Power grid system

Abstract

A grid system includes: a first microgrid coupled to a first power device; a second microgrid coupled to a second power device; the first switch is connected between the first micro-grid and the second micro-grid and is coupled to a third power device; the main power grid is coupled to the first micro-grid and the second micro-grid through the second switch and the third switch and supplies power to the first micro-grid and the second micro-grid; a controller coupled to the first, second and third power devices; and a first element and a second element coupled to the first and second power devices, respectively, where the first and second power devices detect the first element and the second element, respectively, to determine whether the first and second microgrids fail, and when one of the first and second microgrids fails, the first and second elements are coupled to the first and second power devices, respectively. And the power device of the faulted micro-grid controls the loop switch to be switched off.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a power grid system, and more particularly, to a system including a protection strategy for microgrid clusters. BACKGROUND

[0002] According to the current prevailing architecture, a microgrid is mainly defined by a feeder. When an abnormality occurs upstream of the feeder, the microgrid of the feeder can only operate off-grid until the feeder fault is cleared and the microgrid can be restored to parallel operation with the utility. SUMMARY

[0003] The present disclosure relates to a power grid system, and more particularly, to a system including a protection strategy for microgrid clusters.

[0004] According to an embodiment of the present disclosure, the first power device is configured to measure a first current and a first voltage of the first element, and the second power device is further configured to measure a second current and a second voltage of the second element. The first power device is configured to determine whether the first microgrid is faulty based on the first current and the first voltage, and the second power device is configured to determine whether the second microgrid is faulty based on the second current and the second voltage.

[0005] According to an embodiment of the present disclosure, the first power device is configured to detect the first element to determine whether the first microgrid is faulty when the first current is greater than a threshold current, or when the first voltage is less than the second voltage of the second microgrid.

[0006] According to an embodiment of the present disclosure, the second power device is configured to detect the second element to determine whether the second microgrid is faulty when the second current is greater than the threshold current, or when the second voltage is less than the first voltage of the first microgrid.

[0007] In one embodiment of the present application, the power grid system further comprises: a main grid coupled to the first micro-grid and the second micro-grid via a second switch and a third switch, respectively, and configured to supply power to the first micro-grid and the second micro-grid; and the controller is configured to control the first power device and the second power device via a plurality of signals, and when the first power device determines that the first micro-grid fails, the controller controls the first power device to disconnect the second switch via a first signal of the plurality of signals.

[0008] In one embodiment of the present application, when the second power device determines that the second micro-grid fails, the controller controls the second power device to disconnect the third switch via a second signal of the plurality of signals.

[0009] In one embodiment of the present application, when the controller determines that one of the first micro-grid and the second micro-grid fails, the controller further determines whether a margin of the other of the first micro-grid and the second micro-grid is sufficient, and when the margin of the other of the first micro-grid and the second micro-grid is sufficient, the controller turns on the first switch and supplies power to the one of the first micro-grid and the second micro-grid by the other of the first micro-grid and the second micro-grid.

[0010] In one embodiment of the present application, when the first micro-grid fails and the second current is less than a second maximum current, the controller determines that the margin of the second micro-grid is sufficient, and when the second current is equal to the second maximum current, the controller determines that the margin of the second micro-grid is insufficient.

[0011] In one embodiment of the present application, when the second micro-grid fails and the first current is less than a first maximum current, the controller determines that the margin of the first micro-grid is sufficient, and when the first current is equal to the first maximum current, the controller determines that the margin of the first micro-grid is insufficient.

[0012] In one embodiment of the present application, the first power device, the second power device, and the controller are configured to transmit the plurality of signals to each other via an optical fiber network and according to a power interoperability IEC 61850. BRIEF DESCRIPTION OF DRAWINGS

[0013] The subject matter can be better understood by reference to the following paragraphs of implementation and the following drawings in which:

[0014] Figure 1 A schematic diagram of a micro-grid system according to some embodiments of the present disclosure;

[0015] Figure 2 A flowchart of an operation method of a micro-grid system according to some embodiments of the present disclosure;

[0016] Figure 3 This is a schematic diagram of a microgrid system illustrated according to some embodiments of the present disclosure;

[0017] Figure 4 This is a schematic diagram of a microgrid system illustrated according to some embodiments of the present disclosure.

