Isolated grid energy control method and system

Abstract

This application discloses an islanded grid energy control method and system, belonging to the field of energy management and control technology. The islanded grid energy control method includes: acquiring grid topology information and operating condition information collected by terminal devices through a transmission device; dividing the grid into at least one islanded grid based on the topology information; determining the operating state of each islanded grid based on the operating condition information; wherein the operating state includes a steady-state state and a transient state; determining the control command for each islanded grid based on its operating state; and transmitting the control command to the terminal device corresponding to each islanded grid through the transmission device, so that the terminal device maintains the frequency and voltage of each islanded grid at target values ​​according to the control command. This application achieves rapid coordinated control of resources such as gas turbines and loads within the grid during transient steady-state operation, significantly improving the operational stability and power supply reliability of the islanded grid system under various disturbances.

Description

Technical Field

[0001] This application relates to the field of energy management and control technology, specifically to an isolated grid energy control method and system. Background Technology

[0002] The Power Management System (PMS) is a key support system for ensuring the stable and economical operation of the power grid. It achieves coordinated scheduling of power generation and load through centralized monitoring and intelligent dispatching.

[0003] However, isolated power grids lacking external grid support suffer from low inertia and weak disturbance immunity. Their frequency and voltage stability depend heavily on the regulation performance and coordination capabilities of their limited internal generating units. When large-capacity load fluctuations occur in an isolated grid, if the power management system (PMS) responds slowly or poorly, it can easily trigger severe frequency and voltage fluctuations, power oscillations, or even power outages. Therefore, higher demands are placed on the dynamic response speed and multi-unit coordination capabilities of the PMS. Gas turbines, due to their excellent rapid start-up and load regulation performance, have become the core power source for isolated grid operations in offshore oil and gas platforms, islands, remote mining areas, and important industrial bases.

[0004] In recent years, various energy management methods related to gas turbine power generation and islanded or microgrid operation have emerged. These energy management methods mostly focus on single-dimensional objectives, such as power distribution or passive protection against specific faults. They are functionally limited and cannot achieve coordinated control of islanded grids. Summary of the Invention

[0005] This application provides an islanded grid energy control method and system, which realizes rapid coordinated control of resources such as gas turbines and loads during transient steady-state operation, and significantly improves the operational stability and power supply reliability of the islanded grid system under various disturbances.

[0006] In a first aspect, embodiments of this application provide an islanded grid energy control method, applied to a main control device of an islanded grid energy control system. The islanded grid energy control system includes the main control device, a transmission device, and a terminal device. The method includes: acquiring grid topology information and operating condition information collected by the terminal device through the transmission device; dividing the grid into at least one islanded grid based on the topology information; determining the operating state of each islanded grid based on the operating condition information; wherein the operating state includes a steady-state state and a transient state; determining a control command for each islanded grid based on the operating state of each islanded grid; and sending the control command to the terminal device corresponding to each islanded grid through the transmission device, so that the terminal device maintains the frequency and voltage of each islanded grid at a target value according to the control command.

[0007] Secondly, embodiments of this application provide an islanded grid energy control system, the system comprising: a main control device, a transmission device, and a terminal device; the terminal device is configured to: collect grid topology information and operating condition information; the main control device is configured to: divide the grid into at least one islanded grid based on the topology information and the operating condition information, and determine the operating state of each islanded grid; wherein the operating state includes a steady-state state and a transient state; the main control device is further configured to: determine a control command for each islanded grid based on the operating state of each islanded grid; the transmission device is configured to: send the grid topology information and operating condition information collected by the terminal device to the main control device; the transmission device is further configured to: issue the control command to the terminal device corresponding to each islanded grid, so that the terminal device maintains the frequency and voltage of each islanded grid at a target value according to the control command.

[0008] The technical solution provided in this application involves a main control device acquiring grid topology and operating condition information collected by a terminal device via a transmission device. Based on this, the main control device adaptively divides the grid into at least one isolated network according to the topology and operating condition information, and determines the steady-state or transient operating state of each isolated network. This allows the control strategy to accurately match the actual operating conditions of different isolated networks, avoiding the failure risk of a single control mode under complex conditions. Furthermore, the main control device generates appropriate control commands for different operating states of each isolated network and sends them to the corresponding terminal device for execution via the transmission device. This achieves differentiated and coordinated control of transient steady-state conditions in multi-isolated network scenarios, ultimately ensuring that the frequency and voltage of each isolated network can be effectively maintained at the target value. This application fully utilizes the rapid controllability characteristics of gas turbines to achieve rapid coordinated control of resources such as gas turbines and loads within the grid during transient steady-state operation, significantly improving the operational stability and power supply reliability of the isolated network system under various disturbances. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of the structure of an isolated grid energy control system provided in an embodiment of this application; Figure 2 This is a schematic diagram of another isolated grid energy control system provided in an embodiment of this application; Figure 3 A schematic flowchart illustrating an isolated grid energy control method provided in an embodiment of this application; Figure 4 A schematic diagram of the main electrical wiring of a gas turbine islanded network is provided for an embodiment of this application; Figure 5 A schematic diagram illustrating an implementation method of a load frequency control submodule provided in an embodiment of this application; Figure 6 A schematic diagram illustrating an implementation method of an automatic voltage control module provided in an embodiment of this application; Figure 7 This is a schematic flowchart of another isolated grid energy control method provided in an embodiment of this application.

[0011] Figure label: 100. Main control device; 200. Transmission device; 300. Terminal device; 110. Main station stability control; 120. Coordinated control of the main station; 210. Coordinated control remote terminal; 220. Stabilization control substation; 310. Unit control panel. Detailed Implementation

[0012] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0013] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0014] The use of "applies to" or "configured to" in this application implies open and inclusive language, which does not exclude the applicability to or configuration to devices performing additional tasks or steps. Additionally, the use of "based on" implies openness and inclusivity, because processes, steps, calculations, or other actions "based on" one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0015] In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0016] Please see Figure 1 , Figure 1 This is a schematic diagram of an isolated grid energy control system provided in an embodiment of this application. Figure 1 As shown, the isolated grid energy control system includes a main control device 100, a transmission device 200, and a terminal device 300.

[0017] The terminal device 300 is used to collect power grid topology information and operating condition information.

[0018] The main control device 100 is used to: divide the power grid into at least one isolated network based on topology information and operating condition information, and determine the operating state of each isolated network; wherein the operating state includes steady state and transient state.

