Line protection load shedding optimization strategy considering new energy access, implementation method, system, equipment and medium

Abstract

The invention discloses a line protection load shedding optimization strategy considering new energy access and an implementation method, system, equipment and medium, and belongs to the technical field of line protection, and the method comprises the steps: collecting bus line voltage, bus three-phase current and circuit breaker closing state information, and calculating bus frequency based on the bus line voltage; based on a comparison result of the bus frequency slip frequency and a set slip frequency threshold value, whether low-frequency load shedding protection is locked or not is judged; judging whether to lock low-voltage load shedding protection or not based on the voltage change rate; the bus active power is calculated according to the bus voltage and the bus three-phase current, the bus active power is compared with a set power threshold value, and the states of low-frequency load shedding protection and low-voltage load shedding protection are automatically set; and completing verification and determination of the polarity of the current transformer. According to the method, the risk that the power equipment may be lack of protection in the system operation process is solved, overcut in the load reduction process is avoided, the stability and the safety are improved, and different application scenes on site are met.

Description

Technical Field

[0001] This invention relates to the field of line protection technology, specifically to a line protection load reduction optimization strategy and implementation method, system, equipment and medium that takes into account the access of new energy sources. Background Technology

[0002] With the advancement of new power systems, electricity consumption patterns will shift towards bidirectional interaction. The integration of distributed power sources, represented by wind and solar power, not only changes the traditional unidirectional energy flow characteristics of the distribution network, but also makes voltage fluctuations more severe due to the intermittent, volatile, and uncertain nature of power generation, thus posing significant challenges to the protection and control of the power grid.

[0003] Currently, distribution network protection systems cannot automatically activate or deactivate low-frequency and low-voltage load shedding protection functions by identifying current direction. Considering the uncertain timing of power supply and consumption by some small power sources, it's impossible to automatically activate or deactivate these functions through the dispatch system or on-site operators. If low-frequency and low-voltage load shedding functions remain active, over-shearing may occur during load reduction, causing inconvenience to users and impacting the normal operation of power equipment. Therefore, it is necessary to automatically activate and deactivate low-frequency and low-voltage load shedding functions through the protection system's own logic. Summary of the Invention

[0004] In view of the above-mentioned problems, the present invention provides a line protection load reduction optimization strategy, implementation method, system, equipment and medium that takes into account the access of new energy sources.

[0005] Therefore, the technical problem solved by this invention is: how to address the current distribution network protection system's inability to automatically activate or deactivate low-frequency and low-voltage load shedding protection functions by identifying current direction. Considering that the timing of power supply and consumption by some small power systems is uncertain, it is impossible to activate or deactivate low-frequency and low-voltage load shedding functions through the dispatching system or on-site operators. If low-frequency and low-voltage load shedding functions are continuously activated, over-shearing may occur during load reduction, causing inconvenience to users and affecting the normal operation of power equipment.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a line protection load reduction optimization strategy and implementation method considering new energy access, comprising: collecting bus line voltage, bus three-phase current, and circuit breaker closed-position information, and calculating the bus frequency based on the bus line voltage; under the condition that the bus frequency is within the effective frequency range and the circuit breaker is in the closed position, determining whether the low-frequency load reduction protection is enabled based on the bus three-phase current, and determining whether to block the low-frequency load reduction protection based on the comparison result of the bus frequency slip and the set slip threshold; when the bus line voltage meets the set conditions and the bus... Under the premise that the three-phase current meets the conditions for the activation of low-voltage load shedding protection, the low-voltage load shedding protection logic is executed, and the low-voltage load shedding protection is blocked based on the voltage change rate. The active power of the bus is calculated based on the bus line voltage and the three-phase current of the bus, and the active power of the bus is compared with the set power threshold. The status of low-frequency load shedding protection and low-voltage load shedding protection is automatically set. During the commissioning and startup process of the distribution bay, the polarity verification function of the current transformer is activated according to the control word signal, and the polarity of the current transformer is verified and determined by collecting the bus line voltage, the three-phase current of the bus, and the corresponding active power data of the bus.

[0007] As a preferred embodiment of the line protection load reduction optimization strategy and implementation method considering new energy access described in this invention, the step of collecting bus line voltage, bus three-phase current and circuit breaker closing status information, and calculating bus frequency based on bus line voltage includes: extracting bus line voltage and bus three-phase current signals from the corresponding measurement circuits of current transformers and voltage transformers; obtaining the current closing status of the circuit breaker; and performing a frequency extraction operation based on the bus line voltage signal to obtain the current bus frequency.

[0008] As a preferred embodiment of the line protection load reduction optimization strategy and implementation method considering new energy access described in this invention, the following steps are included: Under the condition that the bus frequency is within the effective frequency range and the circuit breaker is in the closed position, determining whether the low-frequency load reduction protection is enabled based on the three-phase bus current, and determining whether to block the low-frequency load reduction protection based on the comparison result of the bus frequency slip and the set slip threshold, include: after obtaining the bus frequency, distinguishing the bus frequency according to the preset effective frequency range, and entering the low-frequency load reduction judgment process when the distinction result meets the conditions; after entering the low-frequency load reduction judgment process, confirming the executability of the protection logic according to the closed position of the circuit breaker; after confirming executability, determining whether the low-frequency load reduction protection is enabled by comparing the three-phase bus current with the set conditions; before executing the low-frequency load reduction, calculating the change in bus frequency to obtain the frequency slip, and determining whether the low-frequency load reduction protection remains enabled based on the comparison result of the slip and the set threshold.

