Effect of optimal placement and regulation of SSVR in microgrid island operation

Microgrid, because of using renewable distributed generation sources, is an appropriate solution of problems such as power demand daily grow, fossil fuels diminution, low efficiency of energy generation and transformation systems, and environmental limitations. Microgrids can be used in grid-connected and island mode operation. Problems such as successful transition to island mode, power quality management, voltage profile improvement through normal and island operation, and synchronous operation improvement of an islanded microgrid when it is connected again, are microgrid challenges in normal and island mode operation. Distribution Flexible Alternative Current Transmission Systems (DFACTS), having characteristics such as fast controllability and high flexibility can be used in microgrids to reduce power loss, improve voltage profile and power quality, and control active and reactive power. In this paper, a method is proposed which employs Particle Swarm Optimization (PSO) algorithm to improve voltage profile and reduce active and reactive power loss in microgrid systems. Optimal position and capacity of DFACTS element and optimal capacity of distributed generation of a microgrid system can be achieved by this method. Furthermore, a technic for locating distributed generation, with using loss sensitivity coefficient is proposed. With the proposed strategy, objective function indices including active and reactive loss index and voltage profile index are optimized while overload conditions and different operation modes conditions of the grid are satisfied. IEEE 33 bus radial network is employed to create a sample microgrid and the proposed technic is applied on it. Obtained results in different operation modes of the microgrid under constant load and overload conditions are analyzed.