Modular control device and system for energy mutual assistance in supply areas

Abstract

The present application relates to the technical field of electric power systems, and discloses a modular control device and system for energy mutual assistance between supply areas, wherein the modular control device is connected to a three-phase AC line, and includes: a plurality of flexible flow control modules, one end of each flexible flow control module is connected in series to the three-phase AC line, the other end of each flexible flow control module is connected to an AC power source through a first isolation transformer, and each flexible flow control module is used to adjust the active power component of the power flow on the three-phase AC line; a plurality of reactive coordination control modules coordinated with the plurality of flexible flow control modules, each reactive coordination control module is connected in series to the three-phase AC line, and each reactive coordination control module is used to adjust the reactive power component of the power flow on the three-phase AC line. The present application realizes precise control of the flow in the process of energy mutual assistance between supply areas through a functional modular setting, and improves the flexibility of power quality management.

Description

Technical Field

[0001] The present application relates to the technical field of power systems, and in particular to a modular control device and system for energy mutual assistance in supply areas. Background Art

[0002] With the advancement of new power system construction and the rapid development of new energy technologies, people have higher and higher requirements for the quality of power loads. However, the power supply capacity of some supply areas is insufficient, resulting in the load growth being out of sync with the development speed of the power grid. In addition, the natural flow of the communication channels between supply areas is small, and the mutual assistance capacity between supply areas is relatively weak. Therefore, it is difficult to effectively enhance the energy mutual assistance between supply areas, which in turn affects the efficiency of power quality management between supply areas. Summary of the invention

[0003] The present application provides a modular control device and system for energy mutual assistance between supply areas, which solves the technical problem of mutual assistance between different supply areas and achieves precise control of the flow in the process of energy mutual assistance between supply areas through functional modular settings. While improving the energy mutual assistance capacity between supply areas, it also increases the flexibility of energy mutual assistance configuration and the technical effect of device utilization.

[0004] In order to achieve the above objectives, the main technical solutions adopted in this application include:

[0005] In a first aspect, an embodiment of the present application provides a modular control device for energy mutual assistance in supply areas, wherein the modular control device is connected to a three-phase AC line between an AC power supply in a first supply area and an AC power supply in a second supply area, and the modular control device includes:

[0006] A plurality of flexible power flow control modules, one end of each of which is connected in series to the three-phase AC line, the other end of each of which is connected to the AC power supply of the first supply area through a first isolation transformer, and each of which is used to adjust the active power component of the power flow on the three-phase AC line to control the transfer of excess energy from the second supply area to the first supply area;

[0007] Multiple reactive coordination control modules cooperate with the multiple flexible power flow control modules, each of the reactive coordination control modules is connected in series to the three-phase AC line, and each of the reactive coordination control modules is used to adjust the reactive power component of the power flow on the three-phase AC line to assist the flexible power flow control module in controlling the excess energy.

[0008] According to the modular control device for energy mutual assistance between supply areas proposed in the embodiment of the present application, the active power component of the power flow on the three-phase AC line is adjusted by the flexible flow control module, and the reactive power component of the power flow on the three-phase AC line is adjusted by the reactive coordination control module. The flexible flow control module and the reactive coordination control module are used in combination to achieve precise control of the flow between supply areas, improve the energy mutual assistance capacity between supply areas, and thus improve the power quality management efficiency between supply areas. In addition, the modular use design of the flexible flow control module and the reactive coordination control module can better cope with different mutual assistance needs between supply areas while improving the energy mutual assistance capacity between supply areas, and increase the flexibility of energy mutual assistance configuration and device utilization.

[0009] Optionally, in some embodiments of the present application, the ratio of the number of the flexible power flow control modules to the number of the reactive coordination control modules is equal to the ratio of the active power component and the reactive power component required to be injected into the three-phase AC line to transfer the excess energy.

[0010] The present application reasonably sets the quantity ratio of flexible flow control modules and reactive coordination control modules, and each flexible flow control module and each reactive coordination control module in the present application are independent functional modules, and the flexible flow control modules and reactive coordination control modules cooperate with each other in flow control. Therefore, the modular combination method is adopted to meet the needs of precise flow control and energy mutual assistance on the three-phase AC line, and also has high configuration flexibility to meet the changes in energy demand in the supply area under different load conditions.

[0011] Optionally, in some embodiments of the present application, each of the flexible power flow control modules includes:

[0012] A multi-winding transformer, wherein the primary winding of the multi-winding transformer is connected to the first isolation transformer, and the multi-winding transformer is used to divide the voltage of the flexible power flow control module;

[0013] a first rectifier bridge, wherein the first rectifier bridge is a fully controlled rectifier bridge composed of six thyristors, wherein a midpoint of a first bridge arm, a midpoint of a second bridge arm, and a midpoint of a third bridge arm of the first rectifier bridge are connected to a secondary winding of the multi-winding transformer, and the first rectifier bridge is used to rectify an AC voltage of the first transformer into a DC voltage;

[0014] A first capacitor, which is connected in parallel to two ends of a bridge arm of the first rectifier bridge, and is used to filter a DC voltage output by the first rectifier bridge;

[0015] A first H-bridge, wherein a bridge arm of the first H-bridge is connected in parallel with a bridge arm of the first rectifier bridge, and a midpoint of a first bridge arm and a midpoint of a second bridge arm of the first H-bridge are connected in series to the three-phase AC line, and the first H-bridge is used to invert a DC voltage output by the first rectifier bridge into an active voltage to adjust the active power component.

