Voltage Control in Low-Voltage Grids Using Distributed Photovoltaic Converters and Centralized Devices

This paper studies the application of distributed and centralized solutions for voltage control in low voltage (LV) grids with high photovoltaic (PV) penetration. In traditional LV grids, the coordination of distributed PV converters and a centralized device would require massive investments in new communication and control infrastructures. The alternative of exploiting distributed PV converters for voltage control is discussed, showing that it can help to stabilize the voltage in the grid connection points also without coordination between them and/or with a centralized unit. The goal of this paper is to investigate how the setup of the voltage controllers inside PV inverters affects the operation of these controllers taking into account the limits for reactive power injection. In addition, the interaction of distributed PV converters with centralized devices (static var compensators and on load tap changers) is analyzed to assess whether additional benefits may come in these cases

太陽光発電の最大利用に向けた低圧配電系統の需要・供給側におけるエネルギーマネジメントに関する研究

早大学位記番号:新7825早稲田大

Incorporation of on-load tap changer transformers in low-voltage network planning

\u3cp\u3eThe introduction of distributed generation in the low-voltage (LV) network can generate bi-directional power flows and thus voltage increases instead of decreases from consumers along the feeder towards the substation. The new generation installed at the consumer premises may induce voltage problems while the loading of the cables is still under nominal values. Conventionally possible resulting voltage violations are solved by reinforcing the network, however smart grid alternatives like voltage control in the LV network can also alleviate the network problems. LV-networks are traditionally designed with medium to low voltage transformers equipped with off-line tap changers. The addition of an on-load tap changer (OLTC) for voltage control can decrease the voltage violations in the network, however this needs to be considered within the optimisation method applied for the planning of the LV-network. In this paper the smart grid alternative of installing an OLTC in this optimisation has been performed. By assessing different OLTC control strategies under conditions with increasing distributed generation over many types of networks, the effectiveness of the OLTC becomes apparent. The OLTC is included in the optimization problem formulation by the introduction of additional voltage constraints and relaxing the constraints in the form of a penalty function. When the introduction of an OLTC is more efficient rather than the conventional strengthening of the network is demonstrated with a case study on the impacts of distributed generation.\u3c/p\u3

Incorporation of on-load tap changer transformers in low-voltage network planning

The introduction of distributed generation in the low-voltage (LV) network can generate bi-directional power flows and thus voltage increases instead of decreases from consumers along the feeder towards the substation. The new generation installed at the consumer premises may induce voltage problems while the loading of the cables is still under nominal values. Conventionally possible resulting voltage violations are solved by reinforcing the network, however smart grid alternatives like voltage control in the LV network can also alleviate the network problems. LV-networks are traditionally designed with medium to low voltage transformers equipped with off-line tap changers. The addition of an on-load tap changer (OLTC) for voltage control can decrease the voltage violations in the network, however this needs to be considered within the optimisation method applied for the planning of the LV-network. In this paper the smart grid alternative of installing an OLTC in this optimisation has been performed. By assessing different OLTC control strategies under conditions with increasing distributed generation over many types of networks, the effectiveness of the OLTC becomes apparent. The OLTC is included in the optimization problem formulation by the introduction of additional voltage constraints and relaxing the constraints in the form of a penalty function. When the introduction of an OLTC is more efficient rather than the conventional strengthening of the network is demonstrated with a case study on the impacts of distributed generation

A comprehensive review of renewables and electric vehicles hosting capacity in active distribution networks

© Copyright 2023 The Author(s). The excessive integration of renewable distributed generation (RDG) and electric vehicles (EVs) could be considered the two most problematic elements representing the greatest threat to the distribution network (DN) technical operation. In order to avoid going beyond technical limitations, the term hosting capacity (HC) was proposed to define the highest permitted amount of distributed generation (DG) or EVs that can be integrated safely into the DN. The connection of RDGs was first brought to the attention of researchers and DN operators since it accounts for the most notable portion of these technical issues. Hence, the phrase ‘DG-HC’ was initially proposed and evolved significantly over the last few years. Currently, EV integration in most DNs worldwide is still low, but given the worldwide support for clean transportation options, expectations are raised for a significant increase. As a result, it is anticipated that over the next years, the effect of EV integration on the DN will be highly noticeable, requiring greater attention from researchers and DN operators to define the accepted limits of EV penetration levels, ‘EV-HC,’ which is expected to pass along the same line of DG-HC. This article provides an in-depth review of both DG-HC and EV-HC. It first analyses how the DG-HC research has grown over the years and then studies the published EV-HC papers, illustrating to what extent there is a similarity between them and, finally, employs these analyses to expect future development in the EV-HC research area. This article includes the different uses of the term HC, the most common performance indices of DG-HC, the various methods for assessing DG-HC, the different techniques for DG-HC enhancement, the effects of integrating EVs on the DG-HC, and finally, calculating and enhancing methods for EV-HC