An interconnection device of a true and false bipolar system and an interconnection operation method thereof

Abstract

The application provides a true and false bipolar system interconnection device and an interconnection operation method thereof, which comprises the following steps: connecting the positive pole of the true bipolar system and the positive pole of the false bipolar system through a first end in a plurality of connection terminals, and connecting the negative pole of the true bipolar system and the negative pole of the false bipolar system through a second end; connecting a positive pole power electronic component and a negative pole power electronic component in series to form a series combination, and connecting the series combination between the first end and the second end; connecting the series point of the series combination with a third end; and controlling the interconnection device to be in no-load state when the true bipolar system is in a normal operation state, and controlling the positive pole power electronic component and the negative pole power electronic component to output the same direct current voltage to maintain the positive and negative pole voltage symmetry of the false bipolar system when the true bipolar system is in a single pole operation state. The true and false bipolar systems can be efficiently interconnected and energy self-balanced, the true bipolar system has the single pole operation ability, and the power supply reliability and operation flexibility are improved.

Description

Technical Field

[0001] This invention relates to the field of DC power transmission technology, specifically to an interconnection device and an interconnection operation method for a true and pseudo bipolar system. Background Technology

[0002] DC transmission systems refer to the transmission of electricity in the form of direct current (DC) within a smart grid. Compared to traditional AC transmission, DC transmission offers advantages such as lower losses, stronger long-distance transmission capabilities, and larger transmission capacity. With the large-scale grid integration of new energy sources, DC transmission technology has been widely applied in long-distance, high-capacity power transmission scenarios, such as intercontinental power grid interconnection and submarine cable transmission.

[0003] There are two main wiring methods used in DC transmission projects: pseudo-bipolar connection (also known as unipolar symmetrical connection) and true bipolar connection. Pseudo-bipolar connection typically uses a star-connected reactor on the converter transformer valve side to create an artificial neutral point, making the DC line symmetrically polarized with respect to ground. This structure is simple to connect, requires no grounding or metallic return line, the converter transformer has no DC bias, and it is economical. However, its reliability is low, it cannot achieve unipolar operation, and it suffers from higher overvoltage and greater difficulty in equipment manufacturing. True bipolar connection consists of two poles, positive and negative, with each pole sharing a common grounding pole. The poles are connected by a metallic return line and grounded at both ends of the converter transformer. Compared to pseudo-bipolar connection, true bipolar connection has a larger transmission capacity and higher system reliability. Even if one pole fails, the other pole can still operate independently. However, its structure is complex, requiring a grounding loop or metallic return line, and the converter transformer must withstand DC voltage. Therefore, it is mostly used in applications requiring high reliability and operational flexibility.

[0004] In projects such as new energy transmission, there may be situations where one end uses pseudo-bipolar wiring to pursue economic efficiency and save land, while the other end uses true bipolar wiring to ensure reliability. Patent CN 119030337 proposes a DC / DC converter and its operation control scheme that can be used for both true bipolar and pseudo-bipolar systems. It can achieve interconnection under steady state and fault self-clearing after a short circuit between the poles on the true bipolar side. However, this interconnection scheme will cause the true bipolar system to lose its ability to operate independently on a single pole. When one pole on the true bipolar side stops operating, the system cannot maintain 50% power delivery like a complete true bipolar system. Summary of the Invention

[0005] To overcome the above-mentioned defects, the present invention provides an interconnection device for true and false bipolar systems, comprising: Multiple terminals, including a first terminal, a second terminal, and a third terminal; the first terminal is connected to the positive terminal of the true bipolar system and the positive terminal of the pseudo bipolar system, the second terminal is connected to the negative terminal of the true bipolar system and the negative terminal of the pseudo bipolar system, and the third terminal is grounded; A positive power electronic component and a negative power electronic component are connected in series to form a series combination, which is connected between the first end and the second end; the series connection point of the series combination is connected to the third end. The controller is electrically connected to the positive power electronic component and the negative power electronic component respectively. The controller is used to control the interconnection device to be unloaded when the true bipolar system is in normal operation; when the true bipolar system is in unipolar operation, the controller controls the positive power electronic component and the negative power electronic component to output the same DC voltage to maintain the positive and negative voltage symmetry of the pseudo bipolar system.

[0006] Optionally, it also includes a first set of AC blocking devices, which are connected between the series connection point and the third terminal; The first set of AC blocking devices is used to block the AC voltage and AC current generated between the positive and negative power electronic components from overflowing to the third terminal.

[0007] Optionally, a first set of energy balancing devices may also be included; The positive electrode power electronic component has a first intermediate lead-out point, and the negative electrode power electronic component has a second intermediate lead-out point; The first set of energy balancing devices is connected between the first intermediate lead and the second intermediate lead; the first set of energy balancing devices is used to provide an AC path for the positive power electronic component and the negative power electronic component to maintain the AC current energy balance between the positive power electronic component and the negative power electronic component.

[0008] Optionally, it may also include at least one set of controllable resistors; the at least one set of controllable resistors is connected between the first end and the second end, and is connected in parallel with the series combination; or, the at least one set of controllable resistors is connected in parallel with the capacitors of the positive power electronic component and / or the sub-modules within the negative power electronic component. The at least one set of controllable resistors is used to consume the extra power transmitted by the pseudo-bipolar system during the transition from normal operation to unipolar operation of the true bipolar system.

