Integrering av elbilsladdare och solceller i distributionsnätet : Påverkan och lösningar med smarta elnät

Sammanfattning: This study aims to examine and quantify the impact from increasing penetration of electric car chargers and solar cells in Mälarenergi's distribution grids. Four different types of low voltage grids are examined: a small rural grid, an older suburban grid, a modern suburban grid and a modern urban grid with multi-dwelling houses. The networks are modeled in Matpower, a MATLAB Power System Simulation Package with grid and metering data from Mälarenergi's NIS (Network Information System), insolation data from Swedish Meteorological and Hydrological Institute (SMHI) and simulated data from an electrical vehicle Home-charing model based on residential activity patterns. The idea has been to use as few assumptions as possible and as much real measurements as possible. The results show that problems such as unwanted voltage levels at the customer's connection points and increasing power flux in the low voltage substation's is to be expected based on aforementioned increasing penetration. The various low voltage networks are affected to varying degrees due to its different structure and type of customers. Measures to increase acceptance for the above mentioned changes have also been reviewed. Line gain shows best properties to reduce both losses and voltage variations. Reactive power compensation in the solar cell's inverters can reduce voltage increases, but with the disadvantage that network losses increase. The use of smart chargers that can control when the charging of electrical vehicles begin charging can both reduce network losses but also the risk of unwanted voltage drops.