Optimal Future Sub-Transmission Volt-Var Planning Tool to Enable High PV Penetration

TL;DR

This paper introduces an advanced planning tool for sub-transmission systems that optimizes reactive power assets to effectively manage voltage issues caused by high PV penetration, reducing costs and improving system stability.

Contribution

It presents a novel integrated planning and operational framework that considers all reactive assets and efficiently handles multiple scenarios for high PV penetration.

Findings

Significant voltage violation reduction achieved.

Lower investment costs compared to conventional methods.

Validated on a large-scale realistic system.

Abstract

This paper proposes a reactive power planning tool for sub-transmission systems to mitigate voltage violations and fluctuations caused by high photovoltaic (PV) penetration and intermittency with a minimum investment cost. The tool considers all existing volt-ampere reactive (var) assets in both sub-transmission and distribution systems to reduce the need of new equipment. The planning tool coordinates with an operational volt-var optimization tool to determine all scenarios with voltage violations and verify the planning results. The planning result of each scenario is the solution of a proposed optimal power-flow framework with efficient techniques to handle a high number of discrete variables. The final planning decision is obtained from the planning results of all selected violated scenarios by using two different approaches - direct combination of all single-step solutions and final investment decision based only on the scenarios that are representative for the power-flow voltage violations at most time steps. The final planning decision is verified using a realistic large-scale sub-transmission system and 5-minute PV and load data. The results show a significant voltage violation reduction with a less investment cost for additional var equipment compared to conventional approaches.