High-quality power supply support device based on time-sharing multiplexing and high-efficiency cooperation of converter

Abstract

The application provides a high-quality power supply support device based on time-sharing multiplexing and high-efficiency cooperation of a converter, comprising: the high-quality power supply support device is composed of a parallel link and an integrated link of a common DC bus; the parallel link and the integrated link both comprise a shared DC bus capacitor; the parallel link further comprises a parallel converter, a double-winding parallel transformer, a first filter inductor and a first filter capacitor; the integrated link further comprises an integrated converter, a three-winding series transformer, a second filter inductor, a second filter capacitor, a bypass switch and an auxiliary capacitor. The device capacity utilization rate is significantly improved, and the active capacity optimization effect is remarkable.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power quality governance, and particularly relates to a high-quality power supply support device based on time-sharing multiplexing and efficient cooperation of converters. BACKGROUND

[0002] With the increasing proportion of renewable energy and power electronic equipment in the distribution network, the power quality problems such as voltage fluctuation, temporary drop, temporary rise, and reactive power, harmonic of the distribution network are increasingly prominent, while the requirements of sensitive loads such as high-end manufacturing and precision machining on power supply quality are also gradually increasing. Therefore, the unified power quality conditioner (UPQC) integrates dynamic voltage compensation, reactive power compensation and harmonic suppression and other functions.

[0003] However, the series converter of the typical UPQC scheme only stabilizes the voltage on the sensitive load side when the grid voltage fluctuates, and is in standby state when the grid is in normal state, so the utilization rate of the device is low. The parallel converter (PC) not only needs to compensate for all the reactive power required by the load when the voltage fluctuates, but also needs to absorb active current to maintain the stability of the DC bus voltage, so the capacity of the parallel converter is often higher than that of the series converter, and the overall active capacity of the device is high, and the cost is high. SUMMARY

[0004] In order to overcome the above technical defects, the present application provides a high-quality power supply support device based on time-sharing multiplexing and efficient cooperation of converters, in order to achieve the above purpose, the present application is realized according to the following technical scheme:

[0005] The present application provides a high-quality power supply support device based on time-sharing multiplexing and efficient cooperation of converters, comprising:

[0006] The high-quality power supply support device is composed of a parallel link and an integrated link of a common DC bus;

[0007] The parallel link and the integrated link both include a shared DC bus capacitor ;

[0008] The parallel link further includes a parallel converter , a double-winding parallel transformer , a first filter inductor , a first filter capacitor ;

[0009] The integrated link further includes an integrated converter , a three-winding series transformer , a second filter inductor , a second filter capacitor Bypass switch S and auxiliary capacitor .

[0010] Optionally, the parallel converter DC positive terminal and the integrated converter DC positive terminal All are connected to the shared DC bus capacitor. The positive terminal of the parallel converter DC negative terminal and the integrated converter DC negative terminal All are connected to the shared DC bus capacitor. The negative electrode.

[0011] Optionally, the dual-winding parallel transformer The dual-winding parallel transformer includes a first winding and a second winding. The same-name terminal of the first winding and the first filter capacitor The positive terminals are all connected to the first filter inductor. One end, the first filter inductor The other end is connected to the parallel converter. First communication terminal The dual-winding parallel transformer The opposite terminal of the first winding and the first filter capacitor The negative terminals are all connected to the parallel converter. Second communication terminal .

[0012] Optionally, the dual-winding parallel transformer The second winding of the transformer is connected to the power grid at the same terminal. The opposite-named terminal of the second winding is grounded.

[0013] Optionally, the three-winding series transformer Including the third winding, fourth winding, and fifth winding, and the second filter inductor One end, the second filter capacitor The positive terminal, one end of the bypass switch S, and the three-winding series transformer The terminals of the third winding with the same name are all connected to the power grid.

[0014] Optionally, the second filter inductor The other end is connected to the integrated converter. The third communication terminal The second filter capacitor The negative terminal and the three-winding series transformer the same name of the fourth winding, are connected to the integrated current transformer the fourth alternating current end .

[0015] Optionally, the three-winding series transformer the negative pole of the auxiliary capacitor are all grounded.

[0016] Optionally, the three-winding series transformer the negative pole of the auxiliary capacitor are all grounded.

[0017] Optionally, the three-winding series transformer the positive pole of the auxiliary capacitor

[0018] Optionally, the three-winding series transformer the negative pole of the auxiliary capacitor

[0019] The present application has the following beneficial effects:

[0020] The device provided by the present application reconfigures the wiring mode of the series link. During normal voltage, the IC can be used as a controlled current source to participate in current quality management. During voltage fluctuation, the IC can be used as a controlled voltage source to participate in voltage quality management, realizing time-sharing multiplexing. Compared with the traditional UPQC, the proposed scheme only needs to add a decoupling branch composed of an auxiliary capacitor, which significantly improves the capacity utilization rate of the device and has a significant effect on active capacity optimization.

