Closing inrush current suppression method and system of CLCC-HVDC system, and medium

Abstract

The invention relates to a closing inrush current suppression method and system for a CLCC-HVDC system, and a medium. The method comprises the following steps: constructing a CLCC-HVDC system simulation model; determining the type and configuration of an alternating current filter, putting the alternating current filter into a CLCC-HVDC system simulation model, constructing an alternating current filter simulation model, and analyzing to obtain an optimal closing mode under the conditions of random closing and phase selection closing; adding an optimal closing mode into the alternating current filter simulation model, putting a circuit breaker into the filter simulation model for simulation under the condition that the circuit breaker is connected with closing resistors with different resistance values in parallel and is not connected with the closing resistors in parallel, and analyzing to obtain an optimal closing resistor; adding the optimal closing resistance into the CLCC-HVDC system simulation model, and comparing and analyzing closing inrush currents at different closing phase angles to obtain an optimal closing phase angle; the optimal switching-on mode, switching-on resistance and switching-on phase angle are applied to the CLCC-HVDC system to suppress switching-on inrush current. Compared with the prior art, closing inrush current can be better inhibited, and safe and stable operation of the system is maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current transmission, and in particular to a closing inrush current suppression method, system and medium for a CLCC-HVDC system. Background Art

[0002] In a DC transmission system, in order to compensate for the large amount of reactive power consumed by the converter station, reduce the harmonic components flowing into the AC system, and limit the AC bus voltage distortion rate within a specified range, a certain number of filter devices must be invested in the converter station.

[0003] Since the capacity of the filter group is large and the switching is frequent, the circuit breaker for the AC filter in the DC converter station must be able to withstand higher break recovery voltage and break larger capacitive current. Equipped with a phase selection closing device or installed with a closing resistor can effectively reduce the overvoltage of the closing surge current, avoid causing a large impact on the system, causing frequent operation of the lightning arrester, DC commutation failure and other adverse consequences.

[0004] However, the research on the closing inrush current suppression method for the high-voltage DC transmission system filter with controllable phase-commutated converter is still in a blank stage. There is little research on the closing inrush current size of different filters and the overvoltage level of related components, which makes it difficult to determine the breaking capacity and insulation coordination of the circuit breaker. In addition, there is no clear standard recommendation for the value of the closing resistance of the 500kV AC filter circuit breaker. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a method, system and medium for suppressing the closing inrush current of a CLCC-HVDC system, which effectively suppress the closing inrush current.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A method for suppressing a closing inrush current of a CLCC-HVDC system comprises the following steps:

[0008] According to the transformation parameters of the actual project, a CLCC-HVDC system simulation model is constructed;

[0009] Determine the type and configuration of the AC filter according to the actual needs and installation conditions of the actual project, put the AC filter into the CLCC-HVDC system simulation model, build an AC filter simulation model, observe the closing inrush current under random closing and phase-selected closing conditions, and obtain the closing method with the best closing inrush current suppression effect;

[0010] The closing mode with the best closing inrush current suppression effect is added to the AC filter simulation model, and the AC filter circuit breaker is put into the filter simulation model for simulation in the case of connecting closing resistors with different resistance values ​​in parallel and not connecting closing resistors, and the closing inrush current, the main capacitor voltage and the heat absorbed by the closing resistor are observed to obtain the closing resistor with the best closing inrush current suppression effect;

[0011] The closing resistor with the best closing inrush current suppression effect is added to the CLCC-HVDC system simulation model, the closing phase angle is changed, and the closing inrush current at different closing phase angles is analyzed by simulation comparison to obtain the closing phase angle with the best closing inrush current suppression effect;

[0012] The closing mode, closing resistance and closing phase angle with the best closing inrush current suppression effect are applied to the CLCC-HVDC system to suppress the closing inrush current.

[0013] Furthermore, the CLCC-HVDC system simulation model includes multiple types of two-terminal power supplies, converter transformers, controllable commutation converters, DC filters, smoothing reactors and DC lines.

[0014] Furthermore, the AC filter simulation model includes the AC filter circuit breaker, capacitor, inductor, resistor and lightning arrester.

[0015] Furthermore, the AC filter circuit breaker includes a main break, an auxiliary break, a parallel capacitor and a closing resistor.

[0016] Furthermore, when the AC filter circuit breaker receives a closing instruction, the main break performs a closing operation before the auxiliary break.

[0017] Furthermore, the closing resistor is put into operation synchronously when the main break is closed, so as to limit the closing overvoltage and closing inrush current.

[0018] Furthermore, when the auxiliary break is closed, the closing resistor is short-circuited to stop the operation of the closing resistor.

[0019] Furthermore, the resistance value of the closing resistor ranges from several hundred to several thousand ohms.