[0016] The flexible power flow control module proposed in the present application utilizes the energy supply of the secondary winding of the first transformer, combined with the rectifier bridge to output a stable DC voltage, and is connected in series with the three-phase AC line after filtering and inversion processing by the first capacitor and the first H-bridge, so as to flexibly adjust the size and direction of the voltage vector injected into the three-phase AC line, and realize precise power flow control with the four-quadrant active power component regulation capability, thereby improving the energy mutual assistance capability between supply areas.

[0017] Optionally, in some embodiments of the present application, each of the flexible power flow control modules further includes:

[0018] A first switch, wherein the first switch is connected between a midpoint of a first bridge arm and a midpoint of a second bridge arm of the first H-bridge, and the first switch is used to control the access of the flexible power flow control module to the three-phase AC line.

[0019] The present application controls the number of each flexible power flow control module connected in series to the three-phase AC line by setting the first switch. By closing the first switch, a short circuit connection is formed between the midpoint of the first bridge arm and the midpoint of the second bridge arm of the flexible power flow control module, thereby controlling the flexible power flow control module to cut off the connection on the three-phase AC line without affecting the series use of other flexible power flow control modules on the three-phase AC line, so as to realize the modular design of the flexible power flow control module and improve the configuration flexibility and module utilization of the flexible power flow control module.

[0020] Optionally, in some embodiments of the present application, each of the reactive coordination control modules includes:

[0021] a second H-bridge, wherein a midpoint of a first bridge arm and a midpoint of a second bridge arm of the second H-bridge are connected in series to the three-phase AC line, and the second H-bridge is used to output a reactive voltage to adjust the reactive power component;

[0022] A second capacitor is connected in parallel at both ends of the bridge arm of the second H-bridge, and the second capacitor is used for filtering the reactive voltage output by the second H-bridge.

[0023] The reactive coordination control module proposed in the present application adopts an H-bridge structure connected in series on the three-phase AC line. By adjusting the reactive power component perpendicular to the line current, it assists the flexible flow control module in the power flow regulation, thereby improving the accuracy of the flow control. At the same time, the stability of the three-phase AC line between the supply areas during the energy mutual assistance process is maintained through the adjustment of reactive power.

[0024] Optionally, in some embodiments of the present application, each of the reactive coordination control modules further includes:

[0025] A second switch, wherein the second switch is connected between a midpoint of a first bridge arm and a midpoint of a second bridge arm of the second H-bridge, and the second switch is used to control the access of the reactive coordination control module to the three-phase AC line.

[0026] The present application controls the number of reactive coordination control modules connected in series to the three-phase AC line by setting the second switch. By closing the second switch, the midpoint of the first bridge arm and the midpoint of the second bridge arm of the reactive coordination control module are short-circuited, thereby controlling the reactive coordination control module to cut off the connection on the three-phase AC line without affecting the series use of other reactive coordination control modules on the three-phase AC line, so as to realize the modular design of the reactive coordination control module and improve the configuration flexibility and module utilization of the reactive coordination control module.

[0027] Optionally, in some embodiments of the present application, the modular control device further includes a parallel compensation control module, which is connected in parallel to the three-phase AC line, and the parallel compensation control module is used to compensate for the current component on the three-phase AC line.

[0028] Optionally, in some embodiments of the present application, the parallel compensation control module includes:

[0029] A commutation unit, the commutation unit being used to compensate for a current component on the three-phase AC line;

[0030] A third switch, one end of which is connected to the commutation unit, and the third switch is used to control the connection of the parallel compensation control module to the three-phase AC line;

[0031] A second isolation transformer, one end of the second isolation transformer is connected to the other end of the third switch, and the other end of the second isolation transformer is connected to the AC power supply of the second supply area.

[0032] Optionally, in some embodiments of the present application, the commutation unit includes three commutation chains, wherein each of the commutation chains includes:

[0033] A third H-bridge, wherein a midpoint of a first bridge arm of the third H-bridge is connected to one end of a third switch;

[0034] A third capacitor, the third capacitor is connected in parallel to two ends of the bridge arm of the third H bridge;

[0035] A fourth H-bridge, wherein a midpoint of a first bridge arm of the fourth H-bridge is connected to a midpoint of a second bridge arm of the third H-bridge, and a midpoint of a second bridge arm of the fourth H-bridge is connected to a midpoint of a second bridge arm of a fourth H-bridge in another commutation chain;

[0036] A fourth capacitor is connected in parallel at both ends of the bridge arm of the fourth H-bridge.

[0037] The parallel compensation control module proposed in this application is independently connected in parallel to the compensation target position on the three-phase AC line, and flexibly outputs reactive current components perpendicular to the line current to the three-phase AC line, thereby providing inertia support for the three-phase AC line and improving the power quality management capabilities in the process of functional energy mutual assistance. The parallel compensation control module adopts a cascade design of three commutation chains in the commutation unit, which can provide stable reactive power compensation and voltage support through precise commutation operations and voltage regulation, thereby improving the power quality and stability on the three-phase AC line. In addition, the on-off control of the third switch is used to control the access of the parallel compensation control module to the three-phase AC line, so that the parallel compensation control module can adapt to different needs to access the three-phase AC line for compensation, so as to realize the modular design of the parallel compensation control module and improve the configuration flexibility.

[0038] Optionally, in some embodiments of the present application, the modular control device further includes a short-circuit current control module, which is connected in series to the three-phase AC line, and the short-circuit current control module is used to control the short-circuit fault current on the three-phase AC line.

[0039] Optionally, in some embodiments of the present application, the short-circuit current control module includes:

[0040] A flow branch, the flow branch is composed of two thyristors connected in series in reverse order, and the flow branch is connected in series to the three-phase AC line to conduct the line when the three-phase AC line is operating normally;

[0041] A disconnecting branch is connected to two ends of the through-current branch and is used to block the short-circuit fault current on the through-current branch when a short-circuit fault occurs in the three-phase AC line.

