Method for deferring demand for electrical energy
Methods and systems are provided for optimizing the control of energy supply and demand. An energy control unit includes one or more algorithms for scheduling the control of energy consumption devices on the basis of variables relating to forecast energy supply and demand. Devices for which energy consumption can be scheduled or deferred are activated during periods of cheapest energy usage. Battery storage and alternative energy sources (e.g., photovoltaic cells) are activated to sell energy to the power grid during periods that are determined to correspond to favorable cost conditions.
1. A method for deferring demand for electrical energy, comprising the computer-implemented steps of:
(1) automatically estimating a cost over a forecasting period for electrical energy at a location, wherein the forecasting period is divided into at least three zones, said zones delineating different modes of operation derived either from a change in the relative prices of multiple sources of energy or changes in demand relative to capacity of the multiple sources, and wherein the cost of electrical energy is estimated based on a forecast of demand for electrical energy in each zone;
(2) determining a demand for electrical energy by one or more devices at the location for which energy consumption can be deferred;
(3) identifying a zone of the at least three zones in which an available marginal power supply capacity is greater than an electrical load of at least one device of the one or more devices;
(4) repeating step (3) to identify contiguous zones having a total duration exceeding a duration of time during which the at least one device is to be operated;
(5) selecting a plurality of the identified contiguous zones as a lower-cost time period; and
(6) automatically deferring electrical consumption for the at least one device from a higher-cost time period to the lower-cost time period, including the computer-implemented step of issuing a command to the at least one device to cause the deferral to occur.
2. The method of claim 1 , wherein the available marginal power supply capacity represents a capacity of a non-grid-based power source.
3. The method of claim 2 , wherein the available marginal power supply capacity represents a capacity of a photovoltaic power source.
4. The method of claim 1 , wherein step (5) includes
(5a) identifying, from the at least three zones, a plurality of candidate intervals for selection as the lower-cost time period, and
(5b) selecting as the lower-cost time period the candidate interval resulting in the lowest cost.
5. The method of claim 1 , wherein step (5) includes
(5a) determining that there is insufficient available marginal power supply capacity to provide the electrical load of the at least one device for an amount of time during which the at least one device is to be operated,
(5b) incrementing demand in each zone by an amount sufficient to provide the electrical load of the at least one device,
(5c) re-estimating the cost over the forecasting period for electrical energy based on the incremented demand in each zone, and
(5d) selecting the portion of the forecasting period having the lowest re-estimated cost as the lower-cost time period.
6. The method of claim 1 , wherein the forecasting period is divided into at least three zones, and wherein step (5) includes
(5a) determining, using a configuration specifying temporal limits on deferral of operation of the at least one device, a candidate interval comprising zones of the at least three zones during which the at least one device may be operated,
(5b) repeating step (5a) so as to identify a plurality of candidate intervals for selection as the lower-cost time period, and
(5c) selecting as the lower-cost time period the candidate interval resulting in the lowest cost.