[0020] According to another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, a closing inrush current suppression method of a CLCC-HVDC system can be implemented.

[0021] According to another aspect of the present invention, a closing inrush current suppression system for a CLCC-HVDC system is provided, comprising:

[0022] System simulation model building module, used to build a CLCC-HVDC system simulation model based on the transformation parameters of the actual project;

[0023] A closing mode selection module is used to determine the type and configuration of the AC filter according to the actual needs and installation conditions of the actual project, put the AC filter into the CLCC-HVDC system simulation model, build a filter simulation model, observe the closing inrush current under random closing and phase selection closing conditions, and obtain the closing mode with the best closing inrush current suppression effect;

[0024] A closing resistor selection module is used to add the closing mode with the best closing inrush current suppression effect to the AC filter simulation model, and respectively put the AC filter circuit breaker into the filter simulation model for simulation with closing resistors of different resistance values ​​connected in parallel and without connecting closing resistors, observe the closing inrush current, main capacitor voltage and closing resistor absorbed heat, and obtain the closing resistor with the best closing inrush current suppression effect;

[0025] A closing phase angle selection module, used for adding the closing resistor with the best closing inrush current suppression effect to the CLCC-HVDC system simulation model, changing the closing phase angle, and obtaining the closing phase angle with the best closing inrush current suppression effect by simulation and comparative analysis at different closing phase angles;

[0026] The closing inrush current suppression module is used to apply the closing mode, closing resistance and closing phase angle with the best closing inrush current suppression effect to the CLCC-HVDC system to suppress the closing inrush current.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention aims at the transformation parameters of the 500kV high-voltage direct current transmission project, constructs a CLCC-HVDC system simulation model, comprehensively considers the influence of closing mode, closing resistance and closing phase angle on the closing inrush current generated by the AC filter of the 500kV high-voltage transmission system, and proposes a closing inrush current suppression method when the filter of the high-voltage direct current transmission system containing a controllable phase-commutated converter is put into use, which can better suppress the closing inrush current and maintain the safe and stable operation of the system, filling the gap that there is no clear standard recommendation for the value of the closing resistance of the 500kV AC filter circuit breaker.

[0029] 2. The present invention determines the type and configuration of the AC filter according to the actual needs and installation conditions of the actual project, puts different AC filters into the CLCC-HVDC system simulation model, constructs an AC filter simulation model, observes the closing inrush current under random closing and phase-selective closing conditions, and obtains the phase-selective closing as a closing method to better suppress the closing inrush current effect, verifying that the phase-selective closing is universal in different filters. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A method flow chart of a closing inrush current suppression method for a CLCC-HVDC system proposed by the present invention;

[0031] Figure 2 It is a structural diagram of the AC filter simulation model;

[0032] Figure 3 Schematic diagram of circuit breaker circuit structure;

[0033] Figure 4 A comparison chart showing the impact of different closing modes on closing inrush current of different filters;

[0034] Figure 5 It is the closing inrush current curve under different closing resistance;

[0035] Figure 6 It is the main capacitor voltage curve under different closing resistance;

[0036] Figure 7 It is the closing resistance heat absorption energy curve diagram under different closing resistances;

[0037] Figure 8 Figure 2 is the closing inrush current curve at different closing phase angles. DETAILED DESCRIPTION

[0038] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0039] Abbreviations involved:

[0040] Controllable Line-commutated Converter: Controllable Line-commutated Converter, CLCC

[0041] High Voltage Direct Current, HVDC

[0042] Example 1

[0043] This embodiment provides a closing inrush current suppression method for a CLCC-HVDC system for a 500kV high voltage direct current transmission system. Figure 1 As shown, the following steps are included:

[0044] S1. Construct a CLCC-HVDC system simulation model based on the transformation parameters of the actual project.

[0045] According to the actual engineering transformation parameters of a converter station, a CLCC-HVDC system simulation model is established in PSCAD software, including two-end power supplies, converter transformers, controllable commutation converters, AC filters, DC filters, smoothing reactors, DC lines, etc. The CLCC-HVDC system is a simulation environment, and the AC filter often needs to be switched in the operation of the high-voltage DC transmission system, which is achieved through circuit breakers.

[0046] S2. Determine the type and configuration of the AC filter according to the actual needs and installation conditions of the actual project, put the AC filter into the CLCC-HVDC system simulation model, build an AC filter simulation model, observe the closing inrush current under random closing and phase-selective closing conditions, and obtain the closing method with the best effect of suppressing the closing inrush current.

