Static Equivalent of Distribution Grids With High Penetration of PV Systems

Abstract

High penetrations of photovoltaic (PV) systems within load pockets in distribution grids have changed pure consumers to prosumers. This can cause technical challenges in distribution and transmission grids, such as overvoltage and reverse power flow. Embedding voltage support schemes into PVs, such as standard cos φ(P) characteristic proposed by the German grid codes, may cause more changes in the steady-state behavior of distribution grids and, in turn, the transmission side. Accordingly, it is important to properly model active distribution grids to analyze the system impacts of these changes to plan and operate future smart power grids. However, due to the high dimension of distribution grids, considering a detailed distribution grid to study the transmission side or a fraction of the distribution grid is either cumbersome or impractical. Therefore, it is required to develop a reasonable equivalent that can fairly capture the dominant behavior of the distribution grids. The aim of this paper is to use gray-box modeling concepts to develop a static equivalent of distribution grids comprising a large number of PV systems embedded with voltage support schemes. In the proposed model, the PV systems are aggregated as a separate entity, and not as a negative load, which is traditionally done. The results demonstrate the superior quality of the proposed model compared with the model with PV systems as the negative load.

Improving Hosting Capacity of Rooftop PVs by Quadratic Control of an LV-Central BSS

“…However, the high integration of rooftop PVs in LV grids creates some technical challenges such as reverse power flow and voltage rise [3]. This reverse power might lead currents to exceed the thermal limit of power lines, and could also make a considerable voltage rise in customer sides of the grid [4].…”

A Survey on Equivalence Modeling for Large-Scale Photovoltaic Power Plants

“…Therefore, in view of the analysis of the grid-connected operation characteristics of large-scale PV power plants, scholars have carried out a large number of modeling studies on grid-connected PV power plants, including the model of the independent core components of PV systems [7][8][9] and the overall model of the system [10][11][12], most of which are based on detailed models of PV power plants. For small and medium PV power plants, detailed models can be established for simulations, however, large-scale PV power plants are usually made up of dozens or even hundreds of PV units.…”

Invisible Units Detection and Estimation Based on Random Matrix Theory

“…Lots of work has been done to study the impacts and risks of invisible units [9]. Little attention, however, has been paid to detection and estimation of said invisible units, especially in the context of a complex distributed grid.…”