Building energy optimization system with battery powered vehicle cost optimization

This application claims priority to and the benefit of U.S. provisional Patent Application No. 62/617,011, entitled “Building Energy Optimization System with Battery Powered Vehicle Cost Optimization,” filed Jan. 12, 2018, which is incorporated herein by reference in its entirety.This application is an application for reissue of U.S. Pat. No. 11,014,466, which issued on May 25, 2021, from U.S. patent application Ser. No. 16/246,342 filed Jan. 11, 2019, which claims the benefit of and priority to U.S. Provisional Patent Application No. 62/617,011 filed Jan. 12, 2018, all of which are incorporated by reference herein in their entireties.

The present disclosure relates generally to a building energy system. The present invention relates more particularly to systems and methods for optimizing an energy system within a building providing energy to battery powered devices. A building energy system, in general, is a system of devices configured to provide and consume the energy loads of a building or campus. A building energy system may include devices such as a central plant configured to serve different types of energy loads, a building management system (BMS) configured to control, monitor, and manage equipment in or around a building area, and external devices configured to connect to the building energy system and consume energy provided by the building energy system.

One implementation of the present disclosure is a building optimization system for charging and discharging a battery of a battery power vehicle. The building optimization system includes a charging system configured to cause the battery of the battery powered vehicle to charge or discharge. The building optimization system also includes an optimization controller including a processing circuit. The processing circuit is configured to receive charging constraints for the battery powered vehicle, determine whether to charge discharge the battery of the battery powered vehicle based on the charging constraints, and cause the charging system to charge or discharge the battery of the battery powered vehicle based on the optimization.

In some embodiments, the charging constraints include a departure time and a particular charge level for the departure time. The processing circuit is configured to cause the charging system to charge or discharge the battery of the battery powered vehicle such that a battery charge level of the battery is at the particular charge level at the departure time.

In some embodiments, the charging constraints include a first charging program that charges and discharges the battery and charges the battery to a predefined amount at a departure time.

In some embodiments, the charging constraints include a second charging program that charges the battery a different charging rates and charges the battery to a predefine amount at a departure time. The second charging program does not allow for the battery to discharge.

In some embodiments, the processing circuit is configured to generate a predicted departure time by receiving schedule events of a schedule associated with a user from a mobile device associated with the user, storing the schedule in a server, and generating the predicted departure time based on the schedule events.

In some embodiments, the processing circuit is configured to generate a predicted departure time by communicating via a wireless network with a mobile device associated with a user, determine a location of the mobile device associated with the user based on the communication via the wireless network with the mobile device, log the location and other previous locations of the mobile device in a location log, and generate the predicted departure time based on a pattern of locations of the mobile device based on the locations of the location log.

In some embodiments, the processing circuit configured to generate a predicted departure time causes the optimization to determine to charge or discharge the battery of the battery powered vehicle so that a charge level of the battery is a predefined amount at the predicted departure time.

In some embodiments, the processing circuit is configured to determine whether to charge or discharge the battery of the battery powered vehicle by performing an optimization with the charging constraints by generating a cost function accounting for cost and revenue generated from purchasing energy from an energy grid to charge the battery of the battery powered vehicle and revenue generated from discharging the battery of the battery powered vehicle to power building equipment or provide power to an energy grid, optimize the cost function to determine whether to charge or discharge the batter at time steps of an optimization window, and cause the charging system to charge or discharge the battery of the battery powered vehicle based on the optimization by causing the charging system to charge or discharge the battery at time steps of the optimization window.

Another implementation of the present disclosure is a building optimization system for charging and discharging a battery of a battery power mobile device. The building optimization system includes a charging system configured to cause the battery of the battery powered mobile device to charge or discharge and optimization controller including a processing circuit. The processing circuit is configured to receive charging constraints for the battery powered mobile device, determine whether to charge or discharge the battery of the battery powered mobile device by performing an optimization with the charging constraints, and cause the charging system to charge or discharge the battery of the battery powered mobile device based on the optimization.

