On-load voltage regulating transformer with commutation failure resistance and control method thereof
By combining a three-phase three-winding transformer with an AC/DC converter, the power electronic control system solves the problems of arc burnout and inaccurate voltage regulation of mechanical tap changers. It enables rapid adjustment of transformer valve-side voltage and AC voltage compensation, thereby improving the stability of the DC system and its ability to withstand commutation failure.
Patent Information
- Application Number
- CN202511664073.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-13
- Publication Date
- 2026-03-20
AI Technical Summary
In existing converter systems, mechanical tap changers suffer from problems such as arc burnout, slow voltage regulation response, high failure rate, and inaccurate voltage regulation, which affect the safe operation of the power grid.
A three-phase, three-winding transformer is combined with two AC/DC converters. Through closed-loop control of power electronic devices, the transformer valve-side voltage can be quickly, continuously, and smoothly regulated, and rapid compensation can be performed when the AC grid voltage drops.
It enables rapid, continuous, and smooth regulation of the transformer valve-side voltage, improves the DC system's ability to withstand commutation failure, and ensures stable grid operation.
Smart Images
Figure CN121710362A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of on-load voltage regulation control, and particularly relates to an on-load voltage regulation transformer with the ability to resist commutation failure and a control method thereof. BACKGROUND
[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute prior art.
[0003] For an ultra-high voltage conventional HVDC power transmission system, a line commutated converter (LCC) is a current source type converter, and its basic working principle is to convert the voltage on the alternating current side to the direct current side according to a certain time sequence through the alternating conduction of thyristors, so as to realize the conversion between alternating current and direct current. The LCC needs the assistance of alternating current voltage for normal operation, and the operating characteristics of the entire system are closely coupled with the alternating current voltage. In order to meet the requirements of large-scale adjustment of direct current power and optimization of reactive power configuration, a multi-position tap changer needs to be configured for the converter transformer to deeply participate in the system operation control.
[0004] The converter transformer with the tap changer can realize the stability or change of the alternating current voltage on the valve side of the LCC through mechanical on-load tap changer voltage regulation, but it has three inherent defects that are difficult to eliminate: 1. Arc is generated during the switching of the tap, which causes mechanical head burnout and transformer insulation oil medium polarization; 2. The action speed of the tap changer is slow, the voltage regulation response time is long, and it is easy to be wrong in grade and position, cannot perform dynamic voltage regulation, and has high failure rate and large maintenance amount; 3. The action time of the mechanical switch has dispersion, so that the voltage regulation time cannot be accurately controlled, and a transition process may occur during voltage regulation, or even the phenomenon of wrong grade and position, which adversely affects the safe operation of the power grid. SUMMARY
[0005] In order to solve the above problems, the present application proposes an on-load voltage regulation transformer with the ability to resist commutation failure and a control method thereof. The present application can not only realize fast, continuous and smooth regulation of the alternating current voltage on the valve side, but also improve the stability of the valve side voltage during the operation of the LCC. When the voltage of the alternating current power grid connected to the direct current power transmission system drops, the present application can also quickly compensate the alternating current voltage through power electronic equipment to avoid commutation failure of the LCC and effectively improve the ability of the direct current system to resist commutation failure.
[0006] According to some embodiments, the present application adopts the following technical scheme: An on-load voltage regulation transformer with the ability to resist commutation failure, comprising one three-phase three-winding transformer and two AC / DC converters, and the two AC / DC converters both have four-quadrant power interval operation ability. The three windings of the transformer are a primary winding, a secondary winding and a balance winding, and the AC / DC converter is a series converter and a parallel converter; The primary winding of the transformer is connected to an AC power grid in series with the AC port of the series converter, the secondary winding of the transformer is connected to the AC port of the LCC, the balance winding of the transformer is directly connected to the AC port of the parallel converter, and the DC port of the series converter is connected to the DC port of the parallel converter.
[0007] As an optional implementation, the parallel converter adopts a double-loop control strategy of a voltage source converter.
[0008] As a further implementation, the DC port voltage of the parallel converter is controlled to be a rated value, and the power balance of the two converters is maintained.
[0009] A control method of a load regulating transformer with commutation failure resistance, applied to a series converter, comprising: The ground voltage of an AC power grid bus connected to the load regulating transformer is collected, the amplitude and phase of the ground voltage are calculated, the deviation of the amplitude from an expected command value of the primary winding voltage amplitude of the transformer is calculated, the series converter AC voltage control command value is determined based on the deviation and the phase, and the final modulation voltage of the series converter is calculated according to the deviation between the series converter AC voltage control command value and a feedback value.
[0010] As an optional implementation, the process of determining the series converter AC voltage control command value based on the deviation and the phase comprises: the calculated deviation is multiplied by the sine of the phase to obtain the series converter AC voltage control command value.
