Time Delays Compensation in the Centralized Control System of a Smart Grid for Providing System Ancillary Services

This chapter deals with the integration of dispersed generation (DG) units in a Smart Grid. . The DG units, when interconnected to the grid through static converters, can provide both energy and system ancillary services (e.g. voltage regulation, voltage harmonic distortion and unbalance compensation). At this purpose, the DG unit converters are coordinated through a centralized control system that provides in real time the reference signals to the control systems of the DG static converters allowing them to provide the aforementioned services. The centralized control system calculates the reference signals using an optimization procedure whose inputs are measurements from the SG busbars and whose outputs are the reference signals. The compensation action is inevitably affected by time delays introduced in the whole process by data acquisition, digital processing and data communication. With particular reference to the waveform distortion compensation, a procedure to compensate the time delays, is illustrated in depth and applied to an actual distribution system. The results of time domain simulations on the Smart Grid, are reported in order to analyze the time delay effects and show the effectiveness of the proposed compensation procedure.