[0009] Optionally, the interconnection device adopts a single-phase arrangement structure or a multi-phase arrangement structure; If the interconnection device adopts the single-phase arrangement structure, it further includes a capacitive filter connected between the first end and the second end, and between the second end and the third end.

[0010] Optionally, if the true bipolar system and the pseudo bipolar system are at different voltage levels, the plurality of terminals may further include a fourth terminal and a fifth terminal. The fourth terminal includes a first tap terminal extending from the middle of the positive power electronic component, which is connected to the positive terminal of the pseudo-bipolar system. The first tap terminal divides the positive power electronic component into a first positive power electronic component and a second positive power electronic component. The fifth terminal includes a second tap terminal extending from the middle of the negative electrode power electronic component, which is connected to the negative electrode of the pseudo-bipolar system. The second tap terminal divides the negative electrode power electronic component into a first negative electrode power electronic component and a second negative electrode power electronic component.

[0011] Optionally, it may also include a second set of AC blocking devices and / or a second set of energy balancing devices; The second set of AC blocking devices includes at least one of the following connection relationships: the second set of AC blocking devices is connected between the fourth terminal and the positive terminal of the pseudo-bipolar system, and the second set of AC blocking devices is connected between the fifth terminal and the negative terminal of the pseudo-bipolar system; The second set of energy balancing devices includes at least one of the following connection relationships: the two ends of the second set of energy balancing devices are respectively connected to the first positive electrode power electronic component and the second positive electrode power electronic component, and the two ends of the second set of energy balancing devices are respectively connected to the first negative electrode power electronic component and the second negative electrode power electronic component.

[0012] Optionally, the first group of AC blocking devices and the second group of AC blocking devices include a bridge arm with multiple sub-modules connected in series, or a reactor, or a transformer, or a bridge arm with multiple power devices connected in series. The first group of energy balancing devices and the second group of energy balancing devices include bridge arms with multiple sub-modules connected in series, or capacitors, or transformers, or bridge arms with multiple power devices connected in series.

[0013] On the other hand, the present invention also provides an interconnection operation method for an interconnection device of a true and false bipolar system, comprising: Monitor the operating status of a true bipolar system; If the operating state is normal operating state, then the true bipolar system and the pseudo bipolar system are controlled to transmit current through the positive and negative lines, and the interconnection device is unloaded; If the operating state is a unipolar operating state, the positive and negative power electronic components in the interconnection device are controlled to output the same DC voltage to maintain the positive and negative voltage symmetry of the pseudo-bipolar system.

[0014] Optional, also includes: Monitor the first energy deviation between the positive electrode power electronic component and the negative electrode power electronic component; Based on the first energy deviation, the positive electrode power electronic component is controlled to output a first positive AC voltage component, and the negative electrode power electronic component is controlled to output a first negative AC voltage component. The first positive AC voltage component and the first negative AC voltage component are used to generate an AC circulating current at the series connection point of the positive and negative power electronic components. The first energy deviation is eliminated by the AC circulating current to maintain the energy balance between the positive and negative power electronic components.

[0015] Optional, also includes: By utilizing the blocking characteristics of the first set of AC blocking devices in the interconnection device, the AC voltage and AC current generated by the positive AC voltage component and the negative AC voltage component are isolated from flowing into the third terminal of the interconnection device.

[0016] Optional, also includes: Monitor the second energy deviation between the positive electrode power electronic component and the negative electrode power electronic component; Based on the second energy deviation, the positive electrode power electronic component is controlled to output a second positive AC voltage component superimposed at the first intermediate lead-out point, and the negative electrode power electronic component is controlled to output a second negative AC voltage component superimposed at the second intermediate lead-out point. Using the second positive AC voltage component and the second negative AC voltage component, an AC current is generated at the first set of energy balancing devices in the interconnected device to eliminate the second energy deviation and maintain the energy balance between the positive and negative power electronic components.

[0017] Optional, also includes: During the transition from normal operation to unipolar operation of the true bipolar system, the transmission power from the pseudo bipolar system is monitored. If the transmission power exceeds the power limit of the single pole in the true bipolar system, at least one set of controllable resistors in the interconnect device is connected to consume the extra power exceeding the power limit of the transmission power.

[0018] On the other hand, the present invention also provides a computer device, characterized in that it includes: one or more processors; The processor is used to store one or more programs; When the one or more programs are executed by the one or more processors, the interconnection operation method of the interconnection device of the true and false bipolar system described in any one of the above is implemented.

[0019] On the other hand, the present invention also provides a computer-readable storage medium, characterized in that it stores a computer program thereon, wherein when the computer program is executed, it implements the interconnection operation method of the interconnection device of the true and false bipolar system described in any one of the above.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides an interconnection device for true and pseudo bipolar systems, comprising: multiple terminals, including a first terminal, a second terminal, and a third terminal; the first terminal connects to the positive terminal of the true bipolar system and the positive terminal of the pseudo bipolar system, the second terminal connects to the negative terminal of the true bipolar system and the negative terminal of the pseudo bipolar system, and the third terminal is grounded; a positive power electronic component and a negative power electronic component, which are connected in series to form a series combination, which is connected between the first terminal and the second terminal; the series connection point of the series combination is connected to the third terminal; a controller, which is electrically connected to both the positive and negative power electronic components; the controller is used to control the interconnection device under no-load when the true bipolar system is in normal operation; and to control the positive and negative power electronic components to output the same DC voltage when the true bipolar system is in unipolar operation, so as to maintain the symmetry of the positive and negative voltages of the pseudo bipolar system. This invention can achieve efficient interconnection and energy self-balancing of true and pseudo bipolar systems, possess the unipolar operation capability of the true bipolar system, and improve power supply reliability and operational flexibility.