In some embodiments, the charging constraints include a departure time and a particular charge level for the departure time. The processing circuit is configured to cause the charging system to charge or discharge the battery of the battery powered mobile device such that a battery charge level of the battery of the battery powered mobile device is at the particular charge level at the departure time.

In some embodiments, the charging constraints include a first charging program that charges and discharges the battery and charges the battery to a predefine amount at a departure time.

In some embodiments, the charging constraints include a second charging program that charges the battery at different charging rates and charges the battery to a predefined amount at a departure time. The second charging program does not allow for the battery to discharge.

In some embodiments, the processing circuit is configured to determine whether to charge or discharge the battery of the battery powered mobile device by performing an optimization with the charging constraints by generating a cost function accounting for cost and revenue generated from purchasing energy from an energy grid to charge the battery of the battery powered mobile device and revenue generated from discharging the battery of the battery powered mobile device to power building equipment or provide power to an energy grid, optimize the cost function to determine whether to charge or discharge the batter at time steps of an optimization window, and cause the charging system to charge or discharge the battery of the battery powered mobile device based on the optimization by causing the charging system to charge or discharge the battery at time steps of the optimization window.

Another implementation of the present disclosure is a method for optimizing a building energy system. The method involves connecting a battery powered device to a charging system connected to a building electrical grid, receiving charging constraints for a battery powered device, performing an optimization with the charging constraints, determining whether to charge or discharge a battery of the battery powered device, and causing the charging system to charge or discharge the battery of the battery powered device based on the optimization.

In some embodiments, receiving charging constraints involves receiving a departure time and a particular charge level for the departure time.

In some embodiments, receiving charging constraints involves selecting a first charging program that includes charging and discharging the battery of the battery powered device and charging the battery of the battery powered device to a predefined amount at a departure time.

In some embodiments, receiving charging constraints involves selecting a second charging program that includes charge the battery of the battery powered device at different charging rates and charging the battery of the battery powered device to a predefine amount at a departure time. The second charging program does not include discharging the battery.

In some embodiments, determining whether to charge of discharge the battery of the battery powered device involves generating a predicted departure time by receiving schedule events of a schedule associated with a user from a mobile device associated with the user, a server configured to store the schedule associated with the user, and generating the predicted departure time based on the one or more schedule events.

In some embodiments, receiving charging constraints involves receiving a predicted departure time that involves determining whether to charge or discharge the battery of the battery powered device such that a charge level of the battery of the battery powered device is a predefined amount at the predicted departure time.

In some embodiments, performing an optimization involves generating a cost function accounting for cost and revenue generated from purchasing energy from an energy grid to charge the battery of the battery powered device and revenue generated from discharging the battery of the battery powered device to power building equipment or provide power to an energy grid, optimize the cost function to determine whether to charge or discharge the batter at time steps of an optimization window, and cause the charging system to charge or discharge the battery of the battery powered device based on the optimization by causing the charging system to charge or discharge the battery at time steps of the optimization window.

Frequency Response Optimization

Referring now to, a frequency response optimization systemis shown, according to an exemplary embodiment. Systemis shown to include a campusand an energy grid. Campusmay include one or more buildingsthat receive power from energy grid. Buildingsmay include equipment or devices that consume electricity during operation. For example, buildingsmay include HVAC equipment, lighting equipment, security equipment, communications equipment, vending machines, computers, electronics, elevators, or other types of building equipment.

In some embodiments, buildingsare served by a building management system (BMS). A BMS is, in general, a system of devices configured to control, monitor, and manage equipment in or around a building or building area. A BMS can include, for example, a HVAC system, a security system, a lighting system, a fire alerting system, and/or any other system that is capable of managing building functions or devices. An exemplary building management system which may be used to monitor and control buildingsis described in U.S. patent application Ser. No. 14/717,593 filed May 20, 2015, the entire disclosure of which is incorporated by reference herein.