[0009] As a preferred embodiment of the line protection load reduction optimization strategy and implementation method considering new energy access described in this invention, the following steps are included: Under the premise that the bus line voltage meets the set conditions and the bus three-phase current meets the conditions for low-voltage load reduction protection activation, the low-voltage load reduction protection logic is executed, and the decision on whether to block the low-voltage load reduction protection is based on the voltage change rate. This includes: after obtaining the bus line voltage, comparing the bus line voltage with the set voltage conditions to determine whether to enter the low-voltage load reduction judgment process; after entering the low-voltage load reduction judgment process, verifying the circuit breaker closing status, and if the closing status meets the conditions, continuing to determine whether the bus three-phase current meets the activation prerequisite for low-voltage load reduction protection; after meeting the activation prerequisite, calculating the change trend of the bus line voltage, and determining the execution status of the low-voltage load reduction protection based on the comparison result between the obtained change rate and the set threshold; during the low-voltage load reduction judgment process, verifying the historical status of the bus line voltage, and completing the determination on whether to continue executing the low-voltage load reduction protection when the bus line voltage previously met the set conditions.

[0010] As a preferred embodiment of the line protection load reduction optimization strategy and implementation method considering the access of new energy sources described in this invention, the step of calculating the bus active power based on the bus line voltage and the three-phase bus current, and comparing the bus active power with a set power threshold, includes: when the current transformer is connected to three phases, calculating the bus active power based on the correspondence between the three-phase voltage and the three-phase current; when the current transformer is connected to two phases, calculating the bus active power based on the relationship between the line voltage and the corresponding phase current; comparing the bus active power with the set power threshold, and entering the load reduction protection state setting process based on the comparison result.

[0011] This preferred solution calculates the bus active power using either three-phase or two-phase voltage-current relationships when there are differences in the current transformer connection circuit. This allows the system to adapt to different types of power distribution site wiring structures, ensuring accurate acquisition of bus active power without adding additional measuring devices, and improving the completeness and adaptability of protection activation / deactivation judgment.

[0012] As a preferred embodiment of the line protection load reduction optimization strategy and implementation method considering new energy access described in this invention, the automatic setting of the low-frequency load reduction protection and low-voltage load reduction protection states includes: when the comparison result shows that the active power of the bus is greater than the set power threshold, setting the low-frequency load reduction protection and low-voltage load reduction protection to an effective state; when the comparison result shows that the active power of the bus is not greater than the set power threshold, setting the low-frequency load reduction protection and low-voltage load reduction protection to an invalid state.

[0013] This preferred solution directly links the comparison results of the bus active power and the power threshold to the status settings of the low-frequency load shedding protection and the low-voltage load shedding protection. It can automatically control the activation or deactivation of the protection function when the load status changes, avoiding false triggering of load shedding actions when the bus is energized or unloaded, and improving the pertinence and adaptability of the protection actions.

[0014] As a preferred embodiment of the line protection load reduction optimization strategy and implementation method considering new energy access described in this invention, the following steps are included: during the commissioning and startup of the distribution bay, the polarity verification function of the current transformer is activated according to the control word signal, and the polarity of the current transformer is verified and determined by collecting bus line voltage, bus three-phase current and corresponding bus active power data. This includes activating the current transformer polarity verification logic according to the control word signal during the commissioning and startup of the distribution bay; after the verification logic is activated, monitoring the bus line voltage, bus three-phase current and corresponding bus active power data. The sampling status of phase current, bus active power, and bus reactive power is checked to ensure they are in normal condition. When the bus line voltage is in a three-phase balanced state, if the bus active power of the corresponding phase is positive and the bus reactive power of the corresponding phase is negative, the polarity of the corresponding phase current transformer is determined to be correct. When the bus line voltage is in a three-phase balanced state, if the bus active power of the corresponding phase is not positive and the bus reactive power of the corresponding phase is not negative, the polarity of the corresponding phase current transformer is determined to be incorrect. The current transformer polarity verification function exits the verification function when the continuous running time reaches the set duration.

[0015] This preferred solution, when the power distribution bay is started, uses the automatic polarity verification function of the current transformer, combined with the voltage, current and power sampling results for logical judgment, to identify polarity wiring errors without relying on manual intervention and promptly exit the abnormal state.

[0016] This invention provides a line protection load reduction optimization strategy and implementation system that takes into account the access of new energy sources.

[0017] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a line protection load reduction optimization strategy and implementation system considering new energy access, comprising: a data acquisition module, a low-frequency load reduction judgment module, a low-voltage load reduction judgment module, a comparison module, and a current transformer polarity verification module; the data acquisition module is used to acquire bus line voltage, bus three-phase current, and circuit breaker closed-position information, and calculate the bus frequency based on the bus line voltage; the low-frequency load reduction judgment module is used to determine whether the low-frequency load reduction protection is met based on the bus three-phase current when the bus frequency is within the effective frequency range and the circuit breaker is in the closed-position condition, and to determine whether to block the low-frequency load reduction protection based on the comparison result of the bus frequency slip and the set slip threshold; The low-voltage load shedding judgment module is used to execute the low-voltage load shedding protection logic when the bus line voltage meets the set conditions and the bus three-phase current meets the low-voltage load shedding protection activation conditions, and to determine whether to block the low-voltage load shedding protection based on the voltage change rate; the comparison module calculates the bus active power based on the bus line voltage and the bus three-phase current, compares the bus active power with the set power threshold, and automatically sets the status of low-frequency load shedding protection and low-voltage load shedding protection; the current transformer polarity verification module is used to activate the current transformer polarity verification function according to the control word signal during the commissioning and startup process of the distribution bay, and to complete the verification and judgment of the current transformer polarity by collecting the bus line voltage, bus three-phase current and corresponding bus active power data.