[0042] Optionally, in some embodiments of the present application, the disconnecting branch includes:

[0043] An uncontrolled rectifier bridge, the uncontrolled rectifier bridge comprising two uncontrolled rectifier bridge arms connected in parallel, each of the uncontrolled rectifier bridge arms being composed of four diodes connected in forward series, and a midpoint of a first bridge arm and a midpoint of a second bridge arm of the uncontrolled rectifier bridge being connected in parallel at both ends of the current-passing branch;

[0044] A capacitor branch, the capacitor branch is connected in parallel to two ends of the uncontrolled rectifier bridge arm, and the capacitor branch is composed of two DC capacitors connected in series;

[0045] The uncontrolled rectifier bridge is used to charge the DC capacitor to transfer the short-circuit fault current on the current-carrying branch.

[0046] The short-circuit current control module proposed in the present application adopts a combination design of a current-carrying branch and a disconnecting branch, and plays the role of a soft switch on the three-phase AC line, ensuring that the three-phase AC line can be turned on during normal operation. At the same time, when a short-circuit fault occurs in the three-phase AC line, the uncontrolled rectifier bridge and capacitor branch in the disconnecting branch can be used to quickly block the short-circuit fault current, thereby improving the short-circuit margin between supply areas, avoiding the short-circuit fault current of a certain supply area from expanding to other supply areas due to the interconnection of the three-phase AC circuit between supply areas, and improving the short-circuit fault response capability in the process of energy mutual assistance between supply areas.

[0047] In a second aspect, an embodiment of the present application provides a supply area energy mutual assistance system, including a three-phase AC line between a first supply area and a second supply area;

[0048] Wherein, the three-phase AC line is provided with the modular control device described in the first aspect embodiment.

[0049] The energy mutual assistance system for supply areas proposed in the embodiment of the present application adjusts the active power component of the power flow on the three-phase AC line through the flexible flow control module, adjusts the reactive power component of the power flow on the three-phase AC line through the reactive coordination control module, and utilizes the mutual coordination and combined use of the flexible flow control module and the reactive coordination control module to achieve precise control of the flow between supply areas, improve the energy mutual assistance capability between supply areas, and thus improve the efficiency of power quality management between supply areas. In addition, the modular use design of the flexible flow control module and the reactive coordination control module can better cope with different mutual assistance needs between supply areas while improving the energy mutual assistance capability between supply areas, and increase the flexibility of energy mutual assistance configuration and device utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0051] Figure 1 A schematic diagram of the circuit topology of a modular control device for energy mutual assistance in supply areas proposed in an embodiment of the present application;

[0052] Figure 2 A schematic diagram of the circuit structure of the flexible power flow control module proposed in the embodiment of the present application;

[0053] Figure 3 A schematic diagram of the circuit structure of the reactive power coordination control module proposed in the embodiment of the present application;

[0054] Figure 4 A schematic diagram of the circuit structure of the parallel compensation control module proposed in the embodiment of the present application;

[0055] Figure 5 A schematic diagram of the circuit structure of the commutation unit proposed in an embodiment of the present application;

[0056] Figure 6 A schematic diagram of the circuit structure of the short-circuit current control module proposed in an embodiment of the present application;

[0057] Figure 7 A schematic diagram of power flow vector control of a modular control device proposed in an embodiment of the present application;

[0058] Figure 8 This is a schematic diagram of the circuit connection of the modular control device proposed in an embodiment of the present application. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0060] With the advancement of new power system construction and the rapid development of new energy technologies, people have higher and higher requirements for the quality of electricity load. Especially for 500 kV supply areas, compared with rural electricity consumption, urban electricity consumption often has the characteristics of more user types, more types of power equipment, larger power consumption, larger load peak-valley difference, and obvious seasonal electricity consumption. With the emergence of new prosumers such as distributed photovoltaics, energy storage, and electric vehicles, however, the power supply capacity of some supply areas is insufficient, resulting in the load growth being out of sync with the development speed of the power grid, which in turn exacerbates the hollowing out of urban power grids.

[0061] Therefore, in some application scenarios, energy mutual assistance is required between supply areas. Energy mutual assistance refers to transferring excess energy from supply areas with excess energy to supply areas with insufficient energy. However, the natural flow of the communication channels between supply areas is small, and the mutual assistance capacity between supply areas is relatively weak. Therefore, it is difficult to effectively enhance the energy mutual assistance between supply areas, which in turn affects the efficiency of power quality management between supply areas.

[0062] In the related technology, a back-to-back flexible direct current solution based on the "AC-DC-AC" conversion method is adopted. This solution relies on two converters to achieve the interconnection between the two AC power systems. However, the two converters on the rectifier side and the inverter side are a whole both physically and functionally, and the device occupies a large area and has high costs. In addition, the actual energy mutual assistance needs faced by the supply area are complex and diverse. This back-to-back flexible direct current solution cannot adapt to different energy mutual assistance needs and separate functions, so it is difficult to maximize the utilization rate of the device.

[0063] The embodiment of the present application provides a modular control device 10 for energy mutual assistance in supply areas, such as Figure 1 As shown, the modular control device is connected to a three-phase AC line between an AC power source 20 in a first supply area and an AC power source 30 in a second supply area. The modular control device 10 includes a plurality of flexible power flow control modules 100 and a plurality of reactive coordination control modules 200 cooperating with the plurality of flexible power flow control modules 100.

