Voltage sensitivity-based demand-side management to reduce voltage unbalance in islanded microgrids

Microgrids (MG) provide advantages such as providing energy supply to areas far from the distribution grid, efficient use of resources by supporting demand management and having a more dynamic grid. However, if an advanced control system is not implemented in the islanded MG, problems of power quality may arise. One of these problems is the voltage unbalance. Increasing the number of single-phase roof-mounted PV plants and the number of electric vehicle charging stations in recent times may negatively affect voltage unbalance. One of the methods used to mitigate this problem is the demand-side management (DSM). Here, a solution method based on DSM is presented for the voltage unbalance problem that may occur in an islanded MG. Thermostatically controlled loads, which are often used for DSM, are preferred as controllable loads. A new and novel control algorithm based on voltage sensitivity have been developed. Effects of TCLs on different buses and phases are determined with voltage sensitivity matrix including neutral components. The proposed control algorithm reduces successfully both the voltage unbalance factor and the number of controlled TCLs. The algorithm was tested with the PSCAD/EMTDC analysis software.