[0018] The present invention provides a computer device, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of the described line protection load reduction optimization strategy and implementation method considering the access of new energy sources.

[0019] The present invention provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the steps of the described method for optimizing line protection load reduction considering new energy access are implemented.

[0020] The beneficial effects of this invention are as follows: This invention achieves automatic activation and deactivation of low-frequency and low-voltage load shedding protection functions by adding active power magnitude judgment to the protection logic. This solves the risk of power equipment lacking protection during system operation, avoids over-shearing during load reduction, and greatly improves system stability and safety. Simultaneously, the control word setting allows selection of the protection CT as two-phase or three-phase, meeting different application scenarios and improving the applicability of the protection. Furthermore, the CT wiring adaptive verification function can quickly determine whether the wiring of the current and voltage circuits in the field is correct, ensuring that the polarity connection of the CT and PT meets the protection requirements and improving the reliability of the protection. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart illustrating an overall process for a line protection load reduction optimization strategy and implementation method considering new energy access, as provided in one embodiment of the present invention.

[0023] Figure 2 This invention provides a low-frequency load shedding protection logic diagram for a line protection load shedding optimization strategy and implementation method that considers new energy access, as provided in one embodiment of the present invention.

[0024] Figure 3 The following is an optimized low-frequency load shedding protection logic diagram of the present invention, which provides a line protection load shedding optimization strategy and implementation method considering the access of new energy sources, as an embodiment of the present invention.

[0025] Figure 4 This is a low-voltage load shedding protection logic diagram of a line protection load shedding optimization strategy and implementation method considering new energy access, provided as an embodiment of the present invention.

[0026] Figure 5 The following is an optimized low-voltage load shedding protection logic diagram of the present invention, which provides a line protection load shedding optimization strategy and implementation method considering the access of new energy sources, as an embodiment of the present invention.

[0027] Figure 6 This is a logic diagram of the CT polarity verification function being forcibly deactivated after a long period of operation, which is provided as an embodiment of the present invention to optimize line protection load reduction considering new energy access and to implement such a method.

[0028] Figure 7 This is a CT polarity verification function enable logic diagram for a line protection load reduction optimization strategy and implementation method considering new energy access, provided as an embodiment of the present invention.

[0029] Figure 8 The present invention provides a CT polarity verification correct logic diagram for a line protection load reduction optimization strategy and implementation method considering new energy access, as provided in one embodiment of the present invention.

[0030] Figure 9 This is a CT polarity check error logic diagram for a line protection load reduction optimization strategy and implementation method considering new energy access, provided as an embodiment of the present invention. Detailed Implementation

[0031] To make the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0032] Example 1, referring to Figure 1 This is one embodiment of the present invention, which provides a line protection load reduction optimization strategy and implementation method considering the access of new energy sources, including: S1. Collect bus line voltage, bus three-phase current and circuit breaker closed position information, and calculate bus frequency based on bus line voltage; S2. Under the condition that the bus frequency is within the effective frequency range and the circuit breaker is in the closed position, determine whether the low-frequency load shedding protection is enabled based on the three-phase current of the bus, and determine whether to block the low-frequency load shedding protection based on the comparison result between the bus frequency slip and the set slip threshold. S3. Under the premise that the bus line voltage meets the set conditions and the three-phase current of the bus meets the conditions for the activation of the low-voltage load shedding protection, execute the low-voltage load shedding protection logic and determine whether to block the low-voltage load shedding protection based on the voltage change rate. S4. Calculate the active power of the bus based on the bus line voltage and the three-phase current of the bus, compare the active power of the bus with the set power threshold, and automatically set the status of low-frequency load shedding protection and low-voltage load shedding protection. S5. During the commissioning and startup process of the power distribution bay, the polarity verification function of the current transformer is activated according to the control word signal, and the polarity of the current transformer is verified and determined by collecting the bus line voltage, bus three-phase current and corresponding bus active power data.

[0033] It should be noted that after new energy sources are connected to the power distribution system, the power flow direction and load characteristics of the power grid become more diverse. Traditional load shedding protection schemes often cannot distinguish whether the line is in a power supply state or a power receiving state, which can easily lead to false triggering or protection failure.

[0034] Meanwhile, in the initial stage of operation of protection equipment, if the polarity of the current transformer wiring is reversed, it may lead to incorrect power direction judgment, thereby affecting the correct execution of protection logic and even causing false protection blocking.

[0035] Therefore, through the steps described in S1–S5, this invention can, while satisfying conditions such as frequency, voltage, and current, further introduce active power judgment logic, combine it with the polarity verification function of the current transformer, realize dynamic control of protection activation and deactivation, and enhance the accuracy and adaptability of the protection logic under complex operating conditions.

