System and method for resynchronization of a microgrid with a large power

Abstract

A method for synchronizing a micro-grid with a large grid is provided. The method includes: receiving, by a computing system, a plurality of first sensor measurements from one or more first sensors; receiving, by the computing system, a plurality of second sensor measurements from the one or more second sensors; determining, by the computing system, whether the microgrid is synchronized with the large grid based on the plurality of first sensor measurements and the plurality of second sensor measurements; controlling, by the computing system, one or more energy assets of the microgrid by providing one or more corrective characteristics to the energy assets based on the microgrid being out of synchronization with the large grid; and providing, by the computing system, instructions to the circuit breaker to connect the microgrid to the large power grid based on synchronization of the microgrid with the large power grid.

Description

Technical Field

[0001] The present disclosure relates to resynchronization of an islanded microgrid with a larger power grid. Background Art

[0002] A microgrid is a local power grid with defined electrical boundaries. A microgrid may include electrical components, such as loads and / or energy generating devices that generate electrical energy. In some cases, a microgrid may include operating modes such as an island mode and a connection mode. In the connection mode, the microgrid may be connected to a large power grid (e.g., a city or state power grid). In the island mode, the microgrid may operate as an island (e.g., disconnected from the large power grid). The microgrid and the large power grid may operate under different operating parameters (e.g., different voltages). When switching between the island mode and the connection mode, certain resynchronization processes may be implemented. However, conventional resynchronization processes typically use complex and expensive methods, involve multiple types of equipment, and focus more on fault detection rather than reconnection. Many of these methods do not mention how they comply with the reconnection standards of the Institute of Electrical and Electronics Engineers (IEEE), do not implement the method from the perspective of a dispatchable inverter based on distributed energy resources (DER), and implement complex and computationally expensive power sharing techniques. Therefore, there is still a need for a simple, scalable, and universal resynchronization process for resynchronizing a microgrid with a large energy grid. Summary of the invention

[0003] A first aspect of the present disclosure provides a method for synchronizing a microgrid with a large power grid, the method comprising: receiving, by a computing system, a plurality of first sensor measurement results from one or more first sensors, wherein the plurality of first sensor measurement results indicate a first amplitude, a first frequency, and a first angle measurement result on a microgrid side of a circuit breaker, the circuit breaker electrically connecting the microgrid to the large power grid; receiving, by the computing system, a plurality of second sensor measurement results from one or more second sensors, wherein the plurality of second sensor measurement results indicate a second amplitude, a second frequency, and a second angle measurement result on a large power grid side of the circuit breaker; determining, by the computing system, whether the microgrid is synchronized with the large power grid based on the plurality of first sensor measurement results and the plurality of second sensor measurement results; controlling, by the computing system, one or more energy assets by providing one or more corrective characteristics to one or more energy assets of the microgrid based on the microgrid being out of synchronization with the large power grid; and providing, by the computing system, instructions to the circuit breaker to connect the microgrid to the large power grid based on the synchronization of the microgrid with the large power grid.

[0004] According to an implementation of the first aspect, the method further includes: receiving large-scale grid information indicating a health status of the large-scale grid from a static transfer switch; determining a state of the microgrid, wherein the state indicates whether the microgrid is in a connected state or an island state, and wherein determining whether the microgrid is synchronized with the large-scale grid is also based on the large-scale grid information indicating that the large-scale grid is healthy and the state of the microgrid indicating that the microgrid is in an island state.

[0005] According to an embodiment of the first aspect, the circuit breaker is a point of common coupling (PCC) between a microgrid and a large power grid, wherein one or more first sensors are configured to obtain a plurality of first sensor measurements from one or more wires connecting the microgrid to the circuit breaker, and wherein one or more second sensors are configured to obtain a plurality of second sensor measurements from one or more wires connecting the circuit breaker to the large power grid.

[0006] According to an implementation of the first aspect, determining whether a microgrid is synchronized with a large power grid includes: determining a difference between a first amplitude and a second amplitude, wherein the first amplitude and the second amplitude indicate voltage amplitude measurement results; comparing the difference with one or more thresholds; and determining whether the microgrid is synchronized based on the comparison.

[0007] According to an implementation of the first aspect, determining whether a microgrid is synchronized with a large power grid includes: determining a difference between a first frequency and a second frequency, wherein the first frequency and the second frequency indicate a frequency of a voltage waveform; comparing the difference with one or more thresholds; and determining whether the microgrid is synchronized based on the comparison.

[0008] According to an implementation of the first aspect, determining whether a microgrid is synchronized with a large power grid includes: determining a difference between a first angle and a second angle, wherein the first angle and the second angle indicate a phase angle; comparing the difference with one or more thresholds; and determining whether the microgrid is synchronized based on the comparison.

[0009] According to an embodiment of the first aspect, determining the difference between the first angle and the second angle is based on synchronizing the first amplitude with the second amplitude and synchronizing the first frequency with the second frequency.

[0010] According to an embodiment of the first aspect, the one or more corrective characteristics include a voltage amplitude resynchronization value, wherein the one or more energy assets adjust a voltage amplitude of the microgrid based on the voltage amplitude resynchronization value.

[0011] According to an embodiment of the first aspect, the one or more corrective characteristics include a voltage-frequency resynchronization value, wherein the one or more energy assets adjust a voltage-frequency of the microgrid based on the voltage-frequency resynchronization value.

[0012] According to an embodiment of the first aspect, the one or more corrective characteristics include an angle error, wherein the one or more energy assets adjust a voltage frequency of the microgrid based on the angle error.

[0013] According to an embodiment of the first aspect, providing instructions to the circuit breaker also includes: obtaining multiple subsequent sensor measurement results from one or more first sensors during a waiting time period; determining whether the microgrid is stable during the waiting time period based on comparing the multiple subsequent sensor measurement results with one or more stability thresholds; and based on determining that the microgrid is stable during the waiting time period, providing instructions to the circuit breaker to connect the microgrid to the large power grid.

[0014] According to an embodiment of the first aspect, the method further comprises: receiving, by the computing system, a user input indicating a waiting period of time.

[0015] According to an implementation of the first aspect, multiple first sensor measurement results include a first group of sensor measurement results obtained by one or more first sensors at a first moment and a second group of sensor measurement results obtained by one or more first sensors at a second moment, wherein determining whether the microgrid is synchronized includes: determining whether the microgrid is synchronized with the large power grid at the first moment based on the first group of sensor measurement results; and determining whether the microgrid is synchronized with the large power grid at the second moment based on the second group of sensor measurement results.

[0016] According to an embodiment of the first aspect, controlling one or more energy assets by providing one or more corrective characteristics to one or more energy assets of a microgrid is based on determining that the microgrid is not synchronized with the large power grid at a first moment, and wherein providing instructions to a circuit breaker to connect the microgrid to the large power grid is based on determining that the microgrid is not synchronized with the large power grid at a second moment.

[0017] The second aspect of the present disclosure provides a system for synchronizing a microgrid with a large power grid. The system includes: a computing system including one or more processors; and a non-transitory computer-readable medium having processor-executable instructions stored thereon, wherein the processor-executable instructions are convenient when executed by one or more processors: receiving a plurality of first sensor measurements from one or more first sensors, wherein the plurality of first sensor measurements indicate a first amplitude, a first frequency, and a first angle measurement on the microgrid side of a circuit breaker, the circuit breaker electrically connecting the microgrid to the large power grid; receiving a plurality of second sensor measurements from one or more second sensors, wherein the plurality of second sensor measurements indicate a second amplitude, a second frequency, and a second angle measurement on the large power grid side of the circuit breaker; determining whether the microgrid is synchronized with the large power grid based on the plurality of first sensor measurements and the plurality of second sensor measurements; controlling one or more energy assets by providing one or more corrective characteristics to one or more energy assets of the microgrid based on the microgrid not being synchronized with the large power grid; and providing instructions to the circuit breaker to connect the microgrid to the large power grid based on the synchronization of the microgrid with the large power grid.

