A turn-to-turn fault discrimination method and system for a hierarchical controllable shunt reactor

Abstract

The application discloses a turn-to-turn fault discrimination method and system of a hierarchical controllable shunt reactor, and is characterized in that the method comprises the following steps: step 1, collecting operation parameters of the hierarchical controllable shunt reactor in real time, and calculating impedance parameters of the reactor under a current working capacity according to a capacity switching condition; and step 2, designing a turn-to-turn fault criterion of the hierarchical controllable shunt reactor, and substituting the impedance parameters into the turn-to-turn fault criterion to monitor turn-to-turn fault discrimination of the reactor. The parameters identified by the application all have actual physical meanings, the protection principle is reliable, and meanwhile, the application is not influenced by power supply characteristics.

Description

Technical Field

[0001] The present invention relates to the field of relay protection for power systems, and more particularly to a method and system for distinguishing inter-turn faults of hierarchical controllable shunt reactors. Background Art

[0002] Currently, power production centers and power consumption centers are located far apart, making local electricity supply impossible. Large-capacity, long-distance transmission systems are required to transport power. With the continuous increase in transmission capacity, existing ultra-high voltage (UHV) transmission systems are experiencing severe capacitive effects. High-voltage shunt reactors are often installed on high-voltage transmission lines to mitigate this capacitive effect. High-voltage shunt reactors can reduce active power losses, suppress power frequency overvoltage and switching overvoltage, and limit backflow current. However, traditional shunt reactors have a fixed capacity and are not adjustable. UHV transmission lines experience significant power flow fluctuations, making it difficult for fixed reactors to effectively and timely control voltage, limiting the transmission capacity of these lines. The large-scale integration of renewable energy sources such as wind and photovoltaic power generation has exacerbated the difficulty of controlling voltage and reactive power on transmission lines. Controllable shunt reactors can adjust the reactive power compensation capacity on demand, dynamically compensating for excess reactive power on transmission lines and improving line voltage stability.

[0003] In power systems, there are high requirements for the reliability of controllable high-voltage reactor protection. Background technology document: Configuration and principle analysis of microcomputer protection for hierarchical high-voltage controllable shunt reactors, Yao Qinglin et al., Automation of Electric Power Systems, Vol. 33, No. 21, November 10, 2009. The document discloses the protection principle for high-voltage controllable shunt reactors during inter-turn short circuits. Currently, the inter-turn protection principle for the control winding of hierarchical controllable shunt reactors is the zero-sequence overcurrent protection principle for the control winding, which is locked by the zero-sequence voltage on the high-voltage side of the reactor. This principle places high demands on the setting value, requiring a reasonable coordination between the zero-sequence voltage locking setting value and the control winding zero-sequence overcurrent setting value. Furthermore, the capacity of the control winding of the hierarchical controllable shunt reactor changes dynamically, causing the fault current to vary under different capacities. This setting value brings great difficulties. If the setting value is mismatched, the protection will fail to operate or malfunction, resulting in an inability to reliably protect the control winding. In serious cases, it will affect the safe and stable operation of the entire power system.

[0004] The turn-to-turn protection principle for the control windings of graded controllable shunt reactors used in existing reactor protection devices cannot detect changes in the control winding capacity, and setting the fixed value is difficult. There is no protection method that is reliable and sensitive to changes in the control winding capacity and easy to set the fixed value. Therefore, it is extremely important to provide a method that can reliably protect the windings. Summary of the Invention

[0005] In order to address the deficiencies in the prior art, the present invention provides a method, system, device and computer-readable storage medium for distinguishing inter-turn faults of a graded controllable shunt reactor. By obtaining the grid-side three-phase voltage, three-phase current and control-side three-phase current of the graded controllable shunt reactor under two normal operating capacities, various parameters of the controllable high-voltage reactor are calculated, thereby distinguishing and protecting inter-turn faults.

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

[0007] The first aspect of the present invention relates to a method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor, comprising the following steps: Step 1, real-time acquisition of operating parameters of the hierarchical controllable shunt reactor, and calculation of the impedance parameters of the reactor at the current working capacity according to the capacity switching conditions; Step 2, designing an inter-turn fault judgment criterion of the hierarchical controllable shunt reactor, and substituting the impedance parameters into the inter-turn fault judgment criterion to monitor the inter-turn fault judgment of the reactor.

