Research On Multi-Agent And WAN Based Adaptive Coordinated Protection

In traditional power system protection schemes, the protection settings are calculated according to the settled, local information, which can hardly satisfy all protection requirements, i.e., selectivity, fast action, sensitivity and reliability, of responding to system faults. When the operation mode of power network changed severely, the traditional settings of many relays in a power system may be infeasible and uncoordinated, which eventually cause the mal-operation of relay. The wide area informatin based adaptive protection can analyze the status of power system according to the variant and globle information, and calculate the adaptive settings matching to the prevailing system condition, which can efficiently solve the problems of traditional protection. The realization of adaptive coordinated protection has been studied deeply in the paper and the main contributions are as follows:A new method to fast trace power network topology in which the graph theory is integrated with artificial search technique is proposed. In this method the node adjacent matrix is used to express the topology inside the substation and a node tree is constructed to represent the connection of network nodes. Under real-time continuous operation situation when switching event of circuit breaker occurs, the proposed method can rapidly trace the topology change within the substation by modifying the node adjacent matrix, then using heuristic search algorithm the former search tree are locally updated, thus the rapid tracking of local power network where the topology is changed is implemented.A new parallel algorithm on modification and boundary equivalents of the node impedance matrix based on a PC cluster is proposed. Through studying the parallel characteristics of the modification and boundary equivalents of the node impedance matrix, a parallel algorithm combining large grained blocking storage with message passing is proposed. Moreover, the formula to calculate boundary equivalents based on node impedance matrix is derived. Furthermore, an optimized strategy on remote memory access (RMA) is utilized to overlap the parallel computation and the communication between the scheduling processor and the sub-processors, which is helpful to improve the computation efficiency.A practical algorithm to quickly determine the break point set (BPS) of directional protective relay in multi-loop power networks is porposed. The determination of BPS is transformed to seek for the Feedback Arc Set (FAS) in directed graph. By a study to the characteristic of FAS, a new practical method to fast acquire FAS is presented and its theoretical basis is proved. Then the method is applied in the heuristic search of the functional dependency set of relays in the power networks. By this way, the BPS of relay can be fast determined. When the topology of power network changed, only the functional dependencies of relative relay need to be modified and the new BPS can be fast determined based on the original search results.An adaptive setting and verifying algorithm for backup relays is proposed, which can provide better line coverage than traditional ones. When the operation mode of network changed, the domain of influence is defined by searching the functional dependency set and influence set of relays. By this way, the settings of relay are quickly verified and adjusted.A Multi-agent and WAN Based Adaptive Coordinated Protection System (MAWBACPS) is proposed. Multi-agents techniques are used to develop the software of the proposed system and WAN for adaptive protection is constructed. By the cooperation of agents, the on-line real-time coordination of the adaptive settings of protective relays can be realized. Using XML to encapsulate KQML primitives, the platform-crossing communication problem between agents is solved. A best-effort protection strategy with permission check is used to guarantee the adaptive settings to operate safely and to be effective in most situations. A simulating system has been developed to verify the feasibility of the proposed protection scheme and algorithm. The experimental results are very positive.