A system for comprehensive suppression of harmonic voltage and harmonic current
Patent Information
- Application Number
- CN202521198405.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-12
- Publication Date
- 2026-10-23
- Estimated Expiration
- 2035-06-12
AI Technical Summary
现有技术提出的对谐波进行综合治理的装置，仍然采用传统方法实现谐波治理，缺少一种谐波电压和谐波电流综合抑制系统解决谐波综合治理问题
[0016]本实用新型的有益效果：本系统可以根据需要补偿的谐波次数实现独立使能和参数独立调节，便于现场调试；谐波补偿限值可以按照需要补偿的谐波次数独立进行设置，从而可以灵活调节谐波电压和谐波电流的补偿程度，在满足相关标准的前提下，进一步减少设备所需容量和运行损耗；采用谐波电压和电流综合抑制，既可以实现对谐波电流的抑制，又同时实现对谐波电压的抑制，进一步提升了谐波治理效果。
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Figure CN224890340U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of power harmonic filter technology, and in particular to a comprehensive system for suppressing harmonic voltage and harmonic current. Background Technology
[0002] In new power systems primarily based on renewable energy generation, the stable transmission, safe grid connection, and absorption capacity of large-scale onshore or offshore wind power generation face numerous difficulties and challenges, with power quality issues being particularly prominent. Because large offshore wind farms use cable lines to collect electrical energy, the inherent spectral characteristics of these lines can cause series / parallel resonance for certain harmonics, leading to excessive harmonic voltage / current content. Furthermore, harmonic voltage sources with unclear origins in the power system, such as background harmonics, can amplify or even exceed harmonic voltage / current limits at the common bus due to the interaction between the power system harmonic impedance, the wind turbine converter impedance, and the collector line impedance.
[0003] Harmonic problems are essentially caused by resonance in the power network under the excitation of harmonic excitation sources (harmonic voltage sources or harmonic current sources). Existing devices for comprehensive harmonic mitigation still use traditional methods, lacking a comprehensive harmonic voltage and current suppression system to solve the overall harmonic mitigation problem. Utility Model Content
[0004] In this section, as well as in the abstract and title of this application, some simplifications or omissions may be made to avoid obscuring the purpose of this section, the abstract, and the title of this application. Such simplifications or omissions shall not be used to limit the scope of this utility model.
[0005] Therefore, the technical problem to be solved by this utility model is that the existing devices for comprehensive harmonic control still use traditional methods to achieve harmonic control, and there is a lack of a comprehensive harmonic voltage and harmonic current suppression system to solve the problem of comprehensive harmonic control.
[0006] To solve the above technical problems, this utility model provides the following technical solution: a comprehensive harmonic voltage and harmonic current suppression system, which includes a grid-connected converter, including the signal source, AC system equivalent impedance, load equivalent impedance and load, wherein the signal source, AC system equivalent impedance, load equivalent impedance and load are connected in sequence; It also includes a control unit, a drive unit, a power unit, and a bridge arm reactor. The control unit generates a voltage modulation signal and sends it to the drive unit. The drive unit generates a drive signal and sends it to the power unit. The power unit modulates the difference between the output voltage and the voltage at the common bus connection point and applies it to the bridge arm reactor. The bridge arm reactor is connected to the common bus connection point between the equivalent impedance of the AC system and the equivalent impedance of the load.
[0007] As a preferred embodiment of the harmonic voltage and harmonic current integrated suppression system of this utility model, the system voltage generated by the signal source generates an AC system current after passing through the AC system equivalent impedance. After passing through the common bus connection point, it is divided into two paths: one is the load current flowing to the load equivalent impedance, and the other is the grid-connected current flowing to the bridge arm reactor.
[0008] As a preferred embodiment of the harmonic voltage and harmonic current integrated suppression system of this utility model, the control unit receives the current reference signal, harmonic current reference signal and grid-connected current given by the upper layer, and transmits them to the quasi-proportional resonant controller.
