Multi-objective Demand Side Management at Distribution Network Level in Support of Transmission Network Operation

This paper proposes a methodology for advanced demand side management (DSM) in the distribution network (DN), catering at the same time for the requirements of the network operator, transmission or distribution, the available flexibility of the demand side, and the preservation of network performance. The assumption is that the distribution network operator is providing balancing services to the transmission system operator through load shaping. For illustrative purposes of the methodology, the steady state voltage stability index, the load margin, is chosen as the network performance indicator. This is evaluated before and after a DSM action, in order to analyse the possible effect of DSM on network loadability. The DSM is initially performed based on optimal power flow calculation to ensure that the distribution system load profile at the grid supply point follows the required (pre-specified) load profile during a 24 hour period. Following this, a particle swarm optimization is used to modify DSM program in those time steps of the planning horizon where load margin is reduced. The results illustrate the extent to which the available flexibility of demand can be used in support of transmission network operation when the preservation of network performance and appropriate load modelling are considered.