Power System Reliability Evaluation Study

With the scale development of power system and the issues of planning, dispatching and recovering of generating plant and power grid, new requirements are proposed for reliability evaluation, such as to evaluate quickly, accurately on line and be suitable for decision-making for investment, and also new challenge and chances are in the face. And therefore, several focus issues of power system reliability evaluation are discussed and researched. This thesis contains the following context:(1) Curve of faulty rate—one of the facility reliability parameter is analyzed. The method of least square theory to obtain system reliability basic parameter is proposed, which supplies theory for reliability basic parameter in practice, makes it in rationalization and blindness to get reliability basic parameter by statistic is disappear.(2) A reduced model of distribution system is proposed, some conceptions such as switch-node and load-interval are defined, and under this model, a new reliability evaluation algorithm suitable to complex radial distribution system is proposed. In this algorithm, only the failure effect of switch-nodes and load-intervals need to be considered, and need not to consider each element in system. In this algorithm, the traverse-search technique is applied to determine the failure effect of the fault event and the reliability indices of complex radial distribution system can be calculated. For complex system that includes more sub-feeders, the proposed algorithm possesses superiority in principle and programming, and the cases such as switches failures, alternative supply and scheduling maintenance, etc., can be taken into account.(3) The system fault tree is constructed of HVDC system and a reliability evaluation algorithm for HVDC based on fault tree analysis (FTA) and Monte Carlo method, is proposed, which combine the advantage of both. Fault tree is taken as reliability model and the reliability action is simulated by Monte Carlo simulation technique, and the reliability parameter is obtained by calculated statistic character of sample stylebook in this algorithm. Reliability distributing rules obtained of HVDC system can direct designers to plan different structures according to different importance, so this algorithm can make instruction for system reliability design. (4) After urban distribution network is equivalent to topological graph, a new adjacent matrix is defined to describe the network structure and the arithmetic relationship between this adjacent matrix and the urban distribution network's operating parameters are deduced. Linear programming model and algorithm to calculate maximum power supply capability for urban distribution network is proposed based on graph theory. The model can find some weaknesses of the network and give pertinence directing suggestion for urban system planning and rebuilding, and can be regarded as scientific and effective tool of programming and designing for urban distribution network.(5) The unit incremental reliability value (UIRV) is used to quantify a reliability component in transmission pricing, and the principle for users of transmission grid to afford reliability fare based on influence on system reliability is analyzed. The state duration sampling approach is utilized in calculating reliability worth assessment of radial distribution systems, and the reliability value indexes are also calculated. The necessary to consider the reason that factors such as reactive power of customers load, service reliability of customers. and location of customers etc in capacity price pricing should not be neglected, is analyzed.