A detection method for remote disconnection of a zero-switching power regional power grid

Abstract

A method for detecting remote disconnection of a regional power grid with zero exchange power is proposed. When the regional power grid is stable, the direction of frequency change of the regional power grid is acquired, and the active power and frequency of the grid-connected tie lines are collected. When the frequency deviation of the grid-connected tie lines is less than a set frequency threshold and the active power is less than the zero-power measurement accuracy, and the time interval between the last load adjustment and the current time exceeds a time threshold, zero-power disconnection monitoring is initiated; otherwise, non-zero-power disconnection monitoring is initiated. After the zero-power disconnection monitoring is initiated, within a set time period, when the change in active power of generators in the regional power grid is less than a set power threshold, load adjustment is performed in the opposite direction of frequency change. During load adjustment, if the frequency change of the grid-connected tie lines is greater than the frequency change threshold and the change in active power of the grid-connected tie lines is less than the power change threshold, the regional power grid is determined to have disconnected; otherwise, the regional power grid is determined not to have disconnected. This method solves the problem of rapid judgment of isolated networks formed by remote disconnection of a regional power grid with near-zero exchange power.

Description

Technical Field

[0001] This disclosure relates to the field of power system safety and stability control technology, and in particular to a method for determining the isolated operation status of a regional power grid under zero exchange power. Background Technology

[0002] Regional power grids containing distributed generation face the risk of isolated operation due to transmission equipment failures. When a regional power grid enters isolated operation, it needs to promptly switch to a self-controlled frequency mode, establishing a new fixed-frequency control mechanism. Otherwise, lacking the frequency stabilization effect of the main grid, the isolated system may rapidly (from hundreds of milliseconds to a few seconds, depending on the magnitude of the power imbalance) exceed or fall below the frequency limit, leading to generator tripping and load shedding. Because the load and generation of a regional power grid are relatively small compared to the main grid, its granularity is larger, making frequency stabilization difficult to restore. Therefore, when a regional power grid is isolated, it needs to switch to a self-controlled frequency operation mode as quickly as possible. This requires determining the isolated operation status of the regional power grid as quickly as possible.

[0003] When the local interconnection line of a regional power grid is disconnected, the regional power grid, due to its monitoring devices on the local circuit breakers, can identify the isolated area within tens of milliseconds. Since AC power grids below 500kV are typically constructed as ring networks and operate in open-loop mode, the disconnection of any one interconnection line usually results in isolated areas. When the local circuit breaker of the regional power grid's external interconnection line fails to operate during a fault, or the circuit breaker on the opposite side trips without a fault, if the power before the fault was relatively high, the isolated area will experience sudden frequency changes or exceed limits. In this case, the isolated area can still be identified by combining local measurements of the regional power grid. However, when the power of the regional power grid's connection to the external grid is very low, and the disconnection of the opposite line does not cause a significant frequency change, there is currently no solution for timely identification of the isolated area when the local circuit breaker is not disconnected.

[0004] In near-zero power grid disconnection scenarios, current technology waits until a further large power imbalance occurs in the isolated grid area, resulting in frequency anomalies, before identifying the isolated grid and implementing frequency control measures. However, these measures, implemented only after a considerable period following the large power imbalance, require significant recovery power and energy. The generator group may not even have the necessary regulatory capacity, leading to frequency recovery failure in the isolated grid area. Therefore, it is necessary to research methods that can quickly identify isolated grids when the power of external interconnections to distributed generation sources is near zero and the remote connection is interrupted. With the development of new energy sources, regional power grids with distributed generation sources are increasingly achieving local power balance, making this method for timely detection of isolated grids under near-zero exchange power disconnection conditions even more crucial. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for detecting remote network disconnection in a zero-exchange-power regional power grid, solving the problem of rapid identification of isolated networks formed by remote network disconnection in a near-zero-exchange-power regional power grid.

[0006] The present invention adopts the following technical solution.