[0036] Example 2, refer to Figures 2-9 As an embodiment of the present invention, based on the previous embodiment, a line protection load reduction optimization strategy and implementation method considering the access of new energy sources are provided, including: This application provides a line protection load reduction optimization strategy and implementation method that takes into account the access of new energy sources for distribution network protection. The activation and deactivation of low-frequency and low-voltage load reduction protection functions are achieved by automatically enabling and deactivating the protection's own logic functions.

[0037] The system identifies whether operating equipment is supplying or consuming power to the system by judging the magnitude of active power. When it is determined to be consuming system power, low-frequency and low-voltage load shedding protection functions are automatically activated. It offers the option to connect two-phase current transformers (CTs) or three-phase CTs to accommodate applications where only A and C phase CTs are connected in the field. Furthermore, to improve protection reliability, this strategy features an adaptive CT wiring verification function, which is activated via control words during the protection equipment commissioning process.

[0038] Furthermore, in step S1, the bus line voltage, bus three-phase current, and circuit breaker closing status information are collected, and the bus frequency is calculated based on the bus line voltage, including the following steps A1-A3: A1. Extract the bus line voltage and bus three-phase current signals from the corresponding measurement circuits of the current transformer and voltage transformer.

[0039] A2. Obtain the current closed position of the circuit breaker.

[0040] A3. Based on the bus line voltage signal, perform a frequency extraction operation to obtain the current bus frequency.

[0041] In this embodiment of the application, the frequency slip in step S2 can be based on the bus frequency change calculated from the bus line voltage. By continuously sampling the bus frequency, the frequency difference between adjacent sampling periods is calculated, and the obtained difference is used as the basis for judging the blocking condition of the low-frequency load shedding protection. When the frequency slip exceeds the set slip threshold, a judgment result for blocking the low-frequency load shedding protection is generated.

[0042] In an alternative implementation, the frequency slip can also be based on the calculated amount of bus frequency change trend. By comparing the changes in bus frequency within multiple consecutive sampling windows, a trend quantity reflecting the frequency drop rate is formed, and the execution status of the low-frequency load shedding protection is determined by comparing the trend quantity with a set threshold.

[0043] In another alternative implementation, the frequency slip can also be obtained by estimating the change in the slope of the bus frequency, and the absolute value of the slope can be used as the criterion variable for low-frequency load shedding protection to identify situations where the frequency drops rapidly.

[0044] This invention uses the frequency slip calculated based on the bus line voltage as the blocking criterion for low-frequency load shedding protection. This enables the low-frequency load shedding protection to promptly identify the rate of frequency change when the bus frequency drops rapidly. By comparing the frequency slip with a set slip threshold, the low-frequency load shedding protection is blocked when the rate of frequency drop exceeds the limit, thereby avoiding false activation due to frequency abrupt changes and achieving accurate determination of the protection logic under complex power grid operating conditions.

[0045] Furthermore, in step S2, under the condition that the bus frequency is within the effective frequency range and the circuit breaker is in the closed position, it is determined whether the conditions for engaging the low-frequency load shedding protection are met based on the three-phase current of the bus, and based on the comparison result between the bus frequency slip and the set slip threshold, it is determined whether to block the low-frequency load shedding protection, including the following steps B1-B4: B1. After obtaining the bus frequency, the bus frequency is distinguished according to the preset effective frequency range, and the low-frequency load reduction judgment process is entered when the distinction result meets the conditions.

[0046] B2. After entering the low-frequency load reduction judgment process, the executability of the protection logic is confirmed according to the closed position of the circuit breaker.

[0047] B3. After confirming feasibility, compare the three-phase current of the busbar with the set conditions to determine whether the prerequisite for the low-frequency load shedding protection is met.

[0048] B4. Before performing low-frequency load shedding, calculate the frequency change of the bus to obtain the frequency slip, and determine whether the low-frequency load shedding protection should remain in the active state based on the comparison result between the slip and the set threshold.

[0049] In this embodiment, the activation of the low-frequency load shedding protection in step B3 is predicated on a combination of the following conditions: the bus frequency is within the effective frequency range, the circuit breaker is in the closed position, and the three-phase current of the bus meets the set conditions. All three conditions are indispensable. When all three conditions are met, the system enters the low-frequency load shedding protection logic and further determines whether the frequency slip meets the blocking conditions.

[0050] In one alternative implementation, the activation of low-frequency load shedding protection can also be achieved through a logical judgment process. First, it is determined whether the bus frequency is within the effective range, then it is determined whether the circuit breaker is closed, and finally the three-phase current of the bus is compared with the preset threshold to form a step-by-step judgment structure of series logic.

[0051] In another alternative implementation, the activation of low-frequency load shedding protection can also be based on pre-confirmation conditions set according to the integrity and real-time requirements of the measurement status. For example, the frequency, current and circuit breaker status can be required to continuously meet several sampling cycles to prevent false judgments triggered by transient fluctuations.

[0052] This invention constructs a low-frequency load shedding protection activation prerequisite based on frequency, circuit breaker status, and three-phase current, avoiding erroneous activation of the low-frequency load shedding protection logic when any critical quantity is abnormal. Especially in non-protected scenarios such as insufficient current, electrical isolation, or circuit breaker not closed, it effectively prevents maloperation and improves the accuracy and completeness of low-frequency load shedding protection judgment.