In some embodiments, campusincludes a central plant. Central plantmay include one or more subplants that consume resources from utilities (e.g., water, natural gas, electricity, etc.) to satisfy the loads of buildings. For example, central plantmay include a heater subplant, a heat recovery chiller subplant, a chiller subplant, a cooling tower subplant, a hot thermal energy storage (TES) subplant, and a cold thermal energy storage (TES) subplant, a steam subplant, and/or any other type of subplant configured to serve buildings. The subplants may be configured to convert input resources (e.g., electricity, water, natural gas, etc.) into output resources (e.g., cold water, hot water, chilled air, heated air, etc.) that are provided to buildings. An exemplary central plant which may be used to satisfy the loads of buildingsis described U.S. patent application Ser. No. 14/634,609 filed Feb. 27, 2015, the entire disclosure of which is incorporated by reference herein.

In some embodiments, campusincludes energy generation. Energy generationmay be configured to generate energy that can be used by buildings, used by central plant, and/or provided to energy grid. In some embodiments, energy generationgenerates electricity. For example, energy generationmay include an electric power plant, a photovoltaic energy field, or other types of systems or devices that generate electricity. The electricity generated by energy generationcan be used internally by campus(e.g., by buildingsand/or central plant) to decrease the amount of electric power that campusreceives from outside sources such as energy gridor battery. If the amount of electricity generated by energy generationexceeds the electric power demand of campus, the excess electric power can be provided to energy gridor stored in battery. The power output of campusis shown inas P. Pmay be positive if campusis outputting electric power or negative if campusis receiving electric power.

Still referring to, systemis shown to include a power inverterand a battery. Power invertermay be configured to convert electric power between direct current (DC) and alternating current (AC). For example, batterymay be configured to store and output DC power, whereas energy gridand campusmay be configured to consume and generate AC power. Power invertermay be used to convert DC power from batteryinto a sinusoidal AC output synchronized to the grid frequency of energy grid. Power invertermay also be used to convert AC power from campusor energy gridinto DC power that can be stored in battery. The power output of batteryis shown as P. Pmay be positive if batteryis providing power to power inverteror negative if batteryis receiving power from power inverter.

In some embodiments, power inverterreceives a DC power output from batteryand converts the DC power output to an AC power output. The AC power output can be used to satisfy the energy load of campusand/or can be provided to energy grid. Power invertermay synchronize the frequency of the AC power output with that of energy grid(e.g., 50 Hz or 60 Hz) using a local oscillator and may limit the voltage of the AC power output to no higher than the grid voltage. In some embodiments, power inverteris a resonant inverter that includes or uses LC circuits to remove the harmonics from a simple square wave in order to achieve a sine wave matching the frequency of energy grid. In various embodiments, power invertermay operate using high-frequency transformers, low-frequency transformers, or without transformers. Low-frequency transformers may convert the DC output from batterydirectly to the AC output provided to energy grid. High-frequency transformers may employ a multi-step process that involves converting the DC output to high-frequency AC, then back to DC, and then finally to the AC output provided to energy grid.

Systemis shown to include a point of interconnection (POI). POIis the point at which campus, energy grid, and power inverterare electrically connected. The power supplied to POIfrom power inverteris shown as P. Pmay be defined as PP, where Pis the battery power and Pis the power loss in the battery system (e.g., losses in power inverterand/or battery). Pand Pmay be positive if power inverteris providing power to POIor negative if power inverteris receiving power from POI. Pand Pcombine at POIto form P. Pmay be defined as the power provided to energy gridfrom POI. Pmay be positive if POIis providing power to energy gridor negative if POIis receiving power from energy grid.

Still referring to, systemis shown to include a frequency response controller. Controllermay be configured to generate and provide power setpoints to power inverter. Power invertermay use the power setpoints to control the amount of power Pprovided to POIor drawn from POI. For example, power invertermay be configured to draw power from POIand store the power in batteryin response to receiving a negative power setpoint from controller. Conversely, power invertermay be configured to draw power from batteryand provide the power to POIin response to receiving a positive power setpoint from controller. The magnitude of the power setpoint may define the amount of power Pprovided to or from power inverter. Controllermay be configured to generate and provide power setpoints that optimize the value of operating systemover a time horizon.