[0047] In the cases of random closing and phase-selected closing, the type and configuration of the AC filter group to be put into use are determined according to the actual needs of the project and the installation situation. According to the absolute minimum number of filter groups table, 6 groups of filters are added during bipolar full-voltage operation, namely 2 groups of HP12 filters, 2 groups of HP24 / 36 filters, 1 group of HP12 / 24 filters, and 1 group of HP24 filters. Observe the closing inrush current of the filter group and conduct a comparative analysis. By comparing the closing inrush current of random closing and phase-selected closing, the effect of phase-selected closing technology in different types of filter configurations (such as HP12, HP24, HP12 / 24, HP24 / 36) can be actually verified. The schematic diagram of the structure of the AC filter simulation model is shown in the figure. Figure 2 The circuit diagram of the circuit breaker is shown in Figure 3 shown.

[0048] During the random closing process of the circuit breaker, a large closing inrush current may be generated. If the phase-selective closing device is used, the closing inrush current can be better suppressed. The suppression effect of different filters is as follows: Figure 4 As shown in the figure, it can be seen that for a variety of different filters, phase selection closing has a more obvious suppression effect on the closing inrush current generated by the AC filter compared with random closing.

[0049] After receiving the closing command from the system, the operating mechanism drives the main break and the auxiliary break to close at the same time. Due to the difference in mechanical travel and moving speed, the main break closes 8 to 11 ms earlier than the auxiliary break. During this period, the closing resistor is put into operation synchronously when the main break is closed, which plays a role in limiting the closing overvoltage and inrush current. After that, the auxiliary break is closed to short-circuit it, and the closing resistor stops running.

[0050] S3. Add the best closing mode to suppress the closing inrush current in the AC filter simulation model, put the AC filter circuit breaker into the filter simulation model for simulation with closing resistors of different resistance values ​​connected in parallel and without connecting the closing resistor, observe the closing inrush current, main capacitor voltage and closing resistor absorbed heat, and obtain the closing resistor with the best closing inrush current suppression effect;

[0051] According to the filter input sequence in the table of the absolute minimum number of filter groups in actual projects, the HP12 filter is put into operation when the filter is put into operation. Add closing resistors with different resistance values ​​of 500 to 2000Ω, and observe the closing inrush current, main capacitor voltage, and closing resistor heat absorption under different closing resistor values. Figure 5 The main capacitor voltage under different closing resistance is shown as Figure 6 The heat absorbed by the closing resistor under different closing resistances is shown in Figure 7 shown.

[0052] Depend on Figure 5 It can be seen that the closing inrush current is small under the closing resistance of 500~1100Ω and 1500Ω. Figure 7 It can be seen that after adding the closing resistor, the heat absorption of the closing resistor decreases as the resistance value increases. Therefore, considering the closing inrush current suppression effect and the heat absorbed by the closing resistor, a 1500Ω closing resistor is selected as the closing resistor with the best closing inrush current suppression effect.

[0053] S4. Add the closing resistor with the best closing inrush current suppression effect to the CLCC-HVDC system simulation model, change the closing phase angle, and compare and analyze the closing inrush current at different closing phase angles through simulation to obtain the closing phase angle with the best closing inrush current suppression effect.

[0054] When a 1500Ω closing resistor is added, the closing phase angle is changed, and the closing inrush current is as follows: Figure 8 As shown in the figure, it can be seen that selecting a closing phase angle of about 120° can suppress the closing inrush current to the greatest extent.

[0055] S5. Apply the closing mode, closing resistance and closing phase angle with the best closing inrush current suppression effect to the CLCC-HVDC system to suppress the closing inrush current.

[0056] In this embodiment, a phase-selective closing mode is selected, and a 1500Ω closing resistor and a closing phase angle of about 120° are applied to the CLCC-HVDC system, thereby effectively suppressing the closing inrush current generated when the AC filter is put into use in the 500kV high-voltage direct current transmission system.

[0057] Example 2

[0058] This embodiment provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, a closing inrush current suppression method of a CLCC-HVDC system can be implemented.

[0059] The rest is the same as in Example 1.

[0060] Example 3

[0061] This embodiment provides a closing inrush current suppression system for a CLCC-HVDC system, including:

[0062] System simulation model building module, used to build a CLCC-HVDC system simulation model based on the transformation parameters of the actual project;

[0063] The closing mode selection module is used to determine the type and configuration of the AC filter according to the actual needs and installation conditions of the actual project, put the AC filter into the CLCC-HVDC system simulation model, build a filter simulation model, observe the closing inrush current under random closing and phase-selected closing conditions, and obtain the closing mode with the best effect of suppressing the closing inrush current;

[0064] A closing resistor selection module is used to add the closing mode with the best closing inrush current suppression effect to the AC filter simulation model, and put the AC filter circuit breaker into the filter simulation model for simulation in the case of connecting closing resistors with different resistance values ​​in parallel and not connecting closing resistors, observe the closing inrush current and the heat absorbed by the closing resistor, and obtain the closing resistor with the best closing inrush current suppression effect;

[0065] The closing phase angle selection module is used to add the closing resistor with the best closing inrush current suppression effect to the CLCC-HVDC system simulation model, change the closing phase angle, and compare and analyze the closing inrush current at different closing phase angles through simulation to obtain the closing phase angle with the best closing inrush current suppression effect;

[0066] The closing inrush current suppression module is used to apply the closing mode, closing resistance and closing phase angle with the best closing inrush current suppression effect to the CLCC-HVDC system to suppress the closing inrush current.

