Method and system for 110 kilovolt side short circuit current control for 330 kilovolt substation

Abstract

The application discloses a 110-kilovolt side short-circuit current control method and system for a 330-kilovolt substation, which quantifies the short-circuit current contribution weight of each branch and identifies a dominant feed-in path based on an improved node admittance matrix method; a fast switch and a current-limiting reactor shunt unit are arranged in the dominant feed-in path, and a fast vacuum circuit breaker is arranged at a bus section position; the fast switch is controlled to be tripped to input the current-limiting reactor to realize targeted current limiting during a fault; if the short-circuit current is still over-standard after current limiting, the fast vacuum circuit breaker is controlled to be tripped to realize temporary separation of the bus; after the fault is removed, the bus is restored to be in parallel; single-phase fault suppression is realized by cooperating with small neutral grounding reactors of multiple main transformers; synchronous short-time power flow regulation and control are realized; and current-limiting parameters are adaptively corrected based on PMU closed loop; and control instructions are transmitted at a millisecond level based on the IEC 61850 GOOSE protocol. The application realizes short-time fault triggering current limiting without changing the normal connection of the power grid, and takes into account the current limiting effect, power supply reliability and economy.

Description

Technical Field

[0001] This invention belongs to the field of power system short-circuit current control technology, and particularly relates to a method and system for controlling the 110 kV side short-circuit current in a 330 kV substation. Background Technology

[0002] With the continuous expansion of the regional power grid and the profound adjustment of the power supply structure, 330 / 110 kV step-down substations are core equipment of the power grid hub. Their 110 kV busbars generally adopt a double-busbar, double-section connection method, with the high-voltage side of the main transformer often operating in parallel, while the medium-voltage side often has an unbroken electromagnetic loop. During the operation of this type of substation, the 110 kV side, as an important power distribution output terminal, undertakes the dual functions of supplying regional power loads and connecting with the power grid. Its short-circuit current level directly affects the safety of power grid equipment, the effectiveness of protection coordination, and the reliability of power supply.

[0003] The current control of short-circuit current on the 110 kV side of the existing 330 kV substation mainly adopts single methods such as main transformer split operation, busbar fixed split operation, installation of conventional current-limiting reactors, and modification of high-impedance transformers. In some scenarios, current limiting is achieved by combining system loop-breaking methods. All of the above methods are based on the core idea of ​​"increasing system impedance and reducing power supply input" and have been applied to a certain extent in engineering.

[0004] While existing short-circuit current control methods can achieve a certain current-limiting effect, they have revealed many inherent defects in engineering practice, failing to simultaneously ensure grid safety, economy, and power supply reliability. Specifically: Impaired power supply reliability: The split operation of main transformers and the fixed split operation of busbars will directly reduce the flexibility of grid wiring. If a power supply section fails, it will be difficult to transfer loads and increase the scope and duration of power outages. The system loop-breaking operation will damage the grid network structure, cause power flow redistribution imbalance, and reduce the static stability margin of the system.

[0005] Poor economic efficiency: Upgrading high-impedance transformers requires replacing the main transformer equipment, which is costly and time-consuming, and has a significant impact on the normal operation of the power grid; conventional current-limiting reactors are connected in series with the line for a long time, which will generate continuous reactive power loss and increase the operating cost of the power grid. At the same time, due to the site limitations of substations, some renovation and expansion sites do not have space to install them.

[0006] The current limiting effect is limited and uncontrollable: a single current limiting method can only achieve local impedance adjustment and has no ability to coordinate and control the multiple feed currents of the 330 kV side power supply, nearby power plants and 110 kV tie lines. The short circuit current on the 110 kV side of some substations is still above 38 kA, which is close to the design margin critical value of the 40 kA rated breaking current of the 110 kV circuit breaker. This limits the selection of equipment and increases the risk of fault interruption.

[0007] The coordination of protection is difficult: the activation and deactivation of conventional current limiting devices lack linkage with the power grid protection system, which can easily lead to a mismatch between the protection action time, setting value and current limiting effect, resulting in protection maloperation and failure to operate.