[0008] Preferably, substituting the impedance parameters into the inter-turn fault criterion also includes: selecting new measurement data from the operating parameters collected in real time according to the capacity switching conditions, and updating the solution results of the impedance parameters by recursion; substituting the updated solution results of the impedance parameters and the operating parameters collected in real time into the inter-turn fault criterion to realize real-time inter-turn fault judgment.

[0009] Preferably, the operating parameters of the graded controllable shunt reactor include the grid-side three-phase voltage, the grid-side three-phase current and the control-side three-phase current of the graded controllable shunt reactor in the working state.

[0010] Preferably, the current working capacity is one of the working capacities of each level of the hierarchical controllable shunt reactor.

[0011] Preferably, the impedance parameters of the reactor are the excitation impedance and the grid-side leakage impedance.

[0012] Preferably, the capacity switching condition includes: monitoring the working capacity of the reactor, and determining that the capacity switching condition is met when the reactor switches the working capacity and no protection action occurs for the current switching; wherein the protection action condition is i1(t)>α1i 1r Or i2(t)>α2i 2r Any one of them is established; where i1(t) is the three-phase current on the grid side, i2(t) is the three-phase current on the control side, i 1r is the grid-side rated current, i 2r is the three-phase current on the control side, α1 and α2 are system coefficients respectively.

[0013] Preferably, the inter-turn fault criterion is:

[0014]

[0015] Among them, R1+jwL1 is the grid side leakage impedance, R m +jwL m is the excitation impedance, is the grid-side voltage phasor, is the grid-side current phasor, is the excitation current phasor, K set is the fault threshold.

[0016] Preferably, if the inter-turn fault criterion is greater than a preset threshold or the slope of the inter-turn fault criterion is greater than a preset threshold, it is determined that an inter-turn fault occurs in the reactor.

[0017] Preferably, monitoring the inter-turn fault determination of the reactor also includes: deploying one or more sets of standard measurement data corresponding to the current hierarchical controllable shunt reactor in advance, and calculating the impedance parameters under the current working capacity in conjunction with the newly added measurement data.

[0018] The second aspect of the present invention relates to a hierarchical controllable shunt reactor inter-turn fault judgment system using the method of the first aspect of the present invention, the system including CTs and PTs arranged on the grid side and control side of the hierarchical controllable shunt reactor, and a fault judgment module; wherein the CTs and PTs on the grid side and the control side are used to collect operating parameters of the hierarchical controllable shunt reactor; the fault judgment module is used to control and calculate the impedance parameters of the reactor at the current working capacity according to the capacity switching conditions, and to design the inter-turn fault judgment criterion of the hierarchical controllable shunt reactor, and substitute the impedance parameters into the inter-turn fault judgment criterion to monitor the inter-turn fault judgment of the reactor.

[0019] The third aspect of the present invention relates to a hierarchical controllable shunt reactor inter-turn fault judgment device using the method in the first aspect of the present invention, wherein the storage medium is used to store instructions; and the processor is used to operate according to the instructions to execute the steps of the method in the first aspect of the present invention.

[0020] A fourth aspect of the present invention relates to a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method in the first aspect of the present invention.

[0021] The present invention has the beneficial effect of, compared to the prior art, providing a method, system, device, and computer-readable storage medium for identifying interturn faults in a hierarchical controllable shunt reactor. By obtaining the grid-side three-phase voltage, three-phase current, and control-side three-phase current of the hierarchical controllable shunt reactor under two normal operating capacities, the present invention calculates various parameters of the controllable high-voltage reactor, thereby enabling interturn fault identification and protection. The parameters identified by the present invention all have practical physical meaning, the protection principle is reliable, and the system is unaffected by power supply characteristics.

[0022] The beneficial effects of the present invention also include:

[0023] 1. The method of the present invention is not affected by the characteristics of the power supply, can identify various parameters in the time domain, and realize real-time fault diagnosis. It can still be used normally in new power systems where renewable energy such as wind power and photovoltaic power accounts for a large proportion.

[0024] 2. The method of the present invention is highly sensitive and can effectively identify small-turn faults. When an inter-turn fault occurs in a hierarchical controllable shunt reactor, the slight changes in the internal parameters of the reactor can be obtained in a timely and accurate manner, thereby tracing the fault source.