[0018] [Symbol Explanation]

[0019] 100: Power Grid System

[0020] 101, 102, 103, 104, 105, 106: Electrical installations

[0021] 110: Main power grid

[0022] 120: Microgrid

[0023] 130: Microgrid

[0024] 140: Controller

[0025] 150: Microgrid

[0026] 200: Operating Instructions

[0027] 201-208: Operation

[0028] 300: Power Grid System

[0029] 400: Power Grid System

[0030] BUS: Bus

[0031] C1~C6: Signals

[0032] C, CC: Protection Curve

[0033] DR120, DR130, DR150: Differential Capacity

[0034] DTR1, DTR2, DTR3: Status data

[0035] G1, G2: Microgrid clusters

[0036] ITR1, ITR2, ITR3: Current values

[0037] Ilm: Preset threshold current value

[0038] NC, NCC: Protection Curve

[0039] R23, R35, RG1: Operating capacity

[0040] R, RR, R110, R120, R130, R150, R120int, R130int, RRG1, RRG2: Operating capacity

[0041] R110', R120', R130' and R150': Protect operating capacity

[0042] R110", R120", R130" and R150": Maximum operating capacity

[0043] RP, RRP: margin

[0044] RTR1, RTR2: Resistance values

[0045] S1~S9: Switches

[0046] TR1, TR2, TR3: Components

[0047] TTR1, TTR2: Temperature

[0048] VTR1, VTR2, VTR3: Voltage values

[0049] Vop: Preset operating load value Detailed Implementation

[0050] The following describes several embodiments of the present invention with reference to the accompanying drawings. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details should not be used to limit the present invention. That is, in some embodiments of the present invention, these practical details are not essential. Furthermore, for the sake of simplicity, some conventional structures and elements will be shown in the drawings in a simple schematic manner.

[0051] In this document, when an element is referred to as a "connection" or "coupled," it may mean an "electrical connection" or "electrical coupling." "Connection" or "coupled" can also be used to indicate the operation or interaction between two or more elements. Furthermore, although terms such as "first," "second," etc., are used herein to describe different elements, these terms are merely used to distinguish elements or operations described using the same technical terms. Unless the context clearly indicates otherwise, these terms do not specifically refer to or imply order or sequence, nor are they intended to limit the scope of this invention.

[0052] Figure 1 This is a schematic diagram of a power grid system 100 illustrated according to an embodiment of the present disclosure. The power grid system 100 includes a main grid 110, microgrids 120 and 130, a controller 140, power devices 101-104, a bus, components TR1 and TR2, and multiple switches S1-S6.

[0053] likeFigure 1 As shown, the main power grid 110 is coupled to the bus BUS via switch S1. Microgrid 120 is coupled to component TR1 via switch S4, and component TR1 is coupled to the bus BUS via switch S2. Microgrid 130 is coupled to component TR2 via switch S5, and component TR2 is coupled to the bus BUS via switch S3. Microgrids 120 and 130 are interconnected via switch S6. Multiple components and devices within the power grid system 100 are coupled via feeders. In some embodiments, when microgrids 120 and 130 operate in parallel with the main power grid 110, this is referred to as grid-connected operation of the power grid system 100.

[0054] In some embodiments, power device 104 is coupled to switch S6. Power device 101 is coupled to switch S1, power device 102 is coupled to each of switches S2 and S4, and power device 103 is coupled to each of switches S3 and S5. Controller 140 further controls the plurality of power devices 101 to 104 respectively via a plurality of signals C1 to C4 to engage or disengage switches S1 to S6.

[0055] In some embodiments, each of the power devices 101-104 may be implemented using an Intelligent Electronic Device (IED). In some embodiments, signals C1-C4 may be implemented using a fiber optic network or cable, and the controller 140 transmits signals C1-C4 to the power devices 101-104 respectively via a virtual channel of power interoperability, such as the communication technology of the virtual channel GOOSE (Generic Object Oriented SubstationEvent) of power interoperability IEC 61850. In some embodiments, components TR1 and TR2 may be implemented using a transformer or other similar electronic components, but this disclosure is not limited thereto.

[0056] In some embodiments, power device 102 is used to detect the status data DTR1 of element TR1 and transmit the status data DTR1 back to controller 140. Power device 103 is used to detect the status data DTR2 of element TR2 and transmit the status data DTR2 back to controller 140. Controller 140 is used to control the switching on and off of switches S2, S4 and switches S3, S5 via signals C2 and C3 respectively through power devices 102 and 103 based on the status data DTR1 and DTR2. Controller 140 is further used to control the switching on and off of switches S1 and S6 via signals C1 and C4 respectively through power devices 101 and 104. Details regarding the switching on and off of switches S1 to S6 will be provided later. Figure 2 Detailed explanations are provided in the corresponding paragraphs.

[0057] In some embodiments, power devices 102 and 103 are used to set the operating capacities R120 and R130 of the electricity required for the operation of microgrids 120 and 130, respectively. Power device 101 is used to set the operating capacity R110 of the electricity required for the operation of the main grid 110. Details regarding the operating capacity will be provided later. Figure 2 Detailed explanations are provided in the corresponding paragraphs.

[0058] In some embodiments, state data DTR1 may include the voltage value VTR1, the current value ITR1, and the temperature TTR1 of component TR1, but this disclosure is not limited to these parameters. State data DTR2 may include the voltage value VTR2, the current value ITR2, and the temperature TTR2 of component TR2, but this disclosure is not limited to these parameters. Further details regarding state data DTR1 and DTR2 will be provided in [the following text is missing from the original] Figure 2 Detailed explanations are provided in the corresponding paragraphs.