[0018] According to an embodiment of the second aspect, the processor executable instructions, when executed by one or more processors, also facilitate: receiving large-scale grid information indicating the health status of the large-scale grid from the static transfer switch; determining the state of the microgrid, wherein the state indicates whether the microgrid is in a connected state or an island state, and wherein determining whether the microgrid is synchronized with the large-scale grid is also based on the large-scale grid information indicating that the large-scale grid is healthy and the state of the microgrid indicating that the microgrid is in an island state.

[0019] According to an embodiment of the second aspect, the circuit breaker is a point of common coupling (PCC) between the microgrid and the large power grid, wherein one or more first sensors are configured to obtain multiple first sensor measurements from one or more wires connecting the microgrid to the circuit breaker, and wherein one or more second sensors are configured to obtain multiple second sensor measurements from one or more wires connecting the circuit breaker to the large power grid.

[0020] According to an implementation of the second aspect, determining whether a microgrid is synchronized with a large power grid includes: determining a difference between a first amplitude and a second amplitude, wherein the first amplitude and the second amplitude indicate voltage amplitude measurement results; comparing the difference with one or more thresholds; and determining whether the microgrid is synchronized based on the comparison.

[0021] According to an implementation of the second aspect, determining whether a microgrid is synchronized with a large power grid includes: determining a difference between a first frequency and a second frequency, wherein the first frequency and the second frequency indicate a frequency of a voltage waveform; comparing the difference with one or more thresholds; and determining whether the microgrid is synchronized based on the comparison.

[0022] A third aspect of the present disclosure provides a non-transitory computer-readable medium having processor executable instructions stored thereon. The processor executable instructions, when executed by one or more controllers, facilitate: receiving a plurality of first sensor measurements from one or more first sensors, wherein the plurality of first sensor measurements indicate a first amplitude, a first frequency, and a first angle measurement on a microgrid side of a circuit breaker, the circuit breaker electrically connecting the microgrid to a large grid; receiving a plurality of second sensor measurements from one or more second sensors, wherein the plurality of second sensor measurements indicate a second amplitude, a second frequency, and a second angle measurement on a large grid side of the circuit breaker; determining whether the microgrid is synchronized with the large grid based on the plurality of first sensor measurements and the plurality of second sensor measurements; controlling one or more energy assets by providing one or more corrective characteristics to one or more energy assets of the microgrid based on the microgrid not being synchronized with the large grid; and providing instructions to the circuit breaker to connect the microgrid to the large grid based on the microgrid being synchronized with the large grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The following will describe the embodiments of the present disclosure in more detail based on the example diagrams. The present disclosure is not limited to the exemplary embodiments. In the embodiments of the present disclosure, all features described and / or illustrated herein may be used alone or in different combinations. The features and advantages of various embodiments of the present disclosure will become apparent by reading the following detailed description with reference to the accompanying drawings, which illustrate the following:

[0024] Figure 1 illustrates a simplified block diagram depicting an exemplary environment for resynchronizing a microgrid with a larger grid in accordance with one or more examples of the present disclosure;

[0025] Figure 2 Pictured Figure 1 A simplified block diagram of one or more devices or systems within an exemplary environment;

[0026] Figure 3 illustrates a simplified block diagram depicting another exemplary environment for resynchronizing a microgrid with a larger grid in accordance with one or more examples of the present disclosure;

[0027] Figure 4 illustrates a process for resynchronizing a microgrid with a larger grid according to one or more examples of the present disclosure;

[0028] Figure 5 depicts an exemplary input / output diagram for resynchronizing a microgrid with a larger grid according to one or more examples of the present disclosure;

[0029] Figure 6 illustrates another process for resynchronizing a microgrid with a larger grid according to one or more examples of the present disclosure; and

[0030] Figures 7 to 10 Another process for resynchronizing a microgrid with a larger grid according to one or more examples of the present disclosure is illustrated. DETAILED DESCRIPTION

[0031] Exemplary aspects of the present disclosure are further described below in conjunction with exemplary embodiments, as shown in the figures. The exemplary embodiments illustrate some embodiments of the present disclosure and are not intended to limit the scope of the present disclosure. In all figures, the same reference numerals represent similar but not necessarily identical elements. The figures are not necessarily drawn to scale, and the sizes of some parts may be exaggerated to more clearly illustrate the examples shown. In addition, the figures provide examples and / or embodiments consistent with the description; however, the description is not limited to the examples and / or embodiments provided in the figures.

[0032] Where possible, any term expressed in the singular form herein is also intended to include the plural form, and vice versa, unless otherwise expressly stated. In addition, as used herein, the terms "a" and / or "an" will mean "one or more", even if the phrase "one or more" is also used herein. In addition, when it is said herein that something is "based on" another thing, it can also be based on one or more other things. In other words, "based on" as used herein means "based at least in part on" or "based at least in part on", unless expressly stated otherwise.

[0033] The present disclosure describes a system and method for resynchronizing a microgrid with a large power grid. For example, in some examples, the present disclosure describes a power management method for dispatchable DER, which is used for resynchronizing an islanded microgrid with a large power grid. For example, the present disclosure provides a system and method for controlling an islanded microgrid by calibrating a PCC waveform with a waveform of a large power grid. This is achieved by simultaneously controlling the dispatchable DER in the island in terms of frequency and voltage. In some cases, the present disclosure provides built-in voltage drop compensation control, which generalizes the method and makes it applicable to a wider range of island operating conditions and has faster resynchronization capabilities. In some cases, the present disclosure does not use complex measurement equipment, such as synchronous phasors. Instead, in such cases, the present disclosure uses simple voltage angle, amplitude and frequency measurement units / sensors on either side of the interconnected circuit breaker.

[0034] In some variations, the present disclosure provides a simple, scalable and general size-based power sharing method designed based on the IEEE 1547 standard for resynchronization of DER-based islanded microgrids with the larger grid. The present disclosure uses an algorithm that takes the difference between the common coupling point (PCC) side and the grid side waveform parameters (such as frequency, angle and amplitude) and issues voltage and frequency control set points for the DER-based grid-forming inverters in the island so that the error between the PCC and grid side frequency, angle and amplitude is minimized. Additionally, and / or alternatively, the algorithm also checks whether these parameters are within an acceptable resynchronization tolerance. If these conditions persist for a user-defined "enter service" waiting period, the algorithm commands the PCC circuit breaker to close and reestablish connection to the larger grid, while commanding the DER inverters to change from grid-forming mode to grid-following mode control.

[0035] Figure 1 A simplified block diagram depicting an exemplary environment for resynchronizing a microgrid with a large grid is illustrated according to one or more examples of the present disclosure. Figure 1 , environment 100 can be a power system or any other type of system including an electrical grid. The electrical grid can include a main grid (e.g., a large electrical grid) and one or more microgrids. A microgrid can be and / or include a group of electrical devices. For example, a microgrid can have electrical boundaries of low-voltage distributed energy resources (DER) and loads that can operate in a controlled, coordinated manner. A microgrid can operate in a connected mode (e.g., a mode in which the microgrid is connected to a large electrical grid and controlled as a single power source from the perspective of the large electrical grid) and an island mode (e.g., a mode in which the microgrid is disconnected from the large electrical grid).

