Load Point Interruptions Research Articles

Analytical Complex Distribution System Reliability Evaluation Considering Stochastic Interruption Durations and Network Reconfigurations

A reliability enhancement scheme for an electric distribution system is impossible to be cost-effective without the guidance of accurate reliability index estimations. As one of the widely used basic reliability indices, average interruption duration is of foremost concern, due to being a straightforward indicator of the electric power supply quality in the aspect of customer satisfaction to the incident response capability of electric utilities to outage events. This paper proposed an analytical distribution system reliability evaluation method that allows for considering stochastic load point interruption durations together with stipulated network reconfiguration constraints. Through case studies on the Roy Billinton Reliability Test System, advantages of the proposed method over a traditional section technique-based reliability evaluation method are discussed. The proposed method is validated to yield more realistic estimations in the case of considering stochastic interruption durations and post-fault network reconfigurations, thus is expected to be capable of supporting economical system reliability-enhancing decision-making.

Impact of Manual Versus Automatic Transfer Switching on the Reliability Levels of an Industrial Plant

Detailed reliability modeling and analysis of industrial plants provides an estimate of the frequency and duration of load point interruptions. The duration of repair and switching activities necessary to restore a unique power system configuration to a normal operating state from an outage state has a significant impact on the power system reliability levels of industrial power systems. This paper presents and discusses the significant variations in the frequency and duration of load point interruptions at an industrial plant due to manual and automatic switching activities. Three case studies with different percentages of open- and short-circuit failure modes of circuit breakers and fuses will also be presented and discussed for both manual and automatic switching restoration activities.

Impact of Circuit Breaker Failure Modes on the Reliability of the Gold Book Standard Network

The failure modes of circuit breakers have a significant impact on individual load point reliability levels of industrial power systems. This paper presents and discusses the significant variations in the frequency and duration of load point interruptions in the IEEE Gold Book Standard Network Configuration due to changes in circuit breaker failure modes. The reliability analysis was based on the zone-branch reliability methodology. Five case studies with different percentages of open- and short-circuit failure modes of circuit breakers and fuses will be presented and discussed in detail.

Reliability methods applied to The IEEE Gold Book Standard Network

Several key reliability indices for industrial and commercial customers are a knowledge of the reliability and the frequency and duration of load point interruptions within their electrical power system networks at their facilities. A reliable equipment data source is key to an accurate analysis. Data sources, such as The IEEE Gold Book provide the user with the necessary data parameters to evaluate the reliability of industrial and commercial power system network configurations. An accurate understanding of component reliability and maintenance actions will provide the necessary availability indices for a reliability analysis approach. This paper discusses The IEEE Bold Book Standard Network and three reliability models: spreadsheet reliability model; GO software tool; and minimal cut-set reliability analysis methodology.

Value-based distribution system reliability planning

Society is becoming increasingly dependent on a cost-effective reliable electric power supply. Unreliable electric power supplies can be extremely costly to electric utilities and their customers. Predictive reliability assessment combines historical outage data and mathematical models to estimate the performance of specific network and system configurations [e.g., IEEE Std. 493-1990]. This paper is concerned with the value-based assessment of proposed modifications to an existing industrial distribution system configuration to minimize the costs of interruptions to both the utility and its industrial customers. This paper presents a series of case studies of an actual industrial load area supplied by two feeder circuits originating from two alternate substations. Each case study reveals the impact on the cost of industrial load point interruptions and the frequency and duration of industrial load point interruptions when various system constraints (e.g., ideal and nonideal protection coordination schemes, substation capacity restrictions, etc.) are imposed on the distribution system. The paper discusses in some detail the variance in reliability performance indexes and their impact on the cost of load point interruptions. A basic conclusion of this paper is that expansion plans of an industrial distribution system can be optimized in terms of reliability by using an economic criterion in which the sum of both the industrial facility interruptions and the utility system costs are minimized.