Local algorithm for the open loop control of thermostatically controlled loads

Recently, much research in demand response has been devoted to the global control of a population of local thermostatically controlled loads (TCLs), especially by modifying the temperature setpoints of programmable communicating thermostats (PCTs). It is now well known that shifting simultaneously and instantaneously the thermostat temperature setpoints of a homogeneous population of TCLs induces oscillations. To avoid this, closed loop control solutions have been proposed, which however necessitate real-time communication from local loads to central controller. Very recently, open loop solutions requiring only particular capabilities of the PCTs have been put forward. This paper shows how exactly simple hysteresis band shift introduces synchronization in a population of homogeneous TCLs and proposes a modification of the simple hysteresis band shift to avoid oscillations by circumventing thermostat synchronization. The algorithm's success is proved theoretically for a homogeneous TCL set. The improvement brought by the algorithm in a moderately heterogeneous case is shown by simulation. The algorithm is also compared to another recently proposed open loop solution.