Multifunctional integrated induction regulation and control filtering distribution transformer device

Abstract

The invention discloses a multifunctional integrated induction regulation and control filtering distribution transformer device, and belongs to the technical field of distribution network energy conservation and loss reduction and electric energy quality control. The device is composed of a distribution transformer (1), a PWM rectification H-bridge module (2), a protection branch circuit (3), a fundamental wave cascade H-bridge module (4), a harmonic wave H-bridge module (5), a harmonic wave connection reactor (6), a fundamental wave connection reactor (7), a system access point (8) and a power supply winding (9). After the distribution transformer reduces the voltage of an alternating current power supply, the other windings except the power supply winding are compensation windings. The N PWM rectification H-bridge modules are divided into two groups, the direct current bus of one group is connected with the harmonic wave H-bridge module and then connected with the harmonic wave connection reactor, and the direct current bus of the other group is connected with the N-1 fundamental wave cascade H-bridge modules and the fundamental wave connection reactor. According to the filtering distribution transformer device, decoupling control among different frequency modules is achieved, the control precision is improved, meanwhile, the overall switching loss of the device is reduced, and the reliability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy saving and loss reduction of distribution network and power quality control, and more specifically to a multifunctional integrated induction control filtering distribution transformer device. Background Art

[0002] A large number of distributed photovoltaic, electric vehicle charging facilities, energy storage equipment, etc. are connected to the distribution network, forming multiple types of market players such as PV operators, EV operators, energy storage operators and load aggregators. Market behavior makes the market players of distributed power sources, energy storage, electric vehicles and other types of power sources at the distribution network level present a random and diverse competition situation, which significantly affects the operation mode, safety level and energy efficiency of the distribution network, especially the analysis, diagnosis and control of distribution network losses are becoming more difficult. It is mainly reflected in:

[0003] (1) It increases the complexity and randomness of system operation and the difficulty of output prediction, causing disordered flow of power flow and frequent fluctuations in network node voltage and harmonic emission levels, which poses new challenges to the analysis and control of distribution network losses.

[0004] (2) Harmonics and disordered power flow make the uncertainty and volatility of distribution network losses more prominent, and loss reduction technologies based on traditional deterministic analysis theory are difficult to adapt and effectively manage;

[0005] (3) There is an urgent need to develop and manufacture multifunctional integrated induction control filtering and distribution transformer devices for active distribution networks that can interact with multiple entities in the distributed power generation market, to support loss analysis and flexible control of multi-agent distribution networks under market conditions.

[0006] At present, the governance work of improving power quality and system energy saving and loss reduction lacks connection and mutual support, which greatly reduces the governance effect. At the technical level, active filters, reactive power compensation devices, three-phase unbalanced governance devices, and high-efficiency distribution transformers have been widely used, but they are relatively independent and single-function devices. At the same time, because they are supplied by different manufacturers, these devices cannot be coordinated and controlled, which not only reduces the performance of the devices, but also may deteriorate the comprehensive indicators of the distribution network. Summary of the invention