[0059] In existing technologies, the current microgrid architecture primarily uses feeders as the regional boundaries of the microgrid. When an upstream component of a feeder malfunctions, the microgrid can only operate offline through that feeder. Only when the feeder fault is resolved can the microgrid reconnect to the main grid.

[0060] In some embodiments, to address the aforementioned problems and enhance operation between the main power grid and the microgrid, the power grid system 100 disclosed herein constructs a smart microgrid by grouping multiple microgrids 120 and 130, and introduces a microgrid group interconnection architecture. The interconnection architecture utilizes virtual channel points and signal communication technology based on the power interoperability IEC 61850 GOOSE (Generic Object Oriented Substation Event) standard to regulate the individual microgrids 120 and 130 within the microgrid group. Therefore, when a component within a microgrid fails, the microgrid system 100 can connect the microgrids 120 and 130 in parallel to a neighboring microgrid via GOOSE to maintain grid-connected operation.

[0061] In some embodiments, IEC 61850 power interoperability is a communication standard in the field of power system automation. The standard enables power system interoperability to integrate various forms of power products. During signal transmission, IEC 61850 GOOSE allows for real-time monitoring of equipment and measurement data, and provides communication models adapted to different devices to achieve signal interoperability between multiple devices and ensure signal transmission stability.

[0062] Figure 2 This is a flowchart illustrating an operation method 200 of a power grid system 100 according to some embodiments of this disclosure.Figure 2 As shown, operation method 200 includes operations 201 to 208.

[0063] Please refer to Figure 1 , 2 The operation method 200 can be executed through the power grid system 100. In various embodiments, the operation method 200 can be executed through various power grid systems and can be applied to... Figure 1 Various scenarios of the microgrid system 100. The following will use the microgrid system 100 as an example to illustrate the operation method 200.

[0064] In operation 201, power device 102 detects the status data DTR1 of component TR1 in power grid system 100. Power device 103 detects the status data DTR2 of component TR2 in power grid system 100. Power grid system 100 performs operation 202 after completing operation 201.

[0065] Specifically, power device 102 detects the voltage value VTR1 and the current value ITR1 across element TR1. Power device 103 detects the voltage value VTR2 and the current value ITR2 across element TR2. Power devices 102 and 103 transmit the detected voltage value VTR1, current value ITR1 and voltage value VTR2, current value ITR2 to controller 140, respectively.

[0066] In some embodiments, the status data of the detection element may include, but is not limited to, the voltage value, current value, operating temperature value, or other similar parameter values ​​of the measuring element.

[0067] In operation 202, controller 140 determines whether components TR1 and TR2 are operating normally or have malfunctioned based on the status data DTR1 and DTR2 detected by power devices 102 and 103, respectively. Power grid system 100 then proceeds to operation 203 after completing operation 202.

[0068] Specifically, power device 102 determines whether component TR1 is operating normally or has malfunctioned based on its voltage value VTR1 and current value ITR1. Power device 103 determines whether component TR2 is operating normally or has malfunctioned based on its voltage value VTR2 and current value ITR2. When component TR1 malfunctions, power device 102 corresponding to component TR1 transmits the fault status to controller 140 in digital signal form via signal C2, and / or when component TR2 malfunctions, power device 103 corresponding to component TR2 transmits the fault status to controller 140 in digital signal form via signal C3.

[0069] In some scenarios, when the current value ITR1 is higher than a preset threshold current value Ilm, the power device 102 determines that the element TR1 has failed. When the current value ITR2 is higher than the preset threshold current value Ilm, the power device 103 determines that the element TR2 has failed. When the voltage value VTR1 is lower than a preset operating load value Vop, the power device 102 determines that the element TR1 has failed. When the voltage value VTR2 is lower than the preset operating load value Vop, the power device 103 determines that the element TR2 has failed.

[0070] In other scenarios, when one of components TR1 and TR2 fails, the voltage value in the status data of the other component TR1 and TR2 is used as the preset operating load value Vop, and at the same time, the preset threshold current value Ilm is used to determine whether components TR1 and TR2 are operating normally or have failed.

[0071] In other scenarios, when the current value ITR1 approaches the preset threshold current value Ilm, or when the internal resistance value RTR1 of component TR1 is abnormal, causing component TR1 to overheat, the power device 102 determines that component TR1 has malfunctioned. When the current value ITR2 approaches the preset threshold current value Ilm, or when the internal resistance value RTR2 of component TR2 is abnormal, causing component TR2 to overheat, the power device 103 determines that component TR2 has malfunctioned.

[0072] In some embodiments, determining a component fault includes determining the component's current and voltage values ​​or other similar parameter values, but this disclosure is not limited thereto. For example, when a short circuit or open circuit occurs in the feeder connected to components TR1 and / or TR2, power devices 102 and 103 determine that components TR1 and / or TR2 have failed, respectively.