[0064] Among them, one end of each flexible power flow control module 100 is connected in series to the three-phase AC line, and the other end of each flexible power flow control module 100 is connected to the AC power supply 20 of the first supply area through the first isolation transformer 40. Each flexible power flow control module 100 is used to adjust the active power component of the power flow on the three-phase AC line to control the transfer of excess energy in the second supply area to the first supply area.

[0065] In some embodiments of the present application, the flexible power flow control module 100 is powered by a multi-winding transformer, and multiple flexible power flow control modules 100 are cascaded and connected in series in a three-phase AC line, which can accurately track the voltage difference between the AC power supplies of two supply areas and output the corresponding active voltage to the three-phase AC line, ultimately achieving flexible and precise regulation of the active power component of the power flow on the three-phase AC line.

[0066] Each reactive coordination control module 200 is connected in series to the three-phase AC line, and each reactive coordination control module 200 is used to adjust the reactive power component of the power flow on the three-phase AC line to assist the flexible power flow control module in controlling the excess energy.

[0067] In some embodiments of the present application, the reactive coordination control module 200 assists the flexible power flow control module 100 in power flow regulation by adjusting the reactive component perpendicular to the line current, thereby improving the accuracy of power flow control while maintaining the stability of the three-phase AC lines between supply areas during the energy mutual assistance process through the regulation of reactive power.

[0068] In summary, the modular control device for energy mutual assistance between supply areas proposed in the embodiment of the present application utilizes the mutual coordination and combined use of the flexible flow control module and the reactive power coordination control module to achieve precise control of the flow between supply areas, improve the energy mutual assistance capability between supply areas, and thus improve the efficiency of power quality management between supply areas. In addition, the modular use design of the flexible flow control module and the reactive power coordination control module can better cope with different mutual assistance needs between supply areas while improving the energy mutual assistance capability between supply areas, thereby increasing the flexibility of energy mutual assistance configuration and device utilization.

[0069] In some embodiments of the present application, the flexible power flow control module 100 and the reactive coordination control module 200 are used in combination in a reasonable ratio, wherein the ratio of the number of flexible power flow control modules 100 to the number of reactive coordination control modules 200 is equal to the ratio of the active voltage component and the reactive voltage component required to be injected into the three-phase AC line to transfer excess energy.

[0070] Specifically, in the process of realizing energy mutual assistance between supply areas, the present application needs to transfer excess energy from the second supply area to the first supply area, and the above-mentioned modular control device needs to inject a certain series voltage into the three-phase AC line to inject active power and reactive power for controlling the power flow into the three-phase AC line. In some embodiments of the present application, the active power component and reactive power component corresponding to the series voltage are calculated in combination with the line impedance, and the above-mentioned active power component is calculated to be 10kW, and the above-mentioned reactive power component is 20kW. It can be determined that the number ratio of the flexible power flow control module 100 and the reactive coordination control module 200 is 1:2.

[0071] It can be seen that the present application realizes separate regulation of active power components and reactive power components by reasonably setting the quantity ratio of the flexible flow control module 100 and the reactive coordination control module 200, so that the flexible flow control module 100 and the reactive coordination control module 200 complement each other's advantages, thereby accurately controlling the flow on the three-phase AC line to transfer excess energy from the supply area with excess energy supply to the supply area with insufficient energy supply.

[0072] Figure 2 The specific circuit structure of the flexible power flow control module 100 in some embodiments of the present application is shown. Specifically, each flexible power flow control module 100 includes a multi-winding transformer 110 , a first rectifier bridge 120 , a first capacitor C1 and a first H-bridge 130 .

[0073] Among them, the primary winding of the multi-winding transformer 110 is connected to the first isolation transformer 40, and the multi-winding transformer 110 is used to divide the voltage of the AC power supply 20 of the first supply area, that is, to divide the voltage of the flexible power flow control module 100. The first rectifier bridge 120 is a fully controlled rectifier bridge composed of six thyristors. The midpoint of the first bridge arm, the midpoint of the second bridge arm, and the midpoint of the third bridge arm of the first rectifier bridge 120 are connected to a secondary winding of the multi-winding transformer 110. The first rectifier bridge 120 is used to rectify the AC voltage of the first transformer 40 into a DC voltage. The first capacitor C1 is connected in parallel at both ends of the bridge arm of the first rectifier bridge 120, and the first capacitor C1 is used to filter the DC voltage output by the first rectifier bridge 120. The bridge arm of the first H-bridge 130 is connected in parallel with the bridge arm of the first rectifier bridge 120, and the midpoint of the first bridge arm and the midpoint of the second bridge arm of the first H-bridge 130 are connected in series on the three-phase AC line. The first H-bridge 130 is used to invert the DC voltage output by the first rectifier bridge 120 into an active voltage to adjust the active power component.

[0074] The flexible power flow control module 100 is powered by a multi-winding transformer combined with a fully controlled rectifier bridge to establish a stable DC voltage, and in this process, the amplitude of the DC voltage can be controlled, and the amplitude can directly determine the size of the active power component finally output by the flexible power flow control module 100. After the DC voltage is filtered by the first capacitor C1, it is input into the first H-bridge 130 for DC to AC inversion processing. By controlling the on and off of each thyristor in the first H-bridge 130, the DC voltage can be inverted into an active voltage vector in any direction, which can be equivalent to an adjustable four-quadrant voltage source. The output active voltage can form a voltage control vector circle, so that the vector direction of the active power component finally output by the flexible power flow control module 100 can be adjusted within the four-quadrant range.

[0075] like Figure 2As shown, each of the flexible power flow control modules further includes a first switch K1, which is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm of the first H bridge 130, and is used to control the access of the flexible power flow control module 100 to the three-phase AC line.