[0007] This invention proposes a method for detecting remote network disconnection in a zero-switching-power regional power grid, comprising:

[0008] When the regional power grid is in a stable state, the direction of frequency change of the regional power grid is obtained, and the active power and frequency of the grid-connected tie lines are collected.

[0009] When the frequency deviation of the grid connection line is less than the set frequency threshold and the active power is less than the zero power measurement accuracy, and the time interval between the last load adjustment exceeds the time threshold, then zero power grid disconnection monitoring is activated; otherwise, non-zero power grid disconnection monitoring is activated.

[0010] After the zero-power grid disconnection monitoring is started, if the change in the active power of generators in the regional power grid is less than the set power threshold within a set time period, the load will be adjusted in the opposite direction of the frequency change.

[0011] During load regulation, if the frequency change of the grid tie line is greater than the frequency change threshold and the active power change of the grid tie line is less than the power change threshold, it is determined that the regional power grid has been disconnected and formed an isolated grid, and isolated grid control is initiated; otherwise, it is determined that the regional power grid has not been disconnected and has not formed an isolated grid.

[0012] Preferably, the active power and frequency of the grid-connected tie line are collected, including:

[0013] The current data of the current transformer and the voltage data of the voltage transformer of the grid-connected tie line are collected by the measurement unit with a millisecond cycle, and the active power and frequency of the grid-connected tie line are calculated with a millisecond cycle.

[0014] The active power and frequency of the grid-connected tie line are measured from the power and frequency measurement unit.

[0015] Preferably, the frequency deviation is the absolute value of the difference between the actual frequency value and the rated frequency, and the set frequency threshold is 1.0 Hz;

[0016] The zero-power measurement accuracy is taken as twice the active power measurement accuracy of the tie line.

[0017] Preferably, the time threshold is the time it takes for the generator to complete 50% of the secondary frequency regulation power control, and the value of the time threshold is greater than or equal to 10s and less than or equal to 30s.

[0018] Preferably, the set duration is the response time of the generator to the secondary frequency regulation power command, and the value range of the set duration is greater than or equal to 5s and less than or equal to 30s; the set power threshold is 1% of the total rated active power of the generators operating in the regional power grid.

[0019] Preferably, when the power generation in the regional power grid changes steadily, load regulation is performed in the opposite direction of frequency change, and the load regulation amount is 2% of the total rated active power of the generators operating in the regional power grid.

[0020] Preferably, the frequency change of the grid connection tie line within 1 second is used as the criterion. The frequency change threshold and power change threshold are determined based on the total rated capacity of thermal and hydropower units in the regional power grid. For regional power grids with a total rated capacity of less than 1000MW, the frequency change threshold of the grid connection tie line within 1 second is 0.2Hz, and the power change threshold is 0.4% of the total rated active power of the generators operating in the regional power grid.

[0021] Preferably, the load regulation flag Sta is set to 1 at the same time as zero-power grid disconnection monitoring is initiated.

[0022] Preferably, a round of load regulation includes N consecutive active adjustments, with a time interval of 1 second between each active adjustment; N is an integer greater than or equal to 3.

[0023] If, after each active adjustment, the frequency change of the grid-connected tie line is greater than the frequency change threshold and the active power change of the grid-connected tie line is less than the power change threshold, then the regional power grid is determined to be disconnected. When the regional power grid is determined to be disconnected after the Nth active adjustment, the load adjustment flag Sta is set to 0, and the time when the disconnection flag is set to 0 is recorded as time t. test-end ;

[0024] If, after each active adjustment, the frequency change of the grid-connected tie line is not greater than the frequency change threshold and the active power change of the grid-connected tie line is not less than the power change threshold, then it is determined that the regional power grid has not been disconnected. When it is determined that the regional power grid has not been disconnected after the Nth active adjustment, the load adjustment flag Sta is set to 0, and the time when the disconnection flag is set to 0 is recorded as time t. test-end .