[0021] This invention also provides an interconnection operation method for an interconnection device based on true and pseudo bipolar systems. In this method, the operating status of the true bipolar system is monitored. If the operating status is normal, the true bipolar system and the pseudo bipolar system are controlled to transmit current through positive and negative lines, and the interconnection device is unloaded. If the operating status is unipolar operation, the positive and negative power electronic components in the interconnection device are controlled to output the same DC voltage to maintain the symmetry of the positive and negative voltages of the pseudo bipolar system. This invention can achieve efficient interconnection and energy self-balancing of true and pseudo bipolar systems, possesses the unipolar operation capability of a true bipolar system, and improves power supply reliability and operational flexibility. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the interconnection device for a true and false bipolar system according to the present invention; Figure 2 This is a schematic diagram of the interconnection device of the series AC blocking device of the present invention; Figure 3 This is a schematic diagram of the interconnection device for connecting the energy balancing device of the present invention; Figure 4 This is a schematic diagram of the structure of an interconnection device under different voltage levels according to the present invention; Figure 5This is a schematic diagram of the structure of an interconnection device under different voltage levels according to the present invention; Figure 6 This is a schematic diagram of the structure of an interconnection device under different voltage levels according to the present invention; Figure 7 This is a schematic diagram of the structure of an interconnection device under different voltage levels according to the present invention; Figure 8 This is a schematic diagram of the structure of an interconnection device under different voltage levels according to the present invention; Figure 9 This is a schematic diagram of the structure of an interconnection device under different voltage levels according to the present invention; Figure 10 This is a schematic diagram of the interconnection operation method of an interconnection device for a true and false bipolar system according to the present invention; Figure 11 This is a schematic diagram of the interconnection operation system architecture of the interconnection device for the true and false bipolar systems of the present invention; Figure 12 This is a schematic diagram of the electronic device of the present invention. Detailed Implementation

[0023] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0024] Example 1: This invention provides an interconnection device for true and pseudo bipolar systems, such as... Figure 1 As shown, it includes: Multiple terminals, including a first terminal, a second terminal, and a third terminal; the first terminal connects to the positive terminal of the true bipolar system and the positive terminal of the pseudo bipolar system, the second terminal connects to the negative terminal of the true bipolar system and the negative terminal of the pseudo bipolar system, and the third terminal is grounded; A positive power electronic component and a negative power electronic component are connected in series to form a series combination. The series combination is connected between the first and second terminals. The series connection point of the series combination is connected to the third terminal. The controller is electrically connected to the positive and negative power electronic components respectively. The controller is used to control the interconnection device to be unloaded when the true bipolar system is in normal operation. When the true bipolar system is in unipolar operation, the controller controls the positive and negative power electronic components to output the same DC voltage to maintain the positive and negative voltage symmetry of the pseudo bipolar system.

[0025] The interconnection device provided in this embodiment of the invention can achieve efficient interconnection and energy self-balancing of true and false bipolar systems, and has the unipolar operation capability of a true bipolar system, thereby improving power supply reliability and operational flexibility.

[0026] like Figure 1As shown, the interconnection device is used to connect true and pseudo bipolar systems, wherein the positive lines of the true bipolar system and the pseudo bipolar system are interconnected, and the negative lines are interconnected. The true bipolar system includes converter station VSC (voltage source converter) 1 and VSC2, and the pseudo bipolar system includes converter station VSC.

[0027] Of the multiple terminals of this interconnection device, the first terminal (point A) is connected to the positive line and can be regarded as the positive common connection point, connecting to the positive terminal of the true bipolar system (such as the output terminal C of VSC1) and the positive terminal of the pseudo bipolar system respectively; the second terminal (point B) is connected to the negative line and can be regarded as the negative common connection point, connecting to the negative terminal of the true bipolar system (such as the output terminal E of VSC2) and the negative terminal of the pseudo bipolar system respectively; the third terminal (point S is led out to ground) serves as a grounding reference point and can be directly connected to the grounding electrode or the ground return line of the true bipolar system (connected to point D).

[0028] exist Figure 1 The positive electrode power electronic component is connected between point A and point S, and the negative electrode power electronic component is connected between point S and point B. The two power electronic components are electrically connected at the series connection point S and connected to the third terminal through point S.

[0029] Both the positive and negative power electronic components can adopt an MMC (Modular Multilevel Converter) or CHB (Cascaded H-bridge) topology. Specifically, the positive and negative power station components can be composed of multiple sub-modules connected in series. This series structure not only facilitates flexible adjustment of the device's voltage level by increasing or decreasing the number of sub-modules to adapt to the needs of true / pseudo-bipolar interconnection projects at different voltage levels, but also possesses inherent redundancy and fault tolerance capabilities.

