Toward semi-autonomous decentralized primary control from demand response

The objective of this paper is to assess the economic viability of a certain form of Demand Response providing primary frequency control. Automatic control is provided by the management of a large population of small electric loads. Loads adapt their instantaneous power consumption using a single modulation factor shared amongst the whole population. This single modulation factor is constrained to evolve within certain limits. The paper discusses how such a control could be of semi-autonomous nature. Indeed, loads would be able to react on a decentralized way by relying on local information and participate very actively to primary control. Feedback information about the average characteristics of the group must be provided. As these characteristics are not changing rapidly, information may be sent on regular time interval. The required information refreshment rate is expected to be sufficiently slow such that it would not hamper the control dynamics and allow for fast delivery of flexible capacity. The most constraining control limits lie in the fact that energy consumption of each load is conserved. Therefore, the control consists in energy consumption shifting. The amount of energy that can be shifted is actually limited by the lower and upper bounds of the modulation factor. Providing a constant flexible capacity requires to couple the control with an energy recovery mechanism. This paper considers energy compensation through purchase/sale of energy on the balancing market. A linear optimisation model is built. The objective is to maximise the value captured by the load group while respecting energy constraint. It results in maximising the participation of loads in the primary control while compensating energy in the most optimal way (price arbitrage). Results of this analysis are provided for historical data’s of frequency deviation observed during the month of January 2012 in the Belgian Control Zone. Prices for upward and downward regulation on the balancing market are also taken from historical analysis. Expected benefits are relatively modest for residential loads (payment of 3€/load/month) and a little more encouraging for industrial loads