[0036] The microgrid can be connected to the large grid via one or more circuit breakers. For example, the circuit breaker can be used to control whether the microgrid operates in a connected mode or an island mode (e.g., whether the microgrid is connected to the large grid). The circuit breaker can be part of and / or associated with a PCC between the microgrid and the large grid. In some cases, the circuit breaker can be a SACE EMAX 2 circuit breaker.

[0037] Entities within the environment 100 may communicate with other systems within the environment 100 via a network 106. The network 106 may be a global area network (GAN) such as the Internet, a wide area network (WAN), a local area network (LAN), or any other type of network or combination of networks. The network 106 may provide wired, wireless, or a combination of wired and wireless communications between entities within the environment 100. For example, the first sensor 102 and the second sensor 104 may be connected to the resynchronization computing system 110 via a wired connection and / or a wireless connection.

[0038] The first sensor 102 and the second sensor 104 include one or more sensors configured to provide sensor information to the resynchronization computing system 110. For example, the first sensor 102 may be located or positioned between the microgrid and the circuit breaker. The first sensor 102 may provide a first sensor measurement indicating an electrical characteristic on the microgrid side. The second sensor 104 may be located or positioned between the circuit breaker and the large power grid. The second sensor 104 may provide a second sensor measurement indicating an electrical characteristic on the large power grid side. The electrical characteristic indicated by the sensor measurements of the first sensor 102 and the second sensor 104 may be any type of electrical characteristic, including voltage, frequency, angle, and / or other types of electrical characteristics. In some examples, the first sensor 102 and the second sensor 104 may be a voltage and / or frequency sensor configured to measure voltage and frequency and provide it to the resynchronization computing system 110. In some variations, the first sensor 102 and / or the second sensor 104 may not include a smart relay and / or a synchronized phasor device.

[0039] The resynchronization computing system 110 ("computing system 110") is a computing system that includes one or more computing devices, computing platforms, systems, servers, and / or other devices capable of performing tasks, functions, and / or other actions for the environment 100. In particular, the computing system 110 can communicate with the first sensor 102 and the second sensor 104 and the microgrid energy asset 108. For example, the computing system 110 can receive sensor measurements from the first sensor 102 and the second sensor 104. Based on these measurements, the computing system 110 can determine a correction characteristic, such as voltage resynchronization, frequency resynchronization, angle resynchronization, and / or other types of electrical characteristics. The computing system 110 can provide the correction characteristic to the microgrid energy asset 108. Based on the correction characteristic, the microgrid energy asset 108 can absorb and / or provide energy (e.g., power) to the microgrid power system. Based on the absorption of energy or the provision of energy, the computing system 110 can determine to switch the microgrid from an island mode to a connected mode. This will be explained in further detail below.

[0040] In some variations, computing system 110 may be implemented using one or more computing platforms, devices, servers, and / or apparatuses. In other variations, computing system 110 may be implemented as an engine, software function, and / or application. In other words, the functionality of computing system 110 may be implemented as software instructions stored in a memory (e.g., a memory) and executed by one or more processors.

[0041] In some examples, computing system 110 may be a computing device associated with a microgrid. For example, computing system 110 may be a computing device located within a microgrid and configured to control one or more functions of the microgrid. In other examples, computing system 110 may be a computing device associated with a circuit breaker. For example, a circuit breaker may include and / or be associated with computing device 110, which is configured to control the circuit breaker and / or the microgrid. In other examples, computing system 110 may be a cloud computing system that controls one or more microgrids and / or a large power grid.

[0042] The microgrid energy assets 108 may be and / or include one or more energy assets of the microgrid. For example, the energy assets 108 may include and / or be distributed energy resources (DER), such as renewable energy and / or batteries (e.g., battery energy storage systems (BESS)). Additionally, and / or alternatively, the energy assets 108 may be and / or include plants (e.g., power plants and / or virtual power plants (VPPs)) and / or other types of energy assets 108 that are configured to generate energy / power for the microgrid and / or absorb energy / power from the microgrid. The VPP may be an aggregated system of energy assets controlled by a software-based platform.

[0043] It should be understood that Figure 1 The exemplary environment depicted in is only an example, and the principles described herein may also be applicable to other environments.

[0044] Figure 21 is a block diagram of an exemplary system and / or device 200 (e.g., computing system 110) within environment 100. Device / system 200 includes a processor 204, such as a central processing unit (CPU), controller and / or logic, which executes computer-executable instructions to implement the functions, processes and / or methods described herein. In some examples, the computer-executable instructions are stored locally and accessed from a non-transitory computer-readable medium, such as storage 210, which can be a hard drive or flash drive. Read-only memory (ROM) 206 includes computer-executable instructions for initializing processor 204, while random access memory (RAM) 208 is main memory for loading and processing instructions executed by processor 204. Network interface 212 can be connected to a wired network or a cellular network, as well as a local area network or a wide area network, such as network 106. Device / system 200 can also include a bus 202 that connects processor 204, ROM 206, RAM 208, storage 210 and / or network interface 212. Components within device / system 200 may communicate with each other using bus 202. The components within device / system 200 are merely exemplary and may not include every component, server, device, computing platform, and / or computing device within device / system 200.

[0045] Figure 3 A simplified block diagram is illustrated that depicts another exemplary environment for resynchronizing a microgrid with a large power grid according to one or more examples of the present disclosure. For example, environment 300 can be an exemplary power grid or power system. Environment 300 can be similar to environment 100, but additional components such as microgrid 302, large power grid 310, circuit breaker 306, and other components are also shown.

[0046] For example, environment 300 includes microgrid 302. Microgrid 302 can be a power grid including microgrid energy assets 108 and loads 304 as described above. Loads 304 can include commercial loads, industrial loads, and / or other types of loads that are configured to use electrical energy. Microgrid energy assets 108 can be configured to provide energy (e.g., power) to microgrid 302 and / or absorb energy from microgrid 302. For example, microgrid energy assets 108 can include DERs such as BESS and / or renewable energy sources. Microgrid 302 also includes computing system 110. As described above, environment 300 is merely exemplary, and in other examples, computing system 110 can be located outside microgrid 302 (e.g., computing system 110 can be coupled to circuit breaker 306 and / or can be a cloud computing system located in the cloud).

[0047] The microgrid 302 is connected to the large grid 310 via a circuit breaker 306 and a static transfer switch (STS) 308. The circuit breaker 306 can be any type of circuit breaker configured to connect the microgrid 302 to the large grid 310 and / or disconnect it from the large grid 310. For example, the circuit breaker 306 can be a SACE EMAX 2 circuit breaker. The STS 308 is a device that switches between power sources. The first sensor 102 is located on the microgrid side (e.g., between the microgrid 302 and the circuit breaker 306). The second sensor 104 is located on the large grid side (e.g., between the circuit breaker 306 and the large grid 310).

[0048] The computing system 110 may communicate with one or more devices within the environment 300 , such as the microgrid energy assets 108 , the first sensor 102 , the second sensor 104 , the circuit breaker 306 , the STS 308 , and / or other devices / components.

[0049] It should be understood that Figure 3 The exemplary environment depicted in is only an example, and the principles described herein may also be applicable to other environments. For example, a large power grid 310 may be associated with multiple microgrids 302. Multiple microgrids 302 may be associated with multiple circuit breakers 306, first sensors 102, and second sensors 104. In operation, multiple microgrids 302 may operate in an island mode or a connected mode.