[0011] As an optional implementation, the process of calculating the final modulation voltage of the series converter according to the deviation between the series converter AC voltage control command value and the feedback value comprises: the difference between the series converter AC voltage control command value and the feedback value is calculated, and the result of the control calculation is superimposed on the series converter AC voltage control command value to obtain the final modulation voltage of the series converter.
[0012] As a further implementation, the control calculation is a PR control.
[0013] As an optional implementation, the following steps are further included: the parallel converter adopts a double-loop control strategy of a voltage source converter, the DC port voltage of the parallel converter is controlled to be a rated value, and the power balance of the two converters is maintained.
[0014] An electronic device comprises a memory and a processor, and computer instructions stored in the memory and running on the processor, when the computer instructions are run by the processor, the steps in the above method are completed.
[0015] Compared with the prior art, the present application has the following advantages: The application combines a traditional three-winding transformer and a power electronic device in series and parallel, controls the valve side winding voltage of the transformer to be fast, continuous and smooth through closed-loop control of the power electronic device, and improves the ability of the DC system to resist commutation failure; not only can the primary winding voltage of the transformer (equivalent to the valve side winding voltage of the LCC) realize basic voltage regulation, but also can quickly compensate the AC voltage when the AC grid voltage drops, maintain the stability of the primary winding voltage of the transformer, and effectively resist the occurrence of LCC commutation failure.
[0016] In order to make the above objectives, characteristics and advantages of the present application more apparent, the following preferred embodiments are specifically described below, and the accompanying drawings are used for detailed description. BRIEF DESCRIPTION OF DRAWINGS
[0017] The drawings constituting a part of the specification of the present application are used to provide further understanding of the present application, the schematic embodiments of the present application and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application.
[0018] Figure 1 It is a schematic diagram of the on-load voltage regulating transformer topology structure of an embodiment.
[0019] Figure 2 It is a structure block diagram of the parallel current converter control strategy of an embodiment.
[0020] Figure 3 It is a structure block diagram of the series current converter control strategy of an embodiment. DETAILED DESCRIPTION
[0021] The present application is further described below in combination with the drawings and embodiments.
[0022] It should be noted that the following detailed description is all exemplary, and is intended to provide further description of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which the present application belongs.
[0023] It should be noted that the terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form, and in addition, it should be understood that when the terms "comprise" and / or "include" are used in the specification, they indicate the presence of a feature, step, operation, device, component and / or combination thereof.
[0024] The embodiments in the present application and the features in the embodiments can be combined with each other without conflict.
[0025] Embodiment one A topology of a load regulating transformer with commutation failure resistance Figure 1 As shown, a three-phase three-winding transformer and two AC / DC converters are used, wherein the AC / DC converters have four-quadrant power interval operation capability. The three windings of the transformer are respectively a primary winding, a secondary winding and a balance winding, and the AC / DC converters can be divided into series converters and parallel converters according to different functions and connection modes.
[0026] The primary winding of the transformer is connected in series with the AC port of the series converter and connected to the AC power grid, the secondary winding of the transformer is connected to the AC port of the LCC, the balance winding of the transformer is directly connected to the AC port of the parallel converter, and the DC port of the series converter is connected to the DC port of the parallel converter.
[0027] Of course, in other embodiments, a mechanical load tap changer can also be configured.
[0028] The parallel converter adopts the traditional double-loop control strategy of the voltage source converter, and a control strategy block diagram thereof is as shown in Figure 2 The DC port voltage of the converter is controlled to be a rated value, and the power balance of the two converters is maintained.
[0029] The series converter adopts a split-phase control scheme, and each phase voltage is independently controlled, the AC voltage amplitude between the primary windings of the transformer is controlled to be a desired command value, and indirect closed-loop control of the secondary winding (valve side winding) is realized. Taking one phase as an example, a control strategy block diagram thereof is as shown in Figure 3 The amplitude Ug_mag and phase of the bus-to-ground voltage Ug of the AC power grid connected to the load regulating transformer are calculated. The deviation of Ug_mag from the desired command value Ug_ref of the voltage amplitude of the primary winding of the transformer is multiplied by After taking the sine, the result is taken as the converter AC voltage control command value Uac_ref. The difference between the converter AC voltage control command value Uac_ref and the feedback value Uac is calculated by the PR controller, and the converter AC voltage control command value Uac_ref is superimposed as the final modulation voltage Um of the converter.
[0030] Embodiment two A control method of a load regulating transformer with commutation failure resistance, applied to a series converter, as shown in Figure 3 includes: The bus-to-ground voltage of the AC power grid connected to the load regulating transformer is collected, the amplitude and phase thereof are calculated, the deviation of the amplitude from the desired command value of the voltage amplitude of the primary winding of the transformer is calculated, the converter AC voltage control command value is determined based on the deviation and the phase, and the final modulation voltage of the converter is calculated according to the deviation between the converter AC voltage control command value and the feedback value.
[0031] The process of determining the converter AC voltage control instruction value based on the deviation amount and the phase includes: the calculated deviation amount multiplied by the sine of the phase as the converter AC voltage control instruction value.
