Improvement of Power System Stability Margins using real power scheduling under normal and network contingencies

Power system planning and operation in present day are more in favour of economic factors and less in terms of technical aspects such as: system security, reliability and stability analysis. Case in point being: the generator scheduling or the pattern in load sharing among the various generators forms a major part in power system planning. Scheduling primarily based on economic criteria, essentially means power contracts that favour cheaper generators, tend to lead to heavy flows, resulting in greater losses threatening stability and security and also leading to lower reserve margins making the system less reliable and thus making such generation patterns undesirable. Such patterns may be economically viable, but with increasing load on existing transmission systems, the problem of voltage stability and voltage collapse become a major concern. In this paper, a fresh approach to generator scheduling, from the transmission system point of view, is based on the generator-load location (Relative Electrical Distance concept). Also, a new network sensitivity index known as LIndex and minimum singular value [MSV] are used as the basis to analyse the improvement in the voltage stability of the system under both normal and line contingency conditions. Detailed case studies with base case and optimized results for practical Indian power systems of 25 bus and 30 bus are presented.