Method and system for determining local optimal configuration design of ferrite ring for suppressing VFTO

Abstract

The present invention discloses a method and system for determining the local optimal configuration design of a ferrite magnetic ring for suppressing VFTO, establishes an equivalent circuit model of all primary side equipment of a gas-insulated substation under VFTO and calculates the VFTO waveform characterization parameters of key nodes under typical working conditions; installs ferrite magnetic rings at the most serious VFTO location of the power station; based on the simulation results, sequentially modifies the configuration quantity, structural dimensions, and materials of the ferrite magnetic rings and performs simulation calculations; according to the simulation calculation results, adjusts the corresponding configuration quantity, structural dimensions, and materials of the ferrite magnetic rings, determines the local optimal values ​​of each corresponding parameter, adjusts the installation position of the ferrite magnetic rings and performs simulation calculations, and obtains the local optimal configuration design scheme of the ferrite magnetic rings suitable for the power station. The present invention can effectively and accurately analyze the configuration of the ferrite magnetic ring for suppressing VFTO for a given power station, greatly saving the protection cost and improving the reliability and effectiveness of the protection.

Description

Technical Field

[0001] The invention belongs to the technical field of power electronics, and in particular relates to a method and a system for determining a local optimal configuration design of a ferrite magnetic ring for suppressing VFTO. Background Art

[0002] Fast transient overvoltage (VFTO) has a short rising edge time of 1-5ns, a maximum amplitude of 2.5pu, a large steepness, a high main oscillation frequency of 1-10MHz, and a large number of continuous pulses, which causes serious damage to the insulation tolerance of the primary side equipment of GIS (gas insulated substation). Due to the difficulty in conducting experimental research on VFTO, simulation modeling of VFTO through electromagnetic transient simulation software has become the most concise, direct and effective way and means to study VFTO. The model construction of GIS equipment under VFTO depends on the design structure and electromagnetic characteristics of the equipment. When studying the VFTO waveform characteristics and insulation coordination of GIS primary side equipment, the influence of VFTO on the interference of secondary side shielded cables and transient ground potential rise can be ignored.

[0003] Ferrite rings have nonlinear magnetic properties and high-frequency loss characteristics, and can be used to suppress VFTO generated by the disconnector operation in the GIS of pumped storage power stations. Since the VFTO waveform characteristics vary with the changes in GIS equipment parameters, the method of using ferrite rings to protect VFTO is not universal, which greatly increases the difficulty of using ferrite rings to protect VFTO, resulting in high cost, poor reliability and effectiveness of using ferrite rings to protect VFTO. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method and system for determining the local optimal configuration design of a ferrite ring for suppressing VFTO, which can effectively and reliably protect VFTO, greatly save protection costs, and improve the reliability and effectiveness of protection.

[0005] In order to solve the above technical problems, the present invention is implemented by the following technical solutions:

[0006] A method for determining a local optimal configuration design of a ferrite ring for suppressing VFTO, comprising:

[0007] Step 1: Establish a GIS equivalent circuit model under VFTO for all primary side devices and networks except the ferrite magnetic ring;

[0008] Step 2: simulate and calculate the actual operating conditions of the GIS in the GIS equivalent circuit model, and extract the VFTO waveform characterization parameters of each device node from the calculation results, and the VFTO waveform characterization parameters are used to determine the suppression effect of VFTO;

[0009] Step 3: According to the simulation calculation results of the actual operating conditions of the GIS, determine the operating condition where the GIS has the most serious VFTO;

[0010] Step 4: Based on the simulation calculation results corresponding to the working condition where the GIS suffers the most severe VFTO, the equipment where the GIS suffers the most severe VFTO is configured with different numbers of ferrite rings for simulation calculation to determine the number of ferrite rings configured for the best suppression effect;

[0011] Step 5: Based on the determined optimal number of ferrite ring configurations, simulate and calculate the same number of ferrite rings but with different structural sizes installed on the GIS equipment that suffers the most from VFTO, and determine the structural size of the ferrite ring with the best suppression effect;

[0012] Step 6: Based on the determined optimal configuration quantity and structural dimensions of ferrite magnetic rings, ferrite magnetic rings of the same quantity and structural dimensions but of different materials are installed on the GIS equipment that suffers the most from VFTO to perform simulation calculations, and determine the ferrite magnetic ring material with the best suppression effect;

[0013] Step 7: Based on the determined optimal configuration quantity, structural dimensions and materials of the ferrite rings, respectively calculate and study the VFTO suppression effect of the ferrite rings installed on equipment at different positions of the GIS, and obtain the local optimal configuration design of the GIS ferrite rings, thereby achieving effective suppression of VFTO.

[0014] Furthermore, in step 1, the equivalent circuit model is established using EMTP-RV electromagnetic transient simulation software, and the equivalent circuit model includes a busbar, a transformer, a bushing, a high-voltage cable, a disconnector, a circuit breaker, a voltage transformer, a metal oxide arrester and an arc model.