[0021] In addition to the purposes, features and advantages described above, the present application has other purposes, features and advantages. The present application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which form a part of the present application, are intended to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. The accompanying drawings do not constitute an inappropriate limitation on the present application. In the drawings:

[0023] Figure 1 is a topological structure diagram of a high-quality power supply support device based on time-sharing multiplexing and efficient cooperation of the current transformer provided by the embodiments of the present application;

[0024] Figure 2 is an equivalent diagram of HPSSD in CQC mode provided by the embodiments of the present application, Figure 2 (a) is an equivalent topological diagram of HPSSD, Figure 2 (b) is an equivalent circuit diagram of HPSSD;

[0025] Figure 3 This is an equivalent diagram of HPSSD in VQC mode provided in the embodiments of this application. Figure 3 (a) is the equivalent topology of HPSSD. Figure 3 (b) is the equivalent circuit diagram of HPSSD. Detailed Implementation

[0026] The embodiments of this application are described in detail below with reference to the accompanying drawings, but this application can be implemented in many different ways as defined and covered by the claims.

[0027] Therefore, in order to solve the above problems, such as Figure 1 As shown, this application proposes a high-quality power supply supporting device (HPSSD) based on converter time-division multiplexing and efficient coordination, including:

[0028] The high-quality power supply support device consists of parallel and integrated components of a common DC bus.

[0029] Both the parallel and integrated circuits include a shared DC bus capacitor. ;

[0030] The parallel connection also includes parallel converters. (parallel converter, PC), dual-winding parallel transformer First filter inductor First filter capacitor The integration process also includes the integration of converters. (Integrated converter, IC), three-winding series transformer Second filter inductor Second filter capacitor Bypass switch S and auxiliary capacitor Parallel converter DC positive terminal and integrated converter DC positive terminal All are connected to the shared DC bus capacitor. The positive terminal, parallel converter DC negative terminal and integrated converter DC negative terminal All are connected to the shared DC bus capacitor. The negative electrode.

[0031] Dual-winding parallel transformer Including the first and second windings, a dual-winding parallel transformer The same-name terminal of the first winding and the first filter capacitor The positive terminals are all connected to the first filter inductor. One end, the first filter inductor The other end is connected to the parallel converter. First communication terminal Dual-winding parallel transformer The opposite terminal of the first winding and the first filter capacitor The negative terminals are all connected to the parallel converter. Second communication terminal Dual-winding parallel transformer The second winding's corresponding terminal is connected to the power grid terminal; the two-winding parallel transformer... The opposite-named terminal of the second winding is grounded.

[0032] Three-winding series transformer Including the third, fourth, and fifth windings, and the second filter inductor. One end, the second filter capacitor The positive terminal, one end of the bypass switch S, and the three-winding series transformer The terminals of the third winding with the same name are all connected to the power grid. The second filter inductor... The other end is connected to the integrated converter The third communication terminal Second filter capacitor The negative terminal and the three-winding series transformer The fourth winding's corresponding port is connected to the integrated converter. The fourth communication terminal Three-winding series transformer The opposite terminals of the fourth winding, the same terminals of the fifth winding, and the auxiliary capacitor The negative terminals are all grounded. Three-winding series transformer. The opposite terminal of the fifth winding is connected to the auxiliary capacitor. The positive terminal. Three-winding series transformer. The other end of the third winding and the other end of the bypass switch S are both connected to the load end.

[0033] exist Figure 1 middle, and These are the grid voltage and current, respectively; and These are the PC output voltage and output current, respectively. and These are the IC output voltage and output current, respectively. , , These are the primary, secondary, and tertiary winding voltages of the series transformer, respectively. , , These are the currents at ports a, b, and c of the secondary and tertiary windings of the series transformer, respectively. , , These are the load voltage, load current, and load impedance, respectively.

[0034] The operating mode of HPSSD is closely related to the power grid conditions. When the power grid voltage is normal, the switch... S When closed, the HPSSD operates in CQC mode. In this mode, the PC and IC jointly provide compensation current to the load, and both converters can be considered equivalent to controlled current sources. The equivalent topology and equivalent circuit of the HPSSD in CQC mode are as follows: Figure 2 (a) and Figure 2 As shown in (b).

[0035] exist Figure 2 In (b), for parallel components, the parallel transformers winding leakage inductance It is taken into account in the equivalent circuit; for the integrated circuit, due to the series transformer The primary winding is short-circuited, and only the secondary and tertiary windings are connected to the equivalent circuit. Furthermore, port c is connected to a high-impedance auxiliary capacitor, forcing the compensation current to flow only through the lower-impedance port b branch. Therefore, only the series transformer... Secondary winding leakage inductance It is taken into account in the equivalent circuit.

[0036] According to Kirchhoff's laws, the load current in CQC mode can be expressed as:

[0037] (1)

[0038] In CQC mode, by controlling the PC and IC to jointly inject current with controllable amplitude, frequency, and phase, various functions of the grid-connected converter can be realized, such as reactive power and harmonic compensation. Taking typical reactive power compensation as an example, the grid provides all the active power required by the load side, while HPSSD provides all the reactive power required by the load.

