Control loops design in a grid supporting mode inverter connected to a microgrid

Abstract

This paper deals with some design aspects of the control loops in a droop-controlled VSI connected to other inverters of greater ratings or to a strong grid, which sets the frequency. The design of a damping resistor in series with the AC filter capacitor is discussed and the impact of strong feedback between the output current and the capacitor voltage is investigated. Moreover an analysis of the derivative droop coefficients is carried out through a simplified equivalent circuit.

Partial Grid Forming Concept for 100% Inverter-Based Transmission Systems

“…However, this somewhat general classification is quite restrictive for the multifaceted nature of the problem, and occasionally unclear, as similar terms are used across the literature for different VSC concepts, as in case of a grid-supporting model presented in [10]. Furthermore, all of the proposed configurations assume that a converter is either forming both the voltage and frequency in the system, or measuring them via a Phase-Locked Loop (PLL) unit.…”

A stability-oriented design method for virtual impedance loop in droop-controlled converters

“…Fig. 2 shows the complete control system of the inverter and the model of the physical connection circuit [4]. The design properties of the controllers and the physical values of the circuit elements are reported in Table I.…”