[0030] Depending on the requirements for fault ride-through capability, cost control, and harmonic performance, submodules can be selected from topologies such as full-bridge, half-bridge, or full-half-bridge submodules. Furthermore, based on the voltage, current, and frequency characteristics of the application scenario, power semiconductor devices such as diodes, thyristors, IGBTs (Insulated Gate Bipolar Transistors), and IGCTs (Integrated Gate-Commutated Thyristors) can also be used. To ensure voltage balance and energy buffering between series-connected submodules, DC-side capacitors (such as film capacitors or electrolytic capacitors) or voltage-equalizing resistors (or voltage-equalizing circuits) can be integrated within the submodules. Through diverse submodule selection and structural design, this interconnect device can adapt to various true and pseudo-bipolar interconnect scenarios, ranging from low-cost distribution network level to high-performance transmission network level.

[0031] The control unit in this interconnected device can acquire voltage and current signals from each port and execute corresponding control logic. For example, it can switch between different control strategies based on the different operating states of the true bipolar system.

[0032] In one scenario, both VSC1 and VSC2 of a true bipolar system are operating normally, with symmetrical voltages between their positive and negative terminals and ground. The potential of the series connection point S is theoretically 0V (ground potential). At this point, the true bipolar system is in a bipolar equilibrium state and is operating normally. The control strategy for this scenario includes monitoring the true bipolar system to ensure it is operating normally and controlling the interconnect device to be unloaded and without current. Specifically, the positive and negative power electronic components in the interconnect device are in an unloaded or bypass state, with zero voltage difference between the two power electronic components. The AC point is directly connected, and the BE point is also directly connected. In this situation, the interconnect device does not actively interfere with the system's power transmission, and the true / false bipolar system is directly interconnected via a DC line.

[0033] In another scenario, if the positive (or negative) converter of a true bipolar system shuts down, or the pole is disconnected and the pole circuit breaker trips, but the system remains operational, the positive (or negative) current will flow into the first (or second) terminal of the three-terminal interconnection device and out from the third and second (or first) terminals, achieving power transfer between the positive (or negative) converter of the pseudo-bipolar system and the true bipolar system. The true bipolar system then switches to unipolar operation mode until it switches to unipolar operation. Without intervention, the voltage asymmetry between the positive and negative poles of the pseudo-bipolar system and ground will be severe, threatening the insulation safety of the equipment. The control strategy for this scenario includes monitoring the true bipolar system to enter unipolar operation (which can be determined by detecting a pole being blocked or the pole current being zero), controlling the positive and negative power electronic components to output the same DC voltage, maintaining the voltage symmetry between the positive and negative poles of the pseudo-bipolar system, and achieving symmetry maintenance and energy balance of the pseudo-bipolar system. Specifically, through this control strategy, the positive and negative poles of the pseudo-bipolar system acquire voltages of equal magnitude but opposite polarity relative to point S, thus restoring the voltage symmetry between the positive and negative poles and enabling continued reduced-power operation. Meanwhile, the non-deactivated pole of the true bipolar system can continue to deliver power normally through the interconnection device, achieving independent unipolar operation. This interconnection device controls the output of two series-connected power electronic components to output the same DC voltage. During unipolar operation on the true bipolar side, it constructs a virtual neutral point for the pseudo-bipolar side, ensuring voltage symmetry and safe, stable operation of the pseudo-bipolar system. This allows the true bipolar system to maintain normal operation of the other pole even when one pole fails, improving system availability.

[0034] When using this interconnection device to achieve energy balancing, the first approach is to utilize the interconnection device itself to balance energy, for example... Figure 2 As shown, the interconnection device may also include a first set of AC blocking devices, which are connected between the series point and the third terminal. The first set of AC blocking devices is used to block the AC voltage and AC current generated between the positive and negative power electronic components from overflowing to the third terminal.

[0035] exist Figure 2 In the first set of AC blocking devices, the first set of devices is connected in series between point S and the third terminal (grounding terminal). Since the lower end of the positive power electronic component and the upper end of the negative power electronic component meet at the series point S, the interconnection device realizes the isolation between the internal AC network and the external ground potential.

[0036] The first set of AC blocking devices can function as DC blocking and AC blocking devices. Specifically, it allows and maintains the flow of AC current generated between the positive and negative power electronic components in the series circuit formed by the two, thus forming a closed internal AC network.

[0037] The first AC blocking device also functions as a controllable blocking device. Specifically, it can effectively block the flow of additional AC voltage and current from the two power electronic components to the third terminal (ground). This prevents additional AC voltage and current from being discharged through the grounding point, ensuring an effective energy transfer channel between the positive and negative power electronic components and preventing interference with the grounding reference point potential of the true bipolar system.

[0038] To achieve energy balance, the controller can control the positive power electronic component to superimpose an additional positive AC voltage component on its DC output voltage. This positive AC voltage component can be a sine wave, square wave, or trapezoidal wave. Simultaneously, it controls the negative power electronic component to superimpose a negative AC voltage component of equal amplitude but opposite phase. Since the AC voltage components output by the two power electronic components have opposite polarities, a potential difference can be formed at the series connection point S, thereby generating an internal AC circulating current in the closed loop of the positive power electronic component - series connection point S - negative power electronic component. This AC commutation carries energy from the power surplus side to the power deficit side, achieving energy balance. It is understandable that this energy balance implementation method is not excluded in different operating states of a true bipolar system.

[0039] During the control process, the energy balance principle that the AC power of the power electronic components equals the DC power can be followed.