[0025] 3. Rapid protection action. The various parameters in the fault judgment criteria can be calculated in advance. When the protection is activated, only the discriminant equation needs to be calculated, eliminating the need for additional calculations. Furthermore, while ensuring timely protection action, the method also supports timely updates of the various parameters in the criteria, such as when switching reactor capacities, to ensure the accuracy of the judgment results.

[0026] 4. The method is not affected by capacity adjustment. When the capacity of the reactor is adjusted during normal operation, since the main structure of the transformer does not change, the impedance parameters of the reactor will not change either. Therefore, inter-turn fault protection can be reliably achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the steps of a method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to the present invention;

[0028] Figure 2 This is a thumbnail diagram of the main structure of a hierarchical controllable shunt reactor in a method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to the present invention;

[0029] Figure 3 A schematic diagram of sensors deployed in a hierarchical controllable shunt reactor in a method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to the present invention;

[0030] Figure 4 Schematic diagram of an equivalent circuit of a hierarchical controllable shunt reactor in a method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to the present invention;

[0031] Figure 5 A schematic diagram of an embodiment of a grid-connected application of a hierarchical controllable shunt reactor in a method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to the present invention;

[0032] Figure 6 The figure is a schematic diagram of simulation results of a 5% control-side inter-turn fault occurring in a hierarchical controllable shunt reactor in a method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to the present invention. DETAILED DESCRIPTION

[0033] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in the present invention are only part of the embodiments of the present invention, not all of the embodiments. Based on the spirit of the present invention, all other embodiments not described in the present invention that are obtained by ordinary technicians in this field based on the embodiments described in the present invention without making creative work should fall within the scope of protection of the present invention.

[0034] Figure 1 The figure is a schematic diagram of the steps of a method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to the present invention. Figure 1 As shown, the first aspect of the present invention relates to a method for determining inter-turn faults of a hierarchical controllable shunt reactor, and the method includes steps 1 and 2.

[0035] A multistage controlled shunt reactor (MCSR) is a type of controllable shunt reactor. Based on the principle of a high-impedance transformer, it designs the transformer's short-circuit impedance to be close to 100%. Thyristor valves, circuit breakers, and other control circuits are connected to the low-voltage side of the MCSR to achieve graded control of the output inductive reactive power.

[0036] The graded controllable shunt reactor can operate at different capacity levels according to different design requirements to meet the system's reactive power compensation needs. In the event of a fault, it can be quickly adjusted to 100% capacity to limit power frequency overvoltage and suppress backflow current.

[0037] Figure 2 This is a thumbnail diagram of the main structure of a hierarchical controllable shunt reactor in a method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to the present invention. Figure 2 The hierarchical controllable shunt reactor disclosed in [1] is a two-stage capacity switching reactor. As the thyristor valves switch, the reactor operates in different capacity modes. In this reactor, the thyristor valves use zero-current switching, allowing the reactor to operate in either a fully open or fully closed state, generating virtually no harmonics or DC components.

[0038] The following embodiments also mention a more commonly used three-level capacity-averaged graded controllable shunt reactor, in which the reactor operates at three capacity levels of 100%, 67%, and 33% of the rated capacity, respectively.

[0039] Step 1: collect the operating parameters of the hierarchical controllable shunt reactor in real time according to the capacity switching conditions, and calculate the impedance parameters of the reactor under the current working capacity.

[0040] In the present invention, the operating parameters of the graded controllable shunt reactor include the grid-side three-phase voltage, grid-side three-phase current and control-side three-phase current of the graded controllable shunt reactor in the working state.

[0041] Figure 3 Schematic diagram of sensors deployed in a hierarchical controllable shunt reactor in a method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to the present invention. Figure 3 As shown, different current sensors (CTs) are deployed on the control and grid sides of the reactor. Furthermore, voltage sensors (PTs) can be deployed at appropriate locations. This allows the method to obtain various operating parameters. Considering the current sensor deployment, CTs can be pre-connected in series at the appropriate locations during the manufacture of the graded controllable shunt reactor. This method can thus pre-determine the three-phase voltage and current on the grid side, as well as the three-phase current on the control side, for the graded controllable reactor under various normal operating capacities.

[0042] Preferably, the impedance parameters of the reactor are the excitation impedance and the grid-side leakage impedance.

