Improved algebraic inverter modeling for four-wire power flow optimization

• Published in: Electric power systems research 2024-09, Vol.234, p.110825, Article 110825
• Main Authors: Heidari, Rahmat, Geth, Frederik
• Format: Article
• Language: English
• Subjects: Control; Grid following inverter; Grid forming inverter; Optimal power flow; Unbalanced distribution grids
• ISSN: 0378-7796; 1873-2046
• DOI: 10.1016/j.epsr.2024.110825

This paper discusses the modeling of inverters used in distributed energy resources in steady state. Modeling the interaction between distribution grids and inverter-based resources is crucial to understand the consequences for the network’s operational and planning processes. This work highlights the limitations of existing models and emphasizes the need for better representations of inverters and their control laws in decision-making contexts. Improved steady-state grid-following and grid-forming inverter models are presented, including both three-leg and four-leg converter variants. The advantages of these improved models in mathematical optimization contexts are showcased by investigating the power quality improvement capabilities of the inverters. Numerical studies integrating the proposed inverter models in a four-wire unbalanced optimal power flow engine are presented, and trade-offs between modeling detail and computational intensity are illustrated. •Review of algebraic inverter models and formulation improvements.•Derive (algebraic) nonlinear programming models for both the inverters and control laws, and perform numerical experiments through IPOPT [10].•Demonstrate the integration of these models into unbalanced optimal power flow engines, up to four-wire [11].•Illustrate how inverter model approximations can lead to sub-par decisions.