[0008] Patent document CN122118635A discloses a short-circuit current control method, device, electronic equipment, and medium for a power system. The power system includes a first AC equivalent grid, a flexible DC grid, and a second AC equivalent grid. The first AC equivalent grid is connected to the first busbar side of the main transformer through an AC circuit breaker. The flexible DC grid and the second AC equivalent grid are respectively connected to the second busbar side of the main transformer. When a short-circuit fault is detected on the first busbar side, the fault type of the short-circuit fault is determined. A short-circuit current suppression strategy corresponding to the fault type is adopted to suppress the short-circuit current of the flexible DC grid, so as to offset the short-circuit current generated when the second AC equivalent grid has a short-circuit fault on the first busbar side, thereby reducing the total short-circuit current fed into the AC circuit breaker.

[0009] Patent document CN120999545A discloses a method for the coordinated suppression of short-circuit current in a receiving-end power grid using a superconducting fault current limiter and the grid structure. The method includes: First, quantifying and constructing a short-circuit current constraint model that considers the configuration of the superconducting fault current limiter and the optimization of the grid structure. Second, addressing the problem of excessive short-circuit current due to the large-scale integration of new energy sources, the superposition of traditional power sources, and the coordinated development of the receiving-end power grid, a collaborative planning model for the configuration of the superconducting fault current limiter and the optimization of the grid structure is established. In this model, the main problem is responsible for long-term planning decisions, with the objective of minimizing the total investment cost; the sub-problems are responsible for verifying the system's safe operation constraints, with the objective of minimizing operating costs.

[0010] Comparative document CN122118635A relies on flexible DC devices to suppress short-circuit current. This scheme depends on flexible DC equipment and is not suitable for conventional 330 / 110kV AC substations without flexible DC configurations. Comparative document CN120999545A mainly targets the planning and configuration of superconducting fault current limiters, resulting in high equipment investment and is mostly used in new power grid planning, making it difficult to adapt to existing substation renovation projects. Existing technologies lack a complete current-limiting scheme that coordinates "dominant feedin path identification, short-time fault impedance activation, temporary busbar separation, main transformer neutral point reactor grounding, and power flow closed-loop adaptive control." Summary of the Invention

[0011] The purpose of this invention is to provide a method and system for controlling short-circuit current on the 110 kV side of a 330 kV substation. This method can achieve the balance between the safety, economy and power supply reliability of the power grid during the short-circuit current control process.

[0012] To achieve the first objective of this invention, the following technical solution is provided: a method for controlling the short-circuit current on the 110 kV side of a 330 kV substation, comprising: Collect design parameters and topology data of the target substation to construct a detailed calculation model of the short-circuit current of the entire network; Based on the improved node admittance matrix method, a unit injection current is applied to the 110 kV bus node. Combined with the fine calculation model of the short-circuit current of the whole network, the contribution weight of each power source and the 110 kV tie line to the short-circuit current of the 110 kV bus is quantified. This method improves upon the traditional method for short-circuit calculation of the nodal admittance matrix. Unlike the traditional iterative solution for short circuits, it directly calculates the current proportion of each feeder branch by applying a unit injection current to the 110kV target bus, thereby obtaining the short-circuit current contribution weight of each branch and enabling rapid identification of the dominant feeder branch.

[0013] Based on the aforementioned contribution weights, the top N high-contribution branches are selected as the fixed main feed-in paths for the 110 kV bus. During the early circuit modification phase, fast-switching current-limiting reactors consisting of fast switches and current-limiting reactors connected in parallel are installed on the top N fixed main feed-in paths. Fast vacuum circuit breakers are also connected in series at the bus sectionalizing switch positions on the 110 kV side. The rule for N is as follows: the contribution ratio of the branches is accumulated from largest to smallest according to the contribution weight. When the accumulated total contribution ratio reaches a preset threshold, the corresponding number of branches is N.

[0014] When a short-circuit fault occurs during operation, the control fast switch is tripped to connect the current-limiting reactor in series into the main feed path circuit to achieve targeted branch current limiting. If the short-circuit current of the busbar is still higher than the safety threshold after the current limiting of the targeted branch, the safety threshold is the short-circuit current allowable value pre-set according to the rated breaking capacity of the circuit breaker, then the fast vacuum circuit breaker is controlled to open to achieve temporary separation of the busbar, and the fault is cleared by the original protection switch. Once the short-circuit fault is reliably cleared, the fast vacuum circuit breaker is closed to restore the busbar parallel operation.