[0019] The main control device 100 is also used to: determine the control commands for each isolated network based on the operating status of each isolated network.

[0020] The transmission device 200 is used to send the power grid topology information and operating condition information collected by the terminal device 300 to the main control device 100.

[0021] The transmission device 200 is also used to: send control commands to the terminal device 300 corresponding to each island network, so that the terminal device 300 maintains the frequency and voltage of each island network at the target value according to the control commands.

[0022] In some embodiments, the main control device 100 includes a stable control master station 110 and a coordinated control master station 120; the stable control master station 110 and the coordinated control master station 120 are connected in communication and are used to alternately execute steady-state control commands and transient control commands according to the operating status of the isolated network.

[0023] Communication between the stability control master station 110 and the coordination control master station 120 adopts the IEC61850 GOOSE fast protocol to achieve millisecond-level status information exchange. The stability control master station 110 and the coordination control master station 120 switch between steady-state control commands and transient control commands based on the isolated network's operating state. Specifically, when the isolated network is in a steady-state state, the coordination control master station 120 executes steady-state control commands; when the isolated network is in a transient state, the stability control master station 110 executes transient control commands and blocks the steady-state control commands of the coordination control master station 120. Through the alternating execution of the stability control master station 110 and the coordination control master station 120, the isolated network can be controlled adaptively in any operating state.

[0024] For further details regarding the steps performed by the main control device 100, the transmission device 200, and the terminal device 300, and their beneficial effects, please refer to the following method embodiments, which will not be elaborated upon here.

[0025] Please see Figure 2 , Figure 2 This is a schematic diagram of another isolated grid energy control system provided in an embodiment of this application. Figure 2 As shown, the main control device 100 in this system is a programmable logic controller (PLC) control master station (master station layer), the transmission device 200 is a PLC remote terminal station (substation layer), and the terminal device 300 is a local control terminal (terminal layer).

[0026] The PLC control master station includes a stability control master station 110 and a coordination control master station 120. The stability control master station 110 and the coordination control master station 120 communicate via an optical transceiver using the IEC61850 GOOSE protocol. The PLC control master station has functions such as topology dynamic identification, power generation control, stability control coordination, generator output capacity calculation, priority management, and load suppression. By uniformly issuing transient and steady-state control commands to the PLC remote terminal stations, the PLC control master station can achieve coordinated power control.

[0027] The master control station 120 is responsible for steady-state regulation and control during normal operation. The power grid operates in a normal state most of the time, with the master control station 120 handling steady-state regulation to cope with minor disturbances.

[0028] The stability control master station 110 is responsible for transient emergency control under fault conditions. When faults such as unit tripping, main transformer tripping, or large load loss occur, the stability control master station 110 executes transient emergency control according to the stability control strategy. During the stability control action, the coordination control master station 120 is locked, and the output of the coordination control master station 120 is in a hold state. The coordination control master station 120 is unlocked after the stability control action is completed.

[0029] The PLC remote terminal station includes a coordination control remote terminal 210 and a stability control substation 220. The coordination control remote terminal 210 and the stability control substation 220 are installed on the gas turbine side and the load side, respectively, and are responsible for accessing resource information such as power sources, grid, and loads, as well as decomposing and distributing commands from higher levels. The coordination control remote terminal 210 completes the access and statistical processing of unit information downstream and sends relevant information to the coordination control master station 120; it also receives power commands from the PLC control master station upstream and completes their distribution, realizing rapid power control of the load and the unit.

[0030] The stability control substation 220 is used to receive remote commands from the upper-level stability control master station 110 and issue cut-off or adjustment commands to the local control terminal. The coordination control remote terminal 210 and the stability control substation 220 have local automatic control functions. When communication with the PLC control master station is interrupted, they can independently execute control of the lower-level equipment according to the preset strategy.

[0031] The local control terminal includes the gas turbine unit control panel (UCP) 310, excitation control system, load switch cabinet, etc. It is used to quickly collect and identify the operating conditions of the power generation unit, and send the power generation unit operating information required for millisecond-level emergency control to the stability control substation 220. The local control terminal is also used to receive load shedding commands or power regulation commands issued by the PLC remote substation, and send them to the controlled unit itself via hardwiring.

[0032] The PLC control master station communicates with the gas turbine unit control panel (UCP) 310 via Modbus RTU / TCP, with some important signals connected via hardwiring. Communication between modules in the isolated grid energy control system uses industry-standard communication protocols for data exchange, including but not limited to Modbus, 101, 103, 104, and IEC 61850 standard communication protocols.

[0033] Please see Figure 3 , Figure 3 This is a flowchart illustrating an islanded grid energy control method provided in an embodiment of this application. This islanded grid energy control method is applied to the main control device of the aforementioned islanded grid energy control system, such as... Figure 3 As shown, the method includes the following steps S310 to S350.

[0034] S310. Obtain power grid topology information and operating condition information collected by the terminal device through the transmission device.

[0035] S320. Divide the power grid into at least one isolated network based on topology information.

[0036] S330. Determine the operating status of each isolated network based on the operating condition information; wherein, the operating status includes steady state and transient state.

[0037] S340. Based on the operating status of each isolated network, determine the control instructions for each isolated network.

[0038] S350: The control command is sent to the terminal device corresponding to each islanded network through the transmission device, so that the terminal device maintains the frequency and voltage of each islanded network at the target value according to the control command.

[0039] Power grid topology information refers to a set of data describing the electrical connection structure of a power grid. This may include the open / closed status of bus tie switches, sectionalizing switches, disconnectors in each incoming and outgoing line bay, tie line switches, and transformer tap positions. Power grid topology information reflects the current physical connection method of the power grid and is the fundamental basis for determining whether and how the power grid can be divided into multiple isolated networks.

[0040] Operating condition information refers to a data set reflecting the real-time operating status of each power generation unit and power consumption unit in the power grid. This information can include the active power, reactive power, terminal voltage, current, frequency, unit operating or shutdown status, current maximum output capacity, unit temperature, fuel quantity, load power, power factor, load priority setting, and load switching status of each power consumption unit. Operating condition information reflects the current dynamic operating status of the power grid and is the data basis for determining the islanded grid operating status and generating control commands.

[0041] In this application's embodiments, an isolated grid refers to a small power system that operates independently, balancing power generation and consumption, without electrical connection to the external power grid or with disconnected tie lines. Isolated grids are characterized by low inertia, weak disturbance rejection capability, and frequency and voltage stability dependent on the regulation performance of internal units. When the regional power grid bus tie switch is disconnected, the originally unified power grid may be divided into multiple electrically isolated isolated grids, each independently balancing power generation and consumption.