[0076] Specifically, if the first switch K1 is disconnected, the flexible power flow control module 100 is connected in series to the three-phase AC line through the midpoint of the first bridge arm and the midpoint of the second bridge arm. If the first switch K1 is closed, a short circuit connection is formed between the midpoint of the first bridge arm and the midpoint of the second bridge arm of the flexible power flow control module 100, thereby disconnecting the corresponding flexible power flow control module 100 from the three-phase AC line. Figure 1 and Figure 2 It can be seen that since multiple flexible flow control modules 100 are connected in series on the three-phase AC line, closing the first switch K1 of some of the flexible flow control modules 100 will only short-circuit the corresponding flexible flow control module 100, and will not affect the access and operation of other flexible flow control modules 100 in the three-phase AC line. Therefore, the present application can flexibly adjust the number of flexible flow control modules 100 connected to the three-phase AC line in a modular combination manner, thereby realizing precise control of the power flow on the three-phase AC line to improve the energy mutual assistance capacity between supply areas.

[0077] Figure 3 The specific circuit structure of the reactive coordination control module 200 in some embodiments of the present application is shown. Specifically, each reactive coordination control module 200 includes a second H-bridge 210 and a second capacitor C2.

[0078] The midpoint of the first bridge arm and the midpoint of the second bridge arm of the second H-bridge 210 are connected in series on the three-phase AC line, and the second H-bridge 210 is used to output a reactive voltage to adjust the reactive power component. The second capacitor C2 is connected in parallel at both ends of the bridge arm of the second H-bridge 210, and the second capacitor C2 is used to filter the reactive voltage output by the second H-bridge 210.

[0079] The reactive coordination control module 200 is connected in series on the three-phase AC line using an H-bridge structure, and assists in the regulation of power flow by adjusting the reactive component perpendicular to the current on the three-phase AC line. Specifically, the second H-bridge adjusts the phase and amplitude of the voltage by controlling the on-off state of the thyristor, thereby generating a voltage component perpendicular to the direction of the AC current in the three-phase AC line, and then generating reactive power injected into the three-phase AC line. The regulation of reactive power has an important influence on the control of power flow. The voltage stability of the three-phase AC line can be improved by regulating reactive power, thereby assisting the power flow regulation of the flexible power flow control module 100 to regulate the distribution of power flow on the three-phase AC line.

[0080] like Figure 3 As shown, each reactive coordination control module 200 further includes a second switch K2, which is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm of the second H-bridge 210, and is used to control the access of the reactive coordination control module 200 to the three-phase AC line.

[0081] Specifically, if the second switch K2 is disconnected, the reactive coordination control module 200 is connected in series to the three-phase AC line through the midpoint of the first bridge arm and the midpoint of the second bridge arm. If the second switch K2 is closed, a short circuit connection is formed between the midpoint of the first bridge arm and the midpoint of the second bridge arm of the reactive coordination control module 200, thereby disconnecting the corresponding reactive coordination control module 200 from the three-phase AC line. Figure 1 and Figure 3 It can be seen that since multiple reactive coordination control modules 200 are connected in series on the three-phase AC line, closing the second switch K2 of some of the reactive coordination control modules 200 will only short-circuit the corresponding reactive coordination control module 200, and will not affect the access and operation of other reactive coordination control modules 200 in the three-phase AC line. Therefore, the present application can flexibly adjust the number of reactive coordination control modules 200 connected to the three-phase AC line in a modular combination, thereby assisting the precise control of the power flow on the three-phase AC line to improve the energy mutual assistance capacity between supply areas. In addition, when a short-circuit fault occurs in the three-phase AC line, the reactive coordination control module 200 can be locked to turn off all the thyristors in the module to block the further spread of the short-circuit fault current.

[0082] In some embodiments of the present application, the flexible power flow control module 100 and the reactive power coordination control module 200 are used in combination and can cooperate with each other in the power flow control process. The superposition combination of the "voltage control vector circle" formed by the flexible power flow control module 100 and the "voltage control vector line" formed by the reactive power coordination control module 200 can fully cover a voltage plane, complement the advantages of the two modules, increase the voltage regulation range, and thus achieve precise control of the power flow between supply areas, and improve the energy mutual assistance capacity of the supply areas.

[0083] In some embodiments of the present application, the modular control device 10 further includes a parallel compensation control module 300 , which is connected in parallel to the three-phase AC line and is used to compensate for the current component on the three-phase AC line.

[0084] The parallel compensation control module 300 proposed in the present application is independently connected in parallel to the compensation target position on the three-phase AC line, and flexibly outputs a reactive current component perpendicular to the line current to the three-phase AC line, thereby providing inertia support for the three-phase AC line. It can cope with the problem of insufficient reactive voltage support in some DC near-areas during the energy mutual assistance process, and can also effectively solve the risks of excessive harmonics and wide-band oscillations in the supply areas of some coastal new energy gathering areas, thereby improving the power quality management capabilities during the functional energy mutual assistance process.

[0085] Specifically, Figure 4 As shown, the parallel compensation control module 300 includes a commutation unit 310, a third switch K3 and a second isolation transformer 320. The commutation unit 310 is used to compensate the current component on the three-phase AC line. One end of the third switch K3 is connected to the commutation unit 310, and the third switch K3 is used to control the access of the parallel compensation control module 300 to the three-phase AC line. One end of the second isolation transformer 320 is connected to the other end of the third switch K3, and the other end of the second isolation transformer 320 is connected to the AC power supply 30 of the second supply area.