[0050] Figure 4 4 illustrates a process for resynchronizing a microgrid with a large grid according to one or more examples of the present disclosure. Process 400 may be performed by Figure 1 and / or Figure 3 4. However, it should be appreciated that any of the following blocks may be performed in any suitable order, and process 400 may be performed in any suitable environment and by any suitable device and / or system.

[0051] In operation, at block 402, computing system 110 receives a plurality of first sensor measurements from one or more first sensors 102. The plurality of first sensor measurements indicate amplitude, frequency, and angle measurements (e.g., first amplitude, first frequency, and first angle measurements) on a microgrid side of a circuit breaker (e.g., circuit breaker 306) that electrically connects a microgrid (e.g., microgrid 302) to a larger grid (e.g., larger grid 310). For example, Figure 3As shown, the computing system 110 can communicate with the first sensor 102. The first sensor 102 can obtain electrical characteristics (e.g., electrical characteristics associated with one or more wires between the microgrid 302 and the circuit breaker 306) from the microgrid side of the circuit breaker 306. The electrical characteristics may include voltage measurements, such as voltage amplitude, frequency, and / or angle measurements (e.g., phase angle measurements). For example, in some variations, the first sensor 102 may include a sensor configured to measure the voltage amplitude of the wires between the microgrid 302 and the circuit breaker 306. Additionally, and / or alternatively, the first sensor 102 may measure the frequency of these wires (e.g., the oscillation rate of the voltage signal). For example, the microgrid 302 may use alternating current (AC) (e.g., three-phase AC power) that circulates at regular intervals (e.g., frequency). In order to connect the microgrid 302 to the large power grid 310, the computing system 110 may seek to synchronize the waveform or signal (e.g., the amplitude and frequency of the voltage waveform) of the microgrid 302 with the waveform of the large power grid 310. For example, when operating in island mode, the microgrid 302 may operate at a different voltage waveform than the waveform from the large grid 310. In order to synchronize with the large grid 310, the microgrid 302 may seek to match or substantially match the waveform of the microgrid 302 with the waveform of the large grid 310. Therefore, at block 402, the first sensor 102 may be configured to obtain measurements of the waveform of the microgrid 302, such as the amplitude and / or frequency of the waveform (e.g., the voltage amplitude and / or frequency of the voltage waveform). In addition, the first sensor 102 may be configured to obtain the phase angle of the microgrid 302 (e.g., the lag or lead between the voltage and / or current waveforms of the microgrid 302). The first sensor 102 may provide these measurements to the computing system 110.

[0052] At block 404, computing system 110 receives a plurality of second measurements from one or more second sensors 104. The plurality of second measurements indicate magnitude, frequency, and angle measurements (e.g., second magnitude, second frequency, and second angle measurements) on the bulk grid side of a circuit breaker (e.g., circuit breaker 306). Figure 3 , the second sensor 104 can measure the electrical characteristics of the wires between the circuit breaker 306 and the large power grid 310. In some cases, the second sensor 104 can measure the electrical characteristics between the circuit breaker 306 and the STS 308. The electrical characteristics can indicate the magnitude, frequency, and / or angle (e.g., phase angle) measurement results associated with the large power grid 310. For example, the electrical characteristics can indicate the voltage magnitude, frequency, and / or phase angle of the voltage signal of the large power grid 310. The second sensor 104 can provide these measurements to the computing system 110.

[0053] At block 406, the computing system 110 determines whether the microgrid (e.g., microgrid 302) is synchronized with the large power grid (e.g., power grid 310) based on the plurality of first sensor measurements and the plurality of second sensor measurements. For example, the computing system 110 may compare one or more measurements from the first sensor measurements with one or more measurements from the second sensor measurements. For example, the computing system 110 may compare the voltage amplitudes of the first sensor measurements and the second sensor measurements to determine whether the microgrid is synchronized. For example, the computing system 110 may determine the difference between the voltage amplitudes of the first sensor measurements and the second sensor measurements. The computing system 110 may also compare the difference with one or more thresholds (e.g., zero, substantially zero, or different values), such as a voltage amplitude threshold. Based on the comparison, the computing system 110 may determine whether the microgrid 302 is synchronized with the large power grid 310. For example, based on the difference being below the threshold, the computing system 110 may determine that the microgrid 302 is synchronized. Based on the difference being above the threshold, the computing system 110 may determine that the microgrid 302 is not synchronized.

[0054] Additionally, and / or alternatively, the computing system 110 may compare the frequency and / or angle of the first sensor measurement and the second sensor measurement. For example, the computing system 110 may compare the difference between the frequency and / or angle of the first sensor measurement and the second sensor measurement to one or more thresholds (e.g., frequency and / or angle thresholds). Based on the comparison, the computing system 110 may determine whether the microgrid 302 is synchronized. For example, based on all three differences in amplitude, frequency, and angle being below a threshold, the computing system 110 may determine that the microgrid 302 is synchronized. Otherwise, the computing system 110 may determine that the microgrid 302 is not synchronized.

[0055] In other words, the computing system 110 compares the electrical characteristic measurements (e.g., voltage amplitude, frequency, and angle) from either side of the circuit breaker 308. The microgrid side indicates the electrical characteristic measurements of the microgrid 302, and the large grid side indicates the electrical characteristic measurements of the large grid 310. The computing system 110 can determine the difference between the two sides (e.g., the microgrid side and the large grid side). Based on the difference substantially reaching zero and / or being below a threshold, the computing system 110 can determine that the microgrid 302 is synchronized with the large grid 310 (e.g., based on the voltage amplitude, frequency, and / or angle of the microgrid matching or nearly matching the voltage amplitude, frequency, and / or angle of the large grid 310, the computing system 110 can determine that the microgrid 302 is synchronized with the large grid 310).

[0056] At block 408, based on the microgrid being out of sync with the larger grid, the computing system 110 controls one or more energy assets (e.g., the microgrid energy assets 108) by providing one or more corrective characteristics to the energy assets. For example, the computing system 110 may provide information indicating the corrective characteristics to the energy assets 108. For example, as described above, the energy assets 108 may include DERs, renewable energy sources, BESSs, and / or other types of energy assets. The energy assets 108 may seek to follow the microgrid waveform (e.g., voltage magnitude, frequency, and / or angle associated with the microgrid 302). The computing system 110 may provide corrective characteristics to the energy assets 108, such as voltage resynchronization (e.g., voltage resynchronization magnitude), frequency resynchronization (e.g., frequency resynchronization value), and / or angle error. Based on providing the corrective characteristics, the energy assets 108 may adjust their energy production and / or absorption. For example, the energy assets 108 may be and / or include one or more BESSs. Based on the corrective characteristics, the BESSs may provide energy to the microgrid 302 and / or absorb energy from the microgrid 302. By providing and / or absorbing energy, the BESS can change the waveform of the microgrid 302. For example, the correction characteristic can indicate voltage resynchronization. Based on the voltage resynchronization, the BESS can provide additional energy to the microgrid 302 to change the voltage waveform, thereby reducing or increasing the amplitude of the voltage waveform. By reducing or increasing the amplitude of the voltage waveform, the first sensor 102 can obtain new sensor measurements that are closer to and / or synchronized with the voltage amplitude of the large power grid 310. Additionally, and / or alternatively, the computing system 110 can provide correction characteristics, such as frequency resynchronization and / or angle error. The BESS can change the frequency and / or angle of the waveform of the microgrid 302 to align them with the frequency and / or angle of the waveform from the large power grid 310. Additionally, and / or alternatively, the energy assets 108 can include DERs such as renewable energy sources. The renewable energy sources can change the power they provide to the microgrid 302 based on the correction characteristics. For example, the renewable energy source may generate additional and / or reduced power based on voltage resynchronization from computing system 110 and / or may change the frequency and / or angle of the generated power based on frequency resynchronization and / or angle error.