[0053] The traditional low-frequency load shedding protection logic before optimization is as follows: Figure 2 As shown, its frequency setting and operating time can be independently adjusted, and it is equipped with a soft pressure plate, a hard pressure plate, and a low-frequency load shedding control word. When any phase of the bus voltage is less than the [low-frequency voltage lockout value], or the measured frequency exceeds the effective range of 44.5Hz to 55.5Hz, it is considered an abnormality of the frequency measurement circuit, and the low-frequency load shedding is blocked. Since the frequency measurement is taken from the bus voltage Uab, a circuit breaker closing criterion is added to the logic. The low-frequency slip lockout function is fixed: when the frequency slip decrease value is greater than the [low-frequency slip lockout value], the low-frequency load shedding is blocked. The low-frequency no-current lockout function is fixed: when all three phase currents are less than the [low-frequency load shedding current lockout value], the low-frequency load shedding is blocked. The low-frequency load shedding action must be based on the premise that the frequency was previously normal.

[0054] The optimized low-frequency load shedding protection logic of this invention is as follows: Figure 3 As shown, the active power magnitude is added to the original criteria, stipulating that the flow from the busbar to the line is the positive direction. When the total active power is greater than 0.5MW, the low-frequency load shedding protection is effective; when the total active power is less than 0.5MW, the low-frequency load shedding protection is ineffective.

[0055] When any phase of the bus voltage is less than the [low-frequency voltage lockout value], or the measured frequency exceeds the effective range of 44.5Hz to 55.5Hz, it is considered an abnormality in the frequency measurement circuit, and low-frequency load shedding is blocked. Since the frequency measurement is taken from the bus voltage Uab, a circuit breaker closing criterion is added to the logic. The low-frequency slippage lockout function is fixed in place: when the frequency slippage decrease is greater than the [low-frequency slippage lockout value], low-frequency load shedding is blocked. The low-frequency no-current lockout function is fixed in place: when all three phase currents are less than the [low-frequency load shedding current lockout value], low-frequency load shedding is blocked. The low-frequency load shedding action must be based on the premise that the frequency was previously normal. When selecting a three-phase CT, the power calculation uses the three-meter method; when selecting a two-phase CT, the power calculation uses the two-meter method.

[0056] The active power calculated using the three-meter method is expressed as follows: in, , , These are the phase voltages of phases A, B, and C, respectively. , , These are the phase currents of phases A, B, and C, respectively, and φ is the load impedance angle (power factor angle) of each phase.

[0057] The active power calculated using the two-table method is expressed as follows: in, , Line voltage, , These are the phase currents of phases A and C, respectively. , This represents the phase difference.

[0058] Furthermore, in step S3, under the premise that the bus line voltage meets the set conditions and the three-phase bus current meets the activation conditions of the low-voltage load shedding protection, the low-voltage load shedding protection logic is executed, and the low-voltage load shedding protection is blocked based on the voltage change rate, including the following steps C1-C4: C1. After obtaining the bus line voltage, compare the bus line voltage with the set voltage conditions to determine whether to enter the low-voltage load shedding judgment process.

[0059] C2. After entering the low-voltage load shedding judgment process, the circuit breaker closing status is checked, and if the closing status meets the conditions, the three-phase current of the busbar is further judged to see if the low-voltage load shedding protection is activated.

[0060] C3. After meeting the conditions for operation, calculate the trend of bus line voltage change, and determine the execution status of low-voltage load shedding protection based on the comparison between the obtained rate of change and the set threshold.

[0061] C4. During the low-voltage load shedding process, the historical status of the bus line voltage is checked, and the determination of whether the low-voltage load shedding protection should continue to be executed is completed when the bus line voltage has met the set conditions.

[0062] In this application embodiment, the execution state of the low-voltage load shedding protection in step C3 can be determined by comprehensively judging the comparison results of the bus line voltage and the set voltage conditions, whether the bus three-phase current meets the input prerequisites, the comparison results of the voltage change rate and the set threshold, and the historical state of the bus line voltage, and is used to control whether the low-voltage load shedding protection logic is executed.

[0063] In one alternative implementation, the execution status of the low-voltage load shedding protection can also be determined by sequentially judging the real-time voltage value, whether the current meets the input conditions, the voltage change trend and historical validity, and maintaining or updating the operation status of the low-voltage load shedding protection logic when all judgment conditions are met.

[0064] In another optional implementation, the execution status of the low-voltage load shedding protection can also be evaluated by performing multi-cycle statistical judgment on the stability of voltage and current through the sliding window method in scenarios where the collected data fluctuates. This, combined with threshold judgment and historical valid criteria, improves the robustness of the status determination.

[0065] This invention constructs an execution status determination mechanism for low-voltage load shedding protection, consisting of voltage judgment, current judgment, voltage change rate, and voltage history status. This avoids the erroneous execution of low-voltage load shedding protection logic under conditions of pipeline voltage transients, circuit breaker non-closed, or insufficient current. It ensures that the protection logic is effectively executed only when there is a real low-voltage risk and the commissioning conditions are met, thereby improving the stability and reliability of low-voltage load shedding protection.

[0066] Specifically, the traditional low-voltage load shedding protection logic before optimization is as follows: Figure 4 As shown, it is equipped with a low-voltage load shearing soft pressure plate, a hard pressure plate, and a low-voltage load shearing control word.