[0015] Furthermore, the busbar model adopts the frequency response lossless transmission line model in the FDQ module in EMTP-RV; the transformer model adopts a model that considers the transferred overvoltage; the bushing model adopts the lossless transmission line and overhead end-to-ground capacitance model; the high-voltage cable model adopts the frequency response CABLE model in the FDQ module; the circuit breaker and disconnector models use lossless transmission lines for equivalent simulation when closed, and use concentrated ground capacitance and break capacitance for simulation when disconnected; the voltage transformer model uses a concentrated capacitance model; the metal oxide arrester model uses a nonlinear resistance / capacitance model that considers the steep wave head response; and the arc model uses a double exponential arc resistance model.

[0016] Furthermore, in step 2, the VFTO waveform characterization parameters include the maximum voltage amplitude, overshoot coefficient, maximum voltage steepness, maximum steepness moment and main oscillation frequency at each device node under various actual working conditions.

[0017] Furthermore, in step 3, the method for determining the working condition where the GIS has the most serious VFTO is: based on the VFTO waveform characterization parameters of each device node under a variety of actual working conditions, determine that the working condition that produces the highest VFTO amplitude is the most serious working condition, and the node device with the largest VFTO amplitude is the device that suffers the most from VFTO.

[0018] Furthermore, in step 4, determining the number of ferrite ring configurations with the best suppression effect specifically includes:

[0019] A single ferrite magnetic ring is equivalent to a trapezoidal network model considering eddy current. At the device where GIS suffers the most severe VFTO, a simulation study is conducted starting from the number 1 to study the suppression effect of the VFTO amplitude and steepness of each node of the equipment when different numbers of ferrite magnetic rings are installed. The optimal configuration number is the number of ferrite magnetic rings when the suppression effect is good and the suppression effect of a single magnetic ring is not significantly reduced.

[0020] Furthermore, in step 5, determining the structural dimensions of the ferrite magnetic ring with the best suppression effect specifically includes:

[0021] Install ferrite rings at the equipment where GIS suffers the most severe VFTO, keep the inner and outer diameters of the ferrite rings constant, modify the axial length of the rings, and change the parameters of the trapezoidal network model of the ferrite rings in the EMTP-RV electromagnetic transient simulation software that takes into account eddy currents. Simulate and calculate the suppression effect of ferrite rings with different axial lengths on the amplitude and steepness of VFTO at each device node. The length corresponding to the ferrite ring with the best suppression effect per unit length of ferrite ring is the optimal axial length.

[0022] Ferrite rings are installed at the equipment where GIS suffers the most serious VFTO. The inner diameter and axial length of the ferrite rings are kept constant, the outer diameter of the rings is changed, and the trapezoidal network model parameters of the ferrite rings considering eddy currents in the EMTP-RV electromagnetic transient simulation software are modified accordingly. The suppression effect of ferrite rings with different outer diameters on the VFTO amplitude and steepness of each device node is simulated and calculated. The optimal outer diameter is the one with a ratio of inner to outer diameter not exceeding 0.7 and the best suppression effect of the ferrite ring per unit length of outer diameter.

[0023] Furthermore, in step 6, determining the ferrite ring material with the best suppression effect specifically includes:

[0024] When selecting the doping material of the ferrite magnetic ring for suppressing VFTO, the ferrite material doped with elements and oxides that increase the magnetic permeability of the ferrite magnetic ring at high frequencies is selected;

[0025] Ferrite rings are installed at the equipment where GIS suffers the most serious VFTO, and the optimal configuration quantity, size and magnetic permeability of the ferrite rings are maintained. The resistivity of the ferrite rings is changed, and the trapezoidal network model parameters of the ferrite rings considering eddy currents in the EMTP-RV electromagnetic transient simulation software are modified accordingly. The VFTO steepness of the first section of the magnetic ring corresponding to different ferrite ring resistivities is simulated and calculated, and the resistivity corresponding to the smallest steepness increment is selected as the optimal magnetic ring resistivity; the optimal ferrite ring material is determined based on the determined magnetic permeability and resistivity.

[0026] Furthermore, in step 7, based on the determined optimal configuration quantity, structural dimensions and materials of the ferrite magnetic rings, the suppression effect of the ferrite magnetic rings on VFTO when installed on equipment at different positions of the GIS is calculated and studied, as follows:

[0027] The optimal configuration quantity, structural size and material of ferrite rings are determined and installed at different key equipment in GIS, and the corresponding parameters in the ladder network model of ferrite rings considering eddy current in the EMTP-RV electromagnetic transient simulation software are modified. The VFTO amplitude and steepness at each device node are simulated and calculated, and the position with the best VFTO suppression effect is selected to obtain the local optimal configuration design of the ferrite ring of the GIS station.

