Circuit-Theoretic Joint Parameter-State Estimation of Utility-Scale Photovoltaic, Battery, and Grid Systems

TL;DR

This work develops a circuit-theoretic, measurement-augmented state estimation framework that jointly estimates grid states, PV outputs, and battery states from a unified aggregated circuit model. By embedding PV and battery physics through equivalent circuits and measurement circuits, the method converts nonlinear relationships into affine constraints and optimizes the residuals of measurement noises under Kirchhoff's laws. The proposed ckt-SE^Re approach, and its parameter-aware variant ckt-PSE^Re, demonstrate improved accuracy, robustness to bad data, and scalability to large 10k-node networks with hundreds of PV/battery interfaces. The results show significant gains over stand-alone approaches, with notable resilience to measurement errors and unknown component parameters, enabling real-time, physically consistent bulk-grid modeling in the presence of high penetrations of PV and storage. The framework has practical implications for grid operation centers, enabling more accurate state estimation and system planning under evolving renewable-rich conditions.

Abstract

Solar PV and battery storage systems have become integral to modern power grids. Therefore, bulk grid models in real-time operation must include their physical behavior accurately for analysis and optimization. AC state estimation is critical to building real-time bulk power systems models. However, current ACSE techniques do not include detailed physics and measurements for battery and PV systems. This results in sub-optimal estimation results and subsequent less accurate bulk grid models for real-time operation. To address these challenges, we formulate a circuit-theoretic AC state estimator with accurate PV and battery systems physics and corresponding measurements. First, we propose an aggregated equivalent circuit model of the solar PV, battery, and traditional grid components. Next, we add measurements from PV and battery systems to the traditional measurement set to facilitate accurate estimation of the overall grid model. Finally, we develop a circuit-theoretic joint parameter-state estimation algorithm that can accurately estimate grid, PV, and battery system states and is robust against erroneous parameters. To demonstrate the efficacy of the proposed framework, we estimate the states of 10k node transmission networks with hundreds of battery+PV-tied systems. We compare the accuracy against the estimation of stand-alone grid, battery, and PV systems.

Figures (14)

• Figure 1: (a)3-bus circuit example (b)with equivalent current source account for power injection (c)with RTUs represented as measurement circuits.
• Figure 2: Equivalent circuit of single diode model.
• Figure 3: Equivalent circuit of $0^{th}$ order battery model.
• Figure 4: Sigmoid efficiency curve used in this work.
• Figure 5: Equivalent circuit of the PV system including measurements.