GENERATOR PRIORITIZATION BASED ON BUS VOLTAGE SENSITIVITY

Abstract

The modern electrical grid faces evolving system conditions due to the out ofordinary increase in renewable energy resources, such as, wind and solar. This surge is driven by the move towards a green future, electrification of transportation, and the expansion of large-scale data centers for activities such as crypto mining and Artificial Intelligence (AI) model training. With the considerable increase in loads it has become unmistakably important to efficiently dispatch resources. Monitoring system voltage within tolerances and proper use of reactive powerresources for voltage control is paramount as seen in the North American Electric Reliability Corporation’s (NERC) reliability standards. With a limited number and controllability of capacitors and reactors, structured usage of generators is of growing importance. System Operators sometimes face difficulties in identifying the most effective generators for voltage control, resulting in delayed response times and potential System Operating Limit (SOL) exceedances if not addressed properly in a timely manner. Traditionally, operators rely on their experience to make these decisions, which may not always be the most practical as the system continually develops. To overcome this limitation, this study proposes a method to prioritize generators forvoltage control by assessing their voltage control sensitivities. Specifically, this approach is based on the use of a small voltage set point variation at selected generator’s buses and calculation of the voltage magnitude changes to the selected monitored load buses by using alternating current (AC) power flow calculations. During the calculation process, to properly evaluate the impact each unit solely has on the overall system, all other voltage/volt-ampere reactive (VAr) control devices (e.g., generators, transformer Load Tap Changers (LTCs), switchable reactors/capacitors) are locked and unable to inject/withdraw VArs from the system. The efficacy of the proposed method has been validated using a realistic systemmodel of Oklahoma Gas and Electric’s (OG&E) transmission system. For the various system’s regions, it has shown that the generators can be properly prioritized by referring to the calculated voltage control sensitivity indices. The results are consistent with System Operator’s operation experience as well as the electrical connectivity between the selected buses and generators. The conventional method for voltage sensitivity analysis involves balancing voltageand reactive power to maintain grid stability. Typically, this involves assessing how changes in reactive and active power affect voltage levels across the grid. However, in this study, the influence of generators with an ability to inject or withdrawal real or reactive power are frozen in a default state to isolate the impact of a sole generator’s voltage variations alone. Despite this simplification, the results remain consistent with traditional grid operations, demonstrating that the proposed method can effectively prioritize generators for voltage control without compromising accuracy. This consistency suggests that the approach is a reliable method for identifying the most effective use of generator resources in the shortest amount of time, providing a streamlined yet effective means for prioritizing generators for voltage control in complex power systems.