[0040] The first group of AC blocking devices includes bridge arms with multiple sub-modules connected in series, or reactors, or transformers, or bridge arms with multiple power devices connected in series.

[0041] In this implementation, the first set of AC blocking devices can form a closed-loop energy transmission, avoiding unnecessary AC stress on the true bipolar system's insulation to ground, thus ensuring equipment safety.

[0042] In addition to the energy balancing framework with internal series circulation shown in the first implementation method above, this embodiment of the invention also provides a second implementation method for achieving energy balancing using this interconnection device. This method involves constructing independent parallel energy balancing branches to achieve power exchange between the positive and negative electrodes, thereby achieving energy balancing. For example... Figure 3 As shown, the interconnection device may also include a first set of energy balancing devices; The positive electrode power electronic component has a first intermediate lead-out point, and the negative electrode power electronic component has a second intermediate lead-out point; The first set of energy balancing devices is connected between the first intermediate lead and the second intermediate lead; the first set of energy balancing devices is used to provide an AC path for the positive and negative power electronic components to maintain the AC current energy balance between the positive and negative power electronic components.

[0043] In this implementation, an electrical connection point can be drawn from the electrical midpoint of the positive power electronic component (such as at 50% of the submodule series link, or at other specific proportional locations) as the first intermediate lead-out point. Similarly, an electrical connection point can be drawn from the electrical midpoint of the negative power electronic component as the second intermediate lead-out point. These two leads electrically divide the originally single long bridge arm into upper and lower parts, providing a new voltage injection interface. The first set of energy balancing devices is directly connected between the two leads, forming an independent AC path connecting the midpoints of the positive and negative power electronic components. The positive and negative power electronic components actively output AC voltage, and the energy balancing device transmits AC current between them to achieve energy balance.

[0044] The first set of energy balancing devices can provide a low-impedance or controllable AC current path. Specifically, it allows the AC components generated by the positive and negative power electronic components to flow between each other through the energy balancing device, achieving AC coupling.

[0045] To achieve energy balance, the controller can generate a specific AC voltage difference between the upper and lower parts of the positive power electronic component and an AC voltage difference with opposite phase between the upper and lower parts of the negative power electronic component. These two sets of AC voltage differences can drive AC current to flow through the energy balancing device. By controlling the direction and magnitude of the current, energy can be pumped from the power surplus side to the power deficit side. This control strategy mainly forms a closed AC energy exchange loop through local AC voltage modulation: upper part of the positive power electronic component - first intermediate lead-first energy balancing device - second intermediate lead-lower part of the negative power electronic component - ground / load loop - upper part of the negative power electronic component - lower part of the positive power electronic component, which can balance energy deviation in real time. It is understandable that this energy balance implementation method is not excluded in different operating states of a true bipolar system.

[0046] During the control process, the energy balance principle that the AC power of the power electronic components equals the DC power can be followed.

[0047] The first energy balancing device comprises bridge arms with multiple sub-modules connected in series, or bridge arms with capacitors, or transformers, or bridge arms with multiple power devices connected in series. The topology of the first energy balancing device can be selected based on requirements for cost, size, and control flexibility.

[0048] In this implementation, the energy balance circuit and the main DC circuit are decoupled to a certain extent in terms of topology, which can improve the flexibility of AC energy injection and reduce the impact on the main DC voltage waveform; and AC injection from the middle point of the power electronic components can reduce the voltage stress and switching losses borne by individual sub-modules.

[0049] To address the power surplus issue caused by the sudden drop in maximum power to 50% when a true bipolar system switches to unipolar operation mode, resulting in the inability of the pseudo bipolar system to match the power instantaneously, in one implementation, the interconnect device may further include at least one set of controllable resistors; at least one set of controllable resistors is connected between the first and second terminals and in parallel with the series combination; or, at least one set of controllable resistors is connected in parallel across the capacitors of the positive power electronic component and / or the submodule within the negative power electronic component. At least one set of controllable resistors is used to dissipate the extra power transmitted by the pseudo-bipolar system during the transition from normal operation to unipolar operation in the true bipolar system.

[0050] This implementation provides at least two ways to connect the controllable resistor: Connection Method 1: Centralized Parallel Connection, for System-Level Energy Consumption. In this connection method, the controllable resistor is treated as an independent energy-consuming unit and is directly connected in parallel between the first terminal A and the second terminal B. At this time, at least one set of controllable resistors is connected across the entire DC bus, which can absorb the overall excess power between the positive and negative terminals.

[0051] Connection Method Two: Distributed Parallel Connection, applied to submodule-level energy consumption. In this connection method, controllable resistors are distributed within the positive and / or negative power electronic components. In each (or group of) submodules constituting the power electronic components, a set of controllable resistors is connected in parallel across the DC-side capacitor (hereinafter referred to as the submodule capacitor) of that submodule. This connection method facilitates uniform heat dissipation, avoids localized overheating, and allows for more precise voltage balance between submodules.

[0052] The above connection methods can be flexibly selected according to the thermal management and space constraints of the actual project, ensuring the survivability and power supply reliability of the interconnected devices under extreme operating conditions.

