Voltage stability analysis of an Urban Distribution Network (UDN) with high penetration of Combined Heat & Power (CHP) generation

The capacity of Combined Heat and Power (CHP) generation connected to Urban Distribution Network (UDN) will increase significantly as a result of EU government targets and initiatives. CHP generators can have a significant impact on the power flow, voltage profile and the power quality for customers and electricity suppliers. The connection of CHP plant at UDN creates a number of technical problems that for individual connections can be mitigated, albeit at a cost to the developer and network operators. For significant volumes of connections, there is an apparent risk of conflict between connections in that inappropriately sized or located plant could constrain greater development of the network and consequently threaten the achievement of government distributed generation energy targets. The steady state voltage rise resulting from the connection of these generators can be a major obstacle to their connection at the lower voltage level in an UDN. The objective of this paper is to use static method to analyse steady state voltage stability. The objective of this proposed approach is not to control bus voltage but to guarantee that generator injections alone do not cause significant voltage rise: a solution in which an UDN operators retains their traditional task of voltage regulation for load demand. The main tool which is used in this paper is load flow analysis performed by ERAC power analysis software. In order to determine the steady-state voltage stability region, a case study of a UDN of fourteen busbars was created. The results obtained were used in the P-V and Q-V method in order to determine voltage stability limits for a number of busbars with CHP generating unit connected. Analyzing the P-V and Q-V curves gives the UDN operator and indication of the maximum amount of power that is allowed to penetrate into UDN generated by CHP plant via any busbar.