[0025] Preferably, after obtaining the regional power grid disconnection status test results from the last load adjustment, the load adjustment flag Sta is set to 0, and the time when the load adjustment flag is set to 0 is taken as the time scale t. test-end The current time t and the time scale t test-end The difference between them is the time interval from the last load adjustment.

[0026] Preferably, if the load adjustment flag Sta is not set to 0, it means that this round of load adjustment cannot determine whether the regional power grid is disconnected, and another round of load adjustment is required.

[0027] The beneficial effects of this invention, compared with the prior art, include at least the following: In a near-zero-power interconnected state of a regional power grid, when a disconnection occurs at the other end of the interconnection line or further away, forming a regional isolated grid, the method proposed in this invention can actively adjust the load test to detect the isolated grid operation status and promptly switch the frequency control mode to the constant-frequency control mode necessary for isolated grid operation. This avoids the loss of frequency stability due to insufficient frequency control capability during large disturbances. This invention solves the problem that current methods for determining isolated grid operation fail in a zero-power interconnected state, and cannot promptly switch the frequency control mode when an isolated grid state occurs, only implementing isolated grid control when a large disturbance causes the isolated grid frequency to exceed the limit, leading to increased accident losses. Attached Figure Description

[0028] Figure 1 This invention presents a flowchart of a detection method for remote disconnection of a zero-exchange-power regional power grid. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0030] This invention proposes a method for detecting remote network disconnection in a zero-switching-power regional power grid, such as... Figure 1 As shown, the detection method includes the following steps:

[0031] Step 1: When the regional power grid is in a stable state, obtain the direction of frequency change of the regional power grid and collect the active power and frequency of the grid-connected tie line.

[0032] In a non-limiting preferred embodiment, the frequency change direction of the regional power grid is the difference between the current frequency and the frequency one second ago.

[0033] In a non-limiting preferred embodiment, the power and frequency of the grid-connected tie line are continuously collected at millisecond intervals. Those skilled in the art can use different sampling periods according to the requirements of grid operation and monitoring.

[0034] In a non-limiting preferred embodiment, the power and frequency of the grid-connected tie line include, but are not limited to:

[0035] The current data of the current transformer and the voltage data of the voltage transformer of the grid-connected tie line are collected by a measurement unit with a millisecond cycle, and the active power and frequency of the grid-connected tie line are calculated with a millisecond cycle; or, the measurement results of the active power and frequency of the grid-connected tie line are obtained from the power and frequency measurement unit, and the measurement period of the measurement results is 10ms or 20ms. The power and frequency measurement unit includes, but is not limited to, a PMU device.

[0036] Step 2: When the frequency deviation of the grid connection line is less than the set frequency threshold and the active power is less than the zero power measurement accuracy, and the time interval between the last load adjustment exceeds the time threshold, then zero power grid disconnection monitoring is started, and the load adjustment flag Sta is set to 1; otherwise, non-zero power grid disconnection monitoring is started.

[0037] In a non-limiting preferred embodiment, the frequency deviation is the absolute value of the difference between the actual frequency value and the rated frequency, and the set frequency threshold is 1.0 Hz; the zero power measurement accuracy is determined by twice the accuracy of the active power measurement device of the tie line. For example, for a tie line with a daily switching power of 200 MW, if the range of the power measurement device is set to 1000 MW and the measurement accuracy of the power measurement device is 0.5 class, i.e. 0.5%, then the active power measurement accuracy of the tie line power measurement device is 5 MW, and the defined zero power measurement accuracy is 10 MW.

[0038] The load regulation in this invention actually involves artificially creating small load power disturbances. The impact of these power fluctuations on the power of the external grid tie lines is observed to determine the regional power grid disconnection status. After the previous load regulation test results show the regional power grid disconnection status and the regional power grid returns to a stable state, the load regulation flag Sta is set to 0. The time when the load regulation flag is set to 0 is taken as the time scale t. test-end The current time t and the time scale t test-end The difference between them is the time interval from the last load adjustment.

