School of Electrical and Electronic Engineering,
University of Western Australia
1. Power System Reliability Assessment
Objective and quantitative reliability assessment of power system can explore the weakness and point out a way for power system planning, operation and maintenance, in order to achieve the goal of keeping security, stability and reliability of power system operation, realizing the integration of reliability and economy. With the increasing of contradiction between supply and demand of electric power as well as advancing of power market mechanism, the application of quantitative reliability evaluation in electric power systems has now evolved to the point at which most utilities use these techniques in one or more areas of their planning, design, and operation. However, most of the techniques in use are based on analytical models and resulting analytical evaluation procedures. Nevertheless, the improvements and availability of high-speed computers with large capacity storage have created the opportunity to analyze many of these reliability problems using stochastic simulation methods and made Monte Carlo simulation a preferable option for many power system reliability applications. Therefore, with the study of the existing models and algorithms for power system reliability evaluation and the nonce application of Monte Carlo simulation to reliability engineering，this project is work on models and algorithm for Bulk power system reliability assessment considering many practical factors by Monte Carlo simulation.
2. Background Information
2.1 Concepts of Power System Reliability
Reliability is an inherent characteristic and a specific measure of any component, device or system, which describes its ability to perform its intended function. In the context of power systems, reliability in general terms is related to the ability of the system to supply electric power to its customers under both static and dynamic conditions, with a mutually acceptable assurance of continuity and quality. Power system reliability assessment can be divided into two basic aspects designated as system adequacy and system security. Power system adequacy assessment is focused on the existence of sufficient facilities within the system to satisfy the consumer load demand within the basic system operational constraints. A Power system includes the facilities necessary to generate sufficient energy and the associated transmission required to transport the energy to the actual bulk supply points (distribution delivery points). Adequacy assessment of power system has been generally conducted using probabilistic techniques. Security considerations in power system are generally considered by focusing on the operation of the system in different operating states designated as normal, alert, emergency, and extreme emergency states. A power system security assessment normally utilizes the traditional deterministic criterion known as the N-1 security criterion in which the loss of any power system component (a contingency) will not result in system failure. In this approach, a system is able to withstand disturbances, i.e., due to power system equipment failures, without violating any system constraints when the system is initially operating in its normal state. An overall power system can be divided into the three basic functional zones of generation, transmission and distribution. Power system adequacy assessment can be conducted in each functional zone and at each hierarchical level. Figure 2.1 shows the three hierarchical levels.
Fig.2.1 hierarchical levels
Reliability assessment at hierarchical level-I (HL-I) involves the ability of the generation facilities to meet the system demand. In hierarchical level-II (HL-II) reliability assessment, the generation and transmission facilities are considered as a composite system or bulk electric system that is responsible for delivering the required...
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