[0028] A system for determining the local optimal configuration design of a ferrite ring for suppressing VFTO, comprising:

[0029] GIS equivalent circuit model building module, used to build GIS equivalent circuit models of all primary side devices and networks under VFTO except ferrite magnetic rings;

[0030] A calculation module is used to simulate and calculate the actual operating conditions of the GIS in the GIS equivalent circuit model, and extract the VFTO waveform characterization parameters of each device node from the calculation results, and the VFTO waveform characterization parameters are used to determine the suppression effect of VFTO;

[0031] The working condition determination module is used to determine the working condition where the GIS has the most serious VFTO according to the simulation calculation results of the actual operating condition of the GIS;

[0032] The module for determining the number of ferrite rings to be configured is used to perform simulation calculations on the equipment with different numbers of ferrite rings configured on the GIS that suffers the most severe VFTO based on the simulation calculation results corresponding to the working condition where the GIS suffers the most severe VFTO, and determine the number of ferrite rings configured for the best suppression effect;

[0033] The ferrite ring structure size determination module is used to perform simulation calculations on the GIS equipment that suffers the most from VFTO by installing the same number of ferrite rings but with different structure sizes based on the determined optimal ferrite ring configuration quantity, so as to determine the ferrite ring structure size with the best suppression effect;

[0034] The ferrite ring material determination module is used to perform simulation calculations on the GIS equipment that suffers the most severe VFTO by installing ferrite rings of the same number and same structural size but different materials based on the determined optimal configuration quantity and structural size of the ferrite rings, so as to determine the ferrite ring material with the best suppression effect;

[0035] The local optimal configuration determination module is used to calculate and study the VFTO suppression effect of the ferrite ring when it is installed on equipment at different positions of the GIS based on the determined optimal configuration quantity, structural size and material of the ferrite ring, so as to obtain the local optimal configuration design of the GIS ferrite ring.

[0036] Compared with the prior art, the present invention has at least the following beneficial effects: the present invention proposes a method for determining the local optimal configuration design of a ferrite magnetic ring for suppressing VFTO. Before the ferrite magnetic ring is installed on the GIS, according to its actual engineering situation, various working conditions of the GIS are simulated and calculated by electromagnetic transient software. Based on the simulation results, the configuration quantity, structural dimensions, and materials of the ferrite magnetic ring are modified in sequence and simulation calculations are performed; according to the simulation calculation results, the corresponding configuration quantity, structural dimensions, and materials of the ferrite magnetic ring are adjusted, the local optimal values ​​of each corresponding parameter are determined, the installation position of the ferrite magnetic ring is adjusted, and simulation calculations are performed to obtain the local optimal configuration design scheme of the ferrite magnetic ring suitable for the power station. The present invention can effectively and accurately analyze the configuration of the ferrite magnetic ring for suppressing VFTO for a given power station, greatly saving the protection cost and improving the reliability and effectiveness of the protection.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the specific implementation modes of the present invention, the drawings required for use in the description of the specific implementation modes will be briefly introduced below. Obviously, the drawings described below are some implementation modes of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A flow chart of a method for determining a local optimal configuration design of a ferrite ring for suppressing VFTO according to the present invention;

[0040] Figure 2 It is the topological structure diagram of GIS of the present invention;

[0041] Figure 3 A diagram of a transformer model for transferring overvoltages considered for the present invention;

[0042] Figure 4 is a structural diagram of a high voltage cable of the present invention;

[0043] Figure 5 The suppression effect of a single magnetic ring on the VFTO amplitude of each node under different numbers of magnetic rings in the embodiment;

[0044] Figure 6 The suppression effect of a single magnetic ring on the VFTO steepness of each node under different numbers of magnetic rings in the embodiment;

[0045] Figure 7 The axial unit length magnetic ring in the embodiment has an effect on suppressing the node VFTO amplitude;

[0046] Figure 8 This is the effect of suppressing the steepness of the node VFTO by the axial unit length magnetic ring in the embodiment;

[0047] Fig. 9 The amplitude suppression effect of the radial magnetic ring per unit length in the embodiment;

[0048] Fig.10 The radial unit length magnetic ring in the embodiment has a suppressing effect on the steepness;

[0049] Fig.11 is the VFTO amplitude of each node in the embodiment;

[0050] Fig.12 The VFTC flowing through the GIS conductive rod in the embodiment changes with the resistivity of the magnetic ring;

[0051] Fig.13 Schematic diagram of various locations of a 500kV GIS of a pumped storage station in an embodiment;

[0052] Fig.14 The figure shows the influence of adding ferrite rings on the VFTO of each node and the amplitude of VFTC flowing through the conductive rod in the embodiment. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] refer to Figure 1 The present invention is a method for determining a local optimal configuration design of a ferrite magnetic ring for suppressing VFTO, comprising:

[0055] Step 1: Establish a gas insulated substation (hereinafter referred to as GIS) equivalent circuit model of all primary side equipment and networks except the ferrite magnetic ring under VFTO.