[0057] In some cases, blocks 402, 404, 406, and / or 408 may be repeated one or more times. For example, based on the microgrid being out of sync, the computing system 110 may provide a correction characteristic. The energy asset 108 may adjust and / or change the waveform of the microgrid 302 based on the correction characteristic (e.g., increase or decrease the amplitude of the voltage waveform). In the next iteration, the computing system 110 may receive a new first sensor measurement (e.g., an updated sensor measurement) indicating a new amplitude, frequency, and angle measurement on the microgrid side of the circuit breaker. The computing system 110 may compare the new first sensor measurement with the second sensor measurement (e.g., the original second sensor measurement or an additional / new second sensor measurement obtained after providing the correction characteristic). Based on the comparison, the computing system 110 may determine whether the microgrid is synchronized. If the microgrid is out of sync, the computing system 110 may determine and provide one or more new correction characteristics to the energy asset. Then, blocks 402, 404, 406, and / or 408 may be repeated until the microgrid is synchronized.

[0058] At block 410, based on the synchronization of the microgrid with the large grid, the computing system 110 provides instructions to the circuit breaker to connect the microgrid to the large grid. In this way, the microgrid can be changed from the island mode to the connection mode. In other words, the circuit breaker can complete the circuit so that the microgrid 302 is connected to the large grid 310 based on the instructions from the computing system 110.

[0059] In some cases, the computing system 110 may determine whether the microgrid side is stable before providing instructions. For example, the computing system 110 may determine a waiting period such as 300 seconds (e.g., a user-defined and / or predefined waiting period). After the waiting period has passed, the computing system 110 may provide instructions to the circuit breaker 306. The computing system 110 may obtain one or more sensor measurements (e.g., obtained from the first sensor 102) during the waiting period (e.g., obtain subsequent sensor measurements). Using the subsequent sensor measurements, the computing system 110 may determine whether the microgrid amplitude, frequency, and angle are stable (e.g., compare them to one or more stability thresholds). For example, if these measurements change, the process 400 may be repeated so that the microgrid 302 is not connected to the large power grid 310 at that time. After the waiting period has passed (e.g., after 300 seconds), the computing system 110 may provide instructions to the circuit breaker to connect the microgrid 302 to the large power grid 310. The process 400 will be described in further detail below.

[0060] Figure 5An exemplary input / output map 500 for resynchronizing a microgrid with a large grid according to one or more examples of the present disclosure is depicted. For example, the input / output map 500 includes a resynchronization function 502, which can be performed by the computing system 110 and / or one or more systems. For example, the process 400 can be part of and / or associated with the resynchronization function 502. The resynchronization function 502 can include inputs such as a microgrid connection state 504, a grid health state 506, a grid side voltage 508, a grid frequency 510, a grid side angle 512, a user-defined entry service period 514, a PCC voltage 516, a PCC frequency 518, and a PCC angle 520. For example, the computing system 110 can obtain the inputs 504-520. Based on the inputs 504-520, the resynchronization function 502 can provide outputs such as a voltage reference 522, a voltage selection 524, a frequency selection 526, a frequency reference 528, and an EMAX 2CB closing command 530.

[0061] The resynchronization function 502 can be associated with a simulation time step Ts (e.g., 50 microseconds (μs)). The microgrid connection state 504 can indicate whether the microgrid 302 is connected to the large grid 310. For example, if the microgrid is operating in an island mode, the microgrid connection state 504 (e.g., "MI") can indicate "1", and if the microgrid is operating in a connected mode, it can indicate "0". The grid health state 506 (e.g., "STS") can indicate the STS grid state, such as "1" if the large grid 310 is healthy, and "0" if the large grid 310 is unhealthy. The grid side voltage 508 ("V g ”) indicates the voltage at the microgrid circuit breaker 306 on the grid side (eg, the large grid side). The PCC voltage 516 (“V pcc ”) indicates the microgrid-side PCC voltage at circuit breaker 306. In other words, PCC voltage 516 indicates the voltage on the microgrid side of circuit breaker 306, and grid-side voltage 508 indicates the voltage on the large grid side of circuit breaker 306. Computing system 110 may determine the difference “ΔV” between these two voltages, which is equal to V g –V pcc Grid frequency 510 (“ω g ”) indicates the frequency on the grid side of the circuit breaker 306 (eg, the frequency on the large grid side of the circuit breaker 306). The PCC frequency 518 (“ω pcc ”) indicates the frequency on the microgrid side of the circuit breaker 306. The computing system 110 may determine the difference “Δω” between the two frequencies, which may be equal to ω g –ω pcc Grid side angle 512 (“δ g”) indicates the grid-side angle of the circuit breaker 306 (eg, the angle at the large grid side of the circuit breaker 306). The PCC angle 520 (“δ pcc ”) indicates the microgrid side angle of the circuit breaker 306. The computing system 110 may determine the difference “Δδ” between the two angles, which may be equal to δ g –δ pcc .

[0062] Based on inputs 504-520, computing system 110 may use resynchronization function 502 to determine outputs 522-530. Voltage reference (“V ref ”) can indicate the voltage reference. The frequency reference (“ω ref ”) can indicate a frequency reference. The voltage reference and frequency reference can be based on the voltage and frequency resynchronization described above. Voltage selection 524 can be a voltage selection that allows the microgrid to track the nominal voltage (e.g., 1 per unit (pu)) or to track the large grid voltage (V g ) and the frequency selection 526 may be a switching signal that allows the microgrid to track the nominal frequency (60 Hertz (Hz)) or to track the large grid frequency (ω g ) The EMAX2 CB close command 530 may indicate a command to close the circuit breaker 306 (eg, to change the microgrid 302 from an island mode to a connected mode in order to connect it to the large grid 310).

[0063] Figure 6 Another process for resynchronizing a microgrid with a large grid according to one or more examples of the present disclosure is illustrated. Process 600 may be performed by Figure 1 and / or Figure 3 6. However, it should be appreciated that any of the following blocks may be performed in any suitable order, and that process 600 may be performed in any suitable environment and by any suitable device and / or system.

[0064] In operation, at block 602 , the computing system 110 may initialize a count (eg, count=0) and initialize Ts (eg, Ts=50 microseconds).

[0065] At block 604 , the computing system 110 accepts the MI state, the STS state, and / or obtains / determines differences (eg, ΔV, Δω, and Δδ). Initially, the computing system 110 may not obtain differences, but after a first iteration, the computing system 110 may obtain differences.

[0066] At box 606, the computing system 110 determines whether MI is 1 and whether STS is 1. If so, the process 600 moves to box 610. If not, the process 600 moves to box 608. For example, MI=1 and STS=1 indicate that the large grid 310 is healthy and the microgrid 302 is operating in island mode. If either is 0 (e.g., the large grid 310 is unhealthy and the microgrid 302 is operating in connected mode), the process 600 proceeds to 608 and repeats. For example, the computing system 110 provides an initial voltage V0 and an initial frequency ω0 to the energy asset. At box 608, the energy asset 608 continues to operate normally based on the initial voltage and initial frequency.