[0015] This invention achieves precise and controllable suppression of short-circuit current without changing the core physical wiring of the power grid or reducing the continuity of power supply, through targeted identification, multi-dimensional current limiting, power flow coordination, and dynamic adaptation.

[0016] Specifically, when multiple main transformers are configured in a substation, one main transformer is reserved to maintain a 330 kV hot standby, and the 110 kV side switch is tripped and taken out of operation, while the remaining main transformers are operating normally on the grid. All main transformer neutral points in the entire station adopt small reactor grounding method, and hot standby main transformers are pre-configured with reactor grounding to ensure that they can be directly connected to the grid and put into operation; The entire station relies on the grounding of multiple main transformer reactors to form a stable zero-sequence path, ensuring that the system still has a reliable zero-sequence grounding path under the N-1 main transformer outage condition. By raising the system's zero-sequence equivalent impedance through full-area reactor grounding, the single-phase ground fault current is limited.

[0017] Specifically, the impedance value of the small reactance grounding method is matched and calculated based on the simulation of the system's zero-sequence short-circuit current level.

[0018] Specifically, the design parameters include the zero-sequence / positive-sequence impedance of the main transformer, the neutral grounding method, and the equivalent parameters of the 110 kV line π type.

[0019] Specifically, when a short-circuit fault occurs during operation, short-term power flow optimization and control also need to be implemented simultaneously. The specific measures are as follows: The active power output of grid-connected power plants will be reduced by 5%-8%, and the reactive power support capacity of regional static var generators (SVG) will be improved to ensure local reactive power balance in 110 kV regions, stabilize bus voltage, and at the same time reduce the short-circuit current boosting effect of remote power sources under fault conditions, thereby helping to strengthen the current limiting effect.

[0020] Specifically, the operation also includes a closed-loop adaptive correction mechanism to adjust the basis for monitoring short-circuit faults. The process of the closed-loop adaptive correction mechanism is as follows: Using a 15-minute cycle, the system verifies the short-circuit capacity and short-circuit current amplitude of each fixed main feed-in path based on real-time data from the PMU. Combined with dynamic changes in load and renewable energy output, the system adaptively corrects the fault current limiting threshold and short-term power flow optimization control parameters and embeds them into the station's IED device. This dynamically adapts to various operating conditions of the power grid, ensuring accurate and reliable current limiting action when a sudden short-circuit fault occurs.

[0021] Specifically, all control commands for the entire station are transmitted synchronously at the millisecond level via the IEC 61850 GOOSE protocol, with a total response time of ≤35ms for command linkage transmission; the total response time for the complete closed-loop process, including data acquisition, logical judgment, and equipment action, is ≤85ms.

