Techno-Economic Assessment of Voltage Control Strategies in Low Voltage Grids

First, we investigate the technical and economic potential of autonomously operating voltage control strategies in low voltage grids with high photovoltaic penetration. The investigated control strategies are based on the reactive power control capabilities of modern photovoltaic inverters and the application of distribution transformers with on-load tap changers. We present a methodology for assessing the technical potential of autonomous voltage control strategies to increase the hosting capacity of low voltage grids and show the results for 40 real German LV grids. Second, we compare the investment and operational costs for conventional grid extension measures with those resulting from the application of autonomous voltage control strategies over a period of 10 years, using real measured load and generation data. Finally, we assess the additional grid loss reduction potential by applying a coordinated control approach, using the reactive power capabilities of the inverters as well as the on-load tap changer. The results clearly highlight the economic benefit of autonomous voltage control strategies by deferring grid reinforcement measures.

I. Introduction

In germany, technically effective and economically efficient voltage control is one of today's major challenges to increase the hosting capacity of low voltage (LV) grids for additional distributed generation (DG) capacity (e.g., photovoltaic (PV)). Besides classical grid reinforcement measures, additional controllability of DG units (e.g., reactive power provision, active power curtailment) and new Smart Grid technologies, such as distribution transformer with on-load tap changer (OLTC), offer additional ways of voltage control. This paper set a focus on autonomously operating voltage control strategies (VCS), which do not require any additional information from remote entities and hence rely on locally measured values only (i.e., no communication between controlling entities).