[0043] Figure 4 This is a schematic diagram of the equivalent circuit of a hierarchical controllable shunt reactor in a method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to the present invention. Figure 4 As shown in the figure, when the hierarchical controllable shunt reactor works at a certain working capacity, the method can be used to equivalently draw a circuit diagram of the reactor, where the side close to the ideal transformer is the control side and the side far away is the grid side. Therefore, there are control side voltage u2(t), grid side voltage u1(t), control side current i2(t), grid side current i1(t), control side equivalent resistance R2, control side equivalent inductance L2, grid side equivalent resistance R1, grid side equivalent inductance L1, equivalent excitation resistance R m , equivalent excitation inductance L m .

[0044] In summary, when the graded controllable shunt reactor operates at a certain working capacity, there is a formula:

[0045]

[0046] Among them, i m (t)=i1(t)+n T i2(t),n T is the transformer ratio.

[0047] According to the above content, the excitation impedance in the impedance parameter is based on Solve, the grid side leakage impedance in the impedance parameter is based on Obtained by calculation.

[0048] Thus, after each capacity switch,

[0049] The method can obtain operating parameters according to capacity switching conditions and calculate impedance parameters.

[0050] Preferably, the current operating capacity is one of the operating capacities of each level of the graded controllable shunt reactor. As mentioned above, the commonly used three-level capacity averaging graded controllable shunt reactor operates at three capacity levels of 100%, 67%, and 33% of the rated capacity.

[0051] Depending on the reactor's actual application scenario, it can switch between three different capacities. Therefore, when the reactor switches between capacities, the method supports real-time acquisition of the reactor's operating parameters and identifies faults based on the updated impedance parameters.

[0052] Preferably, the capacity switching condition includes: monitoring the working capacity of the reactor, and determining that the capacity switching condition is met when the reactor switches the working capacity and no protection action occurs for the current switching; wherein the protection action condition is i1(t)>α1i 1r Or i2(t)>α2i 2r Any one of them is established; where i1(t) is the three-phase current on the grid side, i2(t) is the three-phase current on the control side, i 1r is the grid-side rated current, i 2r is the three-phase current on the control side, α1 and α2 are system coefficients respectively.

[0053] The method will only execute the acquisition of operating parameters and calculation of impedance parameters under the current capacity and the determination of inter-turn faults when the capacity switching condition is met. If the capacity switching condition is not met, the method does not need to acquire and calculate inter-turn faults.

[0054] In this invention, the capacity switching condition is determined by considering whether protective action occurs when the reactor's operating capacity is switched. The protective action is determined based on the real-time current during operation. The system coefficient can be pre-set to a fixed value. Overcurrent is determined based on the rated current on the grid and control sides. If overcurrent occurs, protection is activated, and interturn fault detection is no longer required.

[0055] If the protection fails to activate, the next step, interturn fault determination, can be performed. At this point, the method initiates the collection of operating parameters at the current capacity based on the reactor's capacity switching. The collected operating parameters represent continuous electrical quantity information over a period of time. This electrical quantity information can be used as multiple sets of measurement data to jointly calculate impedance parameters.

[0056] Step 2: Design the inter-turn fault judgment criterion of the hierarchical controllable shunt reactor and substitute the impedance parameters into the inter-turn fault judgment criterion to monitor the inter-turn fault judgment of the reactor.

[0057] In the present invention, the impedance parameter can be used to determine the turn-to-turn fault.

[0058] Preferably, the inter-turn fault criterion is:

[0059]

[0060] Among them, R1+jwL1 is the grid side leakage impedance, R m +jwL m is the excitation impedance, is the grid-side voltage phasor, is the grid-side current phasor, is the excitation current phasor, K set is the fault threshold.

[0061] Preferably, if the inter-turn fault criterion is greater than a preset threshold or the slope of the inter-turn fault criterion is greater than a preset threshold, it is determined that an inter-turn fault occurs in the reactor.

[0062] Specifically, the time domain calculation formula for fault judgment is:

[0063]

[0064] Among them, when the reactor is working normally, it is in high resistance state, K op (t) should be 0 or close to 0. However, if a turn-to-turn fault occurs in the reactor, the operating parameters will not match the impedance parameters calculated in advance. In this case, K op (t) will increase rapidly and fluctuate greatly. Therefore, this method can accurately determine whether a hierarchical controllable reactor has an inter-turn fault.

[0065] Preferably, substituting the impedance parameters into the inter-turn fault criterion also includes: selecting new measurement data from the operating parameters collected in real time according to the capacity switching conditions, and updating the solution results of the impedance parameters by recursion; substituting the updated solution results of the impedance parameters and the operating parameters collected in real time into the inter-turn fault criterion to realize real-time inter-turn fault judgment.