[0022] To achieve the second objective of this invention, the following technical solution is provided: a 110 kV side short-circuit current control system, used to implement the above-mentioned 110 kV side short-circuit current control method, comprising: The short-circuit current sensitivity modeling module selects the fixed dominant feed-in path based on the measured data and topology of the target substation and the associated 110 kV side. The 110 kV line impedance optimization module connects the current-limiting impedance unit, which is connected in parallel with the fast switch and the current-limiting reactor, into the main feed path, and quickly puts the reactor into action at the moment a short-circuit fault occurs to achieve instantaneous current limiting. The main transformer operation strategy optimization module, designed for the main transformer to be connected to the grid and put into operation at any time, raises the system's zero-sequence impedance by relying on the full-domain main transformer reactor grounding structure to suppress single-phase grounding short-circuit current. The 110 kV bus topology dynamic reconfiguration module monitors the grid operation status in real time. When a short circuit fault occurs, it controls the fast vacuum circuit breaker at the section position of the 110 kV side bus to trip and disconnect instantly, blocking the short circuit current feed channel in multiple ways. After the fault is cleared, it quickly closes and resets to restore the parallel operation of the bus. The active power flow guidance control module achieves local reactive power balance in different zones under short-circuit conditions by reducing the active power of the generator units and increasing the reactive power of new energy sources. It also strengthens the overall current limiting effect by coordinating with hardware current limiting to ensure stable system operation. The adaptive closed-loop control submodule is connected to the synchronous phasor measurement unit (PMU) and the intelligent electronic device (IED) in the station. Based on real-time data from the PMU, it performs online verification of the system's short-circuit capacity and periodic adaptive fine-tuning of fault current-limiting parameters. The corrected current-limiting parameters are then sent down and solidified to the IED to dynamically match the changing operating conditions of the power grid and ensure the accuracy and adaptability of the fast-acting control of each current-limiting device in the event of a sudden short-circuit fault.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: The current limiting effect is significant and controllable: it can control the short-circuit current of the 110kV busbar within the safe breaking capacity of the circuit breaker, significantly improving the breaking margin of the circuit breaker; Power supply reliability is unaffected: all current limiting measures are "fault-triggered and normal-recovered", load outage time is less than 0.5 seconds, tie lines have undergone thermal and dynamic stability checks and have no risk of exceeding limits, and the flexibility of grid wiring and static stability margin are unaffected; Excellent engineering economics: No need to replace the main transformer; the upgrade is achieved by simply adding fast switches, current-limiting reactors, and fast vacuum circuit breakers, reducing investment costs by more than 60% compared to upgrading high-impedance transformers; no long-term reactive power loss, significantly reducing grid operating costs. Highly adaptable to engineering projects: The renovation plan only requires the addition of supporting equipment on the basis of the existing wiring, without changing the physical wiring. It has low site requirements and is suitable for various scenarios such as substation renovation and expansion, and new substation construction. The modules can be flexibly combined according to the characteristics of the project, making it highly practical. Excellent protection coordination: All control commands are synchronized at the millisecond level via the IEC 61850 GOOSE protocol, which is highly matched with the action sequence of the power grid protection system, completely solving the problems of protection maloperation and failure to operate. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the 110 kV side short-circuit current control method provided in this embodiment; Figure 2This is a schematic diagram of the optimized electrical main wiring of a 330 kV substation provided in this embodiment. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] like Figure 1 As shown in this embodiment, a short-circuit current control method for the 110 kV side of a 330 kV substation is provided, comprising: Data on the positive / zero sequence impedance of the 330kV main transformer, neutral grounding parameters, π-type equivalent parameters of the 110kV line, and power plant and renewable energy topology were collected. After unified per-unit conversion, positive sequence and zero sequence networks were constructed respectively. Corresponding equivalent branches of renewable energy converters, main transformers and their neutral point reactance branches were added to the BPA basic network model to form an improved network model that matches the operation mode of this station. The BPA short-circuit solver module was called to output the node voltage of the entire network and the short-circuit current of each voltage level bus. The short-circuit feed current of each power source and tie line was extracted. The ratio of the feed current of a branch to the total short-circuit current of the bus was used as the short-circuit contribution weight. The top N high contribution branches were selected as the dominant feed paths according to the weight.

[0027] Based on the aforementioned contribution weight, the top N high-contribution branches are selected as the fixed main feed-in paths of the 110 kV bus. In the early circuit modification stage, fast switch current limiting reactors consisting of fast switches and current limiting reactors connected in parallel are installed on the top N fixed main feed-in paths, and fast vacuum circuit breakers are connected in series at the bus section switch positions on the 110 kV side. When a short circuit fault occurs during operation, the control fast switch is tripped to connect the current-limiting reactor in series into the main feed path circuit to achieve targeted branch current limiting. If the bus short-circuit current is still higher than the safety threshold after the targeted branch current limiting, the fast vacuum circuit breaker is controlled to open to achieve temporary separation of the bus, and the fault is cleared by the original protection switch. Once the short-circuit fault is reliably cleared, the fast vacuum circuit breaker is closed to restore the busbar parallel operation.

[0028] The operation also includes a closed-loop adaptive correction mechanism to adjust the basis for monitoring short-circuit faults. The process of the closed-loop adaptive correction mechanism is as follows: Using a 15-minute cycle, the system verifies the short-circuit capacity and short-circuit current amplitude of each fixed main feed-in path based on real-time data from the PMU. Combined with the dynamic changes in load and renewable energy output, the system adaptively corrects the fault current limiting threshold and the parameters for short-term power flow optimization and control, and then embeds them into the station's IED device.

[0029] More specifically, such as Figure 2 The diagram shown is a schematic of a 330 kV substation optimized using the above scheme.

