Two novel screening methods to decide network configurations to maintain voltage stability using sensitivity analysis

This paper discusses screening methods in the planning stage which are able to find suitable power network configurations to maintain voltage stability. The electrical characteristics of power systems depend strongly on network configuration. However, to find the best network configuration is difficult because there are many objectives and constraints. In this paper, the relation between reactive power loss of transmission networks and voltage sensitivity is made clear to screen out suitable network configurations for maintaining voltage stability from among many candidates; the voltage sensitivity expresses the variation of node voltage magnitude when a unit active power supply is increased from one of the nodes. Two screening methods in the planning stage are proposed. The first method uses linear programming techniques and decides transmission lines which could be disconnected without deteriorating voltage stability; disconnection of transmission lines is effective for reducing the short circuit current though it may worsen the voltage stability. The second proposed is the use of new index called the generator installation site index. The index can be used to determine where a new generator should be installed to best improve the voltage stability. This index is calculated from variation of total demand voltage sensitivity when a unit of active power is supplied from one of the nodes.