[0066] As mentioned above, the operating parameters collected in real time can be used as calculation criteria, but the impedance parameters vary at each different operating capacity. Therefore, it is necessary to solve and update the impedance parameters when it is determined that the capacity switching conditions are met. In the present invention, if no inter-turn fault occurs during the capacity switching, the impedance parameters can be calculated based solely on the multiple sets of parameters collected after the capacity switching. However, if an inter-turn fault occurs before the capacity switching, the calculated impedance parameters are already post-fault parameters and cannot be used to solve the fault criteria. In this case, the method can use a recursive method to correct the deviation.

[0067] Generally, in order to obtain the impedance parameter under the current capacity in time, the method collects a plurality of groups of operation parameters obtained after the capacity switching and the stabilizing of the shunt reactor. Each group of operation parameters corresponds to a same sampling time, and the time intervals between the sampling times can be the same. Each group of operation parameters is substituted into the time-domain calculation formula of the fault criterion to form a multivariate equation, and the equations formed by the plurality of groups of operation parameters are jointly solved to obtain the calculation result of the impedance parameter.

[0068] In an embodiment, a recursive method can be used, for example, the newly added measurement data is selected from the operation parameters obtained after the capacity switching, and then the newly added measurement data is combined with the other groups of measurement data obtained before to solve the equation to obtain the updated impedance parameter.

[0069] A more computationally efficient method is that the method only records the transfer function calculated last time, without retaining the original measurement data used in the last calculation, and the newly added measurement data is jointly solved with the transfer function calculated last time to obtain the impedance parameter at the current time.

[0070] Specifically, the transfer function between the operation parameter at the current time and the impedance parameter is calculated as follows:

[0071]

[0072] In the above formula, θ k-1 is the transfer function at the last time, θ k is the transfer function at the current time, x k is the operation parameter at the current time, and y k is the impedance parameter at the current time. Solving the above formula can obtain the new impedance parameter at the current time.

[0073] The transfer function θ is a function between the operation parameter and the impedance parameter. For n groups of known operation parameters X=(x 1 , x 2 ,..., x n ), the correlation between the plurality of groups of known impedance parameters Y=(y 1 , y 2 ,..., y n ) is θ=X -1 Y.

[0074] Preferably, one or more groups of standard measurement data corresponding to the current hierarchical controllable shunt reactor are deployed in advance, and the newly added measurement data is jointly calculated to obtain the impedance parameter under the current working capacity.

[0075] In one embodiment of the present invention, one or more sets of standard measurement data deployed in advance may be operating parameters of the current reactor when it operates at 100% capacity. Based on these standard parameters, guidance or restrictions can be provided for the value range of the impedance parameter.

[0076] In another embodiment, the pre-deployed set of one or more sets of standard measurement data can be operating parameters collected from the other operating capacity of the shunt reactor before the operating capacity is switched, i.e., the operating parameters used during the last startup of the turn-to-turn fault determination. The method temporarily stores these parameters and references them for the next fault determination.

[0077] Usually, when the reactor switches between different operating capacity levels, Figure 4 The main circuit structure shown does not change, so the various impedance parameters remain relatively stable. Based on this, pre-deployed standard measurement data can be used as a reference for continued impedance parameter calculations, ensuring that the calculated impedance parameters are not affected by interturn faults before capacity switching, and remain accurate.

[0078] like Figure 1 As shown in Figure 2, each time the operating capacity is switched, the method determines whether the capacity switching condition is met and updates the impedance parameters. In addition, the method uses real-time operating parameters to substitute into the inter-turn fault judgment criteria to identify the fault.

[0079] Figure 5 This is a schematic diagram of an embodiment of a hierarchical controllable shunt reactor grid-connected application in a method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to the present invention. Figure 5 As shown, in one embodiment, the hierarchical controllable shunt reactor is connected to the grid connection point of a wind farm with a capacity of 600MVA.

[0080] The rated capacity of the controllable high-voltage reactor is 100Mvar, the rated working voltage is 500kV, and the working capacity is divided into three levels: 33% of the rated capacity, 67% of the rated capacity and 100% of the rated capacity.

