Optimal Security Control And Security Pricing Of Power System

Power system secure operation is a momentous problem relating to the national economy and the people's livelihood and even national security. Since the eighties of twentieth century, widespread blackout due to power system instability occurs frequently over the world. So the on-line security monitoring, assessment and control become more significant which is regarded as the most important line of defense of preventing serious blackout as a result of power system instability. It lacks, however, impelling and systemic methods that can be applied in the on-line security monitoring, assessment and control. The secure operation of power system relates to static security and transient stability, and the transient stability is taken as an illustrative condition in this dissertation. The transient stability of power system is used to be analyzed for a given pre-fault injection by using transient simulation method or transient energy function method. The computation burden of making decision of the optimal security control with these methods is so high that it is difficult to be applied on-line. The fact of that the critical boundary of practical dynamic security region (PDSR) in real power systems can be described as one or a few hyper planes in injection space provides an effective tool for optimizing security control. Based on the PDSR, an optimal security control model and algorithm are developed in this dissertation, which are potential in on-line application. Due to the deregulation of electric power market in China, people has paid more attention to the study of security pricing which is regarded as a valid strategy for enhancing system security. In deregulated electric power markets, however, price functions submitted by participants who attempt to maximize their own benefits differ probably from their true cost functions. This can lead independent system operator (ISO) making worse decision of system security control or security pricing. The problem of how to induce participants to reveal their true economic information must be solved to realize the optimal security control and security pricing. Mechanism design theory in game theory has particular predominance in respect of discovering each participant's true economic information. Based on the mechanism design theory, a novel security market operation mechanism of power system is designed which can induce participants to submit their true cost functions. The main results reached in this dissertation are as follows: 1. Based on the concept of PDSR, a model for making decision of optimal security control and security pricing of power system is suggested with taking transient stability constraints, contingency occurrence probability and system instability impact into account. The objective of this model is to reach the maximum of society welfare through searching optimal critical contingency set. The outputs of this optimization problem are optimal capacity reserve and optimal redispatch power of each participant. 2. Based on the duality principle of optimization technology and the conjugate projection gradient algorithm, a hybrid conjugate projection gradient optimization algorithm of optimal security control is also developed, which has great potential in satisfying the requirement of on-line application of the optimal security control and security pricing of power system. 3. Combining the basic principle of mechanism design in game theory with linear supply function equilibrium (LSFE) theory, an incentive compatible operation mechanism of power system security market, linear supply function incentive revelation mechanism, is suggested. It is capable of encouraging and inducing all participants to present their true economic information. Furthermore, whether or not a participant presents its true economic information is independent of the actions of other participants. By using the mechanism presented here, ISO can make correctly decisions about power system optimal security control and security pricing. The effectiveness of the mechanism is proved theoretically. 4. Based on LSFE theory, a method is developed to calculate the Lerner index of participants with taking information asymmetry and transmission network constraints into account. It provides another effective tool to surveille whether or not participants have presented their true economic information. The rationality and effectiveness of the model and the algorithm of optimal security control and security pricing, the linear supply function incentive revelation mechanism and the method to calculate the Lerner index mentioned above are respectively demonstrated by taking the 10-machines-39-buses New England System, the IEEE 3-machines-9-buses system and a 4-participants example as the illustrative systems.