[0007] In view of this, the present invention provides a multifunctional integrated induction control filtering distribution transformer device, which is used for improving the energy efficiency of medium and low voltage distribution networks and comprehensively managing dynamic power quality. It can not only achieve reliable local power supply and comprehensive management of harmonics, negative sequence and reactive power, but also accept remote dispatching by the dispatching center based on the optimal power flow of the entire network, thereby realizing efficient operation of the distribution network.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] A multifunctional integrated induction control filtering distribution transformer device includes a distribution transformer, a PWM rectifier H-bridge module, a protection branch, a fundamental wave cascade H-bridge module, a harmonic H-bridge module, a harmonic connection reactance, a fundamental wave connection reactance, a system access point and a power supply winding. After the distribution transformer steps down the AC power supply, it charges N PWM rectifier H-bridge modules through N low-voltage windings to establish a DC bus voltage. A protection branch is connected in parallel to the DC bus of each PWM rectifier H-bridge module. When the DC bus has an overvoltage, the protection branch discharges quickly to control the DC bus voltage to not exceed the limit, thereby protecting the safety of power electronic devices. The N PWM rectifier H-bridge modules are divided into two groups, one of which is composed of a PWM rectifier H-bridge module, whose DC bus is connected to the input end of the harmonic H-bridge module, and the other group is composed of N-1 PWM rectifier H-bridge modules, whose DC buses are respectively connected to the input ends of N-1 fundamental wave cascade H-bridge modules. One output terminal A of the harmonic H-bridge module is connected to point B of the fundamental wave connection reactor through the harmonic connection reactor, and then connected to the system access point together. The other end of the harmonic H-bridge module is connected to point C of the fundamental wave connection reactor. The fundamental wave cascade H-bridge module is composed of N-1 single-phase H-bridge modules connected in series, one end of the series output is connected to point C of the fundamental wave connection reactor, and the other end is connected to the neutral point D.

[0010] In the above-mentioned multifunctional integrated induction control filtering distribution transformer device, the value range of N is 3 to 10.

[0011] The harmonic H-bridge module generates 2nd to 29th harmonic currents, and the fundamental cascade H-bridge module generates a fundamental voltage, which respectively form a superposition output of a set compensation current at a system access point through the harmonic connection reactance and the fundamental connection reactance.

[0012] After the distribution transformer steps down the AC power supply, it charges N PWM rectifier H-bridge modules through N low-voltage windings to establish a DC bus voltage, where N is in the range of 3 to 10. A protection branch is connected in parallel to the DC bus of each PWM rectifier H-bridge module. When the DC bus is over-voltage, the protection branch discharges quickly to control the DC bus voltage to be within the limit, thereby protecting the safety of power electronic devices. The N PWM rectifier H-bridge modules are divided into two groups, one of which consists of a PWM rectifier H-bridge module, whose DC bus is connected to the input end of the harmonic H-bridge module, and the other group consists of N-1 PWM rectifier H-bridge modules, whose DC buses are respectively connected to the input ends of N-1 fundamental cascade H-bridge modules. After passing through the harmonic connection reactor, one output terminal A of the harmonic H-bridge module is connected to point B of the fundamental connection reactor, and then connected together to the system access point. The other end of the harmonic H-bridge module is connected to point C of the fundamental connection reactor. The fundamental wave cascade H-bridge module is composed of N-1 single-phase H-bridge modules connected in series, one end of the series output is connected to the C point of the fundamental wave connection reactor, and the other end is connected to the neutral point D.

[0013] In the above multifunctional integrated induction control filtering distribution transformer, the distribution transformer adopts a multi-winding low-voltage design, the power supply winding and the compensation winding are isolated, and the magnetic flux of each winding is interactively coupled in the transformer core magnetic circuit. The high-frequency harmonic compensation circuit and the low-frequency and fundamental compensation circuit operate in parallel to achieve the optimal combination of harmonics and fundamental waves, significantly improving the bandwidth and adaptability of the circuit.

[0014] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a multifunctional integrated induction control filtering distribution transformer device, which has the following advantages:

[0015] The filter transformer device disclosed in the present invention realizes decoupling control between modules of different frequencies, significantly improves the control accuracy, reduces the overall switching loss of the device, improves the working conditions of power electronic devices, and improves reliability. At the same time, through the flexible selection of the N value, the voltage level and capacity scale of the device can be flexibly designed.

[0016] The filtering distribution transformer device disclosed in the present invention can not only realize the comprehensive management of local harmonics, negative sequence and reactive power, but also accept remote dispatch control, support active and reactive power control of access points, realize the global optimal power flow operation of the power grid, and significantly improve the energy efficiency level of the entire network. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0018] Figure 1 This is a main circuit topology diagram of the multifunctional integrated induction control filtering distribution transformer device for loss reduction and power quality management provided by the present invention.

