阅读说明：本技术 一种基于直流集成方式的电力路由器拓扑及其控制方法 (Power router topology based on direct current integration mode and control method thereof ) 是由 张群 李妍 王青山 诸晓骏 王琼 王鑫 李泽森 曹远志 梁海峰 于 2020-12-16 设计创作，主要内容包括：本发明属于综合能源转换装置及控制技术领域,特别涉及一种基于直流集成方式的电力路由器拓扑及其控制方法。其直流集成方式的电力路由器拓扑包括交流端口、直流端口和直流母线；其中交流端口一端与直流母线Vm相连,另一端与外部直流线路(Va、Vb、Vc)相联；其双向交流端口在并网情况下,为直流母线Vm提供稳定电压,同时提供双向功率回路吸收后级电路传输功率或补充直流电路释放功率,功率变换单元用于将直流电转换成交流电。本拓扑电力路由器具备潮流双向精确线性控制器,不仅作为可以实现不同电压网络之间的互联运行,还可以直流电压源或电流源模式运行,实现两种功能的组合集成,有效降低系统成本。(The invention belongs to the technical field of comprehensive energy conversion devices and control, and particularly relates to a power router topology based on a direct current integration mode and a control method thereof. The power router topology of the direct current integration mode comprises an alternating current port, a direct current port and a direct current bus; one end of the alternating current port is connected with the direct current bus Vm, and the other end of the alternating current port is connected with the external direct current lines (Va, Vb and Vc); under the condition of grid connection, the bidirectional alternating current port provides stable voltage for the direct current bus Vm, meanwhile, a bidirectional power loop is provided to absorb transmission power of a post-stage circuit or supplement release power of a direct current circuit, and the power conversion unit is used for converting direct current into alternating current. The topological power router is provided with the tidal current bidirectional accurate linear controller, not only can realize the interconnected operation among different voltage networks, but also can realize the operation in a direct-current voltage source or current source mode, thereby realizing the combined integration of two functions and effectively reducing the system cost.)

1. The electric power router topology based on the direct current integration mode is characterized by comprising an alternating current port, a direct current port and a direct current bus; one end of the alternating current port 3 is connected with the direct current bus Vm, and the other end of the alternating current port is connected with the external direct current lines (Va, Vb and Vc); the direct current side surface comprises a direct current port 1 and a direct current port 2; the direct current port 1 and the direct current port 2 are connected with an internal direct current bus Vm; the alternating current port is a bidirectional alternating current port, stable voltage is provided for the direct current bus Vm under the condition of grid connection, meanwhile, a bidirectional power loop is provided to absorb transmission power of a post-stage circuit or supplement release power of a direct current circuit, the power conversion unit is used for converting direct current into alternating current, and a fully-controlled power device is adopted in the power conversion unit; the circuit topology is a bidirectional alternating current converter, and the specific circuit topology can be a three-phase full bridge circuit or a three-phase half bridge circuit.

2. The power router topology based on the direct current integration mode as claimed in claim 1, wherein the direct current port mainly functions to control the voltage, current or power value at both ends of the output side according to the requirement, so as to achieve the purpose of changing the power flow distribution in the line through the equivalent impedance in the line; the topology structure can be H-bridge topology, buck circuit, boost circuit, or a combination of multiple half-bridge circuits.

3. A control method of a power router based on a direct current integration mode is characterized by comprising the following steps:

when the power router works in an alternating current grid-connected working mode, the alternating current port 3 is connected to a commercial power grid, when a high-voltage direct current power grid transmits to a low-voltage direct current power grid, the power conversion unit at the alternating current port side works in a power mode control mode with a power factor of 1, the direct current side of the alternating current port 3 works in a direct current voltage control mode, when the load power on a direct current bus Vm fluctuates, the direct current voltage at the direct current side of the alternating current port 3 is dynamically adjusted, the power input at the alternating current side of the alternating current port 3 is changed, and the voltage at the direct current side of the alternating current port 3 is adaptively adjusted through direct current feedforward control and direct current voltage control;

when the electric power router works in a power exchange mode and energy is transmitted to an alternating current power grid from a direct current port, the alternating current port works in a direct current voltage control mode, and the alternating current side of the alternating current port works in an alternating current power control mode; and when the output power of the alternating current power grid fluctuates, the direct current bus side direct current port of the direct current port adaptively adjusts the power output.

Technical Field

The invention belongs to the technical field of comprehensive energy conversion devices and control, and particularly relates to a power router topology based on a direct current integration mode and a control method thereof.

