State Estimation And Measurement Placement In Smart Distribution Network

ADO(Advanced Distribution Operation)is one of the main components of smart grid. The main function of ADO is to make the system self-healing. In order to achieve self-healing,power grid should have distribution network topology , which is flexible and reconfigurable, and the ability of monitoring and analysis of the real-time state. DFSM(distribution fast simulation and modeling), which has the advanced software of risk evaluation, self-healing control and optimization, is the core of ADO. DFSM provides mathematical support and prediction ability for smart grid. Finally, the stability, security, reliability and efficiency of the power grid can be improved. Distribution network state estimation,which is an important foundation and one of research challenges for DFSM,provides comprehensive and accurate real-time data for the advanced software systems of DFSM. The main research achievements are as follows:1. Based on OpenDSS and the detailed mathematical models of three-phase components, such as lines, transformers, shunt capacitor and loads,etc, three-phase distribution network state estimation algorithm is established. The real and imaginary parts of node voltages are state variables in this algorithm. It takes into account the winding connections of transformer and voltage regulator, and the taps of transformer. Three-phase imbalance can be estimated by this method with high accuracy.2. In this paper, the Sherman-Morrison formula is applied to deduce the mathematical relationship expression between the measurements and the variance of state variables, and based on that expression, a new method for measurements evaluation and configuration optimization in distribution network is proposed. Compared with these existing methods, this method can avoid the combinatorial explosion problem, and determine the type and the optimal installation site of measurement devices simply and exactly, which can satisfy the precision of the state estimation and minimize the cost of installation . Besides, this method is based on explicit theory and offers fine optimizing solutions. It provide theory and methodological for the assessment and continuous optimization of the existing measurement system, and planning for the measurement configuration of new distribution networks. At the same time based on OpenDSS , the method for measurements evaluation and configuration optimization is realized by VB. Based on the case studies of IEEE13 and IEEE34 distribution network , the validity of the proposed method is proved .