[0053] In addition to the connection methods described above, controllable resistors can also possess active controllable structures and equivalent resistance adjustment capabilities. For example, in an active controllable structure, the controllable resistor is not a simple fixed-value resistor, but a composite branch consisting of a power semiconductor device (such as an IGBT, MOSFET, or thyristor) connected in series with a resistor. The controller can adjust the equivalent resistance of the controllable resistor by changing the control signal of the power semiconductor device. When the power semiconductor device is completely off, the equivalent resistance is infinite, indicating a high-resistance state. When the power semiconductor device is on at high frequency, the equivalent resistance is close to the physical resistance, indicating a low-resistance state. In the default state, if the system is operating normally and there is no power surplus, the controllable resistor can be placed in a high-resistance state. In this state, the controllable resistor consumes almost no power and does not affect system efficiency. Utilizing the fast switching characteristics of power semiconductor devices, the switching on and off of the controllable resistor can be completed in microseconds, achieving rapid response.

[0054] Considering that after a true bipolar system switches to unipolar operation mode, with only half of the converter remaining, the system's maximum power drops to 50% of the original system. During the switching process, the pseudo-bipolar system cannot instantly reduce its power, resulting in a delay and transition. Therefore, during the transition from normal to unipolar operation, the pseudo-bipolar system, due to the inertia and delay of power regulation, maintains a relatively high total input power, leading to additional power exceeding the unipolar operation power limit (such as additional power exceeding 50% transmitted from the pseudo-bipolar system). Therefore, the controller can actively limit the transmission current flowing to the third terminal (i.e., the non-deactivated pole) to ensure that the power transmitted to the negative (or positive) converter of the positive bipolar system does not exceed 50%. Furthermore, since the additional power cannot be delivered in time, it is absorbed by the positive and negative power electronic components. This energy is temporarily stored in the submodule capacitor in the form of an electrical field, manifesting as a momentary rise in capacitor voltage. Once the controller detects that the capacitance exceeds a preset threshold, it immediately drives the power semiconductor device in the controllable resistor to switch from a high-resistance state to a low-resistance state (actively reducing its own resistance). The extra electrical energy stored in the submodule capacitor is converted into heat energy and dissipated through the controllable resistor, stabilizing the capacitor voltage within a safe range. After a transition period, the pseudo-bipolar system completes the power reduction, and its output power gradually decreases and stabilizes near 50% of the rated power. When the controller detects that the power of the pseudo-bipolar system has stabilized and the capacitor voltage has fallen back to a safe range, it can readjust the control signal of the power semiconductor device to restore it to a high-resistance state, stop energy consumption, and the system enters a new steady-state operation. This smooth transition control process can effectively solve the power imbalance problem during the instantaneous derating operation of a true bipolar system and avoid DC overvoltage tripping caused by power surplus.

[0055] Depending on the voltage level, power capacity, and harmonic suppression requirements of the application scenario, the interconnection device can flexibly adopt a single-phase or multi-phase arrangement structure.

[0056] For example, when interconnection devices are applied to small- to medium-capacity distribution networks, a single-phase arrangement can be used. If the interconnection device adopts a single-phase arrangement, it includes one set of positive power electronic components and one set of negative power electronic components, forming a single power transmission channel. In a single-phase structure, the AC voltage component injected to maintain positive and negative energy balance may generate second harmonic ripple voltage and current on the DC bus. If these harmonics are transmitted to a true bipolar or pseudo-bipolar system, they can affect power quality and even induce resonance. Therefore, the interconnection device can also include a capacitive filter.

[0057] A capacitive filter is connected between any two ends of a multi-terminal circuit. For example, a capacitive filter connected between the positive and negative buses, with one end connected to the first terminal and the other end connected to the second terminal, can absorb AC ripple voltage between the positive and negative terminals. Similarly, a capacitive filter connected between the positive and third terminals, with its connection between the first and third terminals, can suppress positive-to-ground harmonics. Likewise, a capacitive filter connected between the negative and third terminals, with its connection between the second and third terminals, can suppress negative-to-ground harmonics.

[0058] For example, a capacitive filter can consist of a high-voltage film capacitor, an electrolytic capacitor bank, or a tuned branch consisting of a capacitor and a reactor connected in series. Its capacitance value can be designed based on the frequency of the injected AC component and the target impedance. In single-phase operation mode, when the positive and negative power electronic components inject AC voltage for energy exchange, the resulting AC current component tends to flow along the path of lowest impedance. Because the capacitive filter exhibits low impedance characteristics to AC signals, most of the AC harmonic current will be confined within the local loop formed by the power electronic components and the capacitive filter, and will not overflow into the external true bipolar or pseudo bipolar DC system lines. Therefore, the voltage purity of the external DC system can be ensured.

[0059] For example, when interconnection devices are applied to high-capacity, high-voltage power transmission projects, a multi-phase arrangement can be adopted. Taking a three-phase arrangement as an example, the interconnection device includes a set of independent positive and negative power electronic components for each phase. The three phases can operate using a control strategy with a 120° phase difference. The three-phase AC components are staggered in time phase, and the specific harmonics generated on the DC side can cancel each other out, providing a smoother power transmission waveform, reducing voltage fluctuations in submodule capacitors, and meeting power quality requirements.