[0019] In the figure, 1-distribution transformer; 2-PWM rectifier H-bridge module; 3-protection branch; 4-fundamental wave cascade H-bridge module; 5-harmonic H-bridge module; 6-harmonic connection reactance; 7-fundamental wave connection reactance; 8-system access point; 9-power supply winding. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The embodiment of the present invention discloses a multifunctional integrated induction control filtering distribution transformer. The idea of ​​the invention is to highly integrate the distribution transformer and the power electronic high-frequency, low-frequency and fundamental wave compensation circuits. The main circuit structure diagram is as follows Figure 1 As shown, the device consists of a distribution transformer 1, a PWM rectifier H-bridge module 2, a protection branch 3, a fundamental wave cascade H-bridge module 4, a harmonic H-bridge module 5, a harmonic connection reactance 6, a fundamental wave connection reactance 7, a system access point 8 and a power supply winding 9.

[0022] After the distribution transformer 1 steps down the voltage of the AC power supply, except for the power supply winding 9, the rest are compensation windings, which charge the N PWM rectifier H-bridge modules 2 through the N low-voltage windings to establish a DC bus voltage. A protection branch 3 is connected in parallel to the DC bus of each PWM rectifier H-bridge module. The value range of N is 3 to 10.

[0023] The N PWM rectifier H-bridge modules are divided into two groups, one of which is composed of a PWM rectifier H-bridge module, whose DC bus is connected to the input end of the harmonic H-bridge module 5, and the other group is composed of N-1 PWM rectifier H-bridge modules, whose DC buses are respectively connected to the input ends of N-1 fundamental cascade H-bridge modules 4. One output end A of the harmonic H-bridge module 5 is connected to point B of the fundamental connection reactor 7 through the harmonic connection reactor 6, and then connected together to the system access point 8, and the other end of the harmonic H-bridge module 5 is connected to point C of the fundamental connection reactor 7. The fundamental cascade H-bridge module 4 is composed of N-1 single-phase H-bridge modules connected in series, one end of the series output is connected to point C of the fundamental connection reactor 7, and the other end is connected to the neutral point D.

[0024] The harmonic H-bridge module 5 generates 2-29th order harmonic currents as a constant current source based on the hysteresis current control algorithm according to the control instruction, and is connected to the system access point 8 through the harmonic connecting reactor 6; the fundamental wave cascade H-bridge module 4 generates a fundamental wave voltage as a constant voltage source based on the carrier phase shift control algorithm according to the control instruction, and the fundamental wave voltage is connected to the system access point 8 through the fundamental wave connecting reactor 7 to generate corresponding active and reactive currents, and the 2-29th order harmonic currents generated by the harmonic H-bridge module are superimposed at the system access point 8 to form the final comprehensive compensation current

[0025] The present invention proposes a multifunctional integrated induction control filtering distribution transformer, whose working principle is that after the distribution transformer 1 steps down and isolates the AC power supply, it charges N PWM rectifier H-bridge modules through N low-voltage windings to establish a DC bus voltage. A protection branch is connected in parallel to the DC bus of each PWM rectifier H-bridge module. When the DC bus is over-voltage, the protection branch discharges quickly to control the DC bus voltage not to exceed the limit, thereby protecting the safety of power electronic devices. The N PWM rectifier H-bridge modules are divided into two groups, one of which is composed of a PWM rectifier H-bridge module, and its DC bus is connected to the input end of the harmonic H-bridge module, and the other group is composed of N-1 PWM rectifier H-bridge modules, and their DC buses are respectively connected to the input ends of N-1 fundamental wave cascade H-bridge modules. The harmonic H-bridge module generates 2-29th harmonic currents as a constant current source based on the hysteresis current control algorithm according to the control instructions, and is connected to the system access point 8 through the harmonic connection reactance; the fundamental wave cascade H-bridge module generates fundamental wave voltage as a constant voltage source based on the carrier phase shift control algorithm according to the control instructions, and the fundamental wave voltage is connected to the system access point through the fundamental wave connection reactance to generate corresponding fundamental wave reactive and active currents, which are superimposed with the 2-29th harmonic currents generated by the harmonic H-bridge module at the system access point to form the final synthetic compensation current. At the same time, the power supply winding 9 provides high-quality electric energy for the power supply load.