[0030] exist Figure 2 The upper part is a 330kV three-half connection distribution area, with 10 330kV outgoing lines. The high-voltage side of the three main transformers (#1, #2, and #3) is connected to the 330kV busbar. The neutral point of each main transformer is equipped with a small reactor grounding to raise the zero-sequence impedance of the system. The medium-voltage side of the main transformer is connected to the lower 110kV four-section busbar distribution area, and a 35kV reactive power compensation branch is led out from the low-voltage side. The 110kV outgoing lines of the main transformers (#1, #2, and #3) are connected in series to fast switches 1, 2, and 3, respectively. Each fast switch is equipped with a parallel current-limiting reactor. Under normal conditions, the fast switches are closed to bypass the reactor. During a short-circuit fault, the fast switches are quickly opened to activate the reactor to limit the short-circuit current. The 110kV four-section busbar is equipped with fast vacuum circuit breakers 4 and 5 in each section. Under normal conditions, the circuit breakers are closed to maintain the parallel operation of the busbars. During a fault, the fast switches are quickly opened to achieve the separate operation of the busbars and block the feed channels of multiple short-circuit currents.

[0031] First, the dominant feed-in path is identified by using a fine calculation model of the short-circuit current of the entire network, and the core branch that contributes the most to the short-circuit current on the 110 kV side is accurately located, solving the problem of "no target and full coverage" in traditional current limiting. For the identified dominant feed path, a fault-targeted current limiting device is achieved by adding a fast switch and a current-limiting reactor in parallel. During normal operation, there is no loss, which ensures the current limiting effect and avoids long-term impedance loss.

[0032] By adjusting the main transformer switching on / off and the neutral grounding method, the zero-sequence and positive-sequence impedances of the system are improved, reducing the short-circuit current feed in from the power supply side, and forming a "source-circuit" coordinated current limiting with the optimization of line impedance.

[0033] When the short-circuit current approaches the threshold, the busbar is temporarily disconnected through a millisecond-level fast vacuum circuit breaker to further reduce the power input to the fault point. After the fault is cleared, the busbar is immediately restored to parallel operation to ensure power supply reliability.

[0034] While implementing all the above current limiting measures, the local reactive power balance of the 110 kV zone is achieved through active and reactive power flow regulation, reducing the decay time constant of the non-periodic component in the short-circuit current, shortening the peak duration, weakening the boosting effect of adjacent power sources, and forming an integrated "hardware + software" regulation with hardware current limiting.

[0035] In addition, the system tracks changes in the power grid's operating status in real time and dynamically adjusts the current limiting parameters to ensure that the short-circuit current remains below 36kA under all operating conditions, thus meeting the circuit breaker's breaking requirements.

[0036] This embodiment also provides a 110 kV side short-circuit current control system, which implements the steps of the above-described 110 kV side short-circuit current control method, including: The short-circuit current sensitivity modeling module constructs a network-wide short-circuit current calculation model based on the measured parameters (main transformer zero-sequence / positive-sequence impedance, neutral grounding method, π-type equivalent parameters of 110 kV lines) and topology of the substation and its connected 110 kV radial network. An improved nodal admittance matrix method is used to apply a unit injection current to the 110 kV bus node, calculate the contribution weight of each power source (330 kV side power source, adjacent power plant) and 110 kV tie line to the short-circuit current of the target bus, and identify the top three branches with the highest sensitivity (dominant feed-in paths) to provide precise targeting for subsequent current limiting measures.

[0037] The 110 kV line impedance optimization module, based on the identification results of the dominant feed-in path, incorporates a fast switch and a current-limiting reactor in parallel in the core branch. This device is a core supporting hardware component, with a significantly smaller footprint than conventional current-limiting reactors. During normal operation, the fast switch is closed and current is carried out without additional impedance loss. In case of a fault, the protection device quickly detects the short-circuit current, controls the fast switch to open within 10 ms, and puts the current-limiting reactor into the circuit, instantly increasing the impedance of the dominant feed-in path to achieve targeted current limiting.