[0056] The equivalent circuit model of the present invention can be established by using EMTP-RV electromagnetic transient simulation software, including busbar, transformer, bushing, high-voltage cable, disconnector, circuit breaker, voltage transformer, metal oxide arrester and arc, wherein the busbar adopts the frequency response lossless transmission line model in the FDQ module of EMTP-RV, the transformer adopts the model considering the transmitted overvoltage, the bushing adopts the lossless transmission line and the overhead end ground capacitance to represent, the high-voltage cable adopts the frequency response CABLE model in the FDQ module, the circuit breaker and the disconnector are closed when the lossless transmission line is used for equivalent simulation, the circuit breaker and the disconnector are opened when the concentrated ground capacitance and the break capacitance are used to represent, the voltage transformer adopts the concentrated capacitance model, the metal oxide arrester adopts the resistance model considering the steep wave head response, and the arc is simulated by the double exponential arc resistance model.

[0057] Exemplarily, in the EMTP-RV software, the following is established: Figure 2 The GIS primary equipment layout diagram is shown in the figure. The voltage level of the GIS is 500kV. The busbar wave impedance is 67.233Ω, the wave speed is 2.947e8m / s, the unit length resistance is 9.19μΩ / m, the power transformer model used in the hydropower station is SSP-480000 / 500, the rated voltage is (520 / ±2×2.5%) / 18kV, the rated capacity is 480 / 480MVA, the connection group number is YNd11, the high-voltage side inductance is 0.1217mH, the high-voltage end resistance is 0.5023Ω, the high-voltage to ground capacitance is 8.86nF, the winding capacitance is 7.02nF, the low-voltage side inductance is 0.00021mH, the low-voltage side resistance is 0.0008Ω, and the low-voltage to ground capacitance is 22.38nF. The model used by the transformer to consider the overvoltage transmission is as follows: Figure 3As shown, the capacitance to ground of the electromagnetic voltage transformer PT and the capacitance to ground of the capacitive voltage transformer CVT are taken as 200pF and 5048pF respectively according to the factory test report. According to the factory test report, the capacitance to ground of the oil and gas casing and the air casing is 330pF and 200pF. When the circuit breaker is in the closed state, the lossy transmission line model is used for equivalent, in which the wave impedance is 61.5Ω, the wave speed is 2.9e8m / s, the length is 2.52m, and the loss is 9.19e-6Ω / m. The capacitance to ground of the two ends of the break is 20pF, the capacitance to ground in the middle of the break is 190pF, and the break capacitance and the equalizing capacitance are equivalent to 600pF. The capacitance of the disconnector break is 15pF, and the capacitance to ground is 25pF. The high-voltage cable model is as follows Figure 4 As shown, it includes a copper core 1, a conductor shielding layer 2, an insulating layer 3, an insulating shielding layer 4, a buffer layer 5, a metal sleeve 6 and an outer sheath 7.

[0058] Step 2, perform simulation calculations under several typical actual operating conditions of GIS, and extract the VFTO waveform characterization parameters of each key node from the calculation results;

[0059] The maximum voltage amplitude, overshoot coefficient, maximum voltage steepness, maximum steepness moment and main oscillation frequency at the load side and power side of the isolating switch are extracted as VFTO waveform characterization parameters.

[0060] Step 3, according to the simulation calculation results under several typical GIS working conditions, determine the most serious VFTO working condition;

[0061] According to the simulation calculation results, the operating condition that may produce the largest VFTO amplitude among all key nodes is defined as the most serious VFTO condition of GIS.

[0062] Step 4: Based on the simulation calculation results of the most severe VFTO condition of GIS, different ferrite rings are configured for the equipment in the power station that suffers from the most severe VFTO, and the number of ferrite rings configured for the best suppression effect is determined;

[0063] Among them, the method for determining the number of ferrite rings configured to achieve the best suppression effect is:

[0064] A trapezoidal network model considering eddy current is used to equate a single ferrite ring. At the device where GIS suffers the most severe VFTO, a simulation is conducted starting from the number 1 to study the suppression effect of the VFTO amplitude and steepness of each node of the equipment when different numbers of ferrite rings are installed. The number of ferrite rings corresponding to the best suppression effect is the optimal configuration number.