[0067] The low-voltage load shedding system includes a circuit breaker closing criterion and a fixed-entry no-current blocking mechanism, operating on the same principle as low-frequency load shedding. The fixed-entry voltage slip blocking function: when a short-circuit fault occurs in the system, if the voltage drop slip detected by the device exceeds the [voltage change rate blocking value], the device will block the low-voltage load shedding function. To prevent maloperation of the low-voltage load shedding system due to PT disconnection, the low-voltage load shedding function is blocked when the line voltage is greater than 20V and the negative sequence voltage is less than 6V. Low-voltage load shedding operation must be based on the assumption that the voltage was previously normal.

[0068] The optimized low-voltage load shedding protection logic of this invention is as follows: Figure 5 As shown, the active power magnitude is added to the original criteria, stipulating that the flow from the busbar to the line is the positive direction. When the total active power is greater than 0.5MW, the low-frequency load shedding protection is effective; when the total active power is less than 0.5MW, the low-frequency load shedding protection is ineffective.

[0069] The low-voltage load shedding system includes a circuit breaker closing criterion and a fixed-operation no-current blocking mechanism. The fixed-operation voltage slippage blocking function: when a short-circuit fault occurs in the system, if the voltage drop slippage detected by the device exceeds the [voltage change rate blocking value], the device will block the low-voltage load shedding function. To prevent maloperation of the low-voltage load shedding system caused by PT disconnection, the low-voltage load shedding function is blocked when the line voltage is greater than 20V and the negative sequence voltage is less than 6V. Low-voltage load shedding operation must be based on the assumption that the voltage was previously normal. When a three-phase CT is selected, the power calculation uses the three-meter method; when a two-phase CT is selected, the power calculation uses the two-meter method.

[0070] Furthermore, in step S4, the active power of the bus is calculated based on the bus line voltage and the three-phase current of the bus, and the active power of the bus is compared with the set power threshold. The states of underfrequency load shedding protection and undervoltage load shedding protection are automatically set, including the following steps D1-D5: D1. When the current transformer is connected to three phases, calculate the active power of the bus based on the correspondence between the three-phase voltage and the three-phase current.

[0071] D2. When the current transformer is connected to two phases, calculate the active power of the bus based on the relationship between the line voltage and the corresponding phase current.

[0072] D3. Compare the active power of the bus with the set power threshold, and enter the load shedding protection state setting process based on the comparison result.

[0073] D4. When the comparison results show that the active power of the bus is greater than the set power threshold, the low-frequency load shedding protection and low-voltage load shedding protection are set to effective status.

[0074] D5. When the comparison results show that the active power of the bus is not greater than the set power threshold, the low-frequency load shedding protection and low-voltage load shedding protection are set to invalid.

[0075] In this embodiment of the application, the current transformer polarity verification function in step S5 is a functional module that can be started by a control word signal during the commissioning and startup of the power distribution bay. After startup, the module continuously monitors the bus line voltage, the three-phase current of the bus, and the sampling status of the bus active power and bus reactive power calculated therefrom. When it is detected that the bus line voltage is in a three-phase balanced state and the active power of the corresponding phase is positive and the reactive power is negative, it is determined that the polarity of the current transformer of that phase is correct. If this condition is not met, it is determined that the polarity is incorrect, and the function will exit after running continuously for a set time.

[0076] In one alternative implementation, the polarity verification function of the current transformer can also be analyzed based on the phase relationship between the voltage and current signals. Under the condition that the sampling state is normal and the three-phase voltage is balanced, the phase angle offset direction and range of the voltage and current waveforms are compared, and the polarity determination result is determined in combination with historical operating data.

[0077] In another alternative implementation, the current transformer polarity verification function can also detect the influence characteristics of current polarity on power direction under stable operating conditions by introducing a low-amplitude test signal, and determine whether the current transformer wiring is correct.

[0078] This invention establishes a current transformer polarity verification function during the commissioning phase of a power distribution bay. By combining the collected bus line voltage, three-phase bus current, and the relationship between bus active and reactive power, the polarity status is automatically determined. This enables rapid self-checking and error identification of the current transformer polarity, avoids abnormal bus power direction judgment due to wiring errors, ensures the correctness of the load shedding protection activation / deactivation logic, and improves the wiring accuracy and protection reliability of the system during commissioning.

[0079] Furthermore, in step S5, during the commissioning and startup process of the power distribution bay, the polarity verification function of the current transformer is activated according to the control word signal. The polarity of the current transformer is verified and determined by collecting the bus line voltage, three-phase bus current, and corresponding bus active power data, including the following steps E1-E5: E1. During the commissioning and startup process of the power distribution bay, the polarity verification logic of the current transformer is started according to the control word signal.

[0080] E2. After the verification logic is started, monitor whether the sampling status of the bus line voltage, bus three-phase current, bus active power and bus reactive power is in a normal state.

[0081] E3. When the bus line voltage is in a three-phase balanced state, if the active power of the corresponding phase is positive and the reactive power of the corresponding phase is negative, the polarity of the current transformer of the corresponding phase is determined to be correct.

[0082] E4. When the bus line voltage is in a three-phase balanced state, if the active power of the corresponding phase bus is not positive and the reactive power of the corresponding phase bus is not negative, it is determined that the polarity of the current transformer of the corresponding phase is incorrect.

[0083] E5. When the current transformer polarity verification function runs for the set duration, the verification function will exit.

[0084] Specifically, this patent also includes a CT wiring adaptive verification function, which is activated via a control word during the commissioning of newly built or expanded power distribution bays.

