Security Region Based Power System Comprehensive Control And Security Pricing

In recent years, power systems security problem is becoming more important than everbefore due to world wide deregulation and interconnection of bulk power systems. It hasbecome an urgent issue to develop faster and more efficient security control methods. Basedon the previous studies on Security Regions, this dissertation systematically investigates theemergency control methods and the comprehensive security control methods, as well assecurity pricing under market circumstance.Firstly, the dissertation develops a concept on Extended Practical Dynamic SecurityRegions(EPDSR) that take emergency control actions into account, and four importantexperiential laws about the EPDSR are discovered. Accordingly, an approach is proposed toquantitatively express the effects of tripping generator, shedding load and their cooperation.Furthermore, a mathematics model for optimal emergency control of transient stability isestablished and an algorithm based on sensitivity index of control actions is given. In thismodel, the effect of a control action is represented by the displacement of EPDSR's criticalhyper-plane boundary on the direction of its exterior normal vector. If a transient unstablecontingency occurs, some appropriate emergency control actions are to be triggered so as tothe enlarged EPDSR can cover the current operating point.Secondly,according to the complementary characteristic of preventive control andemergency control, this dissertation develops a comprehensive security control method basedon the merit of the quantitative analysis ability of Dynamic Security Regions. Taking the totalcontrol cost as the objective function and the inequality in form of hyper-plane as the transientstability constraints, the comprehensive control is converted into an optimization problem.Aiming at the characteristic of this problem, the dissertation proposes an optimization strategycalled "the active restriction relaxation approach" which can classify the contingency sets intotwo subsets that can minimize the total control cost. Then the preventive control and theemergency control respectively maintain the security of the system for each subset. Comparedwith pure preventive control scheme or pure emergency control scheme, the comprehensivesecurity control method is much more economical.Thirdly, in order to specify the impact of power system security on spot prices, anapproach of security price decomposition is proposed. With considering Security Regions asstability constraints and the tree branch angles as optimal variables, the model of optimalpower flow involving both transient stability and steady-state voltage stability is established.Furthermore, according to the theory of marginal cost and the matrix theory, the spot pricescan be decomposed into several components corresponding to various security constraints.The components not only can reflect the impact of a node on one stability problem but alsocan be made use to analyze the apportionment of security costs among all market participants.In conclusion, this dissertation fully takes advantages of the method of Security Regionsin the field of power system stability analysis and control, and establishes a theoretical andengineering foundation for the decision-making of security control scheme and the calculationof security prices.