[0009] As a preferred embodiment of the harmonic voltage and harmonic current integrated suppression system of this utility model, wherein: the output signal of the quasi-proportional resonant controller interacts with the voltage at the common bus connection point to generate a voltage modulation signal.
[0010] As a preferred embodiment of the harmonic voltage and harmonic current integrated suppression system of this utility model, the driving unit receives the voltage modulation signal generated by the control unit and generates a driving signal.
[0011] As a preferred embodiment of the harmonic voltage and harmonic current integrated suppression system of this utility model, the power unit receives the driving signal generated by the driving unit and modulates the output voltage at the output terminal of the power unit.
[0012] As a preferred embodiment of the harmonic voltage and harmonic current integrated suppression system of this utility model, wherein: the bridge arm reactor receives the output voltage and the voltage at the common bus connection point, and generates a grid-connected current which is sent to the control unit.
[0013] As a preferred embodiment of the harmonic voltage and harmonic current comprehensive suppression system of this utility model, it further includes: The compensation unit includes a harmonic current suppression module and a harmonic voltage suppression module. The harmonic current suppression module and the harmonic voltage suppression module work together to generate a harmonic current reference signal. The compensation unit sends the harmonic current reference signal to the control unit.
[0014] As a preferred embodiment of the harmonic voltage and harmonic current integrated suppression system of this utility model, it further includes a harmonic current compensation module, which generates a harmonic current compensation amount and sends the harmonic current compensation amount to the harmonic current suppression module.
[0015] As a preferred embodiment of the harmonic voltage and harmonic current integrated suppression system of this utility model, it further includes an admittance generation module, which generates virtual admittance and sends the virtual admittance to the harmonic voltage suppression module.
[0016] The beneficial effects of this utility model are as follows: This system can be independently enabled and its parameters can be independently adjusted according to the harmonic order that needs to be compensated, which is convenient for on-site debugging; the harmonic compensation limit can be set independently according to the harmonic order that needs to be compensated, so that the compensation degree of harmonic voltage and harmonic current can be flexibly adjusted, and the required capacity and operating loss of equipment can be further reduced while meeting relevant standards; the comprehensive suppression of harmonic voltage and current can suppress both harmonic current and harmonic voltage, further improving the harmonic control effect. Attached Figure Description
[0017] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is the overall schematic diagram of a system for comprehensively suppressing harmonic voltage and harmonic current.
[0018] Figure 2 This is a schematic diagram illustrating the working principle of the harmonic voltage and harmonic current suppression module in a comprehensive harmonic voltage and harmonic current suppression system.
[0019] Figure 3 This is a schematic diagram of the working principle of the harmonic current compensation module in a comprehensive harmonic voltage and harmonic current suppression system.
[0020] Figure 4 This is a schematic diagram of the admittance generation module of a comprehensive harmonic voltage and harmonic current suppression system.
[0021] Figure 5 The waveform diagram generated by establishing a three-dimensional model of the system for comprehensive suppression of harmonic voltage and harmonic current. Detailed Implementation
[0022] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.
[0023] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0024] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.
[0025] Example 1 Reference Figure 1 This is the first embodiment of the present invention, which provides a comprehensive harmonic voltage and harmonic current suppression system. Its grid-connected converter 400 includes a signal source S and an AC system equivalent impedance Z. g Equivalent impedance of load Z L and load LOAD, signal source S, AC system equivalent impedance Z g Equivalent impedance of load Z L Connect it sequentially to the load LOAD; It also includes a control unit 100, a drive unit 200, a power unit 300, and a bridge arm reactor X0. The control unit 100 generates a voltage modulation signal u. m The signal is sent to the drive unit 200, and the drive unit 200 generates a drive signal F. gt The voltage is fed into the power unit 300, which modulates the output voltage u. v The difference between the voltage upcc at the connection point with the common bus and the voltage upcc acts on the bridge arm reactance X0; The bridge arm reactance X0 is connected to the equivalent impedance Z of the AC system. g Equivalent impedance Z of the load L The common busbar connection point A between them.
