A reactive power compensation device and method for power distribution

Abstract

The application discloses a kind of reactive power compensation devices for power transmission and distribution, the reactive power compensation device includes: direct current voltage acquisition module, AC power voltage acquisition module, AC power current acquisition module, reference current amplitude calculation module, reference current phase calculation module, reference current calculation module, modulation signal calculation module, PWM modulation module, reactive power compensation main circuit.The reactive power compensation device greatly reduces the calculation process, realizes simple structure, improves output quality, and can meet the reactive power compensation requirements of power transmission and distribution system.

Description

Technical Field

[0001] This invention relates to a reactive power compensation device and method, and more particularly to a reactive power compensation device and method for power transmission and distribution. Background Technology

[0002] Reactive power compensation in power transmission and distribution systems has always been a major concern. Utilizing reactive power compensation devices can improve the power factor of the system, reduce losses in power transformers and transmission lines, increase power supply efficiency, and improve the power supply environment. Therefore, reactive power compensation devices occupy an indispensable position in power transmission and distribution systems. Proper selection of reactive power compensation devices can minimize losses in the power transmission and distribution system and improve power quality. Conversely, improper selection or use can lead to numerous problems such as voltage fluctuations and increased harmonics in the power transmission and distribution system.

[0003] Existing reactive power compensation devices typically require detecting the reactive component in the load current and then compensating for it. Accurate detection of the reactive component in the load current is crucial for the compensation effect of the device. Current reactive power detection methods are based on instantaneous reactive power theory, requiring dq coordinate transformation. However, using these methods for reactive power detection necessitates multiple coordinate calculations, making the process complex, involving too many control modules, and resulting in poor reliability. Furthermore, existing reactive power compensation devices suffer from poor output quality and synchronization, failing to meet the reactive power compensation requirements of power transmission and distribution systems. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide a reactive power compensation device and method for power transmission and distribution.

[0005] In one embodiment of the present invention, a reactive power compensation device for power transmission and distribution is provided. The reactive power compensation device includes: a DC voltage acquisition module, an AC power supply voltage acquisition module, an AC power supply current acquisition module, a reference current amplitude calculation module, a reference current phase calculation module, a reference current calculation module, a modulation signal calculation module, a PWM modulation module, and a reactive power compensation main circuit.

[0006] The DC voltage acquisition module acquires the DC bus voltage of the reactive power compensation device, and its output terminal is connected to the input terminal of the reference current amplitude calculation module. The DC voltage acquisition module outputs the DC bus acquisition voltage Vdc to the reference current amplitude calculation module.

[0007] The output terminal of the reference current amplitude calculation module is connected to the first input terminal of the reference current calculation module to calculate the amplitude i* of the reference current.

[0008] The AC power supply voltage acquisition module acquires the real-time value of the three-phase AC power supply in the power transmission and distribution system. Its output terminal is connected to the input terminal of the reference current phase calculation module. The output terminal of the reference current phase calculation module is connected to the second input terminal of the reference current calculation module to calculate the phase value of the three-phase reference current.

[0009] The output of the reference current calculation module is connected to the input of the modulation signal calculation module to calculate the three-phase reference current.

[0010] The AC power current acquisition module acquires the real-time value of the three-phase current of the AC power supply in the power transmission and distribution system and inputs it into the modulation signal calculation module.

[0011] The output of the modulation signal calculation module is connected to the input of the PWM modulation module to calculate the three-phase modulation signals Va, Vb, and Vc.

[0012] The output of the PWM modulation module is connected to the input of the reactive power compensation main circuit and is used to drive the reactive power compensation main circuit.

[0013] The reactive power compensation main circuit inverts and generates a reactive power compensation signal, which is then input into the power transmission and distribution system to achieve the function of reactive power compensation.

[0014] Furthermore, the reference current amplitude calculation module calculates the reference current amplitude based on the difference ΔV between the DC-side bus voltage Vdc and the reference voltage Vref. dc The amplitude i of the reference current is calculated using an improved PI regulator. * .

[0015] Furthermore, the improved proportional coefficient s of the improved PI controller kp and integral coefficient s ki for:

[0016]

[0017] Where α and β are adjustment factors, and the preset proportional coefficient k p and integral coefficient k i .

[0018] Furthermore, the amplitude i of the reference current * for:

[0019]

[0020] Furthermore, the reference current phase calculation module uses phase-locked loop technology to calculate the phase angle of the three-phase voltage of the AC power supply as the phase value of the three-phase reference current.

[0021] Furthermore, the reference current calculation module calculates the three-phase reference current based on the amplitude and phase value of the three-phase reference current.

[0022] Furthermore, the modulation signal calculation module calculates the difference between the real-time value of the three-phase current of the AC power supply and the three-phase reference current, respectively, to obtain the three-phase modulation signals Va, Vb, and Vc.