[0086] Furthermore, if Figure 5 As shown, in some embodiments of the present application, the above-mentioned commutation unit 310 includes three commutation chains, wherein each commutation chain includes a third H bridge 311, a third capacitor C3, a fourth H bridge 312 and a fourth capacitor C4. Among them, the midpoint of the first bridge arm of the third H bridge 311 is connected to one end of the third switch K3, the third capacitor C3 is connected in parallel to both ends of the bridge arm of the third H bridge 311, the midpoint of the first bridge arm of the fourth H bridge 312 is connected to the midpoint of the second bridge arm of the third H bridge 311, the midpoint of the second bridge arm of the fourth H bridge 312 is connected to the midpoint of the second bridge arm of the fourth H bridge 312 in other commutation chains, and the fourth capacitor C4 is connected in parallel to both ends of the bridge arm of the fourth H bridge 312.

[0087] It should be noted that Figure 5 The three commutation chains shown correspond to phase A, phase B and phase C in the three-phase AC line, respectively, that is, the complete parallel compensation control module 300 includes three third switches K3 and three second isolation transformers 320, the midpoint of the first bridge arm of the third H bridge 311 of the first commutation chain is connected to the corresponding first third switch K3, and is connected to the A phase line in the three-phase AC line through the first second isolation transformer 320, the midpoint of the first bridge arm of the third H bridge 311 of the second commutation chain is connected to the corresponding second third switch K3, and is connected to the B phase line in the three-phase AC line through the second second isolation transformer 320, and the midpoint of the first bridge arm of the third H bridge 311 of the third commutation chain is connected to the corresponding third third switch K3, and is connected to the C phase line in the three-phase AC line through the third second isolation transformer 320.

[0088] The parallel compensation control module 300 adopts a cascade design of three commutation chains in the commutation unit 310. Each commutation chain is composed of an H-bridge and a filter capacitor. By controlling the on-off state of the thyristor in the H-bridge, the direction and magnitude of the current flowing through the commutation chain are controlled, and a "current control vector circle" is formed, thereby realizing flexible output of reactive power and providing stable reactive power compensation and voltage support. At the same time, the H-bridge structure of the commutation unit 310 can generate a current opposite to the harmonic component in the three-phase AC line through high-frequency switching operation, thereby neutralizing the harmonics to reduce the interference of the harmonics on the three-phase AC line, and can timely monitor the broadband oscillation caused by the current and voltage changes on the three-phase AC line, and then quickly compensate to maintain the smooth operation of the three-phase AC line. It can be seen that the parallel compensation control module 300 has both power quality DC and broadband oscillation suppression functions, thereby improving the power quality and stability on the three-phase AC line.

[0089] In addition, the on-off control of the third switch K3 is used to control the access of the parallel compensation control module 300 to the three-phase AC line, so that the parallel compensation control module 300 can be connected to the three-phase AC line for compensation according to different needs, thereby realizing the modular design of the parallel compensation control module 300 and improving the configuration flexibility.

[0090] In some embodiments of the present application, the modular control device 10 further includes a short-circuit current control module 400, which is connected in series to the three-phase AC line and is used to control the short-circuit fault current on the three-phase AC line.

[0091] The modular control device 10 proposed in this application responds to the risk of fault current diffusion in the process of energy mutual assistance. Specifically, since the three-phase AC line is an interconnected line between two supply areas, once a short-circuit fault occurs in the current system of any one of the supply areas, the short-circuit fault current caused by it will spread over a large area along the three-phase AC line, which is likely to cause more power equipment failures. Therefore, in order to improve the short-circuit margin in the process of energy mutual assistance, the DC disconnection technology is introduced into the AC application through the above-mentioned short-circuit current control module 400, and a combination design of a flow branch and a disconnecting branch is adopted to play the role of a soft switch on the three-phase AC line. When the three-phase AC line and the two supply areas are operating normally, the power flow will pass through the flow branch 410. When a system short circuit occurs in the three-phase AC line or any one of the two supply areas, the flow branch 410 is disconnected, and the short-circuit fault current is transferred to the disconnecting branch for absorption, so as to achieve a rapid response to the short-circuit fault.

[0092] Specifically, Figure 6As shown, the short-circuit current control module 400 includes a flow branch 410 and a disconnection branch 420, wherein the flow branch 410 is composed of two reverse series-connected thyristors, and the flow branch 410 is connected in series to the three-phase AC line to conduct the line when the three-phase AC line is operating normally. The disconnection branch 420 is connected to both ends of the flow branch 410, and the disconnection branch 420 is used to block the short-circuit fault current on the flow branch 410 when a short-circuit fault occurs in the three-phase AC line.

[0093] Further, in some embodiments of the present application, the disconnecting branch 420 includes an uncontrolled rectifier bridge 421 and a capacitor branch 422. The uncontrolled rectifier bridge 421 includes two uncontrolled rectifier bridge arms connected in parallel, and each uncontrolled rectifier bridge arm is composed of four diodes connected in forward series, and the midpoint of the first bridge arm and the midpoint of the second bridge arm of the uncontrolled rectifier bridge are connected in parallel at both ends of the flow branch 410. The capacitor branch 422 is connected in parallel at both ends of the uncontrolled rectifier bridge arm 421, and the capacitor branch 422 is composed of two DC capacitors connected in series.

[0094] The uncontrolled rectifier bridge 421 is a bridge rectifier circuit composed of four diodes, which does not require an external control signal to be turned on or off. If there is a short-circuit fault current on the three-phase AC line, the short-circuit fault current is rectified by the uncontrolled rectifier bridge 421 and then charged to the DC capacitor to transfer the short-circuit fault current on the current branch, thereby improving the short-circuit margin of the three-phase AC line and helping to ensure the safety and stability of the entire power system during the energy mutual assistance process.