[0026] The system voltage V generated by signal source S s The equivalent impedance Z of the AC system g The alternating current i is then generated in the system. sys After passing through the common bus connection point A, it splits into two paths, one of which flows to the load's equivalent impedance Z. L Load current i load The other path is the grid-connected current i flowing to the bridge arm reactance X0. apf .
[0027] Control unit 100 receives current reference signal i given by the upper layer. ref Harmonic current reference signal ih *and grid-connected current i apf And it is sent to the quasi-proportional resonant controller PR.
[0028] The output signal of the quasi-proportional resonant controller PR is related to the voltage u at the common bus connection point. pcc The function generates a voltage modulation signal u m .
[0029] Control unit 100 receives current reference signal i given by the upper layer. ref Harmonic current reference signal i h *and grid-connected current i apf Generates voltage modulation signal u m .
[0030] The drive unit 200 receives the voltage modulation signal u generated by the control unit 100. m Generates drive signal F gt .
[0031] The power unit 300 receives the drive signal F generated by the drive unit 200. gt The output voltage u is modulated at the output terminal of the power unit 300. v .
[0032] Bridge arm reactance X0 receives output voltage u v Voltage u at the connection point with the common bus pcc , generating grid-connected current i apf Send it to control unit 100.
[0033] The overall working principle of this system is as follows: The control unit 100 transmits the current reference signal i given by the upper layer... ref Harmonic current reference signal i h *Add them together, then subtract the grid-connected current i. apf The difference is inverted after passing through a quasi-proportional resonant PR control circuit, and is then compared with the voltage u at the common bus connection point. pcc Adding them together yields the voltage modulation signal u. m Then, the voltage modulation signal u m The signal is fed into the drive unit 200 to achieve SPWM modulation and generate the drive signal F. gt Finally, the drive signal F gt The signal is fed into the power unit 300, controlling the switching of the power electronic switching devices within the power unit 300, and modulating the output voltage u at the output port of the power unit 300. v Voltage u v Voltage u at the connection point with the common bus pcc The difference in voltage applied to the bridge arm reactance X0 generates a grid-connected current i. apf , grid-connected current i apfThe data continues to be sent to control unit 100, cycling multiple times within the control cycle, ultimately achieving the grid-connected current i of the device. apf For the current reference signal i ref With harmonic current reference signal i h Closed-loop tracking control based on the sum of *.
[0034] Example 2 Reference Figure 2 This is the second embodiment of the present invention, which differs from the first embodiment in that: the harmonic voltage and harmonic current integrated suppression system further includes a compensation unit 500, comprising a harmonic current suppression module 501 and a harmonic voltage suppression module 502. The harmonic current suppression module 501 and the harmonic voltage suppression module 502 work together to generate a harmonic current reference signal i. h * The compensation unit 500 will use the harmonic current reference signal i h *Sent to control unit 100.
[0035] The working principle of the harmonic current suppression module 501: It reduces the system current i sys and grid-connected current i apf Subtracting them, we get the load current i. load , then i load Through rotation transformation matrix T h abc-dq The components are projected onto different dq rotating coordinate systems, where the DC component corresponds to the specified harmonic component to be extracted, while other harmonic components are AC quantities. Therefore, a low-pass filter (LPF) is used to filter out the AC components, thus obtaining the DC component. Finally, the DC component is transformed by the inverse transformation matrix T. h dq-abc By transforming to the abc coordinate system, the specified subharmonic current component i can be obtained. h0 *, then i h0 * Harmonic current compensation amount Δi h0 *Add them together to obtain the harmonic current command value i h1 *. When the switch quantity K ih When =1, the harmonic current command value i h1 *As a final reference value, when the switch quantity K ih When =0, 0 is taken as the final reference value.
