Dynamic Model Development and System Study of Ternary Pumped Storage Hydropower

Abstract

The conventional role of pumped storage hydropower (PSH) is energy storage: it generates power when it operates as a hydro turbine, and store energy from the electric grid when pumping water from the lower reservoir to the upper reservoir. As the deployment of power electronic based renewable energy increases in the United States, PSH will play an important role in future electric power grids to help manage the variability from high penetration levels of renewable generation. However, conventional-PSH (C-PSH) is unable to fit the future needs of a system with high renewable energy penetration as it cannot provide regulation service during the pumping mode. For this reason, advanced-PSH (A-PSH) technology is becoming more popular. There is an industry need for the capability in power system studies to model ternary-PSH (T-PSH), as an A-PSH technology that can provide frequency regulation during generating and pumping by using a hydraulic short-circuit (HSC) mode. Presented here is a comprehensive dynamic model of a T-PSH in GE’s commercial simulation platform positive sequence load flow (PSLF). A new governor model for T-PSH technology is developed with detailed gate valve modeling and shared-penstock function. This model system has the capability to simulate seamless transition among three different modes: generating mode, pumping mode, and HSC mode, and switch between all operation modes with tunable transition time during the simulation. The process of this model implementation in PSLF platform is introduced. The developed T-PSH system has been tested and validated on multiple simulation platforms and different sizes of systems. A comparison study between T-PSH and C-PSH has also been conducted both on a small test system and the Western Interconnection system. Several sensitivity studies of parameters in the governor model have been performed to illustrate the influence on the frequency response of the T-PSH system. To reveal the dynamic benefit from T-PSH under extremely high renewable penetration condition, the frequency response of the Western Interconnection has been compared with and without T-PSH under different penetration levels of renewable, which are from 20% to 80%.