A General Mathematical Model for LVRT Capability Assessment of DER-Penetrated Distribution Networks

Abstract

Low voltage ride through (LVRT) is one of the indispensable issues of recent decade in the context of grid codes. LVRT stands for the ability of a generation facility to stay connected during the voltage dip. Despite the numerous discussions in recent works, but they mostly concentrate on the LVRTbased control of distributed energy resources (DERs) integrated into a microgrid and its improvement. However, what has been hidden and not addressed any more yet is an index to measure the LVRT capability of a DER-penetrated distribution network (DPDN) under different voltage sags. This takes precedence when we want to evaluate the LVRT capability of DPDNs with consideration of various LVRT categories of DERs mandated in IEEE 1547 standard. This paper introduces a general framework for LVRT assessment of a DPDN by solving a system of differential algebraic equations (DAEs). Then expected LVRT capability of a DPDN is evaluated by a proposed LVRT index through the implementation of Monte Carlo simulation technique. INDEX TERMS Differential algebraic equation (DAE), Distributed energy resource (DER), Penetrated distribution network (DPDN), Low voltage ride through (LVRT), Monte Carlo

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An Analytical Framework for Evaluating the Impact of Distribution-Level LVRT Response on Transmission System Security

“…This study was carried out with simplifications and aggregation of PVs to reduce the problem complexity. Authors in [28] proposed a general mathematical model for DPDNs that determines the DERs with successful ride-through and the DERs that shall be tripped during the sag event. It gives the lost generation capacity of the DPDNs under various balanced voltage sags originating from the upstream grid.…”

“…The DSO updates the function and resends it to the TSO whenever the corresponding DER capacity or network configuration changes. As it was investigated in [28], the demand variations and even load growth have not a substantial effect on the LVRT capability of the DPDNs. Nevertheless, DSOs can annually update these functions.…”

“…1) Synchronous generators: These types of generators are included in Category I DERs and have the general form of differential-algebraic equations (DAE) in (1) for kth unit [28]. These equations are valid in positive sequence and for negative and zero sequences, just their transient reactance is modelled.…”

“…All the relative differential and algebraic equations can be found in [28]. However, these DERs require a proper reactive current injection strategy to better ride through the abnormal voltage condition.…”