[0042] Operating status characterizes the current dynamic stability level of an isolated grid, including steady-state and transient states. The steady-state state refers to the isolated grid operating normally or under minor disturbances, where frequency deviation is within a small range, voltage deviation is within acceptable limits, and no serious events such as tripping or large load loss occur. In the steady-state state, the isolated grid can maintain frequency and voltage stability through continuous power dispatching.

[0043] Transient state refers to a state where an isolated grid is in operation due to a fault or major disturbance. In this state, the frequency or voltage deviation is significantly beyond the allowable range, or serious events such as unit tripping, main transformer tripping, or large load loss have occurred. In transient state, the isolated grid needs to take emergency control measures (such as load shedding, generator shedding, and power rollback) to quickly restore stability.

[0044] The target value refers to the control objective for islanded grid operation, including the target frequency and target voltage values. In one embodiment of this application, the target frequency is the rated frequency of 50Hz, and the target voltage is the rated voltage (e.g., 220kV). The target frequency value can be a fixed value (e.g., 50Hz) or a set value that is dynamically adjusted according to operating conditions. The ultimate goal of the terminal device executing control commands is to maintain the frequency and voltage of the islanded grid near the target values.

[0045] The terminal device collects grid topology information and operating condition information in the power grid in real time, and uploads the collected grid topology information and operating condition information to the main control device via a transmission device.

[0046] The main control unit divides the power grid into at least one electrically isolated sub-region based on the switch and disconnector status in the power grid topology information. Each sub-region corresponds to an islanded grid area. Based on the disconnector status of all incoming and outgoing line bays within that sub-region, the unit determines which sub-region the power generation or consumption unit connected to that bay belongs to, thus completing the islanded grid division.

[0047] When the master control device determines that the isolated grid is in a steady state, the coordination control master station in the master control device executes steady-state control and generates steady-state control commands. When the master control device determines that the isolated grid is in a transient state, the stability control master station in the master control device executes transient control and generates transient control commands.

[0048] The main control device sends the generated steady-state control command or transient control command to the terminal device corresponding to each islanded network via the transmission device, so that the terminal device can maintain the frequency and voltage of each islanded network at the target value according to the control command.

[0049] In this embodiment, when the isolated network switches from a steady-state state to a transient state, the stability control master station, after determining the transient event, immediately sends a blocking signal to the coordination control master station via the GOOSE protocol. Upon receiving the blocking signal, the coordination control master station retains its output at the current value and does not issue new steady-state scheduling instructions. Then, the stability control master station takes over control, generates and executes transient control instructions. This rapid switching mechanism ensures that steady-state control instructions are blocked immediately upon the occurrence of a transient event, allowing transient control instructions to be executed without interference.

[0050] When an isolated grid transitions from a transient state to a steady state, the stability control master station, after determining the end of the transient process, sends an unlock signal to the coordination control master station via the GOOSE protocol. Upon receiving the unlock signal, the coordination control master station recalculates power dispatch based on the current grid operating state, generates new power dispatch instructions, and issues them for execution. Since some loads or generating units may have been disconnected during the transient process, the new equilibrium point may differ from the pre-transient equilibrium point. The coordination control master station automatically adapts to this change, achieving steady-state control under the new operating state.

[0051] Therefore, the main control device can achieve a smooth transition of control commands when switching operating states.

[0052] The technical solution provided in this application involves a main control device acquiring grid topology and operating condition information collected by a terminal device via a transmission device. Based on this, the main control device adaptively divides the grid into at least one isolated network according to the topology and operating condition information, and determines the steady-state or transient operating state of each isolated network. This allows the control strategy to accurately match the actual operating conditions of different isolated networks, avoiding the failure risk of a single control mode under complex conditions. Furthermore, the main control device generates appropriate control commands for different operating states of each isolated network and sends them to the corresponding terminal device for execution via the transmission device. This achieves differentiated and coordinated control of transient steady-state conditions in multi-isolated network scenarios, ultimately ensuring that the frequency and voltage of each isolated network can be effectively maintained at the target value. Therefore, this application fully utilizes the rapid controllability characteristics of gas turbines to achieve rapid coordinated control of resources such as internal combustion engines and loads during transient steady-state operation, significantly improving the operational stability and power supply reliability of the isolated network system under various disturbances.

[0053] In some embodiments, S320 includes the steps S321 and S322.

[0054] S321. Divide the power grid into at least one isolated grid according to the switch status and disconnector status within the power grid; wherein the switch status includes at least one of the following: bus tie switch status, sectional switch status, and bay switch status.

[0055] S322. Based on the status of the disconnect switches in the line bays of the power generation units or power consumption units within the power grid, assign the power generation units or power consumption units to the corresponding isolated grids.

[0056] In one embodiment of this application, the main control device divides the regional power grid into n isolated grids in real time according to the status of bus tie switches, sectionalizing switches, bay switches and disconnectors within the power grid area, and assigns the unit to the corresponding isolated grid control center according to the status of the disconnectors of the power generation or power consumption unit line bays.

[0057] Specifically, the main control device performs orphanage adaptive partitioning according to the following steps: The first step is for the main control unit to extract the real-time status of all bus tie switches and sectionalizing switches from the power grid topology information. Bus tie switches are switching devices that connect different bus sections at the same voltage level, while sectionalizing switches are switching devices that connect different sections of the same bus. The status of these two types of switches directly determines the connectivity structure of the power grid.

[0058] The second step involves the main control device using the closed bus tie switch and sectionalizing switch as connection paths to divide the regional power grid into at least one electrically isolated sub-region.

[0059] The third step involves the main control device extracting the disconnector status of all incoming and outgoing line bays within each sub-region from the power grid topology information. A bay refers to a complete electrical circuit connecting a power generation unit or power consumption unit to the busbar, including equipment such as circuit breakers, disconnectors, and instrument transformers. The status of the bay's disconnectors determines which sub-region the power generation unit or power consumption unit connected to that bay belongs to.

[0060] Fourth, the main control device assigns each power generation unit and power consumption unit to its corresponding sub-region based on the status of the disconnectors, forming independent isolated grids. Each isolated grid corresponds to an isolated grid control center. Each isolated grid contains a set of power generation units, a set of power consumption units, and the internal transmission and distribution network connecting them. Each isolated grid independently performs power generation and consumption balance control, unaffected by other isolated grid control centers.