[0095] In summary, in some embodiments of the present application, the above-mentioned flexible power flow control module 100, reactive power coordination control module 200, parallel compensation control module 300 and short-circuit current control module 400 are used in combination, so that the advantages of each control module complement each other and jointly realize the functions of power flow mutual assistance, short-circuit isolation, reactive power support and power quality management. For details, please refer to Figure 7 The voltage vector diagram shown is Figure 7 The vector diagram shows the transfer of excess energy from the second supply area with excess function to the first supply area with insufficient function, wherein V1 represents the output voltage of the AC power supply of the first supply area, V2 represents the output voltage of the AC power supply of the second supply area, and I represents the AC current on the three-phase AC circuit. P The active voltage vector output by the flexible power flow control module 100 can be controlled within the four-quadrant range. P The vector direction forms a "voltage control vector circle". QThe reactive voltage vector output by the reactive coordination control module 200 is perpendicular to the AC current on the three-phase AC line, forming a "voltage control vector line". It can be seen that the superposition combination of the flexible power flow control module 100 and the reactive coordination control module 200 can fully cover a voltage plane, increase the voltage regulation range, and thus achieve precise control of the power flow between supply areas.

[0096] Figure 7 I G The current component of the three-phase AC line compensated by the parallel compensation control module 300 can adjust the vector direction and size of the current component after the commutation processing of the commutation unit 310 to form a "current control vector circle", and then flexibly adjust the reactive current component injected into the three-phase AC line to compensate for power quality problems such as insufficient voltage support and wide-band oscillation in the energy mutual assistance process.

[0097] Figure 7 K shown D The figure shows the current blocking effect of the short-circuit current control module 400 on the three-phase AC line. If a short-circuit fault occurs, the short-circuit current control module 400 cuts off the three-phase AC line to achieve the purpose of blocking the short-circuit fault current.

[0098] It should also be noted that Figure 1 X shown L Represents the line impedance of the three-phase AC line, so Figure 7 China-Israel IX L It represents the voltage vector perpendicular to the AC current I generated by the line impedance in the power flow.

[0099] The flexible power flow control module 100 is a series-parallel converter, the reactive power coordination control module 200 is a series converter, and the parallel compensation control module 300 is a parallel converter. In the related art, the same type of converters are usually used together to prevent the voltage and current capabilities from being offset by each other due to improper control. The modular control device 10 proposed in this application overcomes the technical drawbacks of mixed use of the above-mentioned converters. Through the reasonable matching and combination of the above-mentioned flexible power flow control module 100, reactive power coordination control module 200, parallel compensation control module 300 and short-circuit current control module 400, the advantages of each functional module are complemented, so as to jointly output the following: Figure 7 The voltage vector diagram shown forms a comprehensive voltage and current regulation range, thereby improving the accuracy of power flow control and helping to improve the energy mutual assistance capacity between supply areas.

[0100] It should also be noted that Figure 1 The figure shows a connection diagram of each functional module in the modular control device 10 taking a single phase as an example. Figure 8 The specific connection method of the above-mentioned flexible power flow control module 100, reactive power coordination control module 200, parallel compensation control module 300 and short-circuit current control module 400 on the three-phase AC line is shown, wherein the A phase, B phase and C phase of the three-phase AC line are respectively connected in series with the flexible power flow control module 100, the reactive power coordination control module 200 and the short-circuit current control module 400, and in addition, the A phase, B phase and C phase are respectively connected in parallel with the parallel compensation control module 300, wherein each flexible power flow control module 100, reactive power coordination control module 200 and short-circuit current control module 400 can be controlled by the corresponding switch to access the three-phase AC line, and the parallel compensation control module 300 can be configured separately on the three-phase AC line to realize functions such as reactive support, power quality management and elimination of broadband oscillation risks, and can also be used in combination with the flexible power flow control module 100, the reactive power coordination control module 200 and the short-circuit current control module 400 to play a role in assisting power flow control. At the same time, the combined use of the flexible flow control module 100, the reactive power coordination control module 200 and the short-circuit current control module 400 can realize precise flow control and short-circuit fault current blocking functions. Therefore, compared with the energy mutual assistance scheme of the related technology, the modular control device 10 proposed in this application has the advantages of more flexible configuration, higher module utilization and better economy.

[0101] Accordingly, an embodiment of the present application provides a supply area energy mutual assistance system, including a three-phase AC line between a first supply area and a second supply area;

[0102] Wherein, the three-phase AC line is provided with the modular control device 10 described in the above embodiment.

[0103] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0104] Although the embodiments of the present application are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations are all within the scope defined by the appended claims.

[0105] For the convenience of description, the above device is described in various units according to their functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0106] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0107] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the device embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0108] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

[0109] Although the embodiments of the present application have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A modular control device for energy mutual assistance in supply areas, characterized in that: The modular control device is connected to a three-phase AC line between the AC power supply of the first supply area and the AC power supply of the second supply area, and the modular control device includes: A plurality of flexible power flow control modules, one end of each of which is connected in series to the three-phase AC line, the other end of each of which is connected to the AC power supply of the first supply area through a first isolation transformer, and each of which is used to adjust the active power component of the power flow on the three-phase AC line to control the transfer of excess energy from the second supply area to the first supply area; A plurality of reactive coordination control modules coordinated with the plurality of flexible power flow control modules, each of the reactive coordination control modules is connected in series to the three-phase AC line, and each of the reactive coordination control modules is used to adjust the reactive power component of the power flow on the three-phase AC line to assist the flexible power flow control module in controlling the excess energy, wherein the ratio of the number of the flexible power flow control modules to the number of the reactive coordination control modules is equal to the ratio of the active power component to the reactive power component injected into the three-phase AC line to transfer the excess energy, and a voltage plane is fully covered by the superposition combination of the voltage control vector circle formed by the flexible power flow control module and the voltage control vector line formed by the reactive coordination control module; A parallel compensation control module is connected in parallel to the three-phase AC line. The parallel compensation control module is used to compensate for the current component on the three-phase AC line, and provides stable reactive power compensation and voltage support by forming a current control vector circle. The module is combined with the flexible power flow control module and the reactive coordination control module to perform auxiliary power flow control.