Background

The energy comprehensive service station is a new mode of utilizing transformer substation resources to construct, operate, charge and transform (energy storage) stations and data center stations, relies on the advantages of the transformer substation close to users, wide coverage, power guarantee and the like, provides IT infrastructure resources for realizing physical world and digital world connection for the power Internet of things by meeting the service requirements of users on power, computing power, storage, connection and the like nearby, and meets the construction requirements of multi-access edge computing stations in 5G network construction. The multi-station integration is a typical application scene of a comprehensive energy service station, the existing transformer substation is utilized to deeply mine resource values, facilities such as an operation charging station, an energy storage station, a communication base station and a data center station are built, and one-station service meets diversified service requirements of equipment such as the transformer substation, the energy storage station and the data center station. In the scene, the important consideration is the analysis of power supply modes of direct current loads such as a transformer substation, a data center station, a charging and replacing power station, a distributed power supply and a charging pile, and a more efficient and complementary power utilization topological structure is designed, so that the operation energy efficiency level of the whole station is improved. Meanwhile, in the face of the requirement of flexible access of various energy sources, novel multi-port power router equipment needs to be researched, the power supply requirements of various types such as a large number of distributed energy storage equipment, novel loads and renewable energy source equipment for access in the station are met, flexible access of various types of energy sources is realized, and the construction of a comprehensive energy source service station is supported better.

The power router essentially belongs to electromagnetic energy conversion equipment, and the main components of the power router comprise a high-frequency transformer, a power switch device and passive element equipment. The power router can solve the problem that the transformation ratio of the traditional transformer is adjustable in a wide range, and has multiple functions of controlling power flow direction, adjusting power quality, flexibly isolating faults, accessing various charge loads and the like. At present, different scholars worldwide develop different kinds of power router prototypes, for example, 1MVA solid-state transformer prototypes proposed and developed by zurich University of switzerland, a new generation solid-state transformer developed by High Point University research center in the united states, and an electric energy exchanger prototype proposed and developed by the institute of electrical power science in china. The topology type of the power router can be classified in different ways: dividing the bus into a common direct current bus type and a common alternating current bus type according to an internal bus coupling form; the voltage can be divided into single voltage grade and multi-voltage grade according to the voltage characteristics; the direct current power grid can be divided into a radial direct current power grid and a mesh direct current power grid according to a wiring mode. However, in the current research, all multiport power routers are radial direct current systems with single voltage level, and the advantages of various direct current electric equipment cannot be fully integrated, so that different voltage level interfaces, wiring modes and system structures need to be adopted according to local conditions, and the potential of a direct current power supply network in a transformer substation is maximized.

To sum up, the existing power router structure is less concerned about port interconnection of different voltage types, less concerned about internal topology optimization, and also has no seamless switching function between different working conditions.

Compared with the direct current power router researched at present, the power router topology based on the direct current integration mode and the control strategy thereof provided by the invention have the following characteristics and advantages:

1) the bidirectional precise linear power flow control system has a bidirectional precise linear power flow control function, can realize the interconnected operation among different voltage networks, can also operate in a voltage source or current source mode, has flexible and variable control means, and is convenient for flexible access of different types of energy sources or loads.

2) The system has the function of bidirectional direct current fault isolation protection in the network, reduces the number of direct current breakers configured in a line, and can also reduce the system cost.

Disclosure of Invention

The invention aims to provide a power router topology based on a direct current integration mode and a control method thereof, and is characterized in that the power router topology based on the direct current integration mode comprises an alternating current port, a direct current port and an internal direct current bus; one end of the alternating current port 3 is connected with an internal direct current bus Vm, and the other end of the alternating current port is connected with external direct current lines (Va, Vb and Vc); the direct current side surface comprises a direct current port 1 and a direct current port 2; the direct current port 1 and the direct current port 2 are connected with an internal direct current bus Vm;

the alternating current port is a bidirectional alternating current port, stable voltage is provided for the direct current bus Vm under the condition of grid connection, meanwhile, a bidirectional power loop is provided to absorb transmission power of a post-stage circuit or supplement release power of a direct current circuit, the power conversion unit is used for converting direct current into alternating current, and a fully-controlled power device is adopted in the power conversion unit; the circuit topology is a bidirectional alternating current converter, and the specific circuit topology can be a three-phase full bridge circuit or a three-phase half bridge circuit.

The direct current port has the main function of controlling the voltage, the current or the power value at two ends of the output side according to requirements so as to achieve the purpose of changing the power flow distribution in the line through equivalent impedance in the line; the topology structure can be H-bridge topology, buck circuit, boost circuit or a combination of a plurality of half-bridge circuits.

A control method of a power router based on a direct current integration mode is characterized by comprising the following steps:

when the power router works in an alternating current grid-connected working mode, the alternating current port 3 is connected to a high-voltage direct current power grid of a commercial power grid to transmit to a low-voltage direct current power grid, the power conversion unit at the alternating current port side works in a power mode control mode with a power factor of 1, the direct current side of the alternating current port 3 works in a direct current voltage control mode, when the load power on the direct current bus Vm fluctuates, the direct current voltage at the direct current side of the alternating current port 3 is dynamically adjusted, the power input at the alternating current side of the alternating current port 3 is changed, and the direct current side voltage of the alternating current port 3 is adaptively adjusted through direct current feedforward current control and direct current voltage control power output.