[0023] Furthermore, the PWM modulation module modulates the harmonic component V har1 V har2 The three-phase modulation signals Va, Vb, and Vc are injected to obtain new three-phase modulation signals. These new three-phase modulation signals are then compared with the carrier wave to generate corresponding drive signals. The harmonic components V... har1 V har2 for:

[0024]

[0025]

[0026]

[0027] Where N is the number of output levels of the reactive power compensation main circuit, mod is the remainder function, and k = a, b, c.

[0028] In another embodiment of the present invention, a reactive power compensation method for power transmission and distribution is also provided, which uses the above-mentioned reactive power compensation device to realize the reactive power compensation function of the power transmission and distribution system.

[0029] The beneficial technical effects of this invention are:

[0030] (1) This invention discloses a reactive power compensation device and method for power transmission and distribution, which greatly reduces the calculation process and achieves a simple structure.

[0031] (2) This invention discloses an improved PI controller, which improves the proportional coefficient s by setting an improved proportional coefficient s kp and integral coefficient s ki This improves the stability margin and accuracy of the PI controller.

[0032] (3) This invention discloses a PWM modulation module, which injects harmonic components V har1 V har2 This improves the output quality of the reactive power compensation device, meets the reactive power compensation requirements of the power transmission and distribution system, and maintains the synchronization of the reactive power component with the AC power supply. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of a reactive power compensation device for power transmission and distribution provided in an embodiment of the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0037] This application discloses a reactive power compensation device for power transmission and distribution, which is used to perform reactive power compensation for power transmission and distribution systems. It greatly reduces the calculation process, has a simple structure, and can meet the reactive power compensation requirements of power transmission and distribution systems.

[0038] Figure 1 This is a schematic diagram of a reactive power compensation device for power transmission and distribution provided in an embodiment of the present invention. Figure 1 As shown, the reactive power compensation device includes a DC voltage acquisition module, an AC power supply voltage acquisition module, an AC power supply current acquisition module, a reference current amplitude calculation module, a reference current phase calculation module, a reference current calculation module, a modulation signal calculation module, a PWM modulation module, and a reactive power compensation main circuit.

[0039] The output of the DC voltage acquisition module is connected to the input of the reference current amplitude calculation module. The output of the reference current amplitude calculation module is connected to the first input of the reference current calculation module. The output of the AC power supply voltage acquisition module is connected to the input of the reference current phase calculation module. The output of the reference current phase calculation module is connected to the second input of the reference current calculation module. The output of the reference current calculation module is connected to the input of the modulation signal calculation module. The output of the modulation signal calculation module is connected to the input of the PWM modulation module. The output of the PWM modulation module is connected to the input of the reactive power compensation main circuit.

[0040] The reactive power compensation device generates a reactive power compensation signal via an inverter, which is input into the power transmission and distribution system. By adjusting the amplitude and phase of the reactive power compensation signal, the reactive power compensation function is achieved. The DC voltage acquisition module acquires the DC-side bus voltage of the reactive power compensation device and outputs the acquired DC-side bus voltage Vdc to the reference current amplitude calculation module. The reference current amplitude calculation module calculates the current based on the difference ΔV between the acquired DC-side bus voltage Vdc and the reference voltage Vref. dc After using an improved PI regulator, the amplitude i of the reference current is calculated. * The AC power supply voltage acquisition module acquires the real-time values ​​of the three-phase AC power supply voltage in the power transmission and distribution system and inputs them to the reference current phase calculation module. The reference current phase calculation module uses phase-locked loop technology to calculate the phase angle of the three-phase AC power supply voltage as the phase value of the three-phase reference current. The reference current calculation module calculates the three-phase reference current based on the amplitude and phase value of the three-phase reference current. The AC power supply current acquisition module acquires the real-time values ​​of the three-phase AC power supply current in the power transmission and distribution system and inputs them to the modulation signal calculation module. The modulation signal calculation module calculates the difference between the real-time values ​​of the three-phase AC power supply current and the three-phase reference current, respectively, to obtain the three-phase modulation signals Va, Vb, and Vc. The PWM modulation module calculates the drive signal of the reactive power compensation main circuit based on the three-phase modulation signals Va, Vb, and Vc. The reactive power compensation main circuit performs inversion according to the drive signal to generate a reactive power compensation signal, which is injected into the AC system to achieve reactive power compensation.

[0041] Furthermore, existing PI controllers have low stability margins, slow response times, and low accuracy. This embodiment also provides an improved PI controller, which adjusts the preset proportional coefficient k according to formula (1). p and integral coefficient k i Improvements were made, resulting in the improved proportionality coefficient s. kp and integral coefficient s ki Improved proportionality coefficient s kp and integral coefficient s ki It can be adjusted based on the ratio of the DC-side bus voltage Vdc to the reference voltage Vref, improving the stability margin and accuracy of the PI regulator. Specifically:

[0042]

[0043] Where α and β are adjustment factors.

