Abstract :
In a deregulated power system relying on an energy spot market only, it is not possible to guarantee system adequacy. Thus, as long as demand is de facto inelastic in the short run, it is not possible to maintain traditional system security under all circumstances. The normal way to maintain power system security is by way of reserve requirements. This paper addresses the assessment of system security under capacity shortage conditions, where strict adherence to reserve requirements would lead to load shedding. A mixed integer model is used to optimize the use of generation resources with a one-hour time horizon, with the objective to minimize the sum of operational costs and the costs of load disruption. The model is demonstrated on the IEEE RTS-79 test system. It is shown how optimal security can be obtained without the use of fixed reserve requirements. It is also shown that different measures of system security like the loss of load probability, expected energy not served or the probability of system collapse, result in solutions with different security characteristics. The paper concludes that the use of fixed reserve requirements, practical and economical under normal circumstances, leads to high social costs under extreme demand conditions because of the necessity to shed load. Instead, reserve levels should be chosen such that an optimal balance between total costs and security is obtained
Keywords :
power generation dispatch; power system economics; power system security; IEEE RTS-79 test system; capacity constrained conditions; capacity shortage conditions; deregulated power system; energy spot market; expected energy not served; extreme demand conditions; fixed reserve requirements; generation dispatch; generation resources optimisation; high social costs; load disruption costs minimisation; load shedding; loss of load probability; mixed integer model; one-hour time horizon; operational costs minimisation; optimal system security; power system restructuring; probability of system collapse; reserve requirements; system adequacy; Cost function; Energy measurement; Loss measurement; Mathematical model; Power generation; Power generation economics; Power system economics; Power system modeling; Power system security; System testing;