[0036] The working principle of the harmonic voltage suppression module 502 is to reduce the voltage u at the common bus connection point. pcc Subtract the sum of its fundamental frequency positive and negative sequence components u pcc PN The difference is obtained through the rotation transformation matrix T. h abc-dqThe components are projected onto different dq rotating coordinate systems, where the DC component corresponds to the specified harmonic component to be extracted, while other harmonic components are AC quantities. Therefore, a low-pass filter (LPF) is used to filter out the AC components, thus obtaining the DC component. Finally, the DC component is transformed by the inverse transformation matrix T. h dq-abc By transforming to the abc coordinate system, the specified subharmonic voltage component u can be obtained. h * Then combine uh* with the virtual admittance Y vh Multiply to obtain the harmonic current command value i h2 *. When the switch quantity K uh When =1, the harmonic current command value i h2 *As a final reference value, when the switch quantity K uh When =0, 0 is taken as the final reference value.
[0037] The output i of the harmonic voltage suppression module 502 h2 * Or 0, minus the output i of the harmonic current suppression module 501 h1 * Or 0, ultimately yielding the harmonic current reference value i h * It should be noted that the switching quantity K ih and K uh Individual single-cycle enable can be achieved according to each harmonic.
[0038] Example 3 Reference Figure 3 and Figure 4 This is the third embodiment of the present invention, which differs from the previous two embodiments in that: the compensation unit 500 further includes a harmonic current compensation module 503, which generates a harmonic current compensation amount Δi. h0 * And the harmonic current compensation amount Δi h0 * Input the harmonic current suppression module 501.
[0039] Admittance generation module 504 generates virtual admittance Y. vh And virtual admittance Y vh Input is sent to harmonic voltage suppression module 502.
[0040] The working principle of the harmonic current compensation module 503: It converts the system current i sys and grid-connected current i apf Subtraction, after the RMS calculation step h The effective value of the h-th harmonic current i is obtained. hrms , give value i hrms *With i as the feedback value hrms Subtract, then pass through Pl i The regulator ultimately generates the harmonic current compensation amount Δi. h0 * .
[0041] The working principle of the admittance generation module 504 is to convert the voltage u at the common bus connection point into the voltage u at the common bus connection point. pcc Subtract the sum of its fundamental frequency positive and negative sequence components u pcc PN The difference is calculated using the RMS (Real Values) step. h The effective value of the h-th harmonic voltage, u, is obtained. hrms , give value u hrms * With u as the feedback value hrms Subtract, then pass through PI u The regulator ultimately generates the virtual admittance Y. vh .
[0042] Example 4 Reference Figures 1-5 This is the fourth embodiment of the present invention. A corresponding three-terminal system model is built on the PSCAD / EMTDC simulation platform. The AC system rated voltage is 35kV, the AC system short-circuit ratio SCR / XOR = 10 / 10, the load is a purely active load with a rated capacity of 100MW, the APF rated voltage level is 35kV, the rated reactive power is 35MVar, and the bridge arm inductance is 3.8mH. Fifth and seventh harmonic currents with an amplitude of 10% of the rated current are injected on the load side. Harmonic current suppression is enabled by the APF at 2.0s, and harmonic voltage control is enabled at 3.5s. The virtual admittance Yv = 1.5pu. The simulation results are attached. Figure 3 As shown in the figures, the top graph displays the total distortion rate (THD%) of the grid connection point voltage, the middle graph displays the total distortion rate (THD%) of the AC system current, and the bottom graph displays the instantaneous three-phase current waveforms of the AC system. It can be seen from the figures that when only harmonic current suppression is enabled for 2.0s, the THD of both the grid connection point voltage and the AC system side current decreases significantly. When harmonic voltage suppression is further enabled for 3.5s, the THD of both the grid connection point voltage and the AC system side current decreases further. Simulation results show that the comprehensive harmonic voltage and harmonic current suppression system proposed in this invention can significantly reduce the THD of the common bus connection point voltage and the AC system side current.
[0043] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (e.g., changes in the size, dimensions, structure, shape, and proportions of various elements, as well as parameter values (e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of elements may be inverted or otherwise altered, and the nature or number or position of discrete elements may be changed or altered. Therefore, all such modifications are intended to be included within the scope of this utility model. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and not only structural equivalents but also equivalent structures. Without departing from the scope of this invention, other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments. Therefore, this invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.