[0067] At block 610, the computing system 110 continues resynchronization. In particular, the computing system 110 begins with voltage amplitude and frequency calibration. For example, the computing system 110 may perform blocks 402, 404, 406, and / or 408 for voltage amplitude and frequency calibration. For example, the computing system 110 may compare the voltage amplitude and frequency between the first sensor 102 and the second sensor 104 to determine the difference therebetween. The computing system 110 may determine that they are out of sync and provide the energy asset 108 with information such as corrective properties (e.g., voltage resynchronization (V resynch ) and frequency resynchronization (ω resynch )) of the resync value (resync value). Then, at block 608, the energy asset 108 may determine a voltage and frequency reference (e.g., reference value) based on the correction characteristics (e.g., voltage resync and frequency resync). The process 600 may be repeated until they are resynchronized. In some cases, the frequency resync may be equal to the frequency difference (e.g., Δω f ).

[0068] At block 612, after the voltage amplitude and frequency are synchronized, the computing system 110 checks the voltage amplitude and frequency errors to perform a voltage angle calibration. For example, the computing system 110 may continuously perform certain checks. Initially, the computing system 110 checks to ensure that the voltage amplitude and frequency are synchronized. Then, the computing system 110 performs a resynchronization of the voltage angle. For example, at block 620, the computing system 110 checks whether the voltage difference and the frequency difference are substantially close to zero. If not, the computing system 110 similarly proceeds to block 608 and provides correction features, such as voltage resynchronization and frequency resynchronization. In some cases, the frequency resynchronization may be equal to the frequency difference (e.g., Δω). f ).

[0069] If so, computing system 110 provides corrective features, such as voltage resynchronization and frequency resynchronization. In some cases, frequency resynchronization can be equal to the frequency difference (eg, Δω f ) plus the frequency component difference of the angle calibration (e.g., “Δω δ”). For example, reynch =Δω f +Δω δ In other words, in order to align the microgrid with the larger grid in terms of frequency, the frequency at which the microgrid must operate (ω reynch ) is equal to the frequency component required for frequency calibration (Δω f ) plus the frequency component (Δωδ) required for angle calibration.

[0070] At block 614, the computing system 110 determines whether the difference in voltage magnitude, frequency, and angle is substantially equal to zero. If not, the process 600 moves to block 608. For example, if any of the voltage, frequency, or angle is not equal to zero, the process 600 may provide additional corrective features to the energy asset 108. Then, at block 608, the energy asset 108 may adjust the voltage, frequency, and / or angle. The process 600 is then repeated, and steps 602-614 and 620 may be re-performed. If yes, the process 600 moves to block 616.

[0071] In other words, at blocks 602-614 and 620, the computing system 110 may perform resynchronization by checking the differences between the voltage magnitude, frequency, and angle. Based on these differences, the computing system 110 may provide correction characteristics, such as voltage and frequency resynchronization (e.g., resync value) and / or angle error. The energy asset 108 may determine a reference, such as a voltage and / or frequency reference, and adjust the waveform of the microgrid accordingly. Thereafter, the process 600 may be repeated and new measurements may be obtained. After the voltage, frequency, and angle differences are substantially zero (e.g., they are synchronized), the process 600 moves to block 616.

[0072] At block 616, the computing system 110 enters service, updates the count to count+1, determines the waiting period to count*Ts, and checks the waiting period. As described above, the computing system 110 can check the stability of the microgrid (e.g., the difference between the voltage, frequency, and angle is substantially 0 for an extended period of time such as 300 seconds).

[0073] At block 618, computing system 110 checks whether the wait time period is greater than 300. If so, computing system 110 sends a command signal (e.g., for circuit breaker 306 to close), such as an EMAX2 CB closed signal, and process 600 ends. If not, computing system 110 may move back to block 608 and re-implement process 600. For example, computing system 110 may provide a command signal such as an EMAX 2CB open.

[0074] In other words, depending on the status checks performed by process 600 on microgrid connectivity, grid health, ΔV, Δω, and Δδ, computing system 110 switches the voltage and frequency references of the DER integrated control based on the corrective characteristics.

[0075] Referring to process 600, blocks 602-620 may be performed multiple times. For example, initially, computing system 110 determines the health of the grid and current DER operating conditions. Then, computing system 110 may perform code execution for differences in voltage and frequency and angle control, and perform data collection. Next, computing system 110 may perform control execution for cascade control on DER. Then, this may be repeated, computing system 110 determines the health of the grid and current DER operating conditions. Then, computing system 110 may perform code execution for differences in voltage frequency and angle control, and perform data collection. Next, computing system 110 may perform control execution for cascade control on DER. In addition, computing system 110 may again determine the health of the grid and current DER operating conditions. Based on the resynchronization condition being met, computing system 110 may resynchronize the condition to meet control and data collection, and enter service and intentional delay (e.g., 0-300 seconds). Then, computing system 110 may perform EMAX 2 breaker closing (e.g., commanding the breaker to close). Subsequently, computing system 110 may resynchronize conditions to meet control and data acquisition, and enter service with an intentional delay (eg, 300-600 seconds).

[0076] In some cases, the computing system 110 adds P-ω and QV droops by additional active and reactive power set points that are responsible for calibrating the waveforms during the resynchronization process. For example, P-ω and QV droops refer to conventional P (active power)-ω (frequency) droop control loops and Q (reactive power)-V (voltage) droop control loops, such as Figure 8 As shown. This enables multiple DERs to share control set points, driving the microgrid to synchronize with the large grid. First, the computing system 110 checks the connection status of the microgrid and the health of the STS grid. If it is found that the grid is in a healthy (normal) state and the microgrid is in an isolated state, the computing system 110 initiates the resynchronization process. Otherwise, it will continue to check the above states until they change to true.

[0077] Second, the computing system 110 aims to minimize ΔV and Δω so that they are within the IEEE-1547-2018-4.10.4 parameter limits.

[0078] Third, the computing system 110 ensures that ΔV and Δω are within parameter limits and then performs Δδ control.

[0079] Once ΔV, Δω, and Δδ are all minimized, the computing system 110 initiates the entry service period. Here, the ramp rate limit specified by IEEE-1547-2018-4.10.3 is used to control the microgrid power. If the entry service waiting period exceeds the user-defined waiting period (e.g., 300 seconds), the computing system 110 closes the circuit breaker. Otherwise, the circuit breaker remains open. Once the circuit breaker is closed, DER control switches back to the grid following mode. In some cases, the entry service ramp rate limit continues to be implemented for 300 seconds after the circuit breaker is closed.

[0080] In some variations, in the island state, the dispatchable DERs (e.g., energy assets 108) operate in a grid forming mode, where they are responsible for maintaining the island voltage and frequency at nominal values ​​per unit (pu) 1. The computing system 110 uses the resynchronization function 520 to check the grid health status through the STS, and when it finds that the grid is healthy, it initiates the resynchronization process. The computing system 110 uses a voltage drop compensation loop based on proportional integral (PI) control for forming mode voltage control. Voltage amplitude calibration uses this loop implementation. This enables tracking of the PCC voltage amplitude after compensating for any voltage drop in the microgrid.

[0081] The goal of resynchronization is to align the PCC voltage waveform in amplitude, frequency and phase with respect to the bulk grid. After resynchronization is started, voltage amplitude alignment and frequency alignment are achieved. The accuracy and success of these alignments are defined by the acceptable tolerance band parameters.