When the electric power router works in a power exchange mode and energy is transmitted to an alternating current power grid from a direct current port, the alternating current port works in a direct current voltage control mode, and the alternating current side of the alternating current port works in an alternating current power control mode; and when the output power of the alternating current power grid fluctuates, the direct current bus side direct current port of the direct current port adaptively adjusts the power output.

The invention has the beneficial effects that:

1) the topology power router is provided with a tidal current bidirectional accurate linear controller, not only can realize the interconnected operation among different voltage networks, but also can operate in a direct-current voltage source or current source mode, realizes the combined integration of two functions, and effectively reduces the system cost;

2) the system has the function of bidirectional direct-current fault isolation protection in the network, provides direct-current side fault blocking capability, reduces the number of direct-current circuit breakers arranged in a line, facilitates flexible access of various types of energy sources or loads of different types, and is beneficial to supplement and enrich the functions of the internal power supply network of the existing transformer substation.

3) The invention provides an organic integration scheme of converter power flow regulation and control and fault protection strategies, improves the flexibility and reliability of control of an in-station power supply network, and meanwhile enriches and develops the integration of a power electronic system.

Drawings

Fig. 1 shows a topology of a power router in a dc integrated system.

Fig. 2 is a power router application scenario with blocking current limiting capability.

Detailed Description

The invention provides a power router topology based on a direct current integration mode, as shown in fig. 1. The high-voltage direct-current bus is characterized by comprising an alternating-current port 3, a direct-current port 1 and a direct-current port 2, wherein the direct-current bus Vm is arranged in the internal port 2, one end of the alternating-current port 3 is connected with the internal direct-current bus Vm, the other end of the alternating-current port is connected with an external direct-current line, and the alternating-current port 3 is a bidirectional alternating-current port.

The bidirectional alternating current port provides stable voltage for the direct current bus Vm under the condition of grid connection, and simultaneously provides bidirectional power loop to absorb transmission power of a post-stage circuit or supplement release power of a direct current circuit; the fully-controlled power device is a bidirectional alternating current converter, and the specific circuit topology can be a three-phase full-bridge circuit or a three-phase half-bridge circuit (as shown in fig. 2).

The direct current port has the main function of controlling the voltage, the current or the power value at two ends of the output side according to requirements, so that the purpose of changing the power flow distribution in the line through the equivalent impedance in the line is achieved. The topology structure can be H-bridge topology, buck circuit, boost circuit or a combination of a plurality of half-bridge circuits.

The invention also provides a control method of the electric power router, which comprises the following steps:

when the power router works in an alternating current power grid connection mode, an alternating current port is connected to a high-voltage direct current power grid of a commercial power grid, when the power router transmits to a low-voltage direct current power grid, a power converter at the alternating current port side works in a power mode control mode with a power factor of 1, a direct current side of the alternating current port works in a direct current voltage control mode, when load power on a direct current bus fluctuates, direct current voltage at the direct current side of a port of an alternating current unit is dynamically adjusted, power input at the alternating current side of the alternating current port unit is changed, and power output of a voltage unit at the direct current side of the alternating current port is adaptively adjusted through direct current feedforward control and direct current voltage control.

When the electric power router works in a power exchange mode and energy is transmitted to an alternating current power grid from a direct current port, the alternating current port works in a direct current voltage control mode, and the alternating current side of the alternating current port works in an alternating current power control mode; and when the output power of the alternating current power grid fluctuates, the direct current bus side direct current port of the direct current port adaptively adjusts the power output.

Examples

The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and the detailed description.

As shown in fig. 1, the common dc bus power energy router of the present invention includes an ac conversion unit connected to an ac power grid, a common dc bus unit, and a dc port unit connected to a distributed photovoltaic/energy storage; the direct current interface 1 and the direct current interface 2 are respectively connected with a common direct current bus Vm and an alternating current interface 3; the alternating current port 3 of the alternating current converter unit is connected with an alternating current power grid, and the voltages of the alternating current power grid are Va, Vb and Vc respectively; the DC bus voltage is V1, and the DC bus current is I₁(ii) a One side of the DC interface 1 is connected with a DC bus Vm through a DC port, one end of the DC interface is connected with the DC bus, and the voltage of the DC bus is V₂The direct current bus current is I₂(ii) a The DC port 2 at the other side of the DC interface 1 is connected to a photovoltaic/energy storage power supply, one end of the DC interface is connected to a DC bus, and the DC voltage is V₁Direct current is I₁。

