Four-Legs D-STATCOM for Current Balancing in Low-Voltage Distribution Grids

Javier Ballestin-Fuertes,Erika Laporta Puyal,Jose F Sanz-Osorio,Jesus Munoz-Cruzado-Alba,Jacob Rodriguez Rivero,Javier Leiva

doi:10.1109/access.2021.3138827

Abstract

The fast deployment of distributed energy resources (DERs) is creating a series of challenges that should be addressed in the coming years. In particular, distribution grids are playing an increasingly important role in the electricity system. Moreover, the three-phase four-wire structure of this network contribute to the appearance of imbalances and a series of problems derived from them. In this context, distribution system operators (DSOs), as the main responsible for the distribution grid, must ensure the quality of supply to consumers. This paper takes advantage of a four-legs D-STATCOM to remove current imbalances in low-voltage power lines. A 35-kVA prototype has been developed and installed in an urban distribution grid. The effect of the D-STATCOM has been analyzed during its first month of operation, studying and measuring the advantages of providing DERs the ability to perform active balancing to the utility grid. The results show a reduction in current imbalances from 21 % to 0 % and neutral current from 10.3 A to 0.4 A. In addition, a 13 % decrease in cable losses has been estimated and a slight improvement in voltage unbalance factor can be noted.

Highlights

T HE gravity of the climate crisis has already initiated a process of electrification of the energy system, increasing the use of electrical energy, maximizing the penetration of renewable energies and the deployment of clean, safe and connected mobility, among others [1], leading to a change in the electric grid as we know it today.Since 2012, most of the new installed energy capacity has been renewable worldwide, achieving a net addition record of 83 % in 2020 [2]
The power electronics cabinet can be seen on the right side of the picture, while the device is connected to the line inside the left enclosure
The rapid electrification of the power sector is revealing a number of problems that compromise grid stability

Summary

Introduction

T HE gravity of the climate crisis has already initiated a process of electrification of the energy system, increasing the use of electrical energy, maximizing the penetration of renewable energies and the deployment of clean, safe and connected mobility, among others [1], leading to a change in the electric grid as we know it today.Since 2012, most of the new installed energy capacity has been renewable worldwide, achieving a net addition record of 83 % in 2020 [2]. T HE gravity of the climate crisis has already initiated a process of electrification of the energy system, increasing the use of electrical energy, maximizing the penetration of renewable energies and the deployment of clean, safe and connected mobility, among others [1], leading to a change in the electric grid as we know it today. To replace the traditional large combustion power plants is producing a change, from the current centralized electricity model, to a distributed model where distributed energy resources (DER) are becoming especially relevant, as well as the importance of the distribution network in this process. The substitution of gas and oil heating systems by HVAC systems and petrol vehicles by electric vehicles (EV) [4], together with the current profitability of small photovoltaic (PV) installations [5], is evidencing a change in our energy consumption

Objectives

Results

Discussion

Conclusion