Incorporating a demand charge in central plant optimization
First Claim
1. An optimization and control system for a central plant configured to serve building energy loads, the optimization and control system comprising:
- a central plant controller configured to receive load prediction data indicating building energy loads for a plurality of time steps in an optimization period and utility rate data indicating a price of one or more resources consumed by equipment of the central plant to serve the building energy loads at each of the plurality of time steps, the central plant controller comprising;
a high level optimization module configured to generate an objective function that expresses a total monetary cost of operating the central plant over the optimization period as a function of the utility rate data and an amount of the one or more resources consumed by the central plant equipment at each of the plurality of time steps; and
a demand charge module configured to modify the objective function to account for a demand charge indicating a cost associated with a maximum power consumption during a demand charge period different from the optimization period, wherein modifying the objective function comprises applying a weighting factor to one of a demand charge term or a consumption term of the objective function, wherein the weighting factor equalizes the optimization period and the different demand charge period, the objective function comprising a summation of the consumption term and the demand charge term in which one of the consumption term or the demand charge term is multiplied by the weighting factor, wherein the consumption term comprises the amount of the one or more resources consumed by the central plant equipment at each time step of the optimization period multiplied by a cost per unit of the one or more resources, and the demand charge term comprises the maximum power consumption during the demand charge period multiplied by a cost per unit of power consumption;
wherein the high level optimization module is configured to optimize the objective function over the demand charge period subject to a set of constraints to determine an optimal distribution of the building energy loads over multiple groups of the central plant equipment at each of the plurality of time steps, and configured to use the weighting factor to evaluate trade-offs between increasing the consumption term and increasing the demand charge term when optimizing the objective function;
wherein the central plant controller is configured to control the central plant equipment according to a result of optimizing the objective function such that the central plant equipment operate to achieve the optimal distribution of the building energy loads at each of the plurality of time steps.
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Abstract
An optimization system for a central plant includes a processing circuit configured to receive load prediction data indicating building energy loads and utility rate data indicating a price of one or more resources consumed by equipment of the central plant to serve the building energy loads. The optimization system includes a high level optimization module configured to generate an objective function that expresses a total monetary cost of operating the central plant over an optimization period as a function of the utility rate data and an amount of the one or more resources consumed by the central plant equipment. The optimization system includes a demand charge module configured to modify the objective function to account for a demand charge indicating a cost associated with maximum power consumption during a demand charge period. The high level optimization module is configured to optimize the objective function over the demand charge period.
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Citations
18 Claims
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1. An optimization and control system for a central plant configured to serve building energy loads, the optimization and control system comprising:
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a central plant controller configured to receive load prediction data indicating building energy loads for a plurality of time steps in an optimization period and utility rate data indicating a price of one or more resources consumed by equipment of the central plant to serve the building energy loads at each of the plurality of time steps, the central plant controller comprising; a high level optimization module configured to generate an objective function that expresses a total monetary cost of operating the central plant over the optimization period as a function of the utility rate data and an amount of the one or more resources consumed by the central plant equipment at each of the plurality of time steps; and a demand charge module configured to modify the objective function to account for a demand charge indicating a cost associated with a maximum power consumption during a demand charge period different from the optimization period, wherein modifying the objective function comprises applying a weighting factor to one of a demand charge term or a consumption term of the objective function, wherein the weighting factor equalizes the optimization period and the different demand charge period, the objective function comprising a summation of the consumption term and the demand charge term in which one of the consumption term or the demand charge term is multiplied by the weighting factor, wherein the consumption term comprises the amount of the one or more resources consumed by the central plant equipment at each time step of the optimization period multiplied by a cost per unit of the one or more resources, and the demand charge term comprises the maximum power consumption during the demand charge period multiplied by a cost per unit of power consumption; wherein the high level optimization module is configured to optimize the objective function over the demand charge period subject to a set of constraints to determine an optimal distribution of the building energy loads over multiple groups of the central plant equipment at each of the plurality of time steps, and configured to use the weighting factor to evaluate trade-offs between increasing the consumption term and increasing the demand charge term when optimizing the objective function; wherein the central plant controller is configured to control the central plant equipment according to a result of optimizing the objective function such that the central plant equipment operate to achieve the optimal distribution of the building energy loads at each of the plurality of time steps. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for incorporating a demand charge in an optimization and control process for a central plant, the method comprising:
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receiving, at a central plant controller, load prediction data indicating building energy loads for a plurality of time steps in an optimization period and utility rate data indicating a price of one or more resources consumed by equipment of the central plant to serve the building energy loads at each of the plurality of time steps; generating, by a high level optimization module, an objective function that expresses a total monetary cost of operating the central plant over the optimization period as a function of the utility rate data and an amount of the one or more resources consumed by the central plant equipment at each of the plurality of time steps; modifying, by a demand charge module, the objective function to account for a demand charge indicating a cost associated with a maximum power consumption during a demand charge period different from the optimization period, wherein modifying the objective function comprises applying a weighting factor to one of a demand charge term or a consumption term of the objective function, wherein the weighting factor equalizes the optimization period and the different demand charge period, the objective function comprising a summation of the consumption term and the demand charge term in which one of the consumption term or the demand charge term is multiplied by the weighting factor, wherein the consumption term comprises the amount of the one or more resources consumed by the central plant equipment at each time step of the optimization period multiplied by a cost per unit of the one or more resources, and the demand charge term comprises the maximum power consumption during the demand charge period multiplied by a cost per unit of power consumption; optimizing, by the high level optimization module, the objective function over the demand charge period subject to a set of constraints to determine an optimal distribution of the building energy loads over multiple groups of the central plant equipment at each of the plurality of time steps, wherein optimizing the objective function comprises using the weighting factor to evaluate trade-offs between increasing the consumption term and increasing the demand charge term; and controlling, by the central plant controller, the central plant equipment according to a result of optimizing the objective function such that the central plant equipment operate to achieve the optimal distribution of the building energy loads at each of the plurality of time steps. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification