120 may transmit the generator parameters during an initial configuration process between the one or more energy generator systems 120 and the microgrid controller 110. The generator set maximum threshold value and the generator set minimum threshold value may indicate a maximum power load and a minimum power load, respectively, that a generator of an energy generator system 120 may support.

The one or more energy storage systems 122 may be any energy storage device that can store and output AC power. For instance, the one or more energy storage systems 122 may include at least one electrical-chemical energy storage (e.g., a battery), electrical energy storage (e.g., a capacitor, a supercapacitor, or a superconducting magnetic energy storage), mechanical energy storage (e.g., a fly wheel, a pump system), and/or any combination thereof. The one or more energy storage systems 122 may include inverters (individually or collectively) so that the one or more energy storage systems 122 may operate as a power consumer or a power source. The one or more energy storage systems 122 may also include electronic control mechanisms to control (1) how much load the one or more energy storage systems 122 draw, or (2) how much AC power the one or more energy storage systems 122 output.

The one or more energy storage systems 122 may also include communication interfaces. The communication interfaces of the one or more energy generator systems 120 may enable the one or more energy storage systems 122 to communicate with the microgrid controller 110. For instance, the one or more energy storage systems 122 may be connected to the microgrid controller 110 by wired or wireless communication. The one or more energy storage systems 122 may provide the microgrid controller 110 with energy storage data and may receive instructions from the microgrid controller 110.

The energy storage data may include, for each of the at least one energy store, a current energy level (e.g., kilowatt-hours currently stored), total energy storage capacity (e.g., kilowatt-hours of capacity), and/or discharge/charge parameters. The current energy level may be measured by a battery meter of an energy storage. The battery meter may one or combinations of a voltmeter, an amp-hour meter, and/or an impedance-based meter. The discharge/charge parameters may indicate an amount of discharge power and an amount of charge power for a respective energy storage device of the one or more energy storage systems 122. Alternatively, to reduce transmission bandwidth, the energy storage data may omit the discharge/charge parameters, and the one or more energy storage systems 122 may transmit the discharge/charge parameters when the one or more energy storage systems 122 are first connected to the microgrid controller 110.

The one or more energy storage systems 122 may receive requests (e.g., instructions) for the energy storage data to provide the energy storage data and/or continuously provide the energy storage data to the microgrid controller 110. The instructions may include energy storage dispatch (ESD) instructions. An ESD instruction may include an instruction to inject power to a system bus of the power system 106 or absorb power from the system bus of the power system 106. ESD instructions may be provided in control signals (e.g., communication signals that provide the ESD instructions). At least one ESD instruction may be utilized to rapidly stabilize the load, thereby stabilizing the bus frequency of the power system 106 in a time efficient manner, rather than attempting to stabilize the load using the one or more energy generator systems 120 alone. The one or more energy storage systems 122 may control the inverters and the electronic control mechanisms to control (1) quantity of load drawn by the one or more energy storage systems 122, or (2) the amount of AC power output produced by the one or more energy storage systems 122, in accordance with the ESD instructions.

The microgrid controller 110 may include at least one memory device (e.g., one or more memories) for storing instructions (e.g., program code); at least one processor for executing the instructions from the memory device to perform a set of desired operations; and a communication interface (e.g., coupled to a communication bus) for facilitating the communication between various system components. The instructions may be computer-readable instructions for executing a control application. The communication interface of the microgrid controller 110 may enable the microgrid controller 110 to communicate with the one or more energy generator systems 120 and the one or more energy storage systems 122. The microgrid controller 110, while executing the control application, may receive the generator data and the energy storage data (e.g., energy resource information), process the generator data and the energy storage data to generate one or more ESD instructions, and output the ESD instructions to one or more energy generator systems 120 and/or to one or more energy storage systems 122, so that the one or more energy generator systems 120 are protected from transient changes in load.

To process the generator data and the energy storage data to generate the ESD instructions, the control application may include a load stabilization function and/or an SOC function. The control application may also include a generator set limit function and/or energy store discharge/charge limit function to generate the ESD instructions. In some cases, the load stabilization function may be activated while the power system 106 is configured in stand-alone mode in order to provide off-grid load stabilization. Generally, the load stabilization function may ensure that system bus frequencies of the one or more energy generator systems 120 are maintained at a nominal value by causing an amount of power to be absorbed/injected by the one or more energy storage systems 122. The amount of power may be determined based on a difference between an instantaneous load and a moving average of the load. Meanwhile, the SOC function may ensure that the one or more energy storage systems 122 are charged to a target SOC. The target SOC may enable the at least one energy storage system 122 to provide long term beneficial use to the system 100, such as having a range of operation usable by the power system 106, and/or avoid degradation ranges of the one or more energy storage systems 122.

The instructions may include a load stabilization algorithm that may be executed by the microgrid controller 110 to increase a microgrid power quality by reducing the recurrence of frequency deviations that are caused by repetitive load steps (e.g., caused by one or more cyclic loads). Reactive and/or active may be used as a qualifier for loads, where reactive loads contribute to the stabilization algorithm in addition to the active or real loads. The communication interface of the microgrid controller 110 may receive load information corresponding to a current load demand of the loads 108 connected to the microgrid and output one or more control signals (e.g., ESD instructions) for controlling a plurality of energy resource systems associated with the microgrid. The plurality of energy resource systems may include the non-stabilizing group of energy resource systems 112 and the stabilizing group of energy resource systems 114.

One or more processors of the microgrid controller 110 may execute the load stabilization algorithm (e.g., execute instructions associated with the load stabilization algorithm) to generate the one or more control signals based on the load information. Executing the load stabilization algorithm may include generating, based on the load information, one or more first control signals to dynamically control an amount of total output power provided by the stabilizing group of energy resource systems 114 to a power distribution network of the microgrid in order to stabilize one or more cyclic loads on the power distribution network and to maintain the non-stabilizing group of energy resource systems 112 at a substantially constant load.

Executing the load stabilization algorithm may further include generating, based on a total load of the plurality of loads 108, the one or more first control signals to control a first total output power provided by the stabilizing group of energy resource systems 114 to the power distribution network of the microgrid, and generating, based on the total load of the plurality of loads 108, one or more second control signals to control a second total output power provided by the non-stabilizing group of energy resource systems 112 to the power distribution network of the microgrid. Executing the load stabilization algorithm may further include monitoring an SOC of the stabilizing group of energy resource systems 114, calculating a bias power to maintain the SOC of the stabilizing group of energy resource systems within a target range, and calculating the first total output power and the second total output power based on the bias power. The SOC of the stabilizing group of energy resource systems 114 may be a cumulative SOC of the stabilizing group of energy resource systems 114. In some cases, the target range may be a single SOC value (e.g., an SOC target).

Executing the load stabilization algorithm may further include calculating the total load of the plurality of loads 108 based on the load information; calculating a first target load for the non-stabilizing group of energy resource systems 112 and a second target load for the stabilizing group of energy resource systems 114, where a sum of the first target load and the second target load is equal to the total load; measuring the SOC of the stabilizing group of energy resource systems 114; calculating the bias power to maintain the SOC of the stabilizing group of energy resource systems 114 within the target range; calculating the first total output power for the non-stabilizing group of energy resource systems 112 based on the first target load and the bias power; calculating the second total output power for the stabilizing group of energy resource systems 114 based on the second target load and the bias power; controlling, based on the first total output power, the non-stabilizing group of energy resource systems 112 to produce the first total output power; and controlling, based on the second total output power, the stabilizing group of energy resource systems 114 to produce the second total output power.

Executing the load stabilization algorithm may further include the microgrid controller 110 receiving a moving average window setpoint (e.g., from the HMI 102 or external controller 104), calculating a moving average of the total load based on the total load and the moving average window setpoint, and calculating the first target load for the non-stabilizing group of energy resource systems 112 based on the moving average of the total load. Since the sum of the first target load and the second target load is equal to the total load, the microgrid controller 110 may also calculate the second target load by subtracting the first target load from the total load.

Executing the load stabilization algorithm may further include calculating a first total allocated load for the non-stabilizing group of energy resource systems 112 based on the first target load and the bias power, calculating a second total allocated load for the stabilizing group of energy resource systems 114 based on the second target load and the bias power, and calculating the first total output power and the second total output power based on the second total allocated load relative to a discharge power limit (e.g., a kilowatt (kW) limit) of the stabilizing group of energy resource systems 114. Executing the load stabilization algorithm may further include, based on the second total allocated load exceeding the discharge power limit of the stabilizing group of energy resource systems 114: setting the first total output power to a sum of the first total allocated load and the second total allocated load, minus the discharge power limit of the stabilizing group of energy resource systems 114, and setting the second total output power to the discharge power limit of the stabilizing group of energy resource systems 114. Executing the load stabilization algorithm may further include, based on the second total allocated load being less than a charge power limit of the stabilizing group of energy resource systems 114: setting the first total output power to a sum of the first total allocated load, the second total allocated load, and the charge power limit of the stabilizing group of energy resource systems 114, and setting the second total output power to the charge power limit of the stabilizing group of energy resource systems 114. The first total allocated load may be a subtraction of the bias power from the first target load, and the second total allocated load may be a sum of the second target load and the bias power.

Furthermore, the microgrid may be configured, while the microgrid controller 110 is executing the load stabilization algorithm, in a stand-alone state, during which the microgrid is disconnected from an external power distribution system. In other words, the microgrid controller 110 may be configured to set the microgrid in the stand-alone state when executing the load stabilization algorithm. Moreover, the plurality of loads 108 may include at least one non-stable load.

The instructions may include a sequential dispatch algorithm that may be executed by the microgrid controller 110. The sequential dispatch algorithm may be part of the load stabilization algorithm. One or more processors of the microgrid controller 110 may execute the sequential dispatch algorithm (e.g., execute instructions associated with the sequential dispatch algorithm) to maintain the SOC of the stabilizing group of energy resource systems 114 within the target range. For example, executing the sequential dispatch algorithm may include generating, based on the SOC of the stabilizing group of energy resource systems 112 being less than a minimum threshold, the one or more second control signals to control at least one energy resource system (e.g., one or more energy generator systems 120) of the non-stabilizing group of energy resource systems 112 to provide the bias power to the stabilizing group of energy resource systems 114 in order to increase the SOC of the stabilizing group of energy resource systems 114. In addition, executing the sequential dispatch algorithm may include generating, based on the SOC of the stabilizing group of energy resource systems 114 being greater than a maximum threshold, the one or more first control signals to control at least one energy resource system (e.g., one or more energy storage systems 122) of the stabilizing group of energy resource systems 114 to provide the bias power to a power distribution network of the microgrid in order to decrease the SOC of the stabilizing group of energy resource systems 114. The target range of the SOC may be defined by the minimum threshold and the maximum threshold. Alternatively, the minimum threshold and the maximum threshold may be SOC limits that are set within the target range.

One or more energy generator systems 120 may include an engine-generator that provides AC power to the power system 106, which may provide the AC power to the at least one load 108. Generally, an engine-generator may be any device that converts motive power (mechanical energy) into electrical power to output the AC power. An engine-generator may be a gas turbine electrical generator. In such gas turbine electrical generators, fast changes in load from the at least one load 108 may cause a system bus frequency to deviate from a nominal value. The system bus frequency may be a frequency of electrical components of the generator. For instance, such gas turbine electrical generators may have isochronous frequency control governors that may try to maintain the system bus frequency at the nominal value in response to changes of the load of the one or more loads 108. Therefore, during a transient load charge (e.g., a load transient), the system bus frequency may change as the load on the engine-generator changes. However, a rate of return of the system bus frequency back to the nominal value is slower than a desired rate due to an inertia of motion of physical components (e.g., a rotor of a stator-rotor) of the engine-generator. The slow rate of return may reduce power quality of the power system 106. The power quality of the power system 106 may be determined based on the voltage, frequency, and waveform of the power output to the one or more loads 108. A higher power quality may ensure continuity of service for the one or more loads 108, such that the one or more loads 108 are able to properly function as intended. A lower power quality may cause the one or more loads 108 to malfunction, fail prematurely, or not operate at all.

Therefore, avoiding load transients may be beneficial in providing better power quality. However, generally, controlling a load of the one or more loads 108 may not be possible or desirable. Instead, the microgrid controller 110 may control the one or more energy storage systems 122 of the stabilizing group of energy resource systems 114 to act as a power consumer or as an energy source, so that the one or more energy generator systems 120 of the non-stabilizing group of energy resource systems 112 may maintain the system bus frequency at the nominal value, thereby ensuring better power quality. For example, the microgrid controller 110 may execute the load stabilization algorithm in order to control the stabilizing group of energy resource systems 114, to stabilize one or more cyclic loads on the power distribution network and to maintain the non-stabilizing group of energy resource systems 112 at a substantially constant load, which may reduce repeat occurrences of frequency deviations from the nominal value.

The microgrid controller 110 may control the one or more energy storage systems 122 to act as a near instantaneous load or energy source, so that the one or more energy generator systems 120 may maintain the system bus frequency at the nominal value, thereby ensuring better power quality. In one aspect of this disclosure, the microgrid controller 110 may control the one or more energy storage systems 122 to instantaneously inject power when power is needed by the at least one load 108, or instantaneously absorb surplus power generated by the one or more energy generator systems 120. Accordingly, the microgrid controller 110 regulates the power supply such that an exact amount of desired power supply flows in or out of the power system 106 at any given time. The instantaneous injecting/absorbing of power may be performed to control the amount of transient load seen by the power system 106 and thus stabilize the load and resulting system bus frequency of the one or more energy generator systems 120.

FIG. 2 shows a microgrid 200 according to one or more implementations. The microgrid 200 may be an example of the power system 106 described in connection with FIG. 1. The microgrid 200 may include a plurality of DERs 202. The plurality of DERs 202 may include N energy generator systems 120 and M energy storage systems 122, where N and M are integers greater than zero. For example, the plurality of DERs 202 may include a first energy generator system 120-1 and an N^thenergy generator system 120-N. Additionally, the plurality of DERs 202 may include a first energy storage system 122-1 and an M^thenergy storage system 122-M. Each energy generator system 120 may include a power generator 204 and a local generator controller 206. Each energy storage system 122 may include an electric storage device 208 (e.g., one or more batteries and/or capacitors) and a local ESS controller 210.

Each energy generator system 120 may be coupled to a power bus 212 for providing power to one or more loads connected to the power bus 212. Additionally, each energy storage system 122 may be coupled to the power bus 212 for providing power to or absorbing power from the power bus 212 (e.g., for providing power to or absorbing power from one or more components, such as one or more loads and/or one or more energy generator systems 120 connected to the power bus 212).

The microgrid 200 may also include the microgrid controller 110 that is communicatively coupled to the local controllers (e.g., local generator controllers 206 and local ESS controllers 210) of each DER 202 across a communication bus 214. The communication bus 214 may also enable the microgrid 200 to communicate with one or more loads and/or one or more load management systems (e.g., charging systems, fleet management systems, local load controllers, etc.). In some cases, two or more communication buses 214 may be provided. For example, one communication bus may be provided to communicate with local controllers and another communication bus may be provided to communicate with one or more loads and/or one or more load management systems.

Each local generator controller 206 may include any appropriate hardware, software, and/or firmware to sense and control a respective power generator 204, and send information to, and receive information from microgrid controller 110. For example, a local generator controller 206 may be configured to sense, determine, and/or store generator data of its respective power generator 204. The generator data may be sensed, determined, and/or stored in any conventional manner. Each local generator controller 206 may control whether a respective power generator 204 is connected to or disconnected from the power bus 212 (for example, based on an instruction or a control signal received from the microgrid controller 110).

Each local ESS controller 210 may include any appropriate hardware, software, and/or firmware to sense and control a respective electric storage device 208, and send information to, and receive information from microgrid controller 110. For example, a local ESS controller 210 may be configured to sense, determine, and/or store various characteristics of its respective electric storage device 208. Such characteristics of the respective electric storage device 208 may include, among others, a current SOC, a current energy, an SOC minimum threshold, an SOC maximum threshold, and a discharge limit of the respective electric storage device 208. These characteristics of respective electric storage device 208 may be sensed, determined, and/or stored in any conventional manner. Each local ESS controller 210 may control whether a respective electric storage device 208 is connected to or disconnected from the power bus 212 (for example, based on an instruction or a control signal received from the microgrid controller 110).

The microgrid controller 110 may receive or determine a need for charging or discharging of power from the microgrid 200, and may be configured to determine and send signals to allocate a total charge request and/or total discharge request across all of the plurality of DERs 202.

When performing the power allocation functions, the microgrid controller 110 may allocate a certain amount of power from each energy generator system 120 to one or more loads. When performing the power allocation functions, the microgrid controller 110 may allocate a total charge request and/or a total discharge request across the energy storage systems 122 as a function of a usable energy capacity of each energy storage system 122. The usable energy capacity corresponds to the capacity or amount of energy that an energy storage system 122 can receive in response to a total charging request (usable charge energy), or the capacity or amount of energy that an energy storage system can discharge in response to a total discharge request (usable discharge energy). The usable charge energy is a function of a maximum state of charge, current state of charge, and current energy of the energy storage system, and the usable discharge energy is a function of a minimum state of charge, and current energy of the energy storage system 122. The microgrid controller 110 may determine a usable charge/discharge capacity of each energy storage system 122 (e.g., SOC), a desired charge/discharge of each energy storage system 122, a remainder power of each energy storage system 122, and/or an SOH of each energy storage system 122.

Thus, the microgrid controller 110 regulates a power supply of the microgrid 200 such that an exact amount of desired power flows in or out of the power system 106 at any given time. The microgrid controller 110 may regulate the power supply of the microgrid 200 in cooperation with the local generator controllers 206 and the local ESS controllers 210. The microgrid controller 110 may transmit control signals (e.g., instructions) to the local generator controllers 206 and the local ESS controllers 210 to activate (e.g., to bring online), deactivate (to bring offline), or curtail (limit or regulate to a target output) one or more of the DERs 202. Additionally, or alternatively, the microgrid controller 110 may transmit control signals to one or more switches 213 to control a switch state (e.g., an on state or an off state) of the one or more switches 213, for example, to connect one or more DERs 202 to or disconnect one or more DERs 202 from the microgrid 200 (e.g., the power bus 212). The switches 213 may be integrated in one or both interfaces 116 and 118 described in connection with FIG. 1.

In some cases, two or more power buses 212 may be provided. For example, a power bus may be provided to couple one or more power generators 204 to one or more electric storage devices 208 for charging the one or more electric storage devices 208. For example, the microgrid controller 110 may selectively couple a power generator 204 to an electric storage device 208 to charge the electric storage device 208. Thus, the power bus 212 may be part of a power distribution network of the microgrid 200 that may include one or more power buses used to distribute power between loads and/or DERs 202.

The microgrid 200 may include an interface 216 for connecting the microgrid 200 to and disconnecting the microgrid 200 from an electrical power distribution system 218, such as a macrogrid. The interface 216 may include one or more electrical connections used for connecting the microgrid 200 to the electrical power distribution system 218. The interface 216 may include one or more switches or breakers that are controlled by the microgrid controller 110 for connecting the microgrid 200 to and disconnecting the microgrid 200 from the electrical power distribution system 218. For example, the one or more switches or breakers of the interface 216 may connect the power bus 212 (or another system bus) to or disconnect the power bus 212 (or another system bus) from the electrical power distribution system 218. Thus, the microgrid controller 110 may configure the microgrid 200 to operate in a grid-connected mode by connecting the microgrid 200 to the electrical power distribution system 218 or in a stand-alone mode by disconnecting the microgrid 200 from the electrical power distribution system 218.

FIG. 3 shows a block diagram of a first stage 300 of a control method based on a load stabilization algorithm. The first stage 300 includes calculating the first target load Non_STBL_Load for the non-stabilizing group of energy resource systems 112, and calculating the second target load STBL_Load for the stabilizing group of energy resource systems 114. For example, processing unit 301 may receive the load information corresponding to the loads 108 connected to the microgrid, and calculate the total load of the loads 108 based on the load information. Processing unit 302 may receive the total load and the moving average window setpoint. The moving average window setpoint may be a time interval during which an average of the total load is calculated. The average is calculated on a continuous basis, and therefore may be referred to as a moving average. An operator may know a load period of a cyclic load and configure the moving average window setpoint to be greater than approximately twice the load period of the cyclic load. Processing unit 302 may calculate the first target load Non_STBL_Load for the non-stabilizing group of energy resource systems 112 as the moving average of the total load. Processing unit 302 may include a band pass filter or a low pass filter configured to remove noise from the moving average. The first target load Non_STBL_Load may be subtracted from the total load by processing unit 303 (e.g., a subtractor) to calculate the second target load STBL_Load.

FIG. 4 shows a block diagram of a second stage 400 of a control method based on a load stabilization algorithm. The second stage 400 includes measuring an SOC of the stabilizing group of energy resource systems 114, and calculating a bias power SOCBias to maintain the SOC of the stabilizing group of energy resource systems 114 within a target range. For example, processing unit 401 may monitor (e.g., by measuring) the SOC of the stabilizing group of energy resource systems 114. Processing unit 402 may calculate the bias power SOCBias to maintain the SOC of the stabilizing group of energy resource systems 114 within the target range.

Additionally, processing unit 403 may control one or more DERs to maintain the SOC of the stabilizing group of energy resource systems 114 in the target range. For example, based on the SOC of the stabilizing group of energy resource systems 114 being less than a minimum threshold, processing unit 403 may generate the one or more second control signals to control at least one energy generator system 120 of the non-stabilizing group of energy resource systems 112 to provide the bias power SOCBias to the stabilizing group of energy resource systems 114 in order to increase the SOC of the stabilizing group of energy resource systems 114. Additionally, based on the SOC of the stabilizing group of energy resource systems