[0081] By obtaining the grid-side three-phase voltage and current, as well as the control-side three-phase current, of the step-type controllable reactor operating at 33% of its rated capacity and 100% of its rated capacity, various parameters can be calculated. The impedance parameters at the current operating capacity are shown in Table 1.

[0082] Parameter name <![CDATA[R1 / Ω]]> <![CDATA[L1 / H]]> <![CDATA[R m / Oh]]> <![CDATA[L m / H]]> Numerical 8.46 1.33 0.50 265.00

[0083] Table 1 Impedance parameters of reactor at 33% working capacity

[0084] On the other hand, when the graded controllable reactor operates normally at 67% of the rated capacity, due to capacity changes, if the protection is not activated, the electrical quantity information within a certain period of time is selected and saved, and the various parameters are updated with the electrical quantity information under different working capacities saved last time. The updated parameters are shown in Table 2.

[0085] Parameter name <![CDATA[R1 / Ω]]> <![CDATA[L1 / H]]> <![CDATA[R m / Oh]]> <![CDATA[L m / H]]> Numerical 8.45 1.32 0.49 264.69

[0086] Table 2 Impedance parameters of reactor at 67% operating capacity

[0087] Figure 6 This is a schematic diagram of simulation results of a 5% control side inter-turn fault of a hierarchical controllable shunt reactor in a method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to the present invention. Figure 6 As shown, when an inter-turn fault occurs, K op >K set Both are true, so it can be determined that the graded controllable reactor has an internal fault, otherwise it is considered that the graded controllable reactor is working normally.

[0088] In one embodiment of the present invention, the determination time is set to 5 ms.

[0089] The second aspect of the present invention relates to a hierarchical controllable shunt reactor inter-turn fault judgment system using the method of the first aspect of the present invention, the system including CTs and PTs arranged on the grid side and control side of the hierarchical controllable shunt reactor, and a fault judgment module; wherein the CTs and PTs on the grid side and the control side are used to collect operating parameters of the hierarchical controllable shunt reactor; the fault judgment module is used to control and calculate the impedance parameters of the reactor at the current working capacity according to the capacity switching conditions, and to design the inter-turn fault judgment criterion of the hierarchical controllable shunt reactor, and substitute the impedance parameters into the inter-turn fault judgment criterion to monitor the inter-turn fault judgment of the reactor.

[0090] The third aspect of the present invention relates to a hierarchical controllable shunt reactor inter-turn fault judgment device using the method in the first aspect of the present invention, wherein the storage medium is used to store instructions; and the processor is used to operate according to the instructions to execute the steps of the method in the first aspect of the present invention.

[0091] It is understandable that the hierarchical controllable shunt reactor inter-turn fault discrimination includes hardware structures and / or software modules that perform the corresponding functions in order to realize the various functions in the method provided in the above-mentioned embodiment of the present application. Those skilled in the art should easily realize that, in combination with the algorithm steps of each example described in the embodiments disclosed herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0092] The embodiment of the present application can divide the functional modules of the device according to the above method example. For example, each functional module can be divided according to each function, or two or more functions can be integrated into one processing module. The above integrated modules can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the division of modules in the embodiment of the present application is schematic and is only a logical function division. In actual implementation, there may be other division methods.

[0093] A fourth aspect of the present invention relates to a computer-readable storage medium having a computer program stored thereon, wherein the program implements the steps of the method in the first aspect of the present invention when executed by a processor.

[0094] When loading and executing computer program instructions on a computer, corresponding functions are implemented according to the process provided in the embodiments of the present invention. The computer program instructions involved may be assembly instructions, machine instructions, or codes written in a programming language, etc.

[0095] The fifth aspect of the present invention relates to a hierarchical controllable shunt reactor, which includes a high-impedance transformer, multiple auxiliary reactors, multiple thyristor valves, a neutral point reactor, first to fifth CTs, and PTs; wherein,

[0096] The first and second CTs are set at both ends of the control-side winding of the high-impedance transformer. The neutral-point reactor is connected to the low-voltage terminal of the control-side of the high-impedance transformer and then grounded through the fifth CT.

[0097] The third CT and the fourth CT are arranged at both ends of the grid-side winding of the high-impedance transformer.

[0098] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit it, and although the present application has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered within the protection scope of the claims of the present application.