[0039] Specifically, the time threshold is the time it takes for the generator to complete 50% of the secondary frequency regulation power control. The value of the time threshold is greater than or equal to 10s and less than or equal to 30s. In a non-limiting preferred embodiment, the time threshold is 10s.

[0040] In regional power grids that require islanded operation control based on the disconnection status, there are usually dedicated stability control devices responsible for determining whether the regional power grid is disconnected or isolated. However, existing stability control devices typically do not have an interface for adjusting load increases or decreases. Therefore, this invention proposes a method for detecting remote disconnection of a zero-power regional power grid. This method judges and processes zero-power disconnection of tie lines to achieve zero-power disconnection monitoring. For non-zero-power disconnection monitoring of tie lines, it is achieved by a conventional stability control device with non-zero-power disconnection monitoring capabilities.

[0041] Step 3: After the zero-power grid disconnection monitoring is started, within a set time period, when the change in the active power of generators in the regional power grid is less than the set power threshold, the load is adjusted in the opposite direction of the frequency change.

[0042] Specifically, the set duration is the response time of the generator to the secondary frequency regulation power command. The value range of the set duration is greater than or equal to 5s and less than or equal to 30s. In a non-limiting preferred embodiment, the set duration is 10s.

[0043] Specifically, the power threshold is set at 1% of the total rated active power of the generators operating within the regional power grid.

[0044] In a non-limiting preferred embodiment, if the change in the total active power of the actually operating generators within 10 seconds is less than 1% of the total rated active power of the operating generators, then it is determined that the power generation in the regional power grid is stable and there is no active power increase or decrease, indicating that no secondary frequency regulation power command is being executed.

[0045] Specifically, in actual power grids, for regional power grids that require islanded operation control based on the disconnection status, there are usually dedicated stability control devices responsible for determining whether the regional power grid has become islanded. However, existing stability control devices typically lack interfaces for adjusting load increases or decreases. Based on existing methods for determining disconnection or islanding using these stability control devices, it is impossible to determine whether the regional power grid has become islanded when the tie line has zero switching power and the local tie circuit breaker is not open. Therefore, this invention proposes to adjust the load slightly in the opposite direction of frequency change when the regional power grid is in a stable state, thereby enabling active disconnection testing on the actual power grid system. During the active disconnection test, the impact of this power fluctuation on the tie line power is obtained, thus allowing for the determination of whether the regional power grid has become islanded.

[0046] In a non-limiting preferred embodiment, the adjusted load may increase or decrease its output briefly within 1 minute without strict limitations. The adjusted load includes, but is not limited to, electric boilers, condensing equipment, and small electric motor equipment.

[0047] Specifically, depending on the power control interface of the regulated load, different control signals are selected, including: electrical analog control signals, status control signals, or communication control signals. In a non-limiting preferred embodiment, electrical analog control signals include, but are not limited to: 4-20mA current signals and ±5V voltage signals; status control signals include, but are not limited to: 0-1 node signals and switch position signals; communication control signals include, but are not limited to: various communication protocols based on the IP protocol.

[0048] Specifically, when the power generation in the regional power grid changes steadily, load regulation is carried out in the opposite direction of frequency change, and the load regulation amount is 2% of the total rated active power of the generators operating in the regional power grid.

[0049] It is worth noting that those skilled in the art can reasonably select the setting duration, setting power threshold, and load regulation amount based on factors such as the stability requirements of the regional power grid. The preferred values ​​given in this invention are non-limiting preferred choices.

[0050] Step 4: During load regulation, if the frequency change of the grid connection line is greater than the frequency change threshold and the active power change of the grid connection line is less than the power change threshold, then the regional power grid is determined to have been disconnected and formed an isolated grid; otherwise, the regional power grid is determined to have not been disconnected and has not formed an isolated grid.