In some embodiments, frequency response controlleruses power inverterand batteryto perform frequency regulation for energy grid. Frequency regulation is the process of maintaining the stability of the grid frequency (e.g., 60 Hz in the United States). The grid frequency may remain stable and balanced as long as the total electric supply and demand of energy gridare balanced. Any deviation from that balance may result in a deviation of the grid frequency from its desirable value. For example, an increase in demand may cause the grid frequency to decrease, whereas an increase in supply may cause the grid frequency to increase. Frequency response controllermay be configured to offset a fluctuation in the grid frequency by causing power inverterto supply energy from batteryto energy grid(e.g., to offset a decrease in grid frequency) or store energy from energy gridin battery(e.g., to offset an increase in grid frequency).

In some embodiments, frequency response controlleruses power inverterand batteryto perform load shifting for campus. For example, controllermay cause power inverterto store energy in batterywhen energy prices are low and retrieve energy from batterywhen energy prices are high in order to reduce the cost of electricity required to power campus. Load shifting may also allow systemreduce the demand charge incurred. Demand charge is an additional charge imposed by some utility providers based on the maximum power consumption during an applicable demand charge period. For example, a demand charge rate may be specified in terms of dollars per unit of power (e.g., $/kW) and may be multiplied by the peak power usage (e.g., kW) during a demand charge period to calculate the demand charge. Load shifting may allow systemto smooth momentary spikes in the electric demand of campusby drawing energy from batteryin order to reduce peak power draw from energy grid, thereby decreasing the demand charge incurred.

Still referring to, systemis shown to include an incentive provider. Incentive providermay be a utility (e.g., an electric utility), a regional transmission organization (RTO), an independent system operator (ISO), or any other entity that provides incentives for performing frequency regulation. For example, incentive providermay provide systemwith monetary incentives for participating in a frequency response program. In order to participate in the frequency response program, systemmay maintain a reserve capacity of stored energy (e.g., in battery) that can be provided to energy grid. Systemmay also maintain the capacity to draw energy from energy gridand store the energy in battery. Reserving both of these capacities may be accomplished by managing the state-of-charge of battery.

Frequency response controllermay provide incentive providerwith a price bid and a capability bid. The price bid may include a price per unit power (e.g., $/MW) for reserving or storing power that allows systemto participate in a frequency response program offered by incentive provider. The price per unit power bid by frequency response controlleris referred to herein as the “capability price.” The price bid may also include a price for actual performance, referred to herein as the “performance price.” The capability bid may define an amount of power (e.g., MW) that systemwill reserve or store in batteryto perform frequency response, referred to herein as the “capability bid.”

Incentive providermay provide frequency response controllerwith a capability clearing price CP, a performance clearing price CP, and a regulation award Reg, which correspond to the capability price, the performance price, and the capability bid, respectively. In some embodiments, CP, CP, and Regare the same as the corresponding bids placed by controller. In other embodiments, CP, CP, and Regmay not be the same as the bids placed by controller. For example, CP, CP, and Regmay be generated by incentive providerbased on bids received from multiple participants in the frequency response program. Controllermay use CP, CP, and Regto perform frequency regulation.

Frequency response controlleris shown receiving a regulation signal from incentive provider. The regulation signal may specify a portion of the regulation award Regthat frequency response controlleris to add or remove from energy grid. In some embodiments, the regulation signal is a normalized signal (e.g., between −1 and 1) specifying a proportion of Reg. Positive values of the regulation signal may indicate an amount of power to add to energy grid, whereas negative values of the regulation signal may indicate an amount of power to remove from energy grid.

Frequency response controllermay respond to the regulation signal by generating an optimal power setpoint for power inverter. The optimal power setpoint may take into account both the potential revenue from participating in the frequency response program and the costs of participation. Costs of participation may include, for example, a monetized cost of battery degradation as well as the energy and demand charges that will be incurred. The optimization may be performed using sequential quadratic programming, dynamic programming, or any other optimization technique.

In some embodiments, controlleruses a battery life model to quantify and monetize battery degradation as a function of the power setpoints provided to power inverter. Advantageously, the battery life model allows controllerto perform an optimization that weighs the revenue generation potential of participating in the frequency response program against the cost of battery degradation and other costs of participation (e.g., less battery power available for campus, increased electricity costs, etc.). An exemplary regulation signal and power response are described in greater detail with reference to.

Referring now to, a pair of frequency response graphsandare shown, according to an exemplary embodiment. Graphillustrates a regulation signal Regas a function of time. Regis shown as a normalized signal ranging from −1 to 1 (i.e., −1≤Reg≤1). Regmay be generated by incentive providerand provided to frequency response controller. Regmay define a proportion of the regulation award Regthat controlleris to add or remove from energy grid, relative to a baseline value referred to as the midpoint b. For example, if the value of Regis 10 MW, a regulation signal value of 0.5 (i.e., Reg=0.5) may indicate that systemis requested to add 5 MW of power at POIrelative to midpoint b (e.g., P*=10 MW×0.5+b), whereas a regulation signal value of −0.3 may indicate that systemis requested to remove 3 MW of power from POIrelative to midpoint b (e.g., P*=10 MW×−0.3+b).

Graphillustrates the desired interconnection power Pas a function of time. Pmay be calculated by frequency response controllerbased on Reg, Reg, and a midpoint b. For example, controllermay calculate Pusing the following equation:P=Reg×Reg+bwhere P* represents the desired power at POI(e.g., P*=P+P) and b is the midpoint. Midpoint b may be defined (e.g., set or optimized) by controllerand may represent the midpoint of regulation around which the load is modified in response to Reg. Optimal adjustment of midpoint b may allow controllerto actively participate in the frequency response market while also taking into account the energy and demand charge that will be incurred.

In order to participate in the frequency response market, controllermay perform several tasks. Controllermay generate a price bid (e.g., $/MW) that includes the capability price and the performance price. In some embodiments, controllersends the price bid to incentive providerat approximately 15:30 each day and the price bid remains in effect for the entirety of the next day. Prior to beginning a frequency response period, controllermay generate the capability bid (e.g., MW) and send the capability bid to incentive provider. In some embodiments, controllergenerates and sends the capability bid to incentive providerapproximately 1.5 hours before a frequency response period begins. In an exemplary embodiment, each frequency response period has a duration of one hour; however, it is contemplated that frequency response periods may have any duration.

At the start of each frequency response period, controllermay generate the midpoint b around which controllerplans to perform frequency regulation. In some embodiments, controllergenerates a midpoint b that will maintain batteryat a constant state-of-charge (SOC) (i.e. a midpoint that will result in batteryhaving the same SOC at the beginning and end of the frequency response period). In other embodiments, controllergenerates midpoint b using an optimization procedure that allows the SOC of batteryto have different values at the beginning and end of the frequency response period. For example, controllermay use the SOC of batteryas a constrained variable that depends on midpoint b in order to optimize a value function that takes into account frequency response revenue, energy costs, and the cost of battery degradation. Exemplary techniques for calculating and/or optimizing midpoint b under both the constant SOC scenario and the variable SOC scenario are described in detail in U.S. patent application Ser. No. 15/247,883 filed Aug. 25, 2016, U.S. patent application Ser. No. 15/247,885 filed Aug. 25, 2016, and U.S. patent application Ser. No. 15/247,886 filed Aug. 25, 2016. The entire disclosure of each of these patent applications is incorporated by reference herein.

During each frequency response period, controllermay periodically generate a power setpoint for power inverter. For example, controllermay generate a power setpoint for each time step in the frequency response period. In some embodiments, controllergenerates the power setpoints using the equation:P*=Reg×Reg+bwhere P*=P+P. Positive values of P* indicate energy flow from POIto energy grid. Positive values of Pand Pindicate energy flow to POIfrom power inverterand campus, respectively.