The dc interface unit may be in the form of buck, boost, half bridge, or full bridge conversion topology shown in fig. 2 according to actual requirements. The direct current power supply adopts a boost circuit topological structure, and comprises a power switch tube, a diode and a smoothing reactor, wherein the anode of the high-voltage side of a direct current interface is connected to the anode of a direct current bus, the cathode of the high-voltage side of the direct current interface is connected to the cathode of the direct current bus, the cathode of a low-voltage direct current port of the direct current interface and the cathodes of all low-voltage side diode rectifying units are connected to the cathode N of the direct current bus of a low-voltage direct current power grid₂。

The alternating current interface converter unit adopts a three-phase half-bridge conversion topology, and the specific form of the topology structure can be a three-phase full-bridge or multi-level topology and the like according to actual needs.

The design method and control method of the energy router are further described below based on the power router structure of the converter topology structure in the common direct current bus mode.

Assuming that the topological structure and the diode performance of each DC interface unit are completely the same, the characteristics of the low-voltage side diode rectifying unit can show that when the DC interface unit operates stably, the voltage V of the DC port 1 is V₁And a DC port 2 voltage V₂Satisfies the following conditions:

V₁≠V₂、I₁≠I₂ (1)

neglecting the losses of the energy router, the input power and the output power of the energy router are equal, i.e.

V₁*I₁+V₂*I₂＝V_a、b、c*I_a、b、c (1)

When V is₁>V₂，I₂>I₁I.e. the power is transferred from dc port 1 to dc port 2.

The power router based on the common direct current bus can realize bidirectional energy flow.

Power router application scenario with current limiting blocking capability as shown in FIG. 2

The alternating current port is connected to an alternating current power grid, the power conversion unit of the alternating current power grid is used for converting direct current into alternating current, and a fully-controlled power device is adopted in the power conversion unit; the fully-controlled power device is a bidirectional alternating current converter, and the specific circuit topology can be a three-phase full-bridge circuit or a three-phase half-bridge circuit.

The two direct current ports are connected to the photovoltaic cell and the energy storage cell in a subsection mode, the main function of the photovoltaic cell and the energy storage cell is to control voltage, current or power values at two ends of an output side according to requirements, and the topological structure of the photovoltaic cell can be H-bridge topology, buck circuit, boost circuit or combination of a plurality of half-bridge circuits.

When the power router works in an alternating current power grid connection mode, an alternating current port is connected to a high-voltage direct current power grid of a commercial power grid to transmit to a low-voltage direct current power grid, a power converter at the alternating current port side works in a power mode control mode with a power factor of 1, a direct current side of the alternating current port works in a direct current voltage control mode, when load power on a direct current bus fluctuates, direct current voltage at the direct current side of the alternating current port is dynamically adjusted, power input at the alternating current side of the alternating current port is changed, and a voltage unit at the direct current side of the alternating current port adaptively adjusts power output through direct current feedforward control and direct current voltage control.

When the electric power router works in a power exchange mode and energy is transmitted to an alternating current power grid from a direct current port, the alternating current port unit works in a direct current voltage control mode, and the alternating current side of the alternating current port works in an alternating current power control mode; and when the output power of the alternating current power grid fluctuates, the direct current bus side direct current port of the direct current port adaptively adjusts the power output.

The internal conversion unit of the direct current side port adopts a full-control power electronic device, and compared with an alternating current-direct current conversion topology adopting an uncontrolled or semi-controlled power electronic device, the direct current side port internal conversion unit can more accurately control output voltage; the alternating current port can adopt a diode rectifying unit and an uncontrolled power electronic device, the device has strong through-current capacity, high voltage resistance and low cost, and compared with an alternating current-direct current conversion topology adopting a fully controlled power electronic device, the device has the advantages of few required devices, low cost, simple control and mature technology. Different direct current interfaces are connected in parallel at the direct current side, respective advantages can be exerted, voltage stability is achieved, control is simple, cost is low, the direct current power supply is more suitable for various energy flexible access occasions, and meanwhile bidirectional electric energy transmission can be achieved.

The embodiments described above are presented to enable a person having ordinary skill in the art to make and use the invention. It will be readily apparent to those skilled in the art that various modifications to the above-described embodiments may be made, and the generic principles defined herein may be applied to other embodiments without the use of inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications to the present invention based on the disclosure of the present invention within the protection scope of the present invention.

The power router topology with the fault blocking function provided by the invention provides the direct current side fault blocking capability, so that the organic integration of the power flow regulation and control of the converter and the fault protection strategy is realized, the flexibility and the reliability of the control among various energy sources of the comprehensive energy station are improved, and meanwhile, the integration of the comprehensive energy system is abundant and developed.