[0060] In some scenarios, if the true bipolar system and the pseudo bipolar system are at different voltage levels, then except... Figure 1 In addition to the three-terminal interconnection device shown, the wiring ports can also be expanded, such as... Figures 4 to 9 As shown, the multiple terminals also include a fourth terminal and a fifth terminal; The fourth terminal includes a first tap terminal extending from the middle of the positive power electronic component, which is connected to the positive terminal of the pseudo-bipolar system. The first tap terminal divides the positive power electronic component into a first positive power electronic component and a second positive power electronic component. The fifth terminal includes a second tap terminal extending from the middle of the negative power electronic component, which is connected to the negative terminal of the pseudo-bipolar system. The second tap terminal divides the negative power electronic component into a first negative power electronic component and a second negative power electronic component.

[0061] The fourth terminal can be a dedicated tap terminal led out from the electrical center of the positive power electronic component. The potential of this point to ground is about half of the positive voltage of the true bipolar system (assuming the power electronic component structure is symmetrical), thus forming a lower DC voltage output. Similarly, the fifth terminal can be a dedicated tap terminal led out from the electrical center of the negative power electronic component. The potential of this point to ground is about half of the negative voltage of the true bipolar system, thus forming a corresponding negative low voltage output.

[0062] like Figures 4 to 9 As shown, the positive and negative power electronic components are logically or physically divided into two parts (such as an upper half-bridge arm and a lower half-bridge arm) in their internal structure. The positive power electronic component consists of a first positive power electronic component (the upper half-bridge arm in the figure) and a second positive power electronic component (the lower half-bridge arm in the figure) connected in series. Terminal A is connected to the top of the upper part, terminal B is connected to the bottom of the lower part (or grounded through other components), and terminal C is led out from the connection point (midpoint) of the upper and lower half-bridge arms. The negative power electronic component is similar, consisting of a first negative power electronic component (the upper half-bridge arm in the figure) and a second negative power electronic component (the lower half-bridge arm in the figure) connected in series, with terminal D leading out from the midpoint. The voltage between the first and second terminals on the true bipolar side is shared by the complete positive and negative power electronic components, while the voltage between the fourth and fifth terminals on the negative bipolar side is shared by the lower half-bridge arm of the positive power electronic component (i.e., the second positive power electronic component) and the upper half-bridge arm of the negative power electronic component (i.e., the first negative power electronic component). It is understandable that by adjusting the position of the lead-out point in the power electronic component, the voltage ratio on the positive and negative sides can be flexibly set to adapt to various voltage level combinations.

[0063] Correspondingly, the controller can perform hierarchical control on both the true and pseudo bipolar sides. For the positive bipolar side, it controls all submodules in the positive and negative power electronic components to work collaboratively, maintaining stable voltages to ground at both terminals and meeting the power transmission requirements of the true bipolar system. For the negative bipolar side, it dynamically adjusts the ratio of the number of upper and lower half-bridge arm submodules in the positive and negative power electronic components, or compensates for voltage deviations through adjustment strategies. This ensures the power supply quality of the pseudo bipolar system even when voltage fluctuations occur in the true bipolar system. Furthermore, when there is a power imbalance between the true and pseudo bipolar systems, it can control the flow of energy between the upper and lower half-bridge arms in the positive and negative power electronic components, achieving power support across voltage levels.

[0064] Injecting AC components for energy balancing into the positive and negative power electronic components may cause harmonic pollution to the pseudo-bipolar system. Therefore, embodiments of the present invention may further include a second set of AC blocking devices. Furthermore, to perform local power regulation on the pseudo-bipolar system, embodiments of the present invention may further include a second energy balancing device. For example, it may also include a second set of AC blocking devices and / or a second set of energy balancing devices. The second set of AC blocking devices may include at least one of the following connection relationships: the second set of AC blocking devices is connected between the fourth terminal and the positive terminal of the pseudo-bipolar system, and the second set of AC blocking devices is connected between the fifth terminal and the negative terminal of the pseudo-bipolar system. The second set of energy balancing devices may include at least one of the following connection relationships: the two ends of the second set of energy balancing devices are respectively connected to the first positive electrode power electronic component and the second positive electrode power electronic component, and the two ends of the second set of energy balancing devices are respectively connected to the first negative electrode power electronic component and the second negative electrode power electronic component.

[0065] The second set of AC blocking devices may include bridge arms with multiple sub-modules connected in series, or reactors, or transformers, or bridge arms with multiple power devices connected in series; the second set of energy balancing devices may include bridge arms with multiple sub-modules connected in series, or capacitors, or transformers, or bridge arms with multiple power devices connected in series.

[0066] See Figure 4 The second set of AC blocking devices is connected in series between the fourth terminal and the positive terminal of the pseudo-bipolar system. This can be used to filter or block AC ripple voltage generated from the positive power electronic component (especially its lower half-bridge arm, i.e., the second positive power electronic component). The second set of AC blocking devices is also connected in series between the fifth terminal and the negative terminal of the pseudo-bipolar system. This can be used to filter or block AC ripple voltage generated from the negative power electronic component (especially its upper half-bridge arm, i.e., the first negative power electronic component). When both sets of AC blocking devices are present simultaneously, a high level of harmonic distortion can be provided, ensuring that there are no AC components in the outputs on both sides even when AC injection within the positive and negative power electronic components is asymmetrical.