[0051] In a non-limiting preferred embodiment, the frequency change of the grid connection tie line within 1 second is used as the criterion. The frequency change threshold and power change threshold are determined based on the total rated capacity or moment of inertia of the thermal and hydropower units in the regional power grid. For regional power grids with a total rated capacity of less than 1000MW, the frequency change threshold of the grid connection tie line within 1 second is 0.2Hz, and the power change threshold is 20% of the load regulation, that is, 0.4% of the total rated active power of the generators operating in the regional power grid.

[0052] Specifically, a round of load regulation includes N consecutive active adjustments, with a time interval of 1 second between each active adjustment; after each active adjustment, it is determined whether the frequency change of the grid connection tie line is greater than the frequency change threshold and whether the active power change of the grid connection tie line is less than the power change threshold.

[0053] Specifically, step 4 includes:

[0054] If, after each active adjustment, the frequency change of the grid-connected tie line is greater than the frequency change threshold and the active power change of the grid-connected tie line is less than the power change threshold, then the regional power grid is determined to be disconnected. When the regional power grid is determined to be disconnected after the Nth active adjustment, the load adjustment flag Sta is set to 0, and the time when the disconnection flag is set to 0 is recorded as time t. test-end .

[0055] If, after each active adjustment, the frequency change of the grid-connected tie line is not greater than the frequency change threshold and the active power change of the grid-connected tie line is not less than the power change threshold, then it is determined that the regional power grid has not been disconnected. When it is determined that the regional power grid has not been disconnected after the Nth active adjustment, the load adjustment flag Sta is set to 0, and the time when the disconnection flag is set to 0 is recorded as time t. test-end .

[0056] If the load adjustment flag Sta is not set to 0, it means that this round of load adjustment cannot determine whether the regional power grid is disconnected, and another round of load adjustment is required.

[0057] In a non-limiting preferred embodiment, N is an integer greater than or equal to 3.

[0058] Step 5: If it is determined that the regional power grid has been disconnected and formed an isolated grid, start the isolated grid control; if it is determined that the regional power grid has not been disconnected and has not formed an isolated grid, return to step 1.

[0059] Existing methods for determining whether a grid is isolated or disconnected cannot identify an isolated area when the tie line has zero switching power and the local tie circuit breaker is not open. This invention proposes actively creating small fluctuations in load active power within the regional power grid. By observing the impact of these fluctuations on the grid frequency and the impact on active power on external tie lines, it determines whether a grid isolation has occurred. In grid-connected situations, the power system has many generators, resulting in a large moment of inertia; small active power imbalances hardly cause frequency changes. Conversely, in isolated situations, due to the small moment of inertia of the regional power grid, small active power imbalances cause significant frequency changes. Furthermore, judging from changes in tie line active power: in isolated situations, excess power is not output to the external grid, and insufficient power is not supplemented by the external grid; the power on the tie line remains almost unchanged. Conversely, in grid-connected situations, excess power in the regional power grid is output to the external grid through tie lines, and insufficient active power in the regional power grid is supplemented by the external grid through tie lines; the power on the tie lines changes significantly.

[0060] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0061] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0062] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0063] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for detecting remote disconnection of a zero-switching-power regional power grid, characterized in that, include: When the regional power grid is in a stable state, the direction of frequency change of the regional power grid is obtained, and the active power and frequency of the grid-connected tie lines are collected. When the frequency deviation of the grid connection line is less than the set frequency threshold and the active power is less than the zero power measurement accuracy, and the time interval between the last load adjustment exceeds the time threshold, then zero power grid disconnection monitoring is activated; otherwise, non-zero power grid disconnection monitoring is activated. After the zero-power grid disconnection monitoring is started, if the change in the active power of generators in the regional power grid is less than the set power threshold within a set time period, the load will be adjusted in the opposite direction of the frequency change. During load regulation, if the frequency change of the grid tie line is greater than the frequency change threshold and the active power change of the grid tie line is less than the power change threshold, it is determined that the regional power grid has been disconnected and formed an isolated grid, and isolated grid control is initiated; otherwise, it is determined that the regional power grid has not been disconnected and has not formed an isolated grid.

