Maximum Power Reference Tracking Algorithm for Power Curtailment of Photovoltaic Systems

TL;DR

An algorithm for power curtailment of photovoltaic systems under fast solar irradiance intermittency based on the Perturb and Observe technique is presented, which indicates an operation with smaller overshoot, less dc-link voltage oscillations, and improved power reference tracking capability.

Abstract

This paper presents an algorithm for power curtail-ment of photovoltaic (PV) systems under fast solar irradiance intermittency. Based on the Perturb and Observe (P&O) technique, the method contains an adaptive gain that is compensated in real-time to account for moments of lower power availability. In addition, an accumulator is added to the calculation of the step size to reduce the overshoot caused by large irradiance swings. A testbed of a three-phase single-stage, 500 kVA PV system is developed on the OPAL-RT eMEGAsim real-time simulator. Field irradiance data and a regulation signal from PJM (RTO) are used to compare the performance of the proposed method with other techniques found in the literature. Results indicate an operation with smaller overshoot, less dc-link voltage oscillations, and improved power reference tracking capability.

Figures (7)

• Figure 1: Circuit and control system block diagrams of a grid-scale PV system.
• Figure 2: Flowchart of a basic P&O power curtailment algorithm.
• Figure 3: Example of the adaptive $K_{tr}$ adjustment.
• Figure 4: Overshoot response comparison.
• Figure 5: Comparison of DC-link voltage oscillations: (a) method 1, (b) method 2, (c) method 3.