[0073] In some embodiments, when components TR1 and / or TR2 fail, the power devices 102 and / or 103 corresponding to components TR1 and / or TR2 transmit a digital value with logic "1" to the controller 140 via signals C2 and / or C3. Conversely, when components TR1 and / or TR2 do not fail, the power devices 102 and / or 103 corresponding to components TR1 and / or TR2 transmit a digital value with logic "0" to the controller 140 via signals C2 and / or C3.

[0074] For example, when component TR1 fails, power device 102 detects the status data DTR1 of microgrid 120, namely the voltage value VTR1 and current value ITR1 across component TR1. Simultaneously, power device 103 detects the status data DTR2 of microgrid 130, namely the voltage value VTR2 across component TR2 as a preset operating load value Vop. Next, power device 102 further transmits the voltage value VTR1 and current value ITR1 to power device 103 for comparison. When the voltage value VTR1 is lower than the voltage value VTR2 (i.e., the preset operating load value Vop), or when the current value ITR1 is higher than the preset threshold current value Ilm, power device 102 determines that component TR1 has failed.

[0075] In operation 203, when power unit 102 determines that component TR1 has failed, power unit 102 isolates the failed component TR1 and the microgrid 120 connected to the failed component TR1 operates off-grid. When power unit 103 determines that component TR2 has failed, power unit 103 isolates the failed component TR2 and the microgrid 130 connected to the failed component TR2 operates off-grid. After completing operation 203, the power grid system 100 proceeds to operation 204.

[0076] Figure 3 This is a schematic diagram of a power grid system 300 drawn according to some embodiments of the present disclosure. In some embodiments, the power grid system 300 is drawn as follows: Figure 1 Another embodiment of the power grid system 100. The power grid system 300 includes the internal components of the power grid system 100.

[0077] Also refer to Figures 1 to 3 In the scenario of power grid system 300, controller 140 determines that component TR1 has failed. When component TR1 fails, power unit 102 disconnects each of switches S2 and S4, and power unit 104 connects switch S6 to connect microgrid 120 and microgrid 130 in parallel.

[0078] Specifically, in the scenario of power grid system 300, power device 102 measures the voltage value VTR1 and current value ITR1 of element TR1, and transmits these values ​​to controller 140 and power device 103 via signal C1. When power device 102 and controller 140 determine that element TR1 has failed, power device 102 disconnects each of switches S2 and S4, isolating element TR1 from power grid system 300. Then, after element TR1 is isolated from power grid system 300, the microgrid 120 corresponding to the faulty element TR1 operates off-grid. When controller 140 reads the status measured by power device 103 via signal C3 and determines that no element in power grid system 300 has failed, power grid system 300 maintains grid-connected operation.

[0079] In some embodiments, off-grid operation may mean operation by the internal power supply of the microgrid 120 in the absence of power supply from the main grid 110 and other microgrids (e.g., microgrid 130).

[0080] In operation 204, when the controller 140 determines that components TR1 and / or TR2 have failed, the controller 140 calculates and sets the operating capacity R of the power grid system 100. After completing operation 204, the power grid system 100 proceeds to operation 205.

[0081] In the context of power grid system 300, the operating capacity R includes: the operating capacity R110 detected by power device 101 when the main power grid 110 is in operation, and the operating capacities R120 and R130 detected by power devices 102 and 103 when the microgrids 120 and 130 are in operation, respectively.

[0082] In some embodiments, when the operating capacity R110 is operating with the main grid 110, it is lower than or equal to a preset protection capacity of the main grid 110 based on load capacity limitation, namely R110', where R110" is the maximum operating capacity. When the operating capacity R120 is operating with the microgrid 120, it is lower than or equal to a preset protection capacity of the microgrid 120 based on load capacity limitation, namely R120', where R120" is the maximum operating capacity. When the operating capacity R130 is operating with the microgrid 130, it is lower than or equal to a preset protection capacity of the microgrid 130 based on load capacity limitation, namely R130', where R130" is the maximum operating capacity. When the grid system 100 operates at the operating capacity R, the grid system 100 has a protection curve C.

[0083] In some embodiments, the main grid 110 is used to supply power to each of the microgrids 120 and 130, and the operating capacity R110 of the main grid 110 includes the operating capacities R120 and R130 allocated to the microgrids 120 and 130.

[0084] In the scenario of power grid system 300, when component TR1 fails, microgrid 120 operates off-grid. When the protection operation capacity R130' of microgrid 130 is lower than the maximum operation capacity R130", the power unit 103 sets the operation capacity R130' to the maximum operation capacity R130".

[0085] Next, controller 140 calculates a maximum operating difference capacity DR130 between the maximum operating capacity R130" and the operating capacity R130', i.e., difference capacity DR130 = R130" - R130'. Power unit 101 sets the operating capacity R110 of the main power grid 110 during operation to a new protection capacity R110' that is, R110' = R110 - DR130.

[0086] At this time, when the operating capacity of microgrid 130 is set to the maximum operating capacity R130", the power unit 104 sets the operating capacity R23 connected to microgrids 120 and 130 to the maximum operating differential capacity DR130. Here, the operating capacity R23 can represent the operating capacity provided by microgrid 130 to microgrid 120 when microgrid 120 is off-grid.