[0038] The main transformer operation strategy optimization module, designed for substations with multiple main transformer configurations, dynamically adjusts the system impedance through main transformer commissioning / decommissioning control and neutral point grounding method. When three main transformers are configured, one main transformer's 110 kV side switch is shut down while maintaining the 330 kV side as a hot standby, and its neutral point is switched from direct grounding to grounding via a small reactor with an exemplary value of 10 Ω. All main transformer neutral point grounding methods are dynamically configured according to the "N-1" principle to ensure that when any main transformer is decommissioned, the grounding resistance value of the remaining operating main transformers meets the requirement of a 18%-22% increase in the equivalent impedance of the zero-sequence network.

[0039] The 110 kV bus topology dynamic reconfiguration module, while maintaining the physical wiring of the double busbars and double sections, inserts millisecond-level fast vacuum circuit breakers in series at the section switch positions; in the event of a fault, the fast circuit breaker instantly trips to separate the busbars, reducing the power input to the fault point; after the traditional switch reliably clears the fault, the fast circuit breaker immediately closes to restore the busbars to parallel operation, minimizing the impact on power supply continuity.

[0040] The active power flow guidance control module executes synchronously with the above modules, sending control commands to the dispatch master station to optimize power flow through active power output reduction and reactive power output increase; it reduces the active power output of the upstream 330 kV line connected power plant by 5%-8% and increases the reactive power output of the new energy collection station in the same area (SVG dynamic response), achieving a local reactive power balance rate of ≥94% for the 110 kV area, and controlling the bus voltage deviation within the range of +1.2% to -0.8%.

[0041] The adaptive closed-loop control submodule includes a PMU real-time data monitoring submodule and a closed-loop verification and adaptive correction submodule. The PMU real-time data monitoring submodule is used to collect and analyze the short-circuit current, voltage, and power of the 110 kV bus in real time. When the predicted short-circuit current is greater than 32 kA, it automatically triggers the bus topology dynamic reconstruction and power flow control command without manual intervention. Advantages: It improves the automation level of the control method, shortens the fault response time, realizes the predictive execution of current limiting measures, and further improves the accuracy of current limiting. The closed-loop verification and adaptive correction submodule recalculates the short-circuit current sensitivity based on PMU data every 15 minutes. When the change rate of the dominant feed-in path weight is greater than 7% / h, it automatically updates the main transformer parameter library, corrects the grounding resistance setting value and power flow guidance threshold, and saves the relevant data to the local IED device.

[0042] In addition, the above modules transmit and execute between devices within the station via the IEC 61850 GOOSE protocol to achieve millisecond-level instruction synchronization. The timing of actions of each module is highly coordinated, and the response time of the whole process is ≤85ms, ensuring that the current limiting measures match the actions of the protection system and avoiding protection malfunctions and failures to operate.

[0043] Furthermore, the terms "upper," "lower," "inner," "outer," "front," and "rear" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Unless otherwise specifically stated, the relative steps, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0044] Of course, the above description is only a specific embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention should be included in the scope of the claims of the present invention.

[0045] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for controlling short-circuit current on the 110 kV side of a 330 kV substation, characterized in that, include: Collect design parameters and topology data of the target substation to construct a detailed calculation model of the short-circuit current of the entire network; Based on the improved node admittance matrix method, a unit injection current is applied to the 110 kV bus node. Combined with the fine calculation model of the short-circuit current of the whole network, the contribution weight of each power source and the 110 kV tie line to the short-circuit current of the 110 kV bus is quantified. Based on the contribution weight, the top N high contribution branches are selected and used as the fixed main feed-in path of the 110 kV bus. In the early circuit modification stage, fast switch current limiting reactors consisting of fast switches and current limiting reactors connected in parallel are set on the top N fixed main feed-in paths, and fast vacuum circuit breakers are connected in series at the bus section switch position on the 110 kV side. When a short-circuit fault occurs during operation, the control fast switch is tripped to connect the current-limiting reactor in series into the main feed path circuit to achieve targeted branch current limiting. If the bus short-circuit current is still higher than the safety threshold after the targeted branch current limiting, the fast vacuum circuit breaker is controlled to open to achieve temporary separation of the bus, and the fault is cleared by the original protection switch. Once the short-circuit fault is reliably cleared, the fast vacuum circuit breaker is closed to restore the busbar parallel operation.