2. The detection method for remote disconnection of a zero-switching-power regional power grid according to claim 1, characterized in that, Collect the active power and frequency of the grid-connected tie line, including: The current data of the current transformer and the voltage data of the voltage transformer of the grid-connected tie line are collected by the measurement unit with a millisecond cycle, and the active power and frequency of the grid-connected tie line are calculated with a millisecond cycle. The active power and frequency of the grid-connected tie line are measured from the power and frequency measurement unit.

3. The detection method for remote disconnection of a zero-switching power regional power grid according to claim 1, characterized in that, Frequency deviation is the absolute value of the difference between the actual frequency value and the rated frequency. The set frequency threshold is 1.0 Hz. The zero-power measurement accuracy is taken as twice the active power measurement accuracy of the tie line.

4. The detection method for remote disconnection of a zero-switching-power regional power grid according to claim 1, characterized in that, The time threshold is the time it takes for the generator to complete 50% of the secondary frequency regulation power control. The value of the time threshold is greater than or equal to 10s and less than or equal to 30s.

5. The detection method for remote disconnection of a zero-switching power regional power grid according to claim 1, characterized in that, The set duration is the response time of the generator to the secondary frequency regulation power command, and the value range of the set duration is greater than or equal to 5s and less than or equal to 30s; the set power threshold is 1% of the total rated active power of the generators operating in the regional power grid.

6. The detection method for remote disconnection of a zero-switching power regional power grid according to claim 1, characterized in that, When the power generation in the regional power grid changes steadily, load regulation is carried out in the opposite direction of frequency change, and the load regulation amount is 2% of the total rated active power of the generators operating in the regional power grid.

7. The detection method for remote disconnection of a zero-switching-power regional power grid according to claim 1, characterized in that, The frequency change of the grid-connected tie line within 1 second is used as the criterion. The threshold for frequency change and the threshold for power change are determined based on the total rated capacity of thermal and hydropower units in the regional power grid. For regional power grids with a total rated capacity of less than 1000MW, the threshold for frequency change of the grid-connected tie line within 1 second is 0.2Hz, and the threshold for power change is 0.4% of the total rated active power of the generators operating in the regional power grid.

8. The detection method for remote disconnection of a zero-switching power regional power grid according to claim 1, characterized in that, While starting zero-power grid disconnection monitoring, set the load adjustment flag Sta to 1.

9. The detection method for remote disconnection of a zero-switching-power regional power grid according to claim 1, characterized in that, One round of load regulation consists of N consecutive active adjustments, with a time interval of 1 second between each active adjustment; N is an integer greater than or equal to 3. If, after each active adjustment, the frequency change of the grid-connected tie line is greater than the frequency change threshold and the active power change of the grid-connected tie line is less than the power change threshold, then the regional power grid is determined to be disconnected. When the regional power grid is determined to be disconnected after the Nth active adjustment, the load adjustment flag Sta is set to 0, and the time when the disconnection flag is set to 0 is recorded as time t. test-end ; If, after each active adjustment, the frequency change of the grid-connected tie line is not greater than the frequency change threshold and the active power change of the grid-connected tie line is not less than the power change threshold, then it is determined that the regional power grid has not been disconnected. When it is determined that the regional power grid has not been disconnected after the Nth active adjustment, the load adjustment flag Sta is set to 0, and the time when the disconnection flag is set to 0 is recorded as time t. test-end .

10. The detection method for remote disconnection of a zero-switching power regional power grid according to claim 9, characterized in that, After obtaining the regional power grid disconnection status test results from the last load adjustment, the load adjustment flag Sta will be set to 0, and the time when the load adjustment flag is set to 0 will be used as the time scale t. test-end The current time t and the time scale t test-end The difference between them is the time interval from the last load adjustment.

11. The detection method for remote disconnection of a zero-switching-power regional power grid according to claim 10, characterized in that, If the load adjustment flag Sta is not set to 0, it means that this round of load adjustment cannot determine whether the regional power grid is disconnected, and another round of load adjustment is required.

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