[0087] In some embodiments, the operating capacity R may represent the capacity of the main grid or microgrid that can supply power during operation and may be expressed in units of power (e.g., kW). The operating capacity R may include the State of Charge (SOC), generator power, renewable energy, or other similar power supply capacity or devices in the main grid or microgrid, but this disclosure is not limited thereto.

[0088] In some embodiments, the protection curve C is used as a graph to illustrate the relationship between the current supplied by the power grid system 100 during operation and time.

[0089] In operation 205, when component TR1 and / or TR2 fails, controller 140 calculates the capacity margin RP of the adjacent microgrid based on the operating capacity R, and further determines whether the capacity margin RP is sufficient. When the capacity margin RP is sufficient, grid system 100 performs operation 207 after completing operation 205. When the capacity margin RP is insufficient, grid system 100 performs operation 206 after completing operation 205.

[0090] Specifically, in the scenario of power grid system 300, when component TR1 fails and microgrid 120 is operating off-grid, controller 140 determines whether the capacity margin RP of microgrid 130 is sufficient.

[0091] In some scenarios, controller 140 determines whether the operating capacity R130 of microgrid 130 has reached the maximum operating capacity R130". When the operating capacity R130 has reached the maximum operating capacity R130", controller 140 determines that the capacity margin RP of microgrid 130 is insufficient.

[0092] In other scenarios, when the operating capacity R130 does not reach the maximum operating capacity R130", the controller 140 further determines whether the protection operating difference capacity DR120 between the protection operating capacity R120' and the operating capacity R120 of the microgrid 120 is greater than the difference capacity DR130. When the operating difference capacity DR120 is greater than the difference capacity DR130, the controller 140 determines that the capacity margin RP of the microgrid 130 is insufficient. When the operating difference capacity DR120 is less than the difference capacity DR130, the controller 140 determines that the capacity margin RP of the microgrid 130 is sufficient.

[0093] In operation 206, when the controller 140 determines that the capacity margin RP of the adjacent microgrid is insufficient, the microgrid with the faulty component continues to operate off-grid, and the adjacent microgrid maintains its existing protection curve C.

[0094] Specifically, in the scenario of power grid system 300, when controller 140 determines that the capacity margin RP of microgrid 130 is insufficient, microgrid 120 maintains off-grid operation, and adjacent microgrids maintain their existing protection curves C.

[0095] In operation 207, when controller 140 determines that the capacity margin RP of an adjacent microgrid is sufficient, controller 140 connects the microgrid with the faulty component to the adjacent microgrid, forming a microgrid group. After completing operation 207, grid system 300 proceeds to operation 208.

[0096] Specifically, in the context of the power grid system 300, when the controller 140 determines that the capacity margin RP of the microgrid 130 is sufficient, the controller 140 controls the power device 104 to put the switch S6 into operation through the signal C4, so that the microgrid 120 is connected in parallel to the microgrid 130 and forms a microgrid group G1.

[0097] In operation 208, controller 140 calculates the operating capacity of the microgrid group and the main grid 110 based on the paralleled microgrid group, and generates the protection curve NC for the microgrid system. After completing operation 208, grid system 100 completes operation method 200.

[0098] Specifically, in the scenario of power grid system 300, controller 140 calculates the operating capacity RG1 of microgrid group G1 and the operating capacity R110 of main grid 110 based on the parallel microgrids 120 and 130. Controller 140 further generates a protection curve NC that is different from the protection curve C based on microgrid group G1.

[0099] In some embodiments, when microgrids 120 and 130 are connected in parallel, the operating capacity R120 of microgrid 120 is supplied through microgrid 130. Therefore, the operating capacity RG1 has the operating capacity R120 of microgrid 120.

[0100] In other embodiments, when microgrid 120 is operated off-grid, the power generation devices within microgrid 120 can supply a portion of the operating capacity R120int. When microgrids 120 and 130 are connected in parallel, microgrid 130 supplies the insufficient operating capacity of microgrid 120, that is, microgrid 130 supplies the difference between the operating capacity R120 and the operating capacity R120int of microgrid 120. In other words, microgrid 130 supplies the difference between R120 and R120int to microgrid 120.

[0101] In some embodiments, the protection curve NC is used to plot the relationship between the current supplied by the power grid system 300 and time when microgrids 120 and 130 are connected in parallel to form microgrid group G1.

[0102] Figure 4 This is a schematic diagram of a power grid system 400 illustrated according to an embodiment of the present disclosure. The power grid system 400 is a variation of the power grid system 100.

[0103] like Figure 4 As shown, the internal components of the power grid system 400 are similar to those of the power grid system 100, and the notation method of the power grid system 100 is used. Compared with the power grid system 100, the power grid system 400 further includes a microgrid 150, power devices 105 and 106, switches S6, S7, S8 and S9, and component TR3, and the controller 140 further controls the corresponding power devices 105 and 106 through signals C5 and C6 respectively.

