Reliability of power systems define the utility's capability to minimize outage frequency and duration. For regulatory purposes, power system reliability indices are evaluated for performance based regulation (PBR). In the Philippines three performance indicators on system reliability are among the indices evaluated to assess transmission and distribution electric systems for regulatory years involved. System Average Interruption Frequency Index (SAIFI), System Average Interruption Duration Index (SAIDI) and Customer Average Interruption Duration Index (CAIDI) are the indices required by Energy Regulatory Commission (ERC) from the utilities and whose formulas are given below. The data presented herein are acquired from the ERC website and from the National Electrification Administration (NEA) website.
The transmission electric system reliability performance are provided below in the following two figures. The first five years show separated indices for the three regions while the next five years show combined transmission performance for the whole nation. It is revealed from the figures that transmission system SAIFI and SAIDI are lower for the last five years which indicate that outage frequency and duration were minimized in the bulk power system.
The next three figures illustrate the reliability performance of four Distribution Utilities (DUs) in Mindanao. The SAIDI presented here are said to be "Planned" SAIDI, which I assume incurred during scheduled maintenance outages of the DUs. For SAIFI and SAIDI, Cotabato Light and Power Company, Inc. (CLPC) performs better than the other DUs. For CAIDI, Mactan Electric Company, Incorporated (MECO) and Cagayan Electric Power and Light Co., Inc. (CEPALCO) provides minimum customer outage duration. What is interesting is that MECO and CEPALCO reported the same CAIDI values for different four year intervals. The CAIDI formula above does not apply to the CAIDI values as the SAIDI are "Planned". The DU reliability assessment here does not consider the GWh sales and number of customers served of the DU which I believe has an impact to the DU reliability performance. This kind of evaluation is slated in the upcoming articles.
NEA reports a reliability criteria for Electric Cooperatives (ECs). The highest score for this aspect is 5.0 as defined by NEA, which is not reported in their website. Figure below shows that at least four ECs perform up to the par of the NEA reliability criteria.
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