[0065] For example, taking the operating condition of a single transformer on a given GIS single outgoing line as an example, considering the closing operation of the disconnector closest to the source side in the most severe phase, 1, 5, 10, 20, and 50 ferrite magnetic rings with an outer diameter of Φ204mm, an inner diameter of Φ184mm, a thickness of 35mm, a resistivity of 3Ω·cm, and the same magnetic permeability characteristics are installed on the GIS conductive pole near the source side of the disconnector. The variation law of the VFTO amplitude of each node with the number of magnetic rings obtained by the electromagnetic transient simulation software EMTP-RV is shown in Table 1. The suppression effect of a single magnetic ring on the VFTO amplitude and steepness of each node under different numbers of magnetic rings is shown in Table 1. Figure 5 , Figure 6 As shown in FIG. 1 , the number of magnetic rings when the suppression effect is good and the suppression effect of a single magnetic ring is not significantly reduced, that is, 10 is the local optimal number of magnetic rings.

[0066] Table 1

[0067] N / pcs 0 1 5 10 20 50 <![CDATA[U max-DSL / p.u.]]> 1.808 1.763 1.758 1.689 1.584 1.505 <![CDATA[U max-DSS / p.u.]]> 1.834 1.792 1.707 1.646 1.537 1.513 <![CDATA[U max-FRH / p.u.]]> 1.766 1.749 1.819 1.789 1.741 1.608 <![CDATA[U max-PT / p.u.]]> 1.698 1.674 1.638 1.535 1.388 1.181 <![CDATA[U max-TR / p.u.]]> 1.139 1.134 1.121 1.111 1.101 1.096 VFTC / kA 8.92 8.60 7.46 6.50 5.41 3.45

[0068] Step 5: Based on the determined optimal number of ferrite ring configurations, simulate and calculate the same number of ferrite rings but with different structures installed on the GIS equipment that suffers the most from VFTO, and determine the structural size of the ferrite ring with the best suppression effect;

[0069] Ferrite rings are installed at the equipment where GIS suffers the most serious VFTO, the inner and outer diameters of the ferrite rings are kept constant, the axial length of the rings is modified, and the parameters of the trapezoidal network model of the ferrite rings considering eddy currents in the EMTP-RV electromagnetic transient simulation software are changed accordingly. The ferrite rings with different axial lengths are simulated and calculated, and the suppression effect of the VFTO amplitude and steepness of each device node is simulated and calculated. The length of the ferrite ring with the best suppression effect per unit length of ferrite ring is taken as the optimal axial length.

[0070] For example, 10 magnetic rings with the same magnetic characteristics and an outer diameter of Φ204 mm, an inner diameter of Φ184 mm, a resistivity of 3Ω·cm, and the same magnetic properties are installed on the conductive rod near the source side of the disconnector. When the axial length of the magnetic ring is gradually increased from 25 mm to 75 mm, the simulation results show that the variation law of the VFTO amplitude of each node with the axial length of the magnetic ring is as shown in Table 2. The suppression effect of the axial unit length magnetic ring on the node VFTO amplitude and steepness is as follows: Figure 7 , Figure 8 As shown, the length of the ferrite ring corresponding to the best suppression effect of the ferrite ring per unit length is selected, that is, 4.5 mm is the optimal axial length.

[0071] Table 2

[0072]

[0073]

[0074] Ferrite rings are installed at the equipment where GIS suffers the most serious VFTO. The inner diameter and axial length of the ferrite rings are kept constant, the outer diameter of the rings is changed, and the trapezoidal network model parameters of the ferrite rings considering eddy currents in the EMTP-RV electromagnetic transient simulation software are modified accordingly. The suppression effect of ferrite rings with different outer diameters on the VFTO amplitude and steepness of each device node is simulated and calculated. The optimal outer diameter is the one with a ratio of inner to outer diameter not exceeding 0.7 and the best suppression effect of the ferrite ring per unit length of outer diameter.

[0075] For example, 10 ferrite magnetic rings with the same magnetic permeability characteristics and inner diameter of Φ184 mm, axial length of 3.5 mm, resistivity of 3 Ω·cm were installed on the conductive rod near the source side of the disconnector. When the outer diameter gradually increased from Φ194 mm to Φ264 mm, the simulation results showed that the VFTO amplitude of each node varied with the outer diameter of the magnetic ring as shown in Table 3. The suppression effect of the radial unit length magnetic ring on the amplitude and steepness was shown in Table 3. Fig. 9 , Fig.10 As shown, the ratio of the inner and outer diameters is not more than 0.7 and the outer diameter corresponding to the best suppression effect of the ferrite magnetic ring per unit length is selected, that is, 264 is the best outer diameter.

[0076] Table 3

[0077]

[0078]

[0079] Step 6, based on the determined optimal number and structure size of ferrite magnetic rings, simulate and calculate the GIS equipment that suffers the most from VFTO by installing magnetic rings of the same number and structure size but of different materials to determine the ferrite magnetic ring material with the best suppression effect;

[0080] When selecting doping materials for ferrite magnetic rings used to suppress VFTO, focus on ferrite materials doped with elements and oxides that increase the magnetic permeability of the magnetic rings at high frequencies; install ferrite magnetic rings at the equipment where GIS suffers the most serious VFTO, maintain the optimal configuration quantity, size, and magnetic permeability of the ferrite magnetic rings, change the resistivity of the ferrite magnetic rings, and modify the trapezoidal network model parameters of the ferrite magnetic rings considering eddy currents in the EMTP-RV electromagnetic transient simulation software accordingly, simulate and calculate the VFTO steepness of the first section of the magnetic ring corresponding to different ferrite magnetic ring resistivities, and select the resistivity corresponding to the smallest steepness increment as the optimal magnetic ring resistivity; determine the optimal ferrite magnetic ring material to be selected based on the determined magnetic permeability and resistivity.