[0104] Please refer to the following at the same time Figure 4 and Figure 2 Operation method 200 can also be applied to Figure 4 The following describes the operation method 200 using a microgrid system 400 as an example, and assumes that component TR2 fails in the context of the microgrid system 400.

[0105] In operation 201, power devices 102, 103, and 105 respectively detect the status data DTR1, DTR2, and DTR3 of corresponding components TR1, TR2, and TR3 in the power grid system 400. After completing operation 201, the power grid system 400 proceeds to operation 202.

[0106] Specifically, power device 102 measures the voltage value VTR1 and the current value ITR1 across element TR1. Power device 103 measures the voltage value VTR2 and the current value ITR2 across element TR2. Power device 105 measures the voltage value VTR3 and the current value ITR3 across element TR3. Power devices 102, 103, and 105 transmit the measured voltage value VTR1, current value ITR1, voltage value VTR2, current value ITR2, and voltage value VTR3, current value ITR3 to controller 140, respectively.

[0107] In operation 202, power units 102, 103, and 105 determine whether components TR1, TR2, and TR3 have malfunctioned based on status data DTR1, DTR2, and DTR3, respectively. Power grid system 400 performs operation 203 after completing operation 202.

[0108] Specifically, power devices 102, 103, and 105 determine whether components TR1, TR2, and TR3 have malfunctioned based on their corresponding voltage values ​​VTR1, current values ​​ITR1, VTR2, current values ​​ITR2, and VTR3, respectively. When components TR1, TR2, and / or TR3 malfunction, power devices 102, 103, and / or 105 corresponding to components TR1, TR2, and / or TR3 transmit the fault status to controller 140 in the form of digital signals via signals C2, C3, and / or C4.

[0109] In some embodiments, the operation of determining whether components TR1, TR2, and TR3 have failed is similar to... Figure 1 and Figure 2 The operation for determining whether components TR1 and TR2 in the power grid system 100 have failed is similar. For the sake of brevity, only the differences are described in detail here.

[0110] In the scenario of power grid system 400, when component TR2 fails, power device 103 detects the status data DTR2 of microgrid 130, namely the voltage value VTR2 and current value ITR2 across component TR2. Simultaneously, power devices 102 and 105 detect the status data DTR1 and DTR3 of microgrids 120 and 150, respectively, namely the voltage values ​​VTR1 and VTR3 across components TR1 and TR3 as preset operating load values ​​Vop. Next, power device 103 further transmits the voltage value VTR2 and current value ITR2 to power devices 102 and 105 for comparison. When the voltage value VTR2 is lower than either voltage value VTR1 or VTR3, or when the current value ITR2 is higher than a preset threshold current value Ilm, power device 103 determines that component TR2 has failed.

[0111] In some embodiments, when components TR1, TR2, and / or TR3 malfunction, the power devices 102, 103, and / or 105 corresponding to components TR1, TR2, and / or TR3 transmit a digital signal with logic "1" to the controller 140 via signals C2, C3, and / or C4. Conversely, when components TR1, TR2, and / or TR3 do not malfunction, the power devices 102, 103, and / or 105 corresponding to components TR1, TR2, and / or TR3 transmit a digital quantity with logic "0" to the controller 140 via signals C2, C3, and / or C4.

[0112] In operation 203, within the scenario of power grid system 400, when controller 140 determines that component TR2 has failed, controller 140 controls power unit 103 via signal C3 to disconnect each of switches S3 and S5, and disconnects the microgrid 130 corresponding to the failed component from the grid. When controller 140 determines that no component in power grid system 400 has failed, power grid system 400 maintains grid-connected operation. Power grid system 400 performs operation 204 after completing operation 203.

[0113] In operation 204, within the scenario of power grid system 400, when controller 140 determines that component TR2 has failed, controller 140 calculates and sets the operating capacity RR of power grid system 400. Power grid system 400 then proceeds to operation 205 after completing operation 204.

[0114] In this scenario, the operating capacity RR includes: the operating capacity R110 detected by power device 101 when the main grid 110 is in operation, and the operating capacities R120, R130 and R150 detected by power devices 102, 103 and 105 when the microgrids 120, 130 and 150 are in operation, respectively.

[0115] In some embodiments, each of the main grid 110, microgrids 120, 130, and 150 has corresponding protective operating capacities R110', R120', R130', and R150', and maximum operating capacities R110", R120", R130", and R150". When the grid system 400 operates at operating capacity RR, the grid system 400 has a protection curve CC. In some embodiments, the main grid 110 supplies power to each of the microgrids 120, 130, and 150, and the operating capacity R110 of the main grid 110 includes the operating capacities R120, R130, and R150 of the microgrids 120, 130, and 150.

[0116] In the scenario of power grid system 400, when component TR2 fails, microgrid 130 operates off-grid. When the operating capacities R120 and R150 of microgrids 120 and 150 are lower than the maximum operating capacities R130' and R150' respectively, power units 102 and 105 calculate the operable capacity margin.