[0085] The CT wiring adaptive verification function consists of the following modules: CT polarity verification function forced to exit after a long period of operation, CT polarity verification function enabled, CT polarity verification correct, and CT polarity verification error.

[0086] The CT polarity verification function will be forcibly deactivated if it has been in use for an extended period. Once activated, the function will be forcibly deactivated after a duration exceeding 2.78 hours. See the logic diagram below. Figure 6 .

[0087] The CT polarity check logic is only entered after the CT polarity check function is enabled. See the logic diagram below. Figure 7 .

[0088] When the CT polarity check is correct and sampling is normal, if the three-phase voltages are balanced, the active power of the corresponding phase is positive and the reactive power is negative, indicating that the CT polarity of that phase is correct. See the logic diagram below. Figure 8 .

[0089] CT polarity check error. When sampling is normal, if the three-phase voltage is balanced, but the active power of the corresponding phase is not positive or the reactive power is not negative, the CT polarity of that phase is determined to be incorrect. See the logic diagram below. Figure 9 .

[0090] Example 3 is an embodiment of the present invention. This embodiment provides a line protection load reduction optimization strategy and implementation system that takes into account the access of new energy sources, including a data acquisition module, a low-frequency load reduction judgment module, a low-voltage load reduction judgment module, a comparison module, and a current transformer polarity verification module.

[0091] The data acquisition module is used to collect bus line voltage, bus three-phase current and circuit breaker closed position information, and calculate bus frequency based on bus line voltage.

[0092] The low-frequency load shedding judgment module is used to determine whether the low-frequency load shedding protection is enabled based on the three-phase current of the busbar when the busbar frequency is within the effective frequency range and the circuit breaker is in the closed position. Based on the comparison between the busbar frequency slip and the set slip threshold, it determines whether to block the low-frequency load shedding protection.

[0093] The low-voltage load shedding judgment module is used to execute the low-voltage load shedding protection logic when the bus line voltage meets the set conditions and the three-phase current of the bus meets the low-voltage load shedding protection activation conditions, and to determine whether to block the low-voltage load shedding protection based on the voltage change rate.

[0094] The comparison module calculates the active power of the bus based on the bus line voltage and the three-phase current of the bus, compares the active power of the bus with the set power threshold, and automatically sets the status of low-frequency load shedding protection and low-voltage load shedding protection.

[0095] The current transformer polarity verification module is used to activate the current transformer polarity verification function according to the control word signal during the commissioning and startup process of the power distribution bay. It completes the verification and determination of the current transformer polarity by collecting the bus line voltage, bus three-phase current and corresponding bus active power data.

[0096] This embodiment also provides an electronic device applicable to a line protection load reduction optimization strategy and implementation method considering new energy access, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the line protection load reduction optimization strategy and implementation method considering new energy access as proposed in the above embodiment.

[0097] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements a line protection load reduction optimization strategy and implementation method considering new energy access as proposed in the above embodiments.

[0098] The storage medium proposed in this embodiment belongs to the same inventive concept as the implementation strategy and method for line protection load reduction optimization considering new energy access proposed in the above embodiments. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0099] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0100] 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 preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A line protection load reduction optimization strategy and implementation method considering the access of new energy sources, characterized in that: include, Collect bus line voltage, bus three-phase current and circuit breaker closed position information, and calculate bus frequency based on bus line voltage; Under the condition that the bus frequency is within the effective frequency range and the circuit breaker is in the closed state, the low frequency load shedding protection is activated based on the three-phase current of the bus. Based on the comparison between the bus frequency slip and the set slip threshold, it is determined whether the low frequency load shedding protection is blocked. Provided that the bus line voltage meets the set conditions and the three-phase bus current meets the conditions for the activation of the low-voltage load shedding protection, the low-voltage load shedding protection logic is executed, and the low-voltage load shedding protection is blocked based on the voltage change rate. The active power of the bus is calculated based on the bus line voltage and the three-phase current of the bus, and the active power of the bus is compared with the set power threshold. The status of low-frequency load shedding protection and low-voltage load shedding protection is automatically set. During the commissioning and startup process of the power distribution bay, the polarity verification function of the current transformer is activated according to the control word signal, and the polarity of the current transformer is verified and determined by collecting the bus line voltage, bus three-phase current and corresponding bus active power data.

2. The line protection load reduction optimization strategy and implementation method considering new energy access as described in claim 1, characterized in that: The process involves collecting bus line voltage, three-phase bus current, and circuit breaker closing status information, and calculating the bus frequency based on the bus line voltage. Extract the bus line voltage and bus three-phase current signals from the corresponding measurement circuits of the current transformer and voltage transformer; Get the current closed position of the circuit breaker; Based on the bus line voltage signal, perform a frequency extraction operation to obtain the current bus frequency.

3. The line protection load reduction optimization strategy and implementation method considering new energy access as described in claim 2, characterized in that: The process involves determining whether the low-frequency load shedding protection is enabled based on the bus three-phase current, under the condition that the bus frequency is within the effective frequency range and the circuit breaker is in the closed position. It also involves determining whether to block the low-frequency load shedding protection based on a comparison between the bus frequency slip and the set slip threshold. After obtaining the bus frequency, the bus frequency is distinguished according to the preset effective frequency range, and the low-frequency load reduction judgment process is entered when the distinction result meets the conditions. After entering the low-frequency load reduction judgment process, the executability of the protection logic is confirmed according to the closed position of the circuit breaker; After confirming feasibility, the three-phase current of the busbar is compared with the set conditions to determine whether the prerequisite for the activation of the low-frequency load shedding protection is met. Before implementing low-frequency load shedding, the frequency change of the bus is calculated to obtain the frequency slip, and the low-frequency load shedding protection is determined to remain in the active state based on the comparison result between the slip and the set threshold.