[0026] The filter transformer device of the present invention realizes decoupling control between modules of different frequencies, significantly improves the control accuracy, reduces the overall switching loss of the device, improves the working conditions of power electronic devices, and improves reliability. At the same time, through the flexible selection of the N value, the voltage level and capacity scale of the device access can be flexibly designed. While realizing the comprehensive management of local harmonics, negative sequence and reactive power, the device can also accept remote dispatch control, support active and reactive power control of access points, realize the global optimal power flow operation of the power grid, and significantly improve the energy efficiency level of the entire network.

[0027] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0028] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multifunctional integrated induction control filtering distribution transformer, characterized in that: include: Distribution transformer (1), PWM rectifier H-bridge module (2), protection branch (3), fundamental wave cascade H-bridge module (4), harmonic H-bridge module (5), harmonic connection reactance (6), fundamental wave connection reactance (7), system access point (8) and power supply winding (9); The distribution transformer (1) steps down the voltage of the AC power supply and then charges N PWM rectifier H-bridge modules (2) through N low-voltage windings to establish a DC bus voltage. A protection branch (3) is connected in parallel to the DC bus of each PWM rectifier H-bridge module (2); N PWM rectifier H-bridge modules (2) are divided into two groups, one of which is composed of a PWM rectifier H-bridge module (2), whose DC bus is connected in parallel with a protection branch (3) and then connected to the input end of the harmonic H-bridge module (5), and the other group is composed of N-1 PWM rectifier H-bridge modules (2), whose DC bus is connected in parallel with a corresponding protection branch (3) and then respectively connected to the input ends of N-1 fundamental wave cascade H-bridge modules (4); An output terminal A of the harmonic H-bridge module (5) is connected to point B of the fundamental wave connection reactor (7) through the harmonic connection reactor (6), and then connected to the system access point (8) together, and the other end of the harmonic H-bridge module (5) is connected to point C of the fundamental wave connection reactor (7); The fundamental wave cascade H-bridge module (4) is composed of N-1 single-phase H-bridge modules connected in series, one end of the series output is connected to point C of the fundamental wave connection reactor (7), and the other end is connected to the neutral point D; the harmonic H-bridge module (5) is used to generate harmonic current, and the fundamental wave cascade H-bridge module (4) is used to generate fundamental wave voltage. The harmonic H-bridge module (5) and the fundamental wave cascade H-bridge module (4) respectively form a superposition output of a comprehensive compensation current at a system access point (8) through a harmonic connection reactor (6) and a fundamental wave connection reactor (7).

2. A multifunctional integrated induction control filtering and distribution transformer device according to claim 1, characterized in that: The distribution transformer (1) has N low-voltage windings, and the value of N ranges from 3 to 10.

3. A multifunctional integrated induction control filtering and distribution transformer device according to claim 1, characterized in that: The harmonic H-bridge module (5) generates 2-29th order harmonic currents as a constant current source based on a hysteresis current control algorithm according to control instructions; the fundamental wave cascade H-bridge module (4) generates a fundamental wave voltage as a constant voltage source based on a carrier phase shift control algorithm according to control instructions. The fundamental wave voltage is connected to a system access point (8) through a fundamental wave connecting reactance (7) to generate corresponding active and reactive currents. The 2-29th order harmonic currents generated by the harmonic H-bridge module are superimposed at the system access point (8) to form a final comprehensive compensation current.

4. A multifunctional integrated induction control filtering distribution transformer according to any one of claims 1 to 3, characterized in that: After the distribution transformer (1) steps down the voltage of the AC power supply, except for the power supply winding (9), the remaining N low-voltage windings are all compensation windings.

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