[0061] In one embodiment of this application, when the switch state changes (e.g., the bus tie switch changes from closed to open), the main control device re-executes the above-mentioned partitioning steps, thereby achieving dynamic adaptive adjustment of the number of islanded grids. This dynamic partitioning mechanism enables the islanded grid energy control system to automatically adapt to changes in the grid structure and complete partition reconfiguration without manual intervention.

[0062] Please see Figure 4 , Figure 4 This is a schematic diagram of the main electrical wiring of a gas turbine islanded network, provided as an embodiment of this application. Figure 4 As shown, the power grid has a dual-busbar segmented structure, comprising Bus I and Bus II, and includes multiple gas turbine units. When the bus tie switch is closed, Bus I and Bus II are connected as a unified electrical system. The main control device divides the entire regional power grid into one isolated grid control center, to which all generating and consuming units belong. When the bus tie switch is open, Bus I and Bus II are electrically isolated from each other, forming two independent electrical systems. At this time, the regional control will separate into two isolated grid control centers according to the actual number of isolated grids, and assign each generating or consuming bay to the corresponding isolated grid according to the status of the disconnect switches of each incoming and outgoing line bay, so as to dynamically realize the transient steady-state control of the two isolated grids, including frequency load balancing, automatic voltage control, generator available capacity calculation, and generator shedding and load shedding.

[0063] In some embodiments, when the operating state is steady state, the control command for each islanded network is determined based on the operating state of each islanded network, including: determining the required power for each islanded network; the required power includes required active power or required reactive power; determining the steady-state control command for each islanded network based on the required power for each islanded network and the network state of the islanded network; wherein the steady-state control command includes frequency control command and voltage control command.

[0064] In this embodiment, the network state of an isolated grid is used to characterize the electrical connection between the isolated grid and the external network. In one embodiment, the network state includes grid-connected state and isolated state. Grid-connected state refers to the operating state where the isolated grid is connected to the external power grid via a tie line and can exchange power with the external power grid. In grid-connected state, the frequency and voltage of the isolated grid are supported by the external power grid, and the main control objective is to maintain the tie line exchange power at the planned value. Isolated state refers to the operating state where the isolated grid is completely disconnected from the external power grid and operates independently relying on internal power sources. In isolated state, the frequency and voltage of the isolated grid are entirely determined by the internal generator sets, and the main control objective is to maintain the frequency and voltage at their rated values.

[0065] Required active power refers to the total amount of active power generation that needs to be increased or decreased to restore and maintain the islanded grid frequency at its rated value (e.g., 50Hz), calculated by the system. When the islanded grid frequency is lower than the rated value, the required active power is positive, indicating that increased power generation is needed; when the islanded grid frequency is higher than the rated value, the required active power is negative, indicating that decreased power generation is needed. Required reactive power refers to the total amount of reactive power generation that needs to be increased or decreased to restore and maintain the islanded grid voltage at its rated value (e.g., 220kV), calculated by the system. When the islanded grid voltage is lower than the rated value, the required reactive power is positive, indicating that increased reactive power output (i.e., increased excitation) is needed; when the islanded grid voltage is higher than the rated value, the required reactive power is negative, indicating that decreased reactive power output (i.e., decreased excitation) is needed. Steady-state control commands refer to the continuous adjustment commands issued by the main control device when the islanded grid is in a steady-state state.

[0066] In this embodiment, based on different network states of the isolated network, the required active power or required reactive power corresponding to different isolated networks can be calculated. The deviation of the required active power from the sum of the active power setpoints of the gas turbines, or the deviation of the required reactive power from the sum of the reactive power setpoints of the gas turbines, is dynamically corrected by the gas turbine regulation coefficient and then distributed to the unit control panels of each gas turbine to adjust the governor and exciter, thereby maintaining the isolated network frequency and voltage at the target values.

[0067] In some embodiments, when the steady-state control command is a frequency control command, determining the steady-state control command of each islanded network based on the required power of each islanded network and the network state of the islanded network includes: if there is a tie line in the islanded network, determining the required active power based on the tie line exchange deviation; determining a first deviation value of the sum of the required active power and the gas turbine active power setpoint; correcting the first deviation value based on the gas turbine regulation coefficient; and determining a first frequency control command for the islanded network based on the corrected first deviation value; the first frequency control command is used to control the governor of the gas turbine unit to maintain the frequency of the islanded network at the target frequency value.

[0068] A tie line is a transmission line that connects an isolated grid to the external power grid. Through tie lines, the isolated grid can exchange active and reactive power with the external power grid.

[0069] The sum of the active power setpoints for gas turbines refers to the target active power output value set by operators or the upper-level dispatch system for each gas turbine generator unit. This setpoint can be the optimal output value given by the economic dispatch plan, or it can be a value manually set by operators based on the current operating conditions.

[0070] The Regulation Participation Factor (RPF) is a parameter used to determine the proportion of power regulation tasks assigned to each gas turbine unit. The value of RPF determines how power deviations are distributed among the units. The value of RPF is typically between 0 and 1, and the sum of the RPF values ​​of all participating gas turbine units is 1.

[0071] The governor is used to regulate the fuel supply of the gas turbine, thereby controlling the unit's speed and output, and ultimately controlling the frequency of isolated grid operation.

[0072] If a tie line exists in the isolated network, the required active power is determined by the tie line exchange deviation. This tie line exchange deviation can be acquired in real time by power measurement devices installed at both ends of the tie line. Next, the first deviation value is calculated between the required active power and the gas turbine active power setpoint. This first deviation value is then corrected using the gas turbine regulation coefficient to obtain the first frequency control command. The gas turbine governor is then controlled via this first frequency control.

[0073] The embodiments of this application achieve precise control of power exchange between the islanded grid and the external power grid through an adjustment mechanism based on tie-line exchange deviation.

[0074] In some embodiments, when the steady-state control command is a frequency control command, determining the steady-state control command of the isolated network based on the required power of each isolated network and the network state of the isolated network includes: if there is no tie line in the isolated network, determining the required active power based on the regional bus frequency deviation of each isolated network; determining a second deviation value of the sum of the required active power and the gas turbine active power setpoint; correcting the second deviation value based on the gas turbine regulation coefficient; and determining a second frequency control command for the isolated network based on the corrected second deviation value; the second frequency control command is used to control the governor of the gas turbine unit to maintain the frequency of the isolated network at the target frequency value.