[0032] The process of calculating the final modulation voltage of the converter according to the deviation of the converter AC voltage control instruction value and the feedback value includes: the result of the control calculation after the converter AC voltage control instruction value and the feedback value are subtracted, and the converter AC voltage control instruction value is superimposed as the final modulation voltage of the converter.
[0033] The control calculation is PR control.
[0034] Embodiment three An electronic device includes a memory and a processor, and computer instructions stored on the memory and run on the processor, when the computer instructions are run by the processor, the steps in the method provided by embodiment one are completed.
[0035] Those skilled in the art will understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, etc.) containing computer-usable program code. CD - ROM
[0036] The present application is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as combinations of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 The flow or multiple flows and / or blocks Figure 1 The device that implements the functions specified in the flowcharts and / or block diagrams.
[0037] These computer program instructions can also be stored in a computer-readable memory that can direct the computer or other programmable data processing apparatus to work in a specific manner, so that the instructions stored in the computer-readable memory produce a product including instruction devices that implement the functions specified in the flowcharts and / or block diagrams. Figure 1 The flow or multiple flows and / or blocks Figure 1 the function specified in the one or more blocks.
[0038] These computer program instructions can also be loaded into computer or other programmable data processing devices, so that a series of operational steps are performed on the computer or other programmable data processing devices to generate computer-implemented processes, thus the instructions executed on the computer or other programmable data processing devices provide processes for implementing the flows Figure 1 the flow or flows and / or blocks Figure 1 the steps of the function specified in the one or more blocks.
[0039] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Various modifications and changes can be made by those skilled in the art without departing from the spirit and principle of the present application. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art without creative labor within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. An on-load tap-changing transformer capable of withstanding commutation failure, characterized in that, It includes a three-phase three-winding transformer and two AC / DC converters, both of which are capable of operating in the four-quadrant power range. The transformer has three windings: primary winding, secondary winding, and balancing winding. The AC / DC converters are a series converter and a parallel converter, respectively. The primary winding of the transformer is connected in series with the AC port of the series converter and then connected to the AC power grid. The secondary winding of the transformer is connected to the AC port of the LCC. The balancing winding of the transformer is directly connected to the AC port of the parallel converter. The DC port of the series converter is connected to the DC port of the parallel converter.
2. The on-load tap-changing transformer with the ability to resist commutation failure as described in claim 1, characterized in that, The parallel converter adopts a dual closed-loop control strategy of voltage source converter; the DC port voltage of the parallel converter is controlled at the rated value to maintain the power balance of the two converters.
3. The on-load tap-changing transformer with the ability to resist commutation failure as described in claim 1, characterized in that, The series converter adopts a phase-separated control strategy, which collects the AC grid bus voltage to ground connected to the on-load tap-changing transformer, calculates its amplitude and phase, calculates the deviation between the amplitude and the expected command value of the transformer primary winding voltage amplitude, determines the AC voltage control command value of the converter based on the deviation and phase, and calculates the final modulation voltage of the converter based on the deviation between the AC voltage control command value and the feedback value.
4. A load-changing transformer with the ability to resist commutation failure as described in claim 3, characterized in that, The process of calculating the final modulation voltage of the converter based on the deviation between the AC voltage control command value and the feedback value includes: subtracting the AC voltage control command value and the feedback value, and then superimposing the AC voltage control command value of the converter as the final modulation voltage of the converter; the control calculation is PR control.
5. A control method for an on-load tap-changing transformer capable of withstanding commutation failure, characterized in that, Applications in series converters include: The voltage to ground of the AC grid bus connected to the on-load tap-changing transformer is collected, and its amplitude and phase are calculated. The deviation between the amplitude and the expected command value of the voltage amplitude of the transformer primary winding is calculated. Based on the deviation and phase, the AC voltage control command value of the converter is determined. The final modulation voltage of the converter is calculated based on the deviation between the AC voltage control command value and the feedback value.
6. The control method as described in claim 5, characterized in that, The process of determining the AC voltage control command value of the converter based on the deviation and phase includes: multiplying the calculated deviation by the phase sine and using it as the AC voltage control command value of the converter.
7. The control method as described in claim 5, characterized in that, Its characteristics are, The process of calculating the final modulated voltage of the converter based on the deviation between the AC voltage control command value and the feedback value includes: subtracting the AC voltage control command value and the feedback value, calculating the result of the control, and then superimposing the AC voltage control command value of the converter as the final modulated voltage of the converter.
8. The control method as described in claim 7, characterized in that, The control calculation is PR control.
9. The control method as described in claim 5, characterized in that, It also includes the following steps: the parallel converter adopts a dual closed-loop control strategy of voltage source converter to control the DC port voltage of the parallel converter to the rated value and maintain the power balance of the two converters.
10. An electronic device, characterized in that, It includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, which, when executed by the processor, perform the steps of the method according to any one of claims 5-8.