[0117] Next, the controller 140 calculates a protection operation difference capacity DR120 between the maximum operating capacity R120" and the protection operating capacity R120', and a maximum operating difference capacity DR150 between the maximum operating capacity R150" and the protection operating capacity R150'. The controller 140 further compares the maximum operating difference capacity DR120 and DR150. When the difference capacity DR120 is greater than the difference capacity DR150, the power unit 101 sets the protection operating capacity R110' to the new protection capacity R110' of the operating capacity R110' minus the difference capacity DR120. When the difference capacity DR120 is less than the difference capacity DR150, the power unit 101 sets the protection operating capacity R110' to the new protection capacity R110' of the operating capacity R110' minus the difference capacity DR150.

[0118] In some scenarios, when the differential capacity DR120 is greater than the differential capacity DR150, the power unit 104 sets the operating capacity R23 connected to microgrids 120 and 130 to the differential capacity DR120; conversely, when the differential capacity DR120 is less than the differential capacity DR150, the power unit 106 sets the operating capacity R35 connected to microgrids 130 and 150 to the differential capacity DR150.

[0119] In other scenarios, when the differential capacity DR120 is equal to the differential capacity DR150, the power unit 104 sets the operating capacity R23 connected to microgrids 120 and 130 and the operating capacity R35 connected to microgrids 150 and 130 to the differential capacity DR120 or DR150.

[0120] In operation 205, when component TR2 fails, controller 140 calculates the capacity margin RRP of the adjacent microgrid based on the operating capacity RR, and further determines whether the capacity margin RRP is sufficient. If the capacity margin RRP is sufficient, grid system 400 performs operation 207 after completing operation 205. If the capacity margin RRP is insufficient, grid system 400 performs operation 206 after completing operation 205.

[0121] In some scenarios, controller 140 determines whether the operating capacities R120 and R150 have reached their maximum operating capacities R120" and R150" respectively. When the operating capacity R120 has reached its maximum operating capacity R120", controller 140 determines that the capacity margin RRP of microgrid 120 is insufficient. When the operating capacity R150 has reached its maximum operating capacity R150", controller 140 determines that the capacity margin RRP of microgrid 150 is insufficient.

[0122] In other scenarios, when the operating capacities R120 and R150 have not reached the maximum operating capacities R120" and R150", the controller 140 further determines whether the operating capacity R130 of the microgrid 130 is greater than the differential capacity DR120 or DR150. When the operating capacity R130 is greater than either the differential capacity DR120 or DR150, the controller 140 determines that the capacity margin RP of each of the microgrids 120 and 150 is insufficient. When the operating capacity R120 is less than either the differential capacity DR120 or DR150, the controller 140 determines that the capacity margin RP of the microgrids 120 and 130 is sufficient.

[0123] In operation 206, in the context of the power grid system 400, when the controller 140 determines that the capacity margin RRP of each of the microgrids 120 and 150 is insufficient, the microgrid 130 maintains off-grid operation, and the adjacent microgrids maintain their existing protection curves CC.

[0124] In operation 207, within the context of the power grid system 400, when the controller 140 determines that the capacity margin RRP of each of microgrids 120 and 150 is sufficient, the controller 140 further compares the differential capacities DR120 and DR150. When the differential capacity DR120 is greater than the differential capacity DR150, the controller 140 controls the power device 104 to engage switch S9 via signal C4, causing microgrid 120 to be connected in parallel to microgrid 130, forming microgrid group G1. When the differential capacity DR120 is less than the differential capacity DR150, the controller 140 controls the power device 106 to engage switch S8 via signal C5, causing microgrid 130 to be connected in parallel to microgrid 150, forming microgrid group G2. After completing operation 207, the power grid system 400 proceeds to operation 208.

[0125] In some embodiments, when the differential capacity DR120 equals the differential capacity DR150, the controller 140 controls the power devices 104 and 106 to activate switches S9 and S8 via signals C4 and C5, respectively, so that microgrid 120 is connected in parallel to each of microgrids 130 and 150, forming microgrid groups G1 and G2, respectively. In other embodiments, when the differential capacity DR120 equals the differential capacity DR150, the controller 140 may activate one of switches S9 and S8, so that microgrid 120 is connected in parallel to the corresponding microgrid 130 or 150, forming microgrid group G1 or G2.

[0126] In other embodiments, when the capacity margin RRP of each of microgrids 120 and 150 is insufficient, controller 140 may further determine whether the sum of the capacity margins RRP of microgrids 120 and 150 is sufficient. When controller 140 determines that the sum of the capacity margins is sufficient, controller 140 may switch on each of switches S9 and S8, so that microgrid 120 is connected in parallel to each of microgrids 130 and 150, forming microgrid groups G1 and G2 respectively.