2. The modular control device according to claim 1, characterized in that: Each of the flexible power flow control modules comprises: A multi-winding transformer, wherein the primary winding of the multi-winding transformer is connected to the first isolation transformer, and the multi-winding transformer is used to divide the voltage of the flexible power flow control module; A first rectifier bridge, wherein the first rectifier bridge is a fully controlled rectifier bridge composed of six thyristors, wherein a midpoint of a first bridge arm, a midpoint of a second bridge arm, and a midpoint of a third bridge arm of the first rectifier bridge are connected to a secondary winding of the multi-winding transformer, and the first rectifier bridge is used to rectify the AC voltage output by the secondary winding into a DC voltage; A first capacitor, which is connected in parallel to two ends of a bridge arm of the first rectifier bridge, and is used to filter a DC voltage output by the first rectifier bridge; A first H-bridge, wherein a bridge arm of the first H-bridge is connected in parallel with a bridge arm of the first rectifier bridge, and a midpoint of a first bridge arm and a midpoint of a second bridge arm of the first H-bridge are connected in series to the three-phase AC line, and the first H-bridge is used to invert a DC voltage output by the first rectifier bridge into an active voltage to adjust the active power component.

3. The modular control device according to claim 2, characterized in that: Each of the flexible power flow control modules further comprises: A first switch, wherein the first switch is connected between a midpoint of a first bridge arm and a midpoint of a second bridge arm of the first H-bridge, and the first switch is used to control the access of the flexible power flow control module to the three-phase AC line.

4. The modular control device according to claim 1, characterized in that: Each of the reactive coordination control modules comprises: a second H-bridge, wherein a midpoint of a first bridge arm and a midpoint of a second bridge arm of the second H-bridge are connected in series to the three-phase AC line, and the second H-bridge is used to output a reactive voltage to adjust the reactive power component; A second capacitor is connected in parallel at both ends of the bridge arm of the second H-bridge, and the second capacitor is used for filtering the reactive voltage output by the second H-bridge.

5. The modular control device according to claim 4, characterized in that: Each of the reactive coordination control modules further comprises: A second switch, wherein the second switch is connected between a midpoint of a first bridge arm and a midpoint of a second bridge arm of the second H-bridge, and the second switch is used to control the access of the reactive coordination control module to the three-phase AC line.

6. The modular control device according to claim 1, characterized in that: The parallel compensation control module comprises: A commutation unit, the commutation unit being used to compensate for a current component on the three-phase AC line; A third switch, one end of which is connected to the commutation unit, and the third switch is used to control the connection of the parallel compensation control module to the three-phase AC line; A second isolation transformer, one end of the second isolation transformer is connected to the other end of the third switch, and the other end of the second isolation transformer is connected to the AC power supply of the second supply area.

7. The modular control device according to claim 6, characterized in that: The commutation unit includes three commutation chains, wherein each of the commutation chains includes: A third H-bridge, wherein a midpoint of a first bridge arm of the third H-bridge is connected to one end of a third switch; A third capacitor, the third capacitor is connected in parallel to two ends of the bridge arm of the third H bridge; A fourth H-bridge, wherein a midpoint of a first bridge arm of the fourth H-bridge is connected to a midpoint of a second bridge arm of the third H-bridge, and a midpoint of a second bridge arm of the fourth H-bridge is connected to a midpoint of a second bridge arm of a fourth H-bridge in another commutation chain; A fourth capacitor is connected in parallel at both ends of the bridge arm of the fourth H-bridge.

8. The modular control device according to any one of claims 1 to 5, characterized in that: The modular control device further comprises a short-circuit current control module, which is connected in series to the three-phase AC line and is used to control the short-circuit fault current on the three-phase AC line.

9. The modular control device according to claim 8, characterized in that: The short-circuit current control module comprises: A flow branch, the flow branch is composed of two thyristors connected in series in reverse order, and the flow branch is connected in series to the three-phase AC line to conduct the line when the three-phase AC line is operating normally; A disconnecting branch is connected to two ends of the through-current branch and is used to block the short-circuit fault current on the through-current branch when a short-circuit fault occurs in the three-phase AC line.

10. The modular control device according to claim 9, characterized in that: The disconnecting branch comprises: An uncontrolled rectifier bridge, the uncontrolled rectifier bridge comprising two uncontrolled rectifier bridge arms connected in parallel, each of the uncontrolled rectifier bridge arms being composed of four diodes connected in forward series, and a midpoint of a first bridge arm and a midpoint of a second bridge arm of the uncontrolled rectifier bridge being connected in parallel at both ends of the current-passing branch; A capacitor branch, the capacitor branch is connected in parallel to two ends of the uncontrolled rectifier bridge arm, and the capacitor branch is composed of two DC capacitors connected in series; The uncontrolled rectifier bridge is used to charge the DC capacitor to transfer the short-circuit fault current on the current-carrying branch.

11. A supply area energy mutual assistance system, characterized in that: including a three-phase AC line between a first supply area and a second supply area; Wherein, the three-phase AC line is provided with a modular control device according to any one of claims 1-10.

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