An Algorithm For Selecting UHV Access Point And Optimal Allocation Of Fault Current Limiters Based On PSO

Along with the rapid economic development, power demand is growing fast. However, energy resources and energy consumption are not in equilibrium in China. The regions with abundant energy resources are very far from the developed areas.In order to solve the problems rising by the constant growth of power load and uneven distribution of energy resources, energy is transported by UHV.With more and more UHV AC/DC transmission line put into operation, selecting UHV AC/DC access points become more wide spread attention. UHV AC/DC placement selection problem is a complex multi-objective programming problems, current research is mostly done to provide an effective program based on the actual number of cases, considering the bus voltage, transformer capacity,line capacity, short-circuit capacity and the effective short-circuit ratio constraints. This paper presents a method of automatically selecting UHV AC/DC access point considering both security and economy at once. The presented algorithm can automatically determine the global optimal point and line of accessed to system, which satisfy the given constraints, according to the candidate points and the candidate lines.In the meantime, this algorithm is able to consider multiple AC/DC access points and lines of access system. Basic idea of this method is to solve the UHV AC/DC access point economy global optimal solution, which meets the needs of security constraints, by Particle Swarm Optimization (PSO) considering the bus voltage, transformer capacity, line capacity, short-circuit capacity and the effective short-circuit ratio constraints.Meanwhile,with the development of interconnected power grid, expansion of the grid scale becomes faster, the shortcomings of the larger power system show up. Short circuit current has become an urgent problem of grid security, which is one of the main bottlenecks that restricts further development of power grid. This paper presents a new global optimum method for allocation of fault current limiters (FCLs). Allocation of FCLs is to reduce the quantity and total impedance of FCLs and ensure normal operation of power system on the premise of meeting short-circuit current limit. By calculating short-circuit, the branches with FCLs capable of starting up reliably can be determined. Subsequently, the branch-adding method is applied to form admittance matrix. By using PSO, candidate branches can be optimized. Thus searching for the optimal location and the smallest FCLs capacity can be achieved.