Peak demand control in commercial buildings with target peak adjustment based on load forecasting

This paper reports on one of the first peak demand control systems in South Africa that uses direct temperature feedback to implement control limits. The system, which was installed at the Parliament complex in Cape Town, performs peak demand control using overall demand, as well as temperatures reflecting the status of controlled equipment, as objective functions of the control algorithm. Peak demand can thus be optimised without compromising the primary functions of the sheddable loads. For such a system to operate efficiently, it is necessary to accurately model the expected behaviour of sheddable loads. A simple model describing the power usage and internal temperature of equipment was hence integrated into the control algorithm. It is further shown that secondary peaks in demand may occur if the initial target level for peak demand is not optimally chosen. In this paper a new technique is described for optimal adjustment of the target peak level based on time series forecasting of the overall load of the complex.