[0044] After passing through the improved PI regulator, the amplitude i of the reference current is calculated. * As shown in formula (2):

[0045]

[0046] Furthermore, in order to improve the output quality of the reactive power compensation device, meet the reactive power compensation requirements of the power transmission and distribution system, and maintain the synchronization of the reactive power component with the AC power supply, the PWM modulation module converts the harmonic component V... har1 V har2 Injecting three-phase modulation signals Va, Vb, and Vc yields new three-phase modulation signals. These new three-phase modulation signals are then compared with the carrier wave to generate corresponding drive signals. Wherein:

[0047]

[0048]

[0049]

[0050] Where N is the number of output levels of the reactive power compensation device, mod is the remainder function, and k = a, b, c.

[0051] This invention also provides a reactive power compensation method for power transmission and distribution, which utilizes a reactive power compensation device to realize the reactive power compensation function of the power transmission and distribution system.

[0052] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0053] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A reactive power compensation device for power transmission and distribution, characterized in that, The reactive power compensation device includes: a DC voltage acquisition module, an AC power supply voltage acquisition module, an AC power supply current acquisition module, a reference current amplitude calculation module, a reference current phase calculation module, a reference current calculation module, a modulation signal calculation module, a PWM modulation module, and a reactive power compensation main circuit. The DC voltage acquisition module acquires the DC bus voltage of the reactive power compensation device, and its output terminal is connected to the input terminal of the reference current amplitude calculation module. The DC voltage acquisition module outputs the DC bus acquisition voltage Vdc to the reference current amplitude calculation module. The output terminal of the reference current amplitude calculation module is connected to the first input terminal of the reference current calculation module to calculate the amplitude i of the reference current. * ; The AC power supply voltage acquisition module acquires the real-time value of the three-phase voltage of the AC power supply in the power transmission and distribution system, and its output terminal is connected to the input terminal of the reference current phase calculation module. The output terminal of the reference current phase calculation module is connected to the second input terminal of the reference current calculation module to calculate the phase value of the three-phase reference current. The output of the reference current calculation module is connected to the input of the modulation signal calculation module to calculate the three-phase reference current. The AC power current acquisition module acquires the real-time value of the three-phase current of the AC power supply in the power transmission and distribution system and inputs it into the modulation signal calculation module. The output of the modulation signal calculation module is connected to the input of the PWM modulation module to calculate the three-phase modulation signals Va, Vb, and Vc. The output terminal of the PWM modulation module is connected to the input terminal of the reactive power compensation main circuit and is used to drive the reactive power compensation main circuit. The output terminal of the reactive power compensation main circuit is connected to the AC power output terminal of the power transmission and distribution system, and the reactive power compensation signal is generated by the inverter to realize the reactive power compensation function.

2. The reactive power compensation device for power transmission and distribution according to claim 1, characterized in that, The reference current amplitude calculation module calculates the current amplitude based on the difference ΔV between the DC-side bus voltage Vdc and the reference voltage Vref. dc The amplitude i of the reference current is calculated using an improved PI regulator. * .

3. A reactive power compensation device for power transmission and distribution according to claim 2, characterized in that, The improved proportional coefficient s of the improved PI controller kp and integral coefficients s ki for: Where α and β are adjustment factors, and the preset proportional coefficient k p and integral coefficient k i .

4. A reactive power compensation device for power transmission and distribution according to claim 3, characterized in that, The amplitude i of the reference current * for:

5. A reactive power compensation device for power transmission and distribution according to claim 1, characterized in that, The reference current phase calculation module uses phase-locked loop technology to calculate the phase angle of the three-phase voltage of the AC power supply as the phase value of the three-phase reference current.

6. A reactive power compensation device for power transmission and distribution according to claim 1, characterized in that, The reference current calculation module calculates the three-phase reference current based on the amplitude and phase value of the three-phase reference current.

7. A reactive power compensation device for power transmission and distribution according to claim 1, characterized in that, The modulation signal calculation module calculates the difference between the real-time value of the three-phase current of the AC power supply and the three-phase reference current, respectively, to obtain the three-phase modulation signals Va, Vb, and Vc.

8. A reactive power compensation device for power transmission and distribution according to claim 1, characterized in that, The PWM modulation module modulates the harmonic components V har1 V har2 The three-phase modulation signals Va, Vb, and Vc are injected to obtain new three-phase modulation signals. These new three-phase modulation signals are then compared with the carrier wave to generate corresponding drive signals. The harmonic components V... har1 V har2 for: Where N is the number of output levels of the reactive power compensation main circuit, mod is the remainder function, and k = a, b, c.

9. A reactive power compensation method for power transmission and distribution, characterized in that, The reactive power compensation device described in any one of claims 1-8 is used to realize the reactive power compensation function of the power transmission and distribution system.

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