In other embodiments, controllergenerates the power setpoints using the equation:P*=Reg×Res+bwhere Resis an optimal frequency response generated by optimizing a value function. Controllermay subtract Pfrom P* to generate the power setpoint for power inverter(i.e., P=P*−P). The power setpoint for power inverterindicates the amount of power that power inverteris to add to POI(if the power setpoint is positive) or remove from POI(if the power setpoint is negative). Exemplary techniques which can be used by controllerto calculate power inverter setpoints are described in detail in U.S. patent application Ser. No. 15/247,793 filed Aug. 25, 2016, U.S. patent application Ser. No. 15/247,784 filed Aug. 25, 2016, and U.S. patent application Ser. No. 15/247,777 filed Aug. 25, 2016. The entire disclosure of each of these patent applications is incorporated by reference herein.Photovoltaic Energy System with Frequency Regulation and Ramp Rate Control

Referring now to, a photovoltaic energy systemthat uses battery storage to simultaneously perform both ramp rate control and frequency regulation is shown, according to an exemplary embodiment. Ramp rate control is the process of offsetting ramp rates (i.e., increases or decreases in the power output of an energy system such as a photovoltaic energy system) that fall outside of compliance limits determined by the electric power authority overseeing the energy grid. Ramp rate control typically requires the use of an energy source that allows for offsetting ramp rates by either supplying additional power to the grid or consuming more power from the grid. In some instances, a facility is penalized for failing to comply with ramp rate requirements.

Frequency regulation is the process of maintaining the stability of the grid frequency (e.g., 60 Hz in the United States). As shown in, the grid frequency may remain balanced at 60 Hz as long as there is a balance between the demand from the energy grid and the supply to the energy grid. An increase in demand yields a decrease in grid frequency, whereas an increase in supply yields an increase in grid frequency. During a fluctuation of the grid frequency, systemmay offset the fluctuation by either drawing more energy from the energy grid (e.g., if the grid frequency is too high) or by providing energy to the energy grid (e.g., if the grid frequency is too low). Advantageously, systemmay use battery storage in combination with photovoltaic power to perform frequency regulation while simultaneously complying with ramp rate requirements and maintaining the state-of-charge of the battery storage within a predetermined desirable range.

Referring particularly to, systemis shown to include a photovoltaic (PV) field, a PV field power inverter, a battery, a battery power inverter, a point of interconnection (POI), and an energy grid. PV fieldmay include a collection of photovoltaic cells. The photovoltaic cells are configured to convert solar energy (i.e., sunlight) into electricity using a photovoltaic material such as monocrystalline silicon, polycrystalline silicon, amorphous silicon, cadmium telluride, copper indium gallium selenide/sulfide, or other materials that exhibit the photovoltaic effect. In some embodiments, the photovoltaic cells are contained within packaged assemblies that form solar panels. Each solar panel may include a plurality of linked photovoltaic cells. The solar panels may combine to form a photovoltaic array.

PV fieldmay have any of a variety of sizes and/or locations. In some embodiments, PV fieldis part of a large-scale photovoltaic power station (e.g., a solar park or farm) capable of providing an energy supply to a large number of consumers. When implemented as part of a large-scale system, PV fieldmay cover multiple hectares and may have power outputs of tens or hundreds of megawatts. In other embodiments, PV fieldmay cover a smaller area and may have a relatively lesser power output (e.g., between one and ten megawatts, less than one megawatt, etc.). For example, PV fieldmay be part of a rooftop-mounted system capable of providing enough electricity to power a single home or building. It is contemplated that PV fieldmay have any size, scale, and/or power output, as may be desirable in different implementations.

PV fieldmay generate a direct current (DC) output that depends on the intensity and/or directness of the sunlight to which the solar panels are exposed. The directness of the sunlight may depend on the angle of incidence of the sunlight relative to the surfaces of the solar panels. The intensity of the sunlight may be affected by a variety of environmental factors such as the time of day (e.g., sunrises and sunsets) and weather variables such as clouds that cast shadows upon PV field. When PV fieldis partially or completely covered by shadow, the power output of PV field(i.e., PV field power P) may drop as a result of the decrease in solar intensity.