4. The line protection load reduction optimization strategy and implementation method considering new energy access as described in claim 3, characterized in that: Under the premise that the bus line voltage meets the set conditions and the three-phase bus current meets the activation conditions of the low-voltage load shedding protection, the low-voltage load shedding protection logic is executed, and the decision on whether to block the low-voltage load shedding protection is based on the voltage change rate, including: After obtaining the bus line voltage, the bus line voltage is compared with the set voltage conditions to determine whether to enter the low-voltage load shedding judgment process. After entering the low-voltage load shedding judgment process, the circuit breaker closing status is checked, and if the closing status meets the conditions, the bus three-phase current is further judged to see if the low-voltage load shedding protection is put into operation. After the conditions for operation are met, the trend of bus line voltage change is calculated, and the execution status of low-voltage load shedding protection is determined based on the comparison between the obtained rate of change and the set threshold. During the low-voltage load shedding process, the historical status of the bus line voltage is checked, and the determination of whether the low-voltage load shedding protection should continue to be executed is completed when the bus line voltage has met the set conditions.

5. The line protection load reduction optimization strategy and implementation method considering new energy access as described in claim 4, characterized in that: The step of calculating the bus active power based on the bus line voltage and the three-phase bus current, and comparing the bus active power with a set power threshold, includes: When the current transformer is connected to three phases, the active power of the bus is calculated based on the correspondence between the three-phase voltage and the three-phase current. When the current transformer is connected to two phases, the active power of the bus is calculated based on the relationship between the line voltage and the corresponding phase current. The active power of the bus is compared with the set power threshold, and the load shedding protection state setting process is initiated based on the comparison result.

6. The line protection load reduction optimization strategy and implementation method considering new energy access as described in claim 5, characterized in that: The automatic setting of low-frequency load shedding protection and low-voltage load shedding protection states. include, When the comparison results show that the active power of the bus is greater than the set power threshold, the low-frequency load shedding protection and low-voltage load shedding protection are set to be effective. When the comparison results show that the active power of the bus is not greater than the set power threshold, the low-frequency load shedding protection and low-voltage load shedding protection are set to be in an invalid state.

7. The line protection load reduction optimization strategy and implementation method considering new energy access as described in claim 6, characterized in that: During the commissioning and startup process of the power distribution bay, the polarity verification function of the current transformer is activated according to the control word signal. The polarity of the current transformer is verified and determined by collecting data on the bus line voltage, three-phase bus current, and corresponding bus active power. During the commissioning and startup process of the power distribution bay, the polarity verification logic of the current transformer is initiated according to the control word signal. After the verification logic is started, monitor whether the sampling status of the bus line voltage, bus three-phase current, bus active power and bus reactive power is in a normal state. When the bus line voltage is in a three-phase balanced state, if the active power of the corresponding phase is positive and the reactive power of the corresponding phase is negative, the polarity of the current transformer of the corresponding phase is determined to be correct. When the bus line voltage is in a three-phase balanced state, if the active power of the corresponding phase bus is not positive and the reactive power of the corresponding phase bus is not negative, it is determined that the polarity of the current transformer of the corresponding phase is incorrect. The current transformer polarity verification function will exit the verification function when the continuous running time reaches the set duration.

8. A line protection load reduction optimization strategy and implementation system considering the access of new energy sources, applying the line protection load reduction optimization strategy and implementation method considering the access of new energy sources as described in any one of claims 1 to 7, characterized in that, include: Data acquisition module, low-frequency load shedding judgment module, low-voltage load shedding judgment module, comparison module and current transformer polarity verification module; The data acquisition module is used to collect bus line voltage, bus three-phase current and circuit breaker closing status information, and calculate bus frequency based on bus line voltage. The low-frequency load shedding judgment module is used to determine whether the low-frequency load shedding protection is enabled based on the three-phase current of the busbar when the busbar frequency is within the effective frequency range and the circuit breaker is in the closed position. Based on the comparison result between the busbar frequency slip and the set slip threshold, it determines whether to block the low-frequency load shedding protection. The low-voltage load shedding judgment module is used to execute the low-voltage load shedding protection logic under the premise that the bus line voltage meets the set conditions and the three-phase current of the bus meets the low-voltage load shedding protection activation conditions, and to determine whether to block the low-voltage load shedding protection based on the voltage change rate. The comparison module calculates the active power of the bus based on the bus line voltage and the three-phase current of the bus, compares the active power of the bus with the set power threshold, and automatically sets the status of low-frequency load shedding protection and low-voltage load shedding protection. The current transformer polarity verification module is used to activate the current transformer polarity verification function according to the control word signal during the commissioning and startup process of the power distribution bay, and to complete the verification and determination of the current transformer polarity by collecting the bus line voltage, bus three-phase current and corresponding bus active power data.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of any one of claims 1 to 7: a line protection load reduction optimization strategy and implementation method that considers new energy access.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of any one of claims 1 to 7: a line protection load reduction optimization strategy and implementation method that takes into account the access of new energy sources.

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