Claims

1. A method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor, characterized in that: The method comprises the following steps: Step 1: After each capacity switching of the hierarchical controllable shunt reactor, collect the operating parameters of the hierarchical controllable shunt reactor in real time, and recalculate the impedance parameters of the reactor at the current working capacity according to the capacity switching condition; If no inter-turn fault occurs during capacity switching, the impedance parameters are calculated based solely on the operating parameters of the multi-group hierarchical controllable shunt reactors acquired in real time after capacity switching. If an inter-turn fault occurs before the capacity is switched, a recursive method is used to correct the deviation. The correction deviation is: Only the transfer function calculated last time is recorded. New measurement data is selected from the operating parameters obtained after the capacity switch. The new measurement data is solved together with the transfer function calculated last time to obtain the impedance parameters at the current moment. The transfer function between the current operating parameters and the impedance parameters is calculated as: In the above formula, θ k-1 is the transfer function at the previous moment, θ k is the transfer function at the current moment, x k is the operating parameter at the current moment, y k is the impedance parameter at the current moment; The transfer function θ is a function between the operating parameters and the impedance parameters. There are n sets of known operating parameters X=(x 1 , x 2 ,……,x n ) and multiple sets of known impedance parameters Y=(y 1 ,y 2 ,……,y n ) is related to θ=X -1 Y; Step 2: designing an inter-turn fault criterion for the hierarchical controllable shunt reactor, and substituting the impedance parameter into the inter-turn fault criterion to monitor the inter-turn fault determination of the reactor.

2. The method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to claim 1, characterized in that: Substituting the impedance parameter into the inter-turn fault criterion further includes: According to the capacity switching condition, newly added measurement data is selected from the operating parameters collected in real time, and the solution of the impedance parameter is updated in a recursive manner; The updated solution result of the impedance parameter and the operating parameters collected in real time are substituted into the inter-turn fault judgment criterion to achieve real-time inter-turn fault judgment.

3. The method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to claim 1, characterized in that: The operating parameters of the graded controllable shunt reactor include the grid-side three-phase voltage, grid-side three-phase current and control-side three-phase current of the graded controllable shunt reactor in a working state.

4. The method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to claim 1, characterized in that: The current working capacity is one of the working capacities of each level of the hierarchical controllable shunt reactor.

5. The method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to claim 1, characterized in that: The impedance parameters of the reactor are the excitation impedance and the grid-side leakage impedance.

6. The method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to claim 1, characterized in that: The capacity switching conditions include: monitoring the operating capacity of the reactor, and determining that the capacity switching condition is met when the reactor switches the operating capacity and no protection action occurs for the current switching; Among them, the protection action condition is i1(t)>α1i 1r Or i2(t)>α2i 2r Any one is established; Where i1(t) is the three-phase current on the grid side, i2(t) is the three-phase current on the control side, and i 1r is the grid-side rated current, i 2r is the three-phase current on the control side, α1 and α2 are system coefficients respectively.

7. The method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to claim 1, characterized in that: The inter-turn fault criterion is: Among them, R1+jwL1 is the grid side leakage impedance, R m +jwL m is the excitation impedance, is the grid-side voltage phasor, is the grid-side current phasor, is the excitation current phasor, K set is the fault threshold.

8. The method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to claim 7, characterized in that: If the inter-turn fault criterion is greater than a preset threshold or the slope of the inter-turn fault criterion is greater than a preset threshold, it is determined that an inter-turn fault occurs in the reactor.

9. The method for distinguishing inter-turn faults of a hierarchical controllable shunt reactor according to claim 2, characterized in that: The monitoring of the inter-turn fault determination of the reactor further includes: One or more sets of standard measurement data corresponding to the current hierarchical controllable shunt reactor are deployed in advance, and the impedance parameters under the current working capacity are calculated jointly with the newly added measurement data.

10. A turn-to-turn fault identification system for a hierarchical controllable shunt reactor using the method according to any one of claims 1 to 9, characterized in that ； The system includes CTs and PTs arranged on the grid side and control side of the hierarchical controllable shunt reactor, and a fault discrimination module; The CT and PT on the grid side and the control side are used to collect the operating parameters of the hierarchical controllable shunt reactor; The fault discrimination module is used to control and calculate the impedance parameters of the inductor at the current working capacity according to the capacity switching conditions, and to design the inter-turn fault judgment criterion of the hierarchical controllable shunt reactor, and substitute the impedance parameters into the inter-turn fault judgment criterion to monitor the inter-turn fault judgment of the inductor.

11. A terminal comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 9.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 9 are implemented.

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