APPLICATION OF ENERGY-BASED INDEXES IN GENERATING-SYSTEM RELIABILITY-ANALYSIS

The loss of load expectation (LOLE) is the most frequently used reliab ility index in generating system reliability analysis. Energy based re liability indices, however, are receiving more and more attention, par ticularly with regard to systems that have energy limitations or with regard to systems that include intermittent sources. In this paper the use of energy based reliability indices, such as the expected unserve d energy (EUE) and the energy index of unreliability (EIU), is compare d with the use of LOLE in generating system reliability analysis. The comparison is made for two aspects: the minimum required capacity expa nsion (MRCE) if the load is increased and the load carrying capability (LCC) of intermittent sources. To compare the results of applying LOL E, EUE and EIU in generating system capacity expansion, the IEEE Relia bility Test System (RTS) is used as reference. Wind turbines and photo voltaic units are added to the RTS so that the load carrying capabilit y of these intermittent sources can be calculated. The relative differ ences in the computed MRCE are found to be small: less than about 10% of the expansion of the generating capacity. In the case of intermitte nt sources, relative differences of similar magnitude are found for th e load carrying capability. It is found that the differences in MRCE c aused by the use of alternative reliability indices can be related to the slope of the loss of load probability as function of the load. The difference in LCC can be related to the occurrence of hours with high load and low intermittent energy production.