[0082] Once the amplitude and frequency are aligned, phase alignment is performed by activating voltage angle alignment. In this sequence, the dispatchable DER frequency is changed in such a way that the grid angle δ g Angle δ with PCC pcc This is achieved through PI control, which generates an additional frequency setpoint (Δω δ ). After all PCC waveform parameters of the voltage (e.g., amplitude, frequency, and phase) are calibrated and within the tolerance band, the computing system 110 implements the next sequence in the algorithm (e.g., entry into service check and breaker closing). The entry into service specification is defined as an intentional delay (0 to 600 seconds) when the microgrid steady-state voltage and frequency are within the specified range. After the entry into service waiting period ends, the resynchronization process ends, where the PCC breaker is closed and the dispatchable DER control switches to the following mode. At this stage, with the closing of the PCC breaker, the microgrid enters the grid connection mode. This will be described in further detail below.

[0083] Figures 7 to 10Another process 700-1000 for resynchronizing a microgrid with a large grid according to one or more examples of the present disclosure is illustrated. During the island state, the distributed energy resources (DER) operate in a grid forming mode, where they are responsible for maintaining the island voltage and frequency at a nominal value of 1 p.u. The computing system (e.g., the resynchronization computing system 110) can use the resynchronization function to check the grid health status through the static transfer switch (STS), and when it finds that the grid is healthy, it starts the resynchronization process. Under the grid connection condition, the resynchronization process is disabled. Figure 7 The PCC connection status for enabling the resynchronization function is shown. For example, Figure 7 The resynchronization initiation function performed by the computing system is shown. The computing system can use the PCC breaker status and the STS grid check to determine whether to initiate resynchronization between the microgrid and the large grid.

[0084] refer to Figure 8 Once the resynchronization function is enabled, the voltage calibration sequence 802 and the frequency calibration sequence 804 are enabled simultaneously. For example, the computing system can execute the voltage and frequency calibration sequences 802 and 804. In some examples, a voltage control loop forming a power grid is used to track the power grid voltage V g , rather than the nominal voltage V0. In some cases, the forming control mode only tracks the voltage and frequency reference at its DER inverter terminals. Therefore, any voltage drop between the inverter terminals and the PCC must be taken into account. This is achieved by adding a voltage drop compensation loop based on proportional integral (PI) control to the forming mode voltage control. The voltage magnitude calibration sequence 802 is Figure 8 This enables the computing system to track the PCC voltage magnitude after compensating for any voltage drop in the microgrid. Qset and Qout are the reactive power setpoint and output values ​​of the DER in grid forming mode. The reactive power-voltage droop loop generates a ΔVdroop voltage regulation that the DER must track. The grid forming frequency control loop 804 is given a reference grid frequency ω g , rather than the nominal frequency ω0. Since frequency is a global entity, the PCC frequency is the same as the inverter terminal frequency, so no compensation control is required to successfully track the frequency reference. Pset and Pout are the active power setpoint and output values ​​of the DER in grid forming mode. The active power frequency droop loop generates a Δω droop The DER must track the frequency adjustment. The frequency calibration sequence 804 Figure 8 is shown in Part II[b] of . Figure 8 It shows that the frequency calibration component of DER is Δω f , and there is an additional calibration component Δω δ, which comes from the next sequence of the algorithm, called angle calibration 806. Once the amplitude and frequency are calibrated, phase calibration is performed by activating angle calibration 806 (algorithm sequence III). In this sequence, the DER frequency is changed in such a way that the PCC angle δ pcc Angle with the grid δ g This is achieved via PI control, which generates an additional frequency setpoint (Δω δ ). Angle calibration sequence 806 is Figure 8 The integrator block 808 acts on the final frequency reference ω ref , to generate the equivalent inverter angle δe for its operation.

[0085] Fig. 9 The diagram shows the inverter dq (rectangular axis) control, which is the control structure in the DER inverter. Vref and δe are the voltage amplitude and angle reference signals for the inverter operation. These signals can be converted from the abc domain to the dq domain to become the direct-axis reference voltage Vdref and the quadrature-axis reference voltage Vqref, respectively. The measured direct-axis voltage Vd and quadrature-axis voltage Vq are compared with these reference signals to generate an error signal, which passes through a proportional-integral (PI) controller. The output of the PI loop generates equivalent direct-axis and quadrature-axis currents Iqref and Iqref, respectively. These current references are sent through another PI loop to generate the direct-axis component ΔVd and quadrature-axis component ΔVq of the voltage. These signals are decoupled by considering the effects created by the mutual reactances IqωL and IdωL, respectively. Finally, the output is added to the measured direct-axis voltage Vd and quadrature-axis voltage Vq to generate the inverter dq domain reference voltage signals, respectively. and These are converted back to abc domain voltage signals And drives the inverter PWM.

[0086] After all PCC waveform parameters of the voltage (e.g., amplitude, frequency, and phase) are calibrated and within tolerance bands, the computing system moves to the next sequence in the algorithm, entering service check and circuit breaker closing (algorithm sequence IV1002), as shown in FIG. Fig.10 As shown. When the microgrid steady-state voltage and frequency are within the range specified by Table 4 of the Institute of Electrical and Electronics Engineers (IEEE) Standard 1547, the entry-in-service specification is defined as a user-defined intentional delay (e.g., 0 to 600 seconds). After the entry-in-service waiting period ends, the computing system completes the resynchronization process, the PCC breaker is closed, and the DER control is switched to follow mode. At this stage, with the closing of the PCC breaker, the microgrid enters the grid connection mode. This marks the end of the resynchronization process.

[0087] Although embodiments of the present invention have been described and described in detail in the accompanying drawings and the foregoing description, such descriptions and descriptions should be regarded as illustrative or exemplary, rather than restrictive. It should be understood that changes and modifications can be made by ordinary technicians within the scope of the appended claims. In particular, the present invention covers other embodiments with any combination of features from the different embodiments described above and below. For example, various embodiments of kinematics, control, electrical, installation, and user interface subsystems can be used interchangeably without departing from the scope of the present invention. In addition, the statements of the features of the present invention described herein refer to one embodiment of the present invention, not necessarily all embodiments.

[0088] The terms used in the claims should be understood to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article "a" or "the" when introducing an element should not be interpreted as excluding multiple elements. Similarly, the description of "or" should be interpreted as inclusive, so that the description of "A or B" does not exclude "A and B", unless it is clear from the context or the previous description that only one of A and B is expected. In addition, the description of "at least one of A, B and C" should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring that each of the listed elements A, B and C has at least one, regardless of whether A, B and C are related as categories or otherwise. In addition, the description of "A, B and / or C" or "at least one of A, B or C" should be interpreted as including any single entity in the listed elements, such as A, any subset of the listed elements, such as A and B, or the entire list of elements A, B and C.

Claims

1. A method for synchronizing a microgrid with a large power grid, the method comprising: receiving, by a computing system, a plurality of first sensor measurements from one or more first sensors, wherein the plurality of first sensor measurements indicate first amplitude, first frequency, and first angle measurements on a microgrid side of a circuit breaker that electrically connects the microgrid to the larger grid; receiving, by the computing system, a plurality of second sensor measurements from one or more second sensors, wherein the plurality of second sensor measurements indicate second amplitude, second frequency, and second angle measurements on a bulk grid side of the circuit breaker; determining, by the computing system, whether the microgrid is synchronized with the large power grid based on the plurality of first sensor measurements and the plurality of second sensor measurements; Based on the microgrid being out of sync with the larger grid, controlling, by the computing system, the one or more energy assets of the microgrid by providing one or more corrective characteristics to the one or more energy assets; as well as Based on the microgrid being synchronized with the large power grid, the computing system provides instructions to the circuit breaker to connect the microgrid to the large power grid.