[0081] For example, 10 ferrite magnetic rings with an outer diameter of Φ204mm, an inner diameter of Φ184mm, and a thickness of 35mm with the same magnetic permeability characteristics are installed on the conductive rod near the source side of the disconnector. The inhibitory effect of the magnetic rings on the VFTO characteristics of each node is studied when the resistivity ρ of the magnetic rings is 2Ω·cm, 2.5Ω·cm, 3Ω·cm, 3.5Ω·cm, and 4Ω·cm, respectively. The VFTO amplitude of each node and the VFTC flowing through the GIS conductive rod change with the resistivity of the magnetic rings. Fig.11 , Fig.12 As shown in Figure 2, the resistivity ρ is selected as 4Ω·cm.

[0082] Step 7: Based on the determined optimal ferrite ring configuration quantity, structural dimensions and materials, respectively calculate and study the VFTO suppression effect when installed in different GIS position equipment, obtain the local optimal configuration design of the GIS ferrite ring, and thus achieve effective suppression of VFTO.

[0083] The optimal number, size, and material of ferrite rings determined above are installed at different key GIS equipment, and the corresponding parameters in the ladder network model of ferrite rings considering eddy current in the EMTP-RV electromagnetic transient simulation software are modified. The VFTO amplitude and steepness at each device node are simulated and calculated, and the position with the best VFTO suppression effect is selected to obtain the local optimal configuration design of the ferrite rings of the GIS station.

[0084] For example, 10 ferrite magnetic rings with an inner diameter of Φ184 mm, an outer diameter of Φ264 mm, an axial length of 3.5 mm, and a resistivity of 4 Ω·cm are installed at D, X, P, Z, and T in the 500 kV GIS of the pumped storage station, respectively. Fig.13 As shown in Figure 2, its influence on the VFTO of each node and the amplitude of VFTC flowing through the conductive rod is as follows: Fig.14 The steepness changes of each node are shown in Table 4. In order to effectively suppress the amplitude and steepness of VFTC, limit the voltage steepness of winding equipment, and protect the insulation tolerance of each equipment, the ferrite ring should be installed on the conductive rod near the source side of the disconnector, that is, at D.

[0085] Table 4

[0086] Waveform Characterization Parameters D X Z P T <![CDATA[d DSL / kV·ns-1]]> 63.29 63.29 63.29 63.29 63.29 <![CDATA[d DSS / kV·ns-1]]> 63.30 63.30 63.30 63.30 63.30 <![CDATA[d FRH / kV·ns-1]]> 99.27 60.56 60.56 60.56 60.56 <![CDATA[d PT / kV·ns-1]]> 18.31 13.12 12.63 13.47 34.64 <![CDATA[d TR / kV·ns-1]]> 2.16 2.18 2.156 2.08 1.72 <![CDATA[d VFTC / kA·ns-1]]> 0.32 0.90 0.90 0.90 0.90

[0087] A system for determining the local optimal configuration design of a ferrite ring for suppressing VFTO, comprising:

[0088] GIS equivalent circuit model building module, used to build GIS equivalent circuit models of all primary side devices and networks under VFTO except ferrite magnetic rings;

[0089] A calculation module is used to simulate and calculate the actual operating conditions of the GIS in the GIS equivalent circuit model, and extract the VFTO waveform characterization parameters of each device node from the calculation results, and the VFTO waveform characterization parameters are used to determine the suppression effect of VFTO;

[0090] The working condition determination module is used to determine the working condition where the GIS has the most serious VFTO according to the simulation calculation results of the actual operating condition of the GIS;

[0091] The module for determining the number of ferrite rings to be configured is used to perform simulation calculations on the equipment with different numbers of ferrite rings configured on the GIS that suffers the most severe VFTO based on the simulation calculation results corresponding to the working condition where the GIS suffers the most severe VFTO, and determine the number of ferrite rings configured for the best suppression effect;

[0092] The ferrite ring structure size determination module is used to perform simulation calculations on the GIS equipment that suffers the most from VFTO by installing the same number of ferrite rings but with different structure sizes based on the determined optimal ferrite ring configuration quantity, so as to determine the ferrite ring structure size with the best suppression effect;

[0093] The ferrite ring material determination module is used to perform simulation calculations on the GIS equipment that suffers the most severe VFTO by installing ferrite rings of the same number and same structural size but different materials based on the determined optimal configuration quantity and structural size of the ferrite rings, so as to determine the ferrite ring material with the best suppression effect;

[0094] The local optimal configuration determination module is used to calculate and study the VFTO suppression effect of the ferrite ring when it is installed on equipment at different positions of the GIS based on the determined optimal configuration quantity, structural size and material of the ferrite ring, so as to obtain the local optimal configuration design of the GIS ferrite ring.