[0039] When the grid voltage fluctuates, the switch S When disconnected, the HPSSD operates in VQC mode. In this mode, the IC controls the load voltage amplitude to remain stable, effectively functioning as a controlled voltage source; the PC compensation provides compensation current to the load, still effectively functioning as a controlled current source. The equivalent topology and equivalent circuit of the HPSSD in VQC mode are as follows: Figure 3 (a) and Figure 3(b) is shown, wherein is the excitation impedance of the series transformer; , , are the leakage inductances of the primary, secondary and tertiary windings of the series transformer, respectively.

[0040] Assuming the turns ratios of the primary, secondary and tertiary windings of the series transformer are 1:1:1, the voltage relationship of the windings of the transformer can be expressed as:

[0041] (2)

[0042] According to the law of power conservation, the power relationship of the primary, secondary and tertiary windings of the series transformer can be expressed as:

[0043] (3)

[0044] wherein the auxiliary capacitor current can be expressed as:

[0045] (4)

[0046] According to the KCL law, combining equation (2) and equation (3), the current relationship of the primary, secondary and tertiary windings of the series transformer can be expressed as:

[0047] (5)

[0048] According to the KVL law, and combining equation (5), the load current and the inverter output current can be further expressed as:

[0049] (6)

[0050] It can be seen from equation (6) that the load current is determined by the grid current, the PC output current and the IC output current. In addition, the IC output current has the same amplitude and opposite phase as the current at port a of the secondary winding of the series transformer.

[0051] Similarly, based on the KVL law, the IC filter capacitor voltage and the load voltage can be expressed as:

[0052] (7)

[0053] Combining equation (2) and equation (7), the load voltage can be expressed as:

[0054] (8)

[0055] It can be seen from equation (8) that the IC output voltage is equal to the load voltage.

[0056] In summary, the device provided in the application reconstructs the wiring mode of the series link, during normal voltage, the IC can be used as a controlled current source to participate in current quality management; during voltage fluctuation, the IC can be used as a controlled voltage source to participate in voltage quality management, realizing time-sharing multiplexing. Compared with the traditional UPQC, the proposed scheme only needs to add a decoupling branch composed of an auxiliary capacitor, which significantly improves the capacity utilization of the device and has a significant effect on active capacity optimization.

[0057] The preferred embodiments of the application are described above, but the application is not limited to the above, and various modifications and changes can be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A high-quality power supply support device based on converter time-division multiplexing and efficient coordination, characterized in that, include: The high-quality power supply support device consists of parallel links and integrated links of a common DC bus; Both the parallel connection and the integrated connection include a shared DC bus capacitor. C dc ; The parallel connection also includes a parallel converter. H 1. Dual-winding parallel transformer T 1. First filter inductor L 1. First filter capacitor C 1; The integration process also includes an integrated converter. E 1. Three-winding series transformer T 2. Second filter inductor L 2. Second filter capacitor C 2. Bypass switch S and auxiliary capacitor C n ; The parallel converter H DC positive terminal of 1 K 1 and the integrated converter E DC positive terminal of 1 K All 3 are connected to the shared DC bus capacitor. C dc The positive terminal of the parallel converter H DC negative terminal of 1 K 2 and the integrated converter E DC negative terminal of 1 K All 4 are connected to the shared DC bus capacitor. C dc The negative electrode; The dual-winding parallel transformer T 1. The transformer includes a first winding and a second winding, and the dual-winding parallel transformer... T The same-name terminal of the first winding and the first filter capacitor of 1 C The positive terminal of 1 is connected to the first filter inductor. L One end of 1, the first filter inductor L The other end of 1 is connected to the parallel converter. H 1's first communication terminal D 1. The dual-winding parallel transformer T The opposite terminal of the first winding of 1 and the first filter capacitor C The negative terminals of 1 are all connected to the parallel converter. H 1's second communication terminal D 2; The dual-winding parallel transformer T The second winding of transformer 1 is connected to the power grid terminal at the same name terminal. The dual-winding parallel transformer... T The opposite-named terminal of the second winding of 1 is grounded; The three-winding series transformer T 2 includes a third winding, a fourth winding, a fifth winding, and a second filter inductor. L 2, one end, the second filter capacitor C The positive terminal of 2, one end of the bypass switch S, and the three-winding series transformer T The terminals of the third winding of 2 are all connected to the power grid.

2. The apparatus according to claim 1, characterized in that, Second filter inductor L The other end of 2 is connected to the integrated converter. E 1's third communication terminal D 3. The second filter capacitor C The negative terminal of 2 and the three-winding series transformer T The same-named ports of the fourth winding of component 2 are all connected to the integrated converter. E 1's fourth communication terminal D 4.

3. The apparatus according to claim 2, characterized in that, The three-winding series transformer T 2. The opposite-named terminal of the fourth winding, the same-named terminal of the fifth winding, and the auxiliary capacitor. C n The negative terminals are all grounded.

4. The apparatus according to claim 3, characterized in that, The three-winding series transformer T The opposite-named terminal of the fifth winding of 2 is connected to the auxiliary capacitor. C n The positive pole.

5. The apparatus according to claim 4, characterized in that, The three-winding series transformer T The opposite end of the third winding of 2 and the other end of the bypass switch S are both connected to the load end.

Images