2. The method according to claim 1, further comprising: receiving bulk electrical grid information indicative of a health status of the bulk electrical grid from a static transfer switch; determining a state of the microgrid, wherein the state indicates whether the microgrid is in a connected state or an islanded state, and The determining whether the microgrid is synchronized with the large grid is further based on the large grid information indicating that the large grid is healthy and the state of the microgrid indicating that the microgrid is in the island state.

3. The method of claim 1 , wherein the circuit breaker is a point of common coupling (PCC) between the microgrid and the larger grid, wherein the one or more first sensors are configured to obtain the plurality of first sensor measurements from one or more wires connecting the microgrid to the circuit breaker, and wherein the one or more second sensors are configured to obtain the plurality of second sensor measurements from one or more wires connecting the circuit breaker to the larger grid.

4. The method of claim 1 , wherein determining whether the microgrid is synchronized with the large grid comprises: determining a difference between the first amplitude and the second amplitude, wherein the first amplitude and the second amplitude are indicative of a voltage amplitude measurement; comparing the difference to one or more thresholds; as well as A determination is made based on the comparison whether the microgrid is synchronized.

5. The method of claim 1 , wherein determining whether the microgrid is synchronized with the large grid comprises: determining a difference between the first frequency and the second frequency, wherein the first frequency and the second frequency are indicative of a frequency of a voltage waveform; comparing the difference to one or more thresholds; as well as A determination is made based on the comparison whether the microgrid is synchronized.

6. The method of claim 1 , wherein determining whether the microgrid is synchronized with the large grid comprises: determining a difference between the first angle and the second angle, wherein the first angle and the second angle indicate a phase angle; comparing the difference to one or more thresholds; as well as A determination is made based on the comparison whether the microgrid is synchronized. 7 . The method of claim 6 , wherein determining the difference between the first angle and the second angle is based on synchronization of the first amplitude with the second amplitude and synchronization of the first frequency with the second frequency.

8. The method of claim 1, wherein the one or more corrective characteristics include a voltage amplitude resynchronization value, wherein the one or more energy assets adjust a voltage amplitude of the microgrid based on the voltage amplitude resynchronization value.

9. The method of claim 1, wherein the one or more corrective characteristics include a voltage-frequency resynchronization value, wherein the one or more energy assets adjust a voltage-frequency of the microgrid based on the voltage-frequency resynchronization value.

10. The method of claim 1, wherein the one or more corrective characteristics include an angle error, wherein the one or more energy assets adjust a voltage frequency of the microgrid based on the angle error.

11. The method of claim 1 , wherein providing the instruction to the circuit breaker further comprises: obtaining a plurality of subsequent sensor measurements from the one or more first sensors during the waiting period; determining whether the microgrid is stable during the waiting period based on comparing the plurality of subsequent sensor measurements to one or more stability thresholds; as well as Based on determining that the microgrid is stable during the waiting period, the instruction is provided to the circuit breaker to connect the microgrid to the larger grid.

12. The method according to claim 11, further comprising: User input indicating the wait time period is received by the computing system.

13. The method of claim 1 , wherein the plurality of first sensor measurements comprises a first set of sensor measurements obtained by the one or more first sensors at a first time and a second set of sensor measurements obtained by the one or more first sensors at a second time, Wherein determining whether the microgrid is synchronized comprises: determining whether the microgrid is synchronized with the large power grid at the first time based on the first set of sensor measurements; as well as A determination is made based on the second set of sensor measurements whether the microgrid is synchronized with the large grid at the second time.

14. The method of claim 13, wherein controlling the one or more energy assets of the microgrid by providing the one or more corrective characteristics to the one or more energy assets is based on determining that the microgrid is not synchronized with the larger grid at the first time, and Wherein providing the instruction to the circuit breaker to connect the microgrid to the larger grid is based on determining that the microgrid is not synchronized with the larger grid at the second time.

15. A system for synchronizing a microgrid with a large power grid, the system comprising: Computing systems, including: one or more processors; and A non-transitory computer-readable medium having stored thereon processor-executable instructions, wherein the processor-executable instructions, when executed by the one or more processors, facilitate: receiving a plurality of first sensor measurements from one or more first sensors, wherein the plurality of first sensor measurements indicate first amplitude, first frequency, and first angle measurements on a microgrid side of a circuit breaker that electrically connects the microgrid to the larger grid; receiving a plurality of second sensor measurements from one or more second sensors, wherein the plurality of second sensor measurements indicate second magnitude, second frequency, and second angle measurements on a bulk grid side of the circuit breaker; determining whether the microgrid is synchronized with the large power grid based on the plurality of first sensor measurements and the plurality of second sensor measurements; Based on the microgrid being out of synchronization with the larger grid, controlling the one or more energy assets of the microgrid by providing one or more corrective characteristics to the one or more energy assets; and Based on the microgrid being synchronized with the larger grid, instructions are provided to the circuit breaker to connect the microgrid to the larger grid.

16. The system of claim 15, wherein the processor-executable instructions, when executed by the one or more processors, further facilitate: receiving bulk electrical grid information indicative of a health status of the bulk electrical grid from a static transfer switch; determining a state of the microgrid, wherein the state indicates whether the microgrid is in a connected state or an islanded state, and The determining whether the microgrid is synchronized with the large grid is further based on the large grid information indicating that the large grid is healthy and the state of the microgrid indicating that the microgrid is in the island state.

17. The system of claim 15, wherein the circuit breaker is a point of common coupling (PCC) between the microgrid and the larger grid, wherein the one or more first sensors are configured to obtain the plurality of first sensor measurements from one or more wires connecting the microgrid to the circuit breaker, and wherein the one or more second sensors are configured to obtain the plurality of second sensor measurements from one or more wires connecting the circuit breaker to the larger grid.

18. The system of claim 15, wherein determining whether the microgrid is synchronized with the large grid comprises: determining a difference between the first amplitude and the second amplitude, wherein the first amplitude and the second amplitude are indicative of a voltage amplitude measurement; comparing the difference to one or more thresholds; as well as A determination is made based on the comparison whether the microgrid is synchronized.

19. The system of claim 15, wherein determining whether the microgrid is synchronized with the large grid comprises: determining a difference between the first frequency and the second frequency, wherein the first frequency and the second frequency are indicative of a frequency of a voltage waveform; comparing the difference to one or more thresholds; as well as A determination is made based on the comparison whether the microgrid is synchronized.

20. A non-transitory computer-readable medium having processor-executable instructions stored thereon, wherein the processor-executable instructions, when executed by one or more processors, facilitate: receiving a plurality of first sensor measurements from one or more first sensors, wherein the plurality of first sensor measurements indicate first amplitude, first frequency, and first angle measurements on a microgrid side of a circuit breaker that electrically connects the microgrid to a larger grid; receiving a plurality of second sensor measurements from one or more second sensors, wherein the plurality of second sensor measurements indicate second magnitude, second frequency, and second angle measurements on a bulk grid side of the circuit breaker; determining whether the microgrid is synchronized with the large power grid based on the plurality of first sensor measurements and the plurality of second sensor measurements; controlling the one or more energy assets of the microgrid by providing one or more corrective characteristics to the one or more energy assets of the microgrid based on the microgrid being out of synchronization with the larger grid; and Based on the microgrid being synchronized with the larger grid, instructions are provided to the circuit breaker to connect the microgrid to the larger grid.

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