[0075] An isolated grid without a tie line means that there is no electrical connection between the isolated grid and the external power grid, and the grid operates entirely independently relying on its internal power source. This operating mode is common in scenarios where offshore oil and gas platforms, islands, remote mining areas, and important industrial base facilities cannot be connected to a main power grid. Without a tie line, the frequency of the isolated grid is entirely determined by its internal generators, without frequency support from the external power grid.

[0076] The regional bus frequency deviation represents the difference between the actual frequency and the target frequency value of the isolated network bus. This deviation can be acquired in real time by a frequency measurement device installed at the bus. The required active power of the isolated network can be calculated from the regional bus frequency. A second deviation value is then calculated, which is the sum of the required active power and the gas turbine active power setpoint. This second deviation value is then corrected using the gas turbine regulation coefficient, resulting in the second frequency control command used to control the gas turbine governor.

[0077] This application embodiment achieves autonomous control of islanded network frequency through a direct adjustment mechanism based on regional bus frequency deviation.

[0078] In some embodiments, when the steady-state control command is a voltage control command, determining the steady-state control command of each islanded network based on the required power of each islanded network and the network state of the islanded network includes: if there is a tie line in the islanded network, determining the required reactive power based on the power factor deviation; determining a third deviation value of the sum of the required reactive power and the gas turbine reactive power setpoint; correcting the third deviation value based on the gas turbine regulation coefficient; and determining a first voltage control command for the islanded network based on the corrected third deviation value; the first voltage control command is used to control the exciter of the gas turbine unit to maintain the bus voltage of the islanded network at a target voltage value.

[0079] Power factor is a parameter that measures the ratio of active power to apparent power in a power system, defined as the ratio of active power to apparent power. Power factor deviation refers to the difference between the actual power factor and the target power factor on a tie line.

[0080] The exciter is used to provide DC excitation current to the rotor windings of the generator, thereby establishing a magnetic field in the generator's air gap. The response speed and regulation accuracy of the exciter directly determine the effectiveness of voltage control.

[0081] In this embodiment of the application, when a tie line exists in an islanded network, the required reactive power is calculated based on the power factor deviation. Then, a third deviation value is calculated based on the sum of the required reactive power and the gas turbine reactive power setpoint. The third deviation value is corrected using the gas turbine regulation coefficient to obtain a first voltage control command, and the exciter is controlled based on the first voltage control command.

[0082] The embodiments of this application achieve precise control of reactive power exchange in tie lines through an adjustment mechanism based on power factor deviation.

[0083] In some embodiments, when the steady-state control command is a voltage control command, determining the steady-state control command of each islanded network based on the required power of each islanded network and the network state of the islanded network includes: if there is no tie line in the islanded network, determining the required reactive power based on the regional voltage deviation of each islanded network; determining a fourth deviation value of the sum of the required reactive power and the gas turbine reactive power setpoint; correcting the fourth deviation value based on the gas turbine regulation coefficient; and determining a second voltage control command for the islanded network based on the corrected fourth deviation value; the second voltage control command is used to control the exciter of the gas turbine unit to maintain the bus voltage of the islanded network at the target voltage value.

[0084] Regional voltage deviation refers to the difference between the actual voltage and the target voltage value of the isolated network bus.

[0085] When there are no tie lines in the islanded grid, the voltage of the islanded grid is entirely determined by the reactive power output of the internal generator units. Therefore, the coordinated control master station directly determines the required reactive power based on the deviation between the actual voltage of the islanded grid bus and the target voltage value. After determining the required reactive power, a fourth deviation value is calculated, which is the sum of the required reactive power and the gas turbine reactive power setpoint. This fourth deviation value is then corrected using the gas turbine regulation coefficient to obtain the second voltage control command, and the exciter is controlled based on the second voltage control command.

[0086] In this embodiment, autonomous control of the isolated grid voltage is achieved through a direct adjustment mechanism based on regional voltage deviation.

[0087] For example, when the power grid is under normal operating conditions with minor disturbances, the coordinated control master station generates steady-state dispatch commands through the generation control module. The generation control module includes a load frequency control submodule and an automatic voltage control submodule.

[0088] Please see Figure 5 , Figure 5This is a schematic diagram illustrating an implementation method for a load frequency control submodule provided in an embodiment of this application. Figure 5 As shown, each islanded grid control center performs frequency regulation and load sharing for the regional power grid and conducts scheduling to maintain the frequency at the rated value. Multiple gas turbines within the islanded grid each have independent unit control panels capable of receiving and executing setpoint commands for external power or voltage, and can continuously adjust between their minimum stable load and rated power.

[0089] In this embodiment, the isolated network includes tie lines, which can be used to switch between grid-connected and weak network states. The required active power is calculated by the area control signal processor based on the tie line switching deviation.

[0090] If there is no tie line, it is a completely isolated network, and the deviation calculation uses the regional bus frequency deviation of each isolated network. The deviation between the required active power and the sum of the active power setpoints of the gas turbines is distributed to each gas turbine unit after being corrected by the Regulation Participation Factor (RPF) of each gas turbine.

[0091] In some embodiments, the gas turbine regulation coefficient is determined based on the operating mode of the gas turbine unit in an isolated grid; when the gas turbine unit operates in a zero-error isolated grid mode, the rated frequency of the bus is used as the target frequency value; when the gas turbine unit operates in a differential droop mode, the gas turbine regulation coefficient is determined according to the operating status of the gas turbine unit.

[0092] In some embodiments, when a gas turbine unit operating in the isolated grid mode is disconnected or shut down, the operating mode of another gas turbine unit is set to the isolated grid mode according to priority.

[0093] All gas turbine units are assigned an ISO (Independent Isolated Grid) mode priority. The unit with the highest priority number switches to ISO mode, while other units remain in DROOP mode. If an ISO unit is disconnected or shut down, another unit is automatically switched to ISO mode according to priority. If the ISO priority of all units is set to zero, all units will remain in DROOP mode. When the active power deviation exceeds the frequency dead zone, the isolated grid energy control system dynamically sets the RPF (Resource Power Distribution Function) power deviation based on the unit's operating conditions and sends load increase / decrease commands to the control panels of each DROOP unit to restore the bus frequency to near its rated value. ISO mode units always send the rated frequency as the target value to the UCP (Unified Power Controller). In the event of a disturbance, the system coordinates ISO and DROOP units, prioritizing ISO units to ensure sufficient power reserve.

