Optimisation of the load flow calculation method in order to perform techno-economic assessments of low-voltage distribution grids

Abstract

Decentralised power generation may lead to an inverse power flow compared to a centralised power supply system. Thus, voltage rises have to be limited at customer level with minimum extra costs during high PV power injection. Therefore, active and reactive power control of PV inverter will become more and more important because the additional grid operator’s and end customers’ investments could be nearly neglected. The decentralised control has to be triggered directly by the line voltage at the PV inverter ensuring an efficient use based on static characteristics, which are defined by the grid operator without the need of additional investment in IT infrastructure. The voltage dependent control of decentralised power generators is not implemented in the open source load flow calculation software Matpower. An elegant solution was found by integrating the dynamic change in active and reactive power directly into the load flow equations. This provides the basis for the techno-economic assessments which will be performed for different low-voltage distribution grid classes in Switzerland, Germany and Austria