2. The method for controlling the short-circuit current on the 110 kV side of a 330 kV substation according to claim 1, characterized in that, When multiple main transformers are configured in a substation, a single main transformer is reserved to maintain a 330 kV side hot standby and to be taken out of operation by the 110 kV side switch being tripped, while the remaining main transformers are operating normally on the grid. All main transformer neutral points in the entire station adopt small reactor grounding method, and hot standby main transformers are pre-configured with reactor grounding to ensure that they can be directly connected to the grid and put into operation; The entire station relies on the grounding of multiple main transformer reactors to form a stable zero-sequence path, ensuring that the system still has a reliable zero-sequence grounding path even under the condition of main transformer N-1 outage. By raising the system's zero-sequence equivalent impedance through full-area reactor grounding, the single-phase ground fault current is limited.

3. The method for controlling the short-circuit current on the 110 kV side of a 330 kV substation according to claim 2, characterized in that, The impedance value of the small reactance grounding method is matched and calculated based on the simulation of the system's zero-sequence short-circuit current level.

4. The method for controlling the short-circuit current on the 110 kV side of a 330 kV substation according to claim 1, characterized in that, The design parameters include the zero-sequence / positive-sequence impedance of the main transformer, the neutral grounding method, and the equivalent parameters of the 110 kV line π type.

5. The method for controlling the short-circuit current on the 110 kV side of a 330 kV substation according to claim 1, characterized in that, When a short-circuit fault occurs during operation, short-term power flow optimization and control also need to be carried out simultaneously. The specific measures are as follows: Lower the preset active power output ratio of grid-connected power plants, and coordinate with improving the reactive power support capacity of regional renewable energy SVG.

6. The method for controlling the short-circuit current on the 110 kV side of a 330 kV substation according to claim 1, characterized in that, The operation also includes a closed-loop adaptive correction mechanism to adjust the basis for monitoring short-circuit faults. The process of the closed-loop adaptive correction mechanism is as follows: The system uses real-time data collected by the synchronous phasor measurement unit at a preset cycle to verify the short-circuit capacity of the system and the short-circuit current amplitude of each fixed dominant feed-in path. Combined with the dynamic changes in load and new energy output, the system adaptively corrects the fault current limiting start-up threshold and the parameters of short-term power flow optimization and control, and then distributes and solidifies them to the intelligent electronic equipment in the station.

7. The method for controlling the short-circuit current on the 110 kV side of a 330 kV substation according to claim 1, characterized in that, All control commands for the entire station are transmitted synchronously at the millisecond level via the IEC 61850 GOOSE protocol, with a total response time of ≤35ms for command linkage transmission.

8. A 110 kV side short-circuit current control system, characterized in that, The steps for implementing the short-circuit current control method for the 110 kV side of a 330 kV substation as described in any one of claims 1 to 7 include: The short-circuit current sensitivity modeling module is electrically connected to an external measured data source. It is used to calculate the contribution weight of the short-circuit current of each branch based on the topology and electrical parameters of the target substation and its associated 110 kV side, and to filter and output a fixed dominant feed-in path. The 110 kV line impedance optimization module is used to connect the current-limiting impedance unit, which is connected in parallel with the fast switch and the current-limiting reactor, into the main feed path. When a short-circuit fault occurs, the reactor is triggered to quickly switch on, so as to achieve instantaneous current limiting during the fault. The main transformer operation strategy optimization module, designed for the main transformer to be connected to the grid and put into operation at any time, raises the system's zero-sequence impedance by relying on the full-domain main transformer reactor grounding structure to suppress single-phase grounding short-circuit current. The 110 kV bus topology dynamic reconfiguration module monitors the grid operation status in real time. When a short circuit fault occurs, it controls the fast vacuum circuit breaker at the section position of the 110 kV side bus to trip and disconnect instantly, blocking the short circuit current feed channel in multiple ways. After the fault is cleared, it quickly closes and resets to restore the parallel operation of the bus. The active power flow guidance control module performs refined regulation under short-circuit conditions by reducing the active power of the generator unit and increasing the reactive power of the renewable energy source. The adaptive closed-loop control submodule is connected to the synchronous phasor measurement unit and the intelligent electronic equipment in the station. Based on the real-time data collected by the synchronous phasor measurement unit, it completes the online verification of the system short-circuit capacity, periodic adaptive fine-tuning of the fault current limiting parameters, and sends the corrected current limiting parameters to the IED to dynamically match the changing operating conditions of the power grid.

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