[0094] Please see Figure 6 , Figure 6This is a schematic diagram illustrating an implementation method of an automatic voltage control module provided in an embodiment of this application. Figure 6 As shown, this embodiment includes a tie line, and the required reactive power is calculated by the regional control signal processor based on the power factor deviation. If there is no tie line, the deviation is calculated using the regional voltage deviation. The deviation between the required reactive power and the sum of the regional gas turbine reactive power setpoints is corrected by the RPF and then distributed to each gas turbine unit. After the reactive power deviation is superimposed on the gas turbine units, a reactive power regulation command is sent to adjust the exciter to maintain the bus voltage at the rated value of 220kV.

[0095] In some embodiments, the power adjustment for each gas turbine unit in the steady-state control command is less than or equal to the current available capacity corresponding to that gas turbine unit; the current available capacity is determined based on the minimum of the following: the power limit set by the user, the generator output diagram, and the maximum working capacity of the generator.

[0096] In this embodiment, the main control device cannot exceed the output capacity boundary of the gas turbine unit when distributing power commands. Therefore, the aforementioned isolated grid energy control system also includes a generator capacity calculation module.

[0097] The available capacity is either active power reserve or reactive power reserve, and this value is the minimum of the following three factors: (1) User-input limit. The interactive screen of the isolated grid energy control system provides a way to manually set the active power output limit and reactive power output limit. The energy management system will not allocate loads outside these boundaries; (2) Maximum active power capacity of the generator. The calculation of the generator's active power capacity is completed by the generator UCP. The UCP calculates the maximum active power capacity at the current moment based on factors such as ambient temperature, atmospheric pressure, and fuel calorific value, and sends it to the isolated grid energy control system for active power reserve calculation; (3) Generator output diagram. The generator output diagram is the generator PQ capacity curve, through which the maximum reactive power capacity corresponding to the current active power output can be obtained. By selecting the minimum of the above three factors, the current active power reserve or reactive power reserve can be calculated. Among them, the generator PQ capacity curve is a relationship curve describing the maximum reactive power (Q) capacity that a synchronous generator can safely provide under different active power (P) outputs.

[0098] In some embodiments, when the operating state is transient, control commands for each isolated grid are determined based on the operating state of each isolated grid, including: when the regional frequency of the isolated grid is less than a first frequency threshold, performing load shedding operations according to a preset priority until the difference between the required load shedding and the selected load shedding is within the active power setpoint range corresponding to the frequency dead zone boundary; when the regional frequency of the isolated grid is greater than a second frequency threshold, if the required back-off power is less than or equal to the current load shedding capacity, controlling the gas turbine unit to reduce power output according to the required back-off power; if the required back-off power is greater than the current load shedding capacity, performing a generator shedding operation according to a preset priority and the current unit output.

[0099] The current load shedding capacity refers to the total amount of electrical load that the system can actively cut off based on preset priorities at the current moment.

[0100] The process of disconnecting a gas turbine generator set refers to the emergency disconnection (de-connection) of one or more operating gas turbine generator sets from the grid by disconnecting the circuit breaker, so that they immediately stop supplying power to the grid.

[0101] The preset priority is a cut-off priority value set for each gas turbine unit. In one embodiment of this application, the preset priority value can be set to an integer from 1 to 100. Units with lower priority values ​​are cut off first during the cut-off operation, while units with higher priority values ​​have a higher retention priority and are less likely to be cut off.

[0102] When the power grid experiences significant disturbances or even a fault, it enters a transient state. In this situation, the stability control master station generates transient control commands through the stability control coordination module to achieve low-frequency load shedding and high-frequency power backoff. In this embodiment, the rated frequency is 50Hz, and the threshold is set to 1Hz. When the regional frequency deviation is within ±1Hz, the generation control module performs secondary frequency regulation to maintain frequency stability. When the regional frequency deviation exceeds ±1Hz, the stability control master station performs load shedding, power backoff, or even generator shutdown according to a preset priority.

[0103] For example, the first frequency threshold is 49 Hz and the second frequency threshold is 51 Hz.

[0104] For the low-frequency control submodule, when the regional frequency is <49Hz, the stabilization master station will shed loads according to preset priorities to maintain the regional frequency at the rated 50Hz. During this process, the stabilization master station will send a signal to block the power generation control module to prevent over-adjustment from causing system oscillations. According to the under-shedding principle, the load shedding module selects loads to be shed sequentially according to the set load priorities until the difference between the required load shedding and the selected load shedding is within the active power setpoint range corresponding to the frequency dead zone boundary. That is, (required load shedding - selected load shedding) ∈ [0, P]. s1 ]. Among them, P s1This is the active power setpoint corresponding to the frequency dead zone boundary. Once the regional frequency stabilizes and the stability control action is discontinued, the generation control continues to coordinate steady-state loads at the new equilibrium point.

[0105] For the high-frequency control submodule, when the regional frequency is >51Hz, the stability control master station will compare the back-off power value with the current load that can be shed (the difference between the current total regional output power and the lower limit of the regional adjustable power). If the back-off power is less than the current load that can be shed, the stability control will send a power back-off command to the power generation control module to quickly reduce the output and control the gas turbine unit to reduce the power output. If the power to be back-off is greater than the current load that can be shed, the tripping operation will be performed according to the preset priority and the current unit output.

[0106] In some embodiments, if the power to be rolled back is greater than the current load shedding capacity, a turbine shedding operation is performed according to a preset priority and the current unit output, including: determining candidate gas turbine units for which a turbine shedding operation is required based on the preset priority; determining the target gas turbine unit for the turbine shedding operation based on the output of each gas turbine unit among the candidate gas turbine units; performing a turbine shedding operation on the target gas turbine unit when the selected shedding amount corresponding to the target gas turbine unit is equal to the power to be rolled back; adjusting the target gas turbine unit according to the minimum over-cut amount and performing a turbine shedding operation on the adjusted target gas turbine unit when the selected shedding amount corresponding to the target gas turbine unit is greater than the power to be rolled back; and performing a load shedding operation based on the over-cut amount when the selected shedding amount corresponding to the target gas turbine unit is greater than the power to be rolled back.

[0107] Candidate gas turbine units refer to the set of gas turbine units that are selected according to preset priorities and may be cut off in this turbine cut-off operation.

[0108] The target gas turbine unit refers to the set of gas turbine units that are ultimately selected from the candidate gas turbine units to perform the turbine cut-off operation.

