A Feedforward Control-Based Power Decoupling Strategy for Grid-Forming Grid-Connected Inverters

Abstract

Grid-forming inverters, which are represented by droop control and virtual synchronous generator control, have been widely studied and applied because of their excellent grid-supporting ability and smooth off-grid switching. When a grid-forming inverter is connected to a microgrid or utility grid, the control loops of active power and reactive power will be coupled because of the voltage phase difference, which will affect the power control performance. This paper first derives the small-signal linearized model of the system, based on which a frequency feedforward control and an amplitude feedforward control are proposed to decouple the active power and reactive power control loops, respectively. The proposed decoupling strategy directly modifies the reference values through feedforward with an easily implementable principle that is applicable to various control coordinate systems, control coordinate systems, and control structures. By comparing system models with and without the proposed decoupling strategy, its effectiveness can be theoretically proven. Time-domain simulations and hardware experiments are presented to further validate its effectiveness.

Optimal Observer-Based Power Imbalance Allocation for Frequency Regulation in Shipboard Microgrids

“…The frequency deviation of SMGs is mainly determined by the active power, while the voltage is affected by the reactive power [23]. This can be mathematically proven following the steps reported in [24], where it can be derived that:…”

“…where ∆P(t), ∆Q(t) represent the variation of active and reactive power, respectively, γ 1 , γ 2 are positive constants, and ∆V(t) is the voltage variation at the synchronous machine terminals. A basic decoupler, as proposed in [24], can also be used to ensure conditions (6a) and (6b) to further solve more advanced control problems, such as power imbalance allocation or LFC problems. Therefore, SMG control can be divided into two different problems.…”

A Grid-Connected Inverter with Grid-Voltage-Weighted Feedforward Control Based on the Quasi-Proportional Resonance Controller for Suppressing Grid Voltage Disturbances

“…Considering the power grid voltage stability analysis, as shown in Figure 10, setting G 1 (s) = Z C (s)/(Z L1 (s) + Z C (s)), G 2 can be expressed as per Equation (12).…”

“…With proper design, it can meet the minimum grid requirements, i.e., total harmonic distortion (THD) below 5%. However, due to the characteristics of LCL-type filters, their frequency response exhibits resonance peaks, making them highly sensitive to grid disturbances and prone to current distortion [10][11][12].…”

Engineering Fastest Control: A New Process Control Method for Thermal Power Units

“…The EFPI parameters exhibit favorable tracking capabilities for variations in process characteristics. Additionally, the feedforward control quantity is calculated to determine the amount of feedforward control [24] based on changes in the set load and load rate of the unit. Figure 13 illustrates the utilization of the load function [15] to adjust the parameters of engineering fastest proportional-integral (EFPI) and the engineering fastest load observer (EFLO) based on the load set for the unit.…”