normal system conditions, and are exposed during system disturbances. A study of hidden failures of the protective systems is undertaken to uncover their modes of failures, and to determine means of supervising their actions in times of highly stressed power system operations. The main contribution of this paper is to develop and document a method of quantitative analysis of the significance of hidden failures of protection systems. A complete protection system was designed for the New England 39-bus system and the hidden failure modes were used to develop regions of vulnerability and a vulnerability index. Through this analysis, critical protection systems, whose hidden failures would have a major impact on cascading failures or blackouts of the power system, can be identified These protection systems are candidates for increased monitoring and control, which would help alleviate the problems posed by hidden failures.

A new fault location algorithm using direct circuit analysis for distribution systems

Abstract: The unbalanced nature of distribution systems due to single-phase laterals and loads gives difficulty in the fault location. This paper proposes a new fault location algorithm developed by the direct three-phase circuit analysis for unbalanced distribution systems, which has not been investigated due to high complexity. The proposed algorithm overcomes the limit of the conventional algorithm, which requires the balanced system. It is applicable to any power system, but especially useful for the unbalanced distribution systems. Its effectiveness has been proved through many EMTP simulations.

Fault diagnosis of electric power systems based on fuzzy Petri nets

Abstract: In this paper, Fuzzy Petri Nets (FPN) is used as a modeling tool to build fault diagnosis models aimed to accurately diagnose faults when some incomplete and uncertain alarm information of protective relays and circuit breakers is detected. In order to understand the significance of fault diagnosis models more conveniently, the definition and structure of FPNs are necessarily introduced at first. Then, models of fault diagnosis based on FPN are built, and their corresponding logical testifications are carried out. Finally, the validity and feasibility of this method is illustrated by simulation examples. It is shown from seven cases that the faulted system elements can be diagnosed correctly by use of these models, and a satisfying result can also be achieved even in the situation with large amount of incomplete and uncertain alarm information.

Transient-Voltage-Based Protection Scheme for DC Line Faults in the Multiterminal VSC-HVDC System

Abstract: DC line faults are major issues for a multiterminal high-voltage direct current (HVDC) system based on voltage-source converter (VSC). The fault current increases quickly along with a large peak, and complete isolation of the faulted system is not a viable option. Therefore, protection with high selectivity and accuracy is essential. In this paper, a new protection scheme for dc line in multiterminal VSC-HVDC system is proposed, which consists of a main protection and a backup protection. Both the protection principles are based on the supplemental inductor placed at each end of the dc line. Fault identification can be achieved by calculating the ratio of the transient voltages (ROTV) at both sides of the inductor. The main protection is able to detect the fault quickly without communication, while the backup protection is a pilot method based on the ROTVs at both ends of dc line, which is employed to identify the high-resistance faults and offer a backup in case the former fails. Comparison with some previous protection methods shows that the performance of the proposed protection scheme is promising. Numerous simulation studies carried out in PSCAD/EMTDC and real-time digital simulator (RTDS) under various conditions have demonstrated that fault identification with high selectivity and strong robustness against fault resistance and disturbance can be achieved by employing the proposed protection scheme.