[0067] The rest is the same as in Example 1.

[0068] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for suppressing closing inrush current of a CLCC-HVDC system, characterized in that: The following steps are involved: According to the transformation parameters of the actual project, a CLCC-HVDC system simulation model is constructed; Determine the type and configuration of the AC filter according to the actual needs and installation conditions of the actual project, put the AC filter into the CLCC-HVDC system simulation model, build an AC filter simulation model, observe the closing inrush current under random closing and phase-selected closing conditions, and obtain the closing method with the best closing inrush current suppression effect; The closing mode with the best closing inrush current suppression effect is added to the AC filter simulation model, and the AC filter circuit breaker is put into the AC filter simulation model for simulation in the case of connecting closing resistors with different resistance values ​​in parallel and not connecting closing resistors, and the closing inrush current, the main capacitor voltage and the heat absorbed by the closing resistor are observed to obtain the closing resistor with the best closing inrush current suppression effect; The closing resistor with the best closing inrush current suppression effect is added to the CLCC-HVDC system simulation model, the closing phase angle is changed, and the closing inrush current at different closing phase angles is analyzed by simulation comparison to obtain the closing phase angle with the best closing inrush current suppression effect; The closing mode, closing resistance and closing phase angle with the best closing inrush current suppression effect are applied to the CLCC-HVDC system to suppress the closing inrush current.

2. The closing inrush current suppression method of the CLCC-HVDC system according to claim 1, characterized in that: The CLCC-HVDC system simulation model includes multiple types of two-terminal power supplies, converter transformers, controllable commutation converters, DC filters, smoothing reactors and DC lines.

3. The closing inrush current suppression method of the CLCC-HVDC system according to claim 1, characterized in that: The AC filter simulation model includes the AC filter circuit breaker, capacitor, inductor, resistor and lightning arrester.

4. The closing inrush current suppression method of the CLCC-HVDC system according to claim 1, characterized in that: The AC filter circuit breaker comprises a main break, an auxiliary break, a parallel capacitor and a closing resistor.

5. The closing inrush current suppression method of the CLCC-HVDC system according to claim 4, characterized in that: When the AC filter circuit breaker receives a closing instruction, the main break performs a closing operation before the auxiliary break.

6. The closing inrush current suppression method of the CLCC-HVDC system according to claim 4, characterized in that: The closing resistor is put into operation synchronously when the main break is closed, so as to limit the closing overvoltage and closing inrush current.

7. The closing inrush current suppression method of the CLCC-HVDC system according to claim 4, characterized in that: When the auxiliary break is closed, the closing resistor is short-circuited to stop the operation of the closing resistor.

8. The closing inrush current suppression method of the CLCC-HVDC system according to claim 1, characterized in that: The resistance value of the closing resistor ranges from several hundred to several thousand ohms.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the closing inrush current suppression method of the CLCC-HVDC system based on transfer learning according to any one of claims 1 to 8 can be implemented.

10. A closing inrush current suppression system for a CLCC-HVDC system, characterized in that: include: System simulation model building module, used to build a CLCC-HVDC system simulation model based on the transformation parameters of the actual project; A closing mode selection module is used to determine the type and configuration of the AC filter according to the actual needs and installation conditions of the actual project, put the AC filter into the CLCC-HVDC system simulation model, build a filter simulation model, observe the closing inrush current under random closing and phase selection closing conditions, and obtain the closing mode with the best closing inrush current suppression effect; A closing resistor selection module is used to add the closing mode with the best closing inrush current suppression effect to the AC filter simulation model, and respectively put the AC filter circuit breaker into the filter simulation model for simulation with closing resistors of different resistance values ​​connected in parallel and without connecting closing resistors, observe the closing inrush current, main capacitor voltage and closing resistor absorbed heat, and obtain the closing resistor with the best closing inrush current suppression effect; A closing phase angle selection module, used for adding the closing resistor with the best closing inrush current suppression effect to the CLCC-HVDC system simulation model, changing the closing phase angle, and obtaining the closing phase angle with the best closing inrush current suppression effect by simulation and comparative analysis at different closing phase angles; The closing inrush current suppression module is used to apply the closing mode, closing resistance and closing phase angle with the best closing inrush current suppression effect to the CLCC-HVDC system to suppress the closing inrush current.

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