[0067] See Figure 5 The first set of energy balancing devices is connected between the fourth and fifth terminals. The second set of energy balancing devices is connected between the upper and lower half-arms of the positive power electronic component and between the upper and lower half-arms of the negative power electronic component. When a unipolar fault occurs in the true bipolar system and the unbalanced power is mainly concentrated in the pseudo-bipolar system, the second set of energy balancing devices can be driven first. The second set of energy balancing devices can also independently adjust the active and reactive power flowing to the pseudo-bipolar system, improving the system control flexibility and decoupling capability.

[0068] remove Figure 4 and Figure 5 In addition to the connection method, the second set of AC blocking devices and the second set of energy balancing devices can also be configured according to... Figure 6 , Figure 7 , Figure 8 and Figure 9 The connection methods shown are for accessing various control needs.

[0069] To address the technical shortcomings of existing true / false bipolar interconnected systems, which often result in complete system shutdown or significant power limitation after a fault in one pole of the true bipolar side, this solution proposes an interconnection device that supports independent operation of a single pole in a true bipolar system. For true / false bipolar system interconnection scenarios, this interconnection scheme can establish a non-exited pole operating path using the interconnection device after a primary pole of the true bipolar system fails, balancing power transmission between the positive and negative poles of the true bipolar side, and achieving independent and reliable operation of the single pole of the true bipolar system under true / false bipolar interconnection. Specifically, by configuring segmented power electronic components with midpoint lead-out capability in the interconnection device, along with a second set of energy balancing devices and a second set of AC blocking devices, the electrical connection relationship can be dynamically reconstructed after one pole of the true bipolar system fails, establishing an independent operating mode where only the non-exited pole bears the power transmission. Simultaneously, controllable resistors and energy balancing circuits are used to dissipate the transient surplus power during switching and block the transmission of AC components to the false bipolar side. Thus, while ensuring power quality, continuous, stable, and independent operation of the true bipolar system under extreme fault conditions is achieved, maximizing system availability.

[0070] Example 2: Based on the same inventive concept, this invention also provides a method flow for interconnecting a true and false bipolar system interconnection device, such as... Figure 10 As shown, it includes: Step 101: Monitor the operating status of the true bipolar system; Step 102: If the operating status is normal, control the true bipolar system and the pseudo bipolar system to transmit current through the positive and negative lines, and the interconnection device is unloaded; Step 103: If the operating state is unipolar operation, the positive and negative power electronic components in the control interconnection device output the same DC voltage to maintain the positive and negative voltage symmetry of the pseudo-bipolar system.

[0071] The embodiments of the present invention can achieve efficient interconnection and energy self-balancing of true and false bipolar systems, possess the unipolar operation capability of a true bipolar system, and improve power supply reliability and operational flexibility.

[0072] The interconnection device for the true and false bipolar systems involved in the embodiments of the present invention is as shown in the above embodiments, and the repeated parts will not be described again.

[0073] In step 101 above, the interconnection device can collect the operating status signals of the true bipolar system in real time through the controller. These signals include, for example, the voltage and current of the positive pole and the negative pole of the true bipolar system, the lockout / unlocking status of the converter station of the true bipolar system, and DC line protection action signals (such as inter-pole short-circuit protection and grounding protection). After collecting the operating status signals, the controller can calculate the inter-pole imbalance and voltage deviation of the true bipolar system. If the voltage deviation is 0, the inter-pole imbalance is less than the set imbalance threshold, and there is no protection lockout, then the true bipolar side is determined to be in normal operating condition. Otherwise, if the current or voltage of one pole of the true bipolar system is 0, and the signal of that pole exiting operation is received, while the other pole (the pole that has not exited operation) still maintains high voltage output, then the true bipolar system is determined to be in unipolar operating condition.

[0074] In one implementation, during step 102 above, when the true bipolar system is in normal operation, the controller can control the interconnecting device to be in an unloaded bypass state with the aim of minimizing losses. For example, it can control all sub-modules in the positive and negative power electronic components to be bypassed or output at zero level, or close the parallel bypass switch (if any). In this case, the true bipolar system and the pseudo bipolar system operate independently through their respective converter stations, and the interconnecting device does not actively inject power, but only exists as a low-impedance channel (or is electrically isolated).

[0075] In one implementation, in step 103 above, when the true bipolar system is in unipolar operation, the controller can immediately unlock the positive and negative power electronic components of the interconnecting device. The controller aims to control the positive and negative power electronic components in a coordinated manner, using the voltage difference between the positive and negative terminals of the interconnecting device and ground as the rated half-pole voltage of the pseudo-bipolar system. For example, the controller adjusts the number of sub-modules in the positive power electronic component to output a specific DC voltage. Since one pole of the true bipolar system is deactivated, the positive power electronic component must undertake the task of converting the high voltage of the pole that is not deactivated in the true bipolar system or supporting the positive voltage required by the pseudo-bipolar system. The controller also controls the negative power electronic component to output a DC voltage with the same amplitude but opposite polarity as the positive power electronic component, ensuring that the positive and negative voltages provided by the interconnecting device to the pseudo-bipolar system always remain symmetrical about ground potential.

[0076] For the problem of energy accumulation or loss due to load asymmetry between positive and negative power electronic components, or due to unipolar disconnection in a true bipolar system, one implementation method may also include: Monitor the first energy deviation between the positive and negative power electronic components; Based on the first energy deviation, the positive electrode power electronic component is controlled to output a first positive AC voltage component, and the negative electrode power electronic component is controlled to output a first negative AC voltage component. An AC circulating current is generated