[0044] Furthermore, in order to provide a concise description of exemplary embodiments, not all features of actual embodiments (i.e., those features that are not relevant to the best mode of carrying out the present invention as currently considered, or those features that are not relevant to implementing the present invention) may be omitted.
[0045] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.
[0046] It should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.
Claims
1. A comprehensive harmonic voltage and harmonic current suppression system, characterized in that: include, Grid-connected converter (400), including signal source (S), AC system equivalent impedance (Z) g ), load equivalent impedance (Z) L ) and load (LOAD), signal source (S), AC system equivalent impedance (Z) g ), load equivalent impedance (Z) L The load and load are connected in sequence. It also includes a control unit (100), a drive unit (200), a power unit (300), and a bridge arm reactor (X0), wherein the control unit (100) generates a voltage modulation signal u m The signal is fed into the drive unit (200), which generates a drive signal F. gt The voltage is fed into a power unit (300), which modulates the output voltage u. v Voltage u at the connection point with the common bus pcc The difference is applied to the bridge arm reactance (X0). The bridge arm reactance (X0) is connected to the equivalent impedance (Z) of the AC system. g ) and load equivalent impedance (Z L At the common bus connection point (A) between ).
2. The harmonic voltage and harmonic current comprehensive suppression system as described in claim 1, characterized in that: The system voltage V generated by the signal source (S) s After the equivalent impedance (Z) of the AC system g The AC system current i is then generated. sys After passing through the common bus connection point (A), it splits into two paths, one of which flows to the equivalent impedance (Z) of the load. L The load current i load The other path is the grid-connected current i flowing to the bridge arm reactance (X0). apf .
3. The harmonic voltage and harmonic current comprehensive suppression system as described in claim 2, characterized in that: The control unit (100) receives the current reference signal i given by the upper layer. ref Harmonic current reference signal i h *and grid-connected current i apf And it is sent to the quasi-proportional resonant controller (PR).
4. The harmonic voltage and harmonic current comprehensive suppression system as described in claim 3, characterized in that: The output signal of the quasi-proportional resonant controller (PR) is related to the voltage u at the common bus connection point. pcc The function generates a voltage modulation signal u m .
5. The harmonic voltage and harmonic current comprehensive suppression system as described in claim 4, characterized in that: The drive unit (200) receives the voltage modulation signal u generated by the control unit (100). m Generates drive signal F gt .
6. The harmonic voltage and harmonic current comprehensive suppression system as described in claim 5, characterized in that: The power unit (300) receives the drive signal F generated by the drive unit (200). gt The output voltage u is modulated at the output terminal of the power unit (300). v .
7. The harmonic voltage and harmonic current comprehensive suppression system as described in claim 6, characterized in that: The bridge arm reactance (X0) receives the output voltage u v Voltage u at the connection point with the common bus pcc , generating grid-connected current i apf It is sent to the control unit (100).
8. The harmonic voltage and harmonic current comprehensive suppression system as described in claim 7, characterized in that: It also includes, The compensation unit (500) includes a harmonic current suppression module (501) and a harmonic voltage suppression module (502). The harmonic current suppression module (501) and the harmonic voltage suppression module (502) work together to generate a harmonic current reference signal i. h * The compensation unit (500) will use the harmonic current reference signal i h *Sent to control unit (100).
9. The harmonic voltage and harmonic current comprehensive suppression system as described in claim 8, characterized in that: It also includes a harmonic current compensation module (503), which generates a harmonic current compensation amount Δi. h0 * And the harmonic current compensation amount Δi h0 * The signal is fed into the harmonic current suppression module (501).
10. The harmonic voltage and harmonic current comprehensive suppression system as described in claim 9, characterized in that: It also includes an admittance generation module (504), which generates a virtual admittance Y. vh And virtual admittance Y vh The signal is fed into the harmonic voltage suppression module (502).