Competitive framework for procurement of interruptible load services

This paper deals with optimal procurement of interruptible load services within secondary reserve ancillary service markets in deregulated power systems. The proposed model is based on an optimal power flow framework and can aid the independent system operator (ISO) in real-time selection of interruptible load offers. The structure of the market is also proposed for implementation. Various issues associated with procurement of interruptible load such as advance notification, locational aspect of load, power factor of the loads, are explicitly considered. It is shown that interruptible load market can help the ISO maintain operating reserves during peak load periods. Econometric analysis reveals that a close relationship exits between the reserve level and amount of interruptible load service invoked. It was also found that at certain buses, market power exists with the loads, and that could lead to unwanted inefficiencies in the market. Investing in generation capacity at such buses can mitigate this. The CIGRE 32-bus system appropriately modified to include various customer characteristics is used for the study.