A Virtual Synchronous Machine implementation for distributed control of power converters in SmartGrids

Abstract

a b s t r a c tThe ongoing evolution of the power system towards a "SmartGrid" implies a dominant role of power electronic converters, but poses strict requirements on their control strategies to preserve stability and controllability. In this perspective, the definition of decentralized control schemes for power converters that can provide grid support and allow for seamless transition between grid-connected or islanded operation is critical. Since these features can already be provided by synchronous generators, the concept of Virtual Synchronous Machines (VSMs) can be a suitable approach for controlling power electronics converters. This paper starts with a discussion of the general features offered by the VSM concept in the context of SmartGrids. A specific VSM implementation is then presented in detail together with its mathematical model. The intended emulation of the synchronous machine characteristics is illustrated by numerical simulations. Finally, stability is assessed by analysing the eigenvalues of a small-signal model and their parametric sensitivities.

Evaluation of Virtual Synchronous Machines With Dynamic or Quasi-Stationary Machine Models

“…1, the investigated configuration consists of a VSM-controlled VSC connected to an external grid through a LC filter, and the VSC is operated with conventional decoupled PI current controllers in the SSRF. Thus, the statespace equations of the electrical system, the current controllers and the active damping algorithm assumed for suppressing LC filter oscillations are well established and can be directly adapted from [19], [20], [25]. The equations for the currents in the filter inductor, the grid side currents, and the voltage of the filter capacitor can be derived directly from the circuit in Fig.…”

VSC-HVDC for Frequency Support (a review)

“…The definition of a synchronverter is introduced in [24] and highlights the differences from a VSG with the prominent difference being the lack of short term energy storage. Use of a VSG to enhance grid stability is discussed in [25] and [26] in which the swing equation is modelled to determine a virtual rotor angular velocity. Grid phase angle measurements and the determination of a virtual rotor phase angle allow a VSG to control the difference between the two.…”

Decentralized Coordination Power Control for Islanding Microgrid Based on PV/BES-VSG

“…(10) Then, the output power of each inverter unit is controlled as shown in (11). (11) State IV: The total load is larger than the sum of the total PVmaximum power and the total battery discharging power limits, as shown in (12).…”

“…So far, the developments of VSG for microgrids are focused on enhancing system stability [9], [10], distributed control of converters [11] for power system and power sharing in microgrids [12].…”