[0109] Selective shunting capacity refers to the total power generation removed from the isolated grid after the target gas turbine unit is disconnected.

[0110] Minimum over-cutting refers to the smallest positive difference between the selected cutting amount and the required power reduction during generator tripping operations. When the selected cutting amount is greater than the required power reduction, there is over-cutting (i.e., too much generating power is cut off). The principle of minimum over-cutting requires that, under the premise that the selected cutting amount is greater than or equal to the required power reduction, the selected cutting amount should be as close as possible to the required power reduction, that is, the over-cutting should be as small as possible, so as to reduce the impact on the normal operation of the isolated grid.

[0111] In this embodiment, candidate gas turbine units that can be cut off are first selected based on a preset priority. Then, the target unit for actual cut-off is selected based on the real-time output of each candidate unit. Subsequently, different processing is performed according to the relationship between the total amount of target unit to be cut off and the required power back to the system. If the two are exactly equal, the unit is cut off directly; if the amount to be cut off is insufficient, units are continuously added according to the minimum over-cut principle until the demand is met; if the amount to be cut off exceeds the required power back to the system, the excess power cut off (over-cut) is balanced through load shedding. When the regional frequency stabilizes and the stabilization control action is discontinued, the power generation control continues to coordinate steady-state load at the new equilibrium point, thereby minimizing the impact on the normal operation of the isolated grid and the impact on user power supply while ensuring that the frequency quickly recovers to a safe range.

[0112] In this embodiment, after determining that load shedding or generator shedding is necessary, the priority module sorts the loads according to priority after obtaining the target shedding amount, thereby selecting the loads or generators to be shedding. The priority module determines the priority setting value, which determines the probability of the unit being disconnected when the strategy is triggered. Taking loads as an example, loads with lower priority values ​​are selected for shedding first. Different priority settings can be set for different faults. When a tripping fault occurs, the islanded grid energy control system will immediately calculate the total power loss and generate the power shedding amount after confirming the fault occurrence.

[0113] The required power shedding is based on the power flow before the load or generator trips (usually 200ms before a fault). The stability control master station selects units to be shelved sequentially according to load priority until the selected shedding amount is greater than or equal to the required shedding amount. If the selected shedding amount exceeds a certain threshold of the required shedding amount, optimization measures will be adopted. The last n selected loads in the current scheme will be replaced to form a new combination to meet the required load shedding amount, as close as possible to the required shedding amount. When a load reduction is required, the stability control master station will match the load reduction target from low to high priority settings. If one or more generators are under manual control or prohibited from being shelved by the islanded grid energy control system, their priority should be set to 0.

[0114] For inductive loads like large electric motors, the reactive power demand at startup is typically 6 to 8 times the rated value. If the generator's reactive power output is insufficient, protection mechanisms may be triggered during startup. The load suppression module is mainly used to limit the startup of motor bays when the generator's reserve capacity is insufficient or to limit the increase in load on motor bays. The specific strategy is: if the generator set's reactive power reserve capacity - reactive power demand at the moment of large load startup - correction value > 0, then motor startup is allowed; otherwise, startup is suppressed.

[0115] Please see Figure 7 , Figure 7 This is a schematic flowchart of another islanded grid energy control method provided in an embodiment of this application. Figure 7As shown, the method specifically includes the following steps S701 to S709.

[0116] S701, Collect power grid topology information and operating condition information.

[0117] The terminal device collects power grid topology information and operating condition information, and the collected power grid topology information and operating condition information are uploaded to the main control device through the transmission device.

[0118] S702: Determine the power grid status, exchange information with the main control device, and complete the adaptive partitioning of multiple isolated networks.

[0119] S703, Determine the status of an isolated network.

[0120] Determine whether the isolated network is in a transient or steady state. If it is in a transient state, execute step S704; if it is in a steady state, execute step S705.

[0121] S704. Determine the cutting target based on the preset priority and the required cutting amount.

[0122] S705. Calculate the current available capacity.

[0123] S706, Generate steady-state control commands.

[0124] S707, Generate transient control instructions.

[0125] S708. The transmission device receives steady-state control commands or transient control commands and sends them to the terminal device.

[0126] S709. Determine if the frequency and voltage are stable. If stable, end the control process; if unstable, return to step S701.

[0127] The specific implementation methods and beneficial effects of the above steps S701 to S709 have been explained in the above embodiments and will not be repeated here.

[0128] The islanded grid energy control method and system provided in this application are adapted to the islanded grid characteristics of gas turbines, and possess the functions of distinguishing regional power grid operating states, identifying and coordinating action control, and providing rapid dynamic response for power distribution. The embodiments of this application include at least the following beneficial effects: (1) Through topology identification and dynamic partitioning, it is possible to simultaneously realize steady-state and transient coordinated action control of regional power grid in grid-connected, single-island and multi-island scenarios, overcoming application scenario limitations.

[0129] (2) The main station can dynamically perform power allocation and load reduction functions according to the unit's operating status, realize multi-unit collaborative control, and improve the overall regulation characteristics of the isolated grid system.

[0130] (3) The main control station judges the transient steady state of the power grid in real time and quickly exchanges status information with the coordination control station through the GOOSE protocol. Based on the power grid status, it promptly selects to perform steady-state power allocation or transient actions to maintain the stable operation of the isolated grid.

[0131] In summary, the embodiments of this application, by rapidly collecting and identifying the operating conditions of power generation or power consumption units, realize the optimized power allocation and load shedding of multiple gas turbine units, effectively suppress frequency fluctuations under impulsive loads, avoid power oscillations caused by inconsistent response paces of multiple gas turbine units, and improve the stability of islanded grid operation.

[0132] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0133] The above provides a detailed description of an isolated grid energy control method and system provided by the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for controlling energy in isolated grids, characterized in that, A main control device applied to an isolated grid energy control system, the isolated grid energy control system further including a transmission device and a terminal device; the method includes: The power grid topology information and operating condition information collected by the terminal device are obtained through the transmission device; Based on the topology information, the power grid is divided into at least one isolated network; The operating status of each isolated network is determined based on the operating condition information; wherein, the operating status includes a steady state and a transient state; Based on the operating status of each isolated network, the control instructions for each isolated network are determined; The control command is sent to the terminal device corresponding to each isolated network through the transmission device, so that the terminal device maintains the frequency and voltage of each isolated network at the target value according to the control command.

