Speaker: Emma Stewart
Date: Tue, March 05, 2013
Location: 90-1099, LBNL
The interconnection process can be a laborious and expensive process for both utilities and developers. High PV penetration levels create a number of challenges for the management and operation of the utility grid. This study presents work being completed in Hawaii to improve and innovate the interconnect process, separating perceived issues from real technical concerns. Existing interconnection methods and standards such as IEEE 1547, Hawaii Rule 14H and California Rule 21 are evaluated in emerging high penetration scenarios. These rules define a 15% DG penetration level as a potential trigger for detailed interconnect studies. Historically, the 15% screen for PV penetration, was selected based on probability of islanding. Within the Hawaiian utilities, many distribution feeders by far exceed this penetration filter. Utilities have limited demand observability at the distribution system level. If data is available, it is often on a longer time scale than required 1 to 30 seconds or with gaps in data. Such data can inform generation dispatch, but there is no visibility of irradiance fluctuations at this scale.
The interaction and coordination between LTC, capacitor, and inverter operations for increased PV penetration and varying operational scenarios are a concern of many system operators. Variability is not normally considered part of the interconnection study. This issue is generally not a problem for single distribution sites, but when a large cluster or node of sites experiences highly variable cloud cover, there could be increased tap changer operations, and inverter tripping.
Ongoing work focuses on improving the interconnection process by identifying real issues with increasing levels of PV at the distribution level versus simply assuming ”rules of thumb” that may no longer benefit the technical conditions emerging today.