Optimal Power Flow with Weighted Chance Constraints and General Policies for Generation Control

TL;DR

This paper introduces a convex Weighted Chance Constrained Optimal Power Flow (WCC-OPF) model that handles general control policies and accounts for violation severity, improving risk management in renewable-heavy power systems.

Contribution

It presents the WCC-OPF formulation that extends standard CC-OPF to include general policies and weighted constraints, enhancing realism and computational efficiency.

Findings

WCC-OPF reduces severe overloads compared to standard CC-OPF.

Flexible control policies lower operational costs at the same risk level.

The problem remains convex for any convex weighting function.

Abstract

Due to the increasing amount of electricity generated from renewable sources, uncertainty in power system operation will grow. This has implications for tools such as Optimal Power Flow (OPF), an optimization problem widely used in power system operations and planning, which should be adjusted to account for this uncertainty. One way to handle the uncertainty is to formulate a Chance Constrained OPF (CC-OPF) which limits the probability of constraint violation to a predefined value. However, existing CC-OPF formulations and solutions are not immune to drawbacks. On one hand, they only consider affine policies for generation control, which are not always realistic and may be sub-optimal. On the other hand, the standard CC-OPF formulations do not distinguish between large and small violations, although those might carry significantly different risk. In this paper, we introduce the Weighted CC-OPF (WCC-OPF) that can handle general control policies while preserving convexity and allowing for efficient computation. The weighted chance constraints account for the size of violations through a weighting function, which assigns a higher risk to a higher overloads. We prove that the problem remains convex for any convex weighting function, and for very general generation control policies. In a case study, we compare the performance of the new WCC-OPF and the standard CC-OPF and demonstrate that WCC-OPF effectively reduces the number of severe overloads. Furthermore, we compare an affine generation control policy with a more general policy, and show that the additional flexibility allow for a lower cost while maintaining the same level of risk.