[0127] In operation 208, within the context of power grid system 400, when microgrid 120 and microgrid 130 are connected in parallel, controller 140 calculates the operating capacity RRG1 of microgrid group G1. When microgrid 130 and microgrid 150 are connected in parallel, controller 140 calculates the operating capacity RRG2 of microgrid group G2. Controller 140 further generates a protection curve NCC, different from the protection curve CC, based on either the operating capacity RRG1 or the operating capacity RRG2. After completing operation 208, power grid system 400 completes operation method 200.

[0128] In some embodiments, when microgrids 120 and 130 are connected in parallel, the operating capacity R130 of microgrid 130 is supplied through microgrid 120. When microgrids 130 and 150 are connected in parallel, the operating capacity R130 of microgrid 130 is supplied through microgrid 150. Therefore, the operating capacity RRG2 has the operating capacity R130 of microgrid 130.

[0129] In other embodiments, when microgrid 130 is off-grid, the power generation devices within microgrid 130 can supply a portion of the operating capacity R130int. When microgrids 120 and 130 are connected in parallel, microgrid 120 supplies the operating capacity RRG1 of microgrid 130, which is the difference between the operating capacity R130 and the operating capacity R130int. When microgrids 130 and 150 are connected in parallel, microgrid 150 supplies the operating capacity RRG2 of microgrid 130, which is the difference between the operating capacity R130 and the operating capacity R130int.

[0130] In some embodiments, the protection curve NCC is used to plot the relationship between the current supplied by the power grid system 400 and time when microgrids 120 and 130 are connected in parallel to form microgrid group G1, or when microgrids 130 and 150 are connected in parallel to form microgrid group G2.

[0131] Unless otherwise specified, the terms used herein generally have their ordinary meaning in the context of this art, the content of this disclosure, and the specific content thereof. Certain terms used to describe this disclosure will be discussed elsewhere in this specification to provide additional guidance to those skilled in the art in describing this disclosure.

[0132] While specific embodiments of the present disclosure have been disclosed in relation to the above embodiments, these embodiments are not intended to limit the present disclosure. Various alternatives and modifications can be made by those skilled in the art without departing from the principles and spirit of the present disclosure. Therefore, the scope of protection of the present disclosure is determined by the appended claims.

Claims

1. A power grid system, characterized in that, include: A first microgrid, coupled to a first power unit; A second microgrid, coupled to a second power unit; A first switch is electrically connected between the first microgrid and the second microgrid, and coupled to a third power device; A controller is coupled to the first power device, the second power device and the third power device; as well as A first element and a second element are respectively coupled to the first power device and the second power device. The first power device and the second power device are respectively used to detect the first component and the second component to determine whether the first microgrid and the second microgrid have malfunctioned, and When one of the first microgrid and the second microgrid fails, the third power device is used to activate the first switch.

2. The power grid system according to claim 1, characterized in that, The first power device is used to measure a first current and a first voltage of the first element, and the second power device is further used to measure a second current and a second voltage of the second element. The system determines whether a fault has occurred in the first microgrid based on the first current and the first voltage, and determines whether a fault has occurred in the second microgrid based on the second current and the second voltage.

3. The power grid system according to claim 2, characterized in that, When the first current is greater than a threshold current, or when the first voltage is less than the second voltage of the second microgrid, the first power device detects the first element to determine that the first microgrid has malfunctioned.

4. The power grid system according to claim 3, characterized in that, When the second current is greater than the threshold current, or when the second voltage is less than the first voltage of the first microgrid, the second power device detects the second element to determine that the second microgrid has malfunctioned.

5. The power grid system according to claim 1, characterized in that, Also includes: A main power grid is coupled to the first microgrid and the second microgrid via a second switch and a third switch, respectively, and is used to supply power to the first microgrid and the second microgrid; The controller controls the first and second power devices through multiple signals. When the first power device determines that the first microgrid has failed, the controller controls the first power device to disconnect from the second switch via a first signal among the plurality of signals.

6. The power grid system according to claim 5, characterized in that, When the second power device determines that the second microgrid has failed, the controller controls the second power device to disconnect from the third switch via a second signal among the plurality of signals.

7. The power grid system according to claim 2, characterized in that, When a fault occurs in either the first microgrid or the second microgrid, the controller further determines whether the margin of the other microgrid is sufficient. When the margin of the first microgrid and the other of the second microgrid is sufficient, the controller activates the first switch, and the other of the first microgrid and the second microgrid supplies power to the first microgrid and the other of the second microgrid.

8. The power grid system according to claim 7, characterized in that, When the first microgrid fails and the second current is less than a second maximum current, the controller determines that the margin of the second microgrid is sufficient, and When the second current equals the second maximum current, the controller determines that the margin of the second microgrid is insufficient.

9. The power grid system according to claim 8, characterized in that, When the second microgrid experiences a fault and the first current is less than a first maximum current, the controller determines that the margin of the first microgrid is sufficient, and When the first current equals the first maximum current, the controller determines that the margin of the first microgrid is insufficient.

10. The power grid system according to claim 5, characterized in that, The first power unit, the second power unit, and the controller transmit the plurality of signals to each other via a fiber optic network and in accordance with an electrical interoperability standard IEC 61850.

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