[0095] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for determining the local optimal configuration design of a ferrite ring for suppressing VFTO, characterized in that: include: Step 1: Establish a GIS equivalent circuit model under VFTO for all primary side devices and networks except the ferrite magnetic ring; Step 2: simulate and calculate the actual operating conditions of the GIS in the GIS equivalent circuit model, and extract the VFTO waveform characterization parameters of each device node from the calculation results, and the VFTO waveform characterization parameters are used to determine the suppression effect of VFTO; Step 3: According to the simulation calculation results of the actual operating conditions of the GIS, determine the operating condition where the GIS has the most serious VFTO; Step 4: Based on the simulation calculation results corresponding to the working condition where the GIS suffers the most severe VFTO, the equipment where the GIS suffers the most severe VFTO is configured with different numbers of ferrite rings for simulation calculation to determine the number of ferrite rings configured for the best suppression effect; Step 5: Based on the determined optimal number of ferrite ring configurations, simulate and calculate the same number of ferrite rings but with different structural sizes installed on the GIS equipment that suffers the most from VFTO, and determine the structural size of the ferrite ring with the best suppression effect; Step 6: Based on the determined optimal configuration quantity and structural dimensions of ferrite magnetic rings, ferrite magnetic rings of the same quantity and structural dimensions but of different materials are installed on the GIS equipment that suffers the most from VFTO to perform simulation calculations, and determine the ferrite magnetic ring material with the best suppression effect; Step 7: Based on the determined optimal configuration quantity, structural dimensions and materials of the ferrite rings, respectively calculate and study the VFTO suppression effect of the ferrite rings installed on equipment at different locations of the GIS to obtain the local optimal configuration design of the GIS ferrite rings.

2. The method for determining the local optimal configuration design of a ferrite ring for suppressing VFTO according to claim 1 is characterized in that: In the step 1, the equivalent circuit model is established using EMTP-RV electromagnetic transient simulation software, and the equivalent circuit model includes a busbar, a transformer, a bushing, a high-voltage cable, a disconnector, a circuit breaker, a voltage transformer, a metal oxide arrester and an arc model.

3. The method for determining the local optimal configuration design of a ferrite ring for suppressing VFTO according to claim 2 is characterized in that: The busbar model adopts the frequency response lossless transmission line model in the FDQ module of EMTP-RV; the transformer model adopts the model considering the transmitted overvoltage; the bushing model adopts the lossless transmission line and overhead end-to-ground capacitance model; the high-voltage cable model adopts the frequency response CABLE model in the FDQ module; the circuit breaker and disconnector models use lossless transmission lines for equivalent simulation when closed, and use concentrated ground capacitance and break capacitance for simulation when disconnected; the voltage transformer model uses a concentrated capacitance model; the metal oxide arrester model uses a nonlinear resistance / capacitance model considering the steep wave head response; the arc model uses a double exponential arc resistance model.

4. The method for determining the local optimal configuration design of a ferrite ring for suppressing VFTO according to claim 1 is characterized in that: In step 2, the VFTO waveform characterization parameters include the maximum voltage amplitude, overshoot coefficient, maximum voltage steepness, maximum steepness moment and main oscillation frequency at each device node under various actual working conditions.

5. The method for determining the local optimal configuration design of a ferrite ring for suppressing VFTO according to claim 1 is characterized in that: In step 3, the method for determining the working condition where the GIS has the most serious VFTO is: based on the VFTO waveform characterization parameters of each device node under a variety of actual working conditions, determine that the working condition where the VFTO amplitude is the highest is the most serious working condition, and the node device with the largest VFTO amplitude is the device that suffers the most from VFTO.

6. The method for determining the local optimal configuration design of a ferrite ring for suppressing VFTO according to claim 1, characterized in that: In step 4, determining the number of ferrite ring configurations with the best suppression effect specifically includes: A single ferrite magnetic ring is equivalent to a trapezoidal network model considering eddy current. At the device where GIS suffers the most severe VFTO, a simulation study is conducted starting from the number 1 to study the suppression effect of the VFTO amplitude and steepness of each node of the equipment when different numbers of ferrite magnetic rings are installed. The optimal configuration number is the number of ferrite magnetic rings when the suppression effect is good and the suppression effect of a single magnetic ring is not significantly reduced.