2. The method according to claim 1, characterized in that, The step of dividing the power grid into at least one isolated network based on the topology information includes: The power grid is divided into at least one isolated grid according to the switch status and disconnector status within the power grid; wherein the switch status includes at least one of the following: bus tie switch status, sectionalizing switch status, and bay switch status; Based on the disconnector status of the line bays of the power generation units or power consumption units within the power grid, the power generation units or power consumption units are assigned to the corresponding isolated grids.

3. The method according to claim 1, characterized in that, When the operating state is a steady state, determining the control command for each isolated network based on its operating state includes: Determine the required power for each of the aforementioned islanded networks; the required power includes the required active power or the required reactive power; The steady-state control command for each isolated network is determined based on the required power of each isolated network and the network status of the isolated network; wherein the steady-state control command includes a frequency control command and a voltage control command.

4. The method according to claim 3, characterized in that, When the steady-state control command is a frequency control command, determining the steady-state control command for each isolated network based on its required power and network status includes: If there are tie lines in the isolated network, the required active power is determined based on the tie line switching deviation; Determine the first deviation value of the sum of the required active power and the gas turbine active power setpoint; The first deviation value is corrected based on the gas turbine regulation coefficient, and a first frequency control command for the gas turbine is determined based on the corrected first deviation value; the first frequency control command is used to control the governor of the gas turbine unit to maintain the frequency of the isolated grid at the target frequency value.

5. The method according to claim 3, characterized in that, When the steady-state control command is a frequency control command, determining the steady-state control command for each isolated network based on its required power and network status includes: If there is no tie line in the isolated network, the required active power is determined based on the regional bus frequency deviation of each isolated network. Determine a second deviation value for the sum of the required active power and the gas turbine active power setpoint; The second deviation value is corrected based on the gas turbine regulation coefficient, and a second frequency control command for the gas turbine is determined based on the corrected second deviation value; the second frequency control command is used to control the governor of the gas turbine unit to maintain the frequency of the isolated grid at the target frequency value.

6. The method according to claim 3, characterized in that, When the steady-state control command is a voltage control command, determining the steady-state control command for each islanded grid based on its required power and network status includes: If there are tie lines in the isolated network, the required reactive power is determined based on the power factor deviation; Determine the third deviation value of the sum of the required reactive power and the gas turbine reactive power setpoint; The third deviation value is corrected based on the gas turbine regulation coefficient, and a first voltage control command for the gas turbine is determined based on the corrected third deviation value. The first voltage control command is used to control the exciter of the gas turbine unit to maintain the bus voltage of the isolated grid at the target voltage value.

7. The method according to claim 3, characterized in that, When the steady-state control command is a voltage control command, determining the steady-state control command for each islanded grid based on its required power and network status includes: If there is no tie line in the islanded network, the required reactive power is determined based on the area voltage deviation of each islanded network; Determine the fourth deviation value of the sum of the required reactive power and the gas turbine reactive power setpoint; The fourth deviation value is corrected based on the gas turbine regulation coefficient, and a second voltage control command for the gas turbine is determined based on the corrected fourth deviation value. The second voltage control command is used to control the exciter of the gas turbine unit to maintain the bus voltage of the isolated grid at the target voltage value.

8. The method according to any one of claims 3 to 7, characterized in that, In the steady-state control command, the power adjustment amount for each gas turbine unit is less than or equal to the current available capacity of that gas turbine unit. The current available capacity is determined based on the minimum of the following: the power limit set by the user, the generator output diagram, and the generator's maximum working capacity.

9. The method according to any one of claims 4 to 7, characterized in that, The gas turbine regulation coefficient is determined based on the operating mode of the gas turbine unit in an isolated grid. When the gas turbine unit is operating in the error-free isolated network mode, the gas turbine unit uses the rated frequency of the bus as the target frequency value; When the gas turbine unit is operating in differential droop mode, the gas turbine adjustment coefficient is determined according to the operating status of the gas turbine unit.

10. The method according to claim 9, characterized in that, When the gas turbine unit operating in the isolated grid mode is disconnected or shut down, the operating mode of another gas turbine unit is set to the isolated grid mode according to priority.

11. The method according to claim 1, characterized in that, When the operating state is transient, determining the control command for each isolated network based on its operating state includes: When the regional frequency of the isolated network is less than the first frequency threshold, load shedding operation is performed according to a preset priority until the difference between the required load shedding and the selected load shedding is within the active power set value range corresponding to the frequency dead zone boundary. If the regional frequency of the isolated grid is greater than the second frequency threshold, and the required backoff power is less than or equal to the current load shedding capacity, the gas turbine unit will reduce its power output according to the required backoff power; if the required backoff power is greater than the current load shedding capacity, the turbine will be tripped according to the preset priority and the current unit output.

12. The method according to claim 11, characterized in that, If the required power reduction is greater than the current load shedding capacity, then a tripping operation is performed according to a preset priority and the current unit output, including: Candidate gas turbine units that need to be switched off are determined based on preset priorities; Based on the output of each gas turbine unit in the candidate gas turbine units, the target gas turbine unit for the turbine switching operation is determined; When the selected cut-off amount corresponding to the target gas turbine unit is equal to the required back-off power, a cut-off operation is performed on the target gas turbine unit. If the selected cut-off amount corresponding to the target gas turbine unit is less than the required power reduction, then the target gas turbine unit is adjusted according to the minimum overcut amount, and a cut-off operation is performed on the adjusted target gas turbine unit. If the selected load factor corresponding to the target gas turbine unit is greater than the required power reduction, then a load shedding operation is performed based on the over-load factor.

13. An isolated grid energy control system, characterized in that, The system includes: a main control device, a transmission device, and a terminal device; The terminal device is used to: collect power grid topology information and operating condition information; The main control device is used to: divide the power grid into at least one isolated network based on the topology information and the operating condition information, and determine the operating state of each isolated network; wherein the operating state includes a steady state and a transient state; The main control device is also used to: determine the control command for each of the isolated networks based on the operating status of each isolated network; The transmission device is used to: send the power grid topology information and operating condition information collected by the terminal device to the main control device; The transmission device is further configured to: send the control command to the terminal device corresponding to each of the isolated networks, so that the terminal device maintains the frequency and voltage of each isolated network at the target value according to the control command.

14. The islanded grid energy control system according to claim 13, characterized in that, The main control device includes a stability control master station and a coordination control master station; The communication connection between the stability control master station and the coordination control master station is used to switch between steady-state control commands and transient control commands according to the operating status of the isolated network.

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