7. The method for determining the local optimal configuration design of a ferrite ring for suppressing VFTO according to claim 1, characterized in that: In step 5, determining the structural dimensions of the ferrite magnetic ring with the best suppression effect specifically includes: Install ferrite rings at the equipment where GIS suffers the most severe VFTO, keep the inner and outer diameters of the ferrite rings constant, modify the axial length of the rings, and change the parameters of the trapezoidal network model of the ferrite rings in the EMTP-RV electromagnetic transient simulation software that takes into account eddy currents. Simulate and calculate the suppression effect of ferrite rings with different axial lengths on the amplitude and steepness of VFTO at each device node. The length corresponding to the ferrite ring with the best suppression effect per unit length of ferrite ring is the optimal axial length. Ferrite rings are installed at the equipment where GIS suffers the most serious VFTO. The inner diameter and axial length of the ferrite rings are kept constant, the outer diameter of the rings is changed, and the trapezoidal network model parameters of the ferrite rings considering eddy currents in the EMTP-RV electromagnetic transient simulation software are modified accordingly. The suppression effect of ferrite rings with different outer diameters on the VFTO amplitude and steepness of each device node is simulated and calculated. The optimal outer diameter is the one with a ratio of inner to outer diameter not exceeding 0.7 and the best suppression effect of the ferrite ring per unit length of outer diameter.

8. The method for determining the local optimal configuration design of a ferrite ring for suppressing VFTO according to claim 1, characterized in that: In step 6, determining the ferrite ring material with the best suppression effect specifically includes: When selecting a doping material for a ferrite magnetic ring for suppressing VFTO, a ferrite material doped with elements and oxides that increase the magnetic permeability of the ferrite magnetic ring at high frequencies is selected; Ferrite rings are installed at the equipment where GIS suffers the most serious VFTO, and the optimal configuration quantity, size and magnetic permeability of the ferrite rings are maintained. The resistivity of the ferrite rings is changed, and the trapezoidal network model parameters of the ferrite rings considering eddy currents in the EMTP-RV electromagnetic transient simulation software are modified accordingly. The VFTO steepness of the first section of the magnetic ring corresponding to different ferrite ring resistivities is simulated and calculated, and the resistivity corresponding to the smallest steepness increment is selected as the optimal magnetic ring resistivity; the optimal ferrite ring material is determined based on the determined magnetic permeability and resistivity.

9. The method for determining the local optimal configuration design of a ferrite ring for suppressing VFTO according to claim 1, characterized in that: In step 7, based on the determined optimal configuration quantity, structural dimensions and materials of the ferrite magnetic rings, the suppression effect of the ferrite magnetic rings on VFTO when installed on equipment at different positions of the GIS is calculated and studied, as follows: The optimal configuration quantity, structural size and material of ferrite rings are determined at different device nodes of GIS, and the corresponding parameters in the ladder network model of ferrite rings considering eddy current in the EMTP-RV electromagnetic transient simulation software are modified. The VFTO amplitude and steepness at each device node are simulated and calculated, and the position with the best VFTO suppression effect is selected to obtain the local optimal configuration design of the ferrite ring of the GIS station.

10. A system for determining the local optimal configuration design of a ferrite ring for suppressing VFTO, characterized in that: include: GIS equivalent circuit model building module, used to build GIS equivalent circuit models of all primary side devices and networks under VFTO except ferrite magnetic rings; A calculation module is used to simulate and calculate the actual operating conditions of the GIS in the GIS equivalent circuit model, and extract the VFTO waveform characterization parameters of each device node from the calculation results, and the VFTO waveform characterization parameters are used to determine the suppression effect of VFTO; The working condition determination module is used to determine the working condition where the GIS has the most serious VFTO according to the simulation calculation results of the actual operating condition of the GIS; The module for determining the number of ferrite rings to be configured is used to perform simulation calculations on the equipment with different numbers of ferrite rings configured on the GIS that suffers the most severe VFTO based on the simulation calculation results corresponding to the working condition where the GIS suffers the most severe VFTO, and determine the number of ferrite rings configured for the best suppression effect; The ferrite ring structure size determination module is used to perform simulation calculations on the GIS equipment that suffers the most from VFTO by installing the same number of ferrite rings but with different structure sizes based on the determined optimal ferrite ring configuration quantity, so as to determine the ferrite ring structure size with the best suppression effect; The ferrite ring material determination module is used to perform simulation calculations on the GIS equipment that suffers the most severe VFTO by installing ferrite rings of the same number and same structural size but different materials based on the determined optimal configuration quantity and structural size of the ferrite rings, so as to determine the ferrite ring material with the best suppression effect; The local optimal configuration determination module is used to calculate and study the VFTO suppression effect of the ferrite ring when it is installed on equipment at different positions of the GIS based on the determined optimal configuration quantity, structural size and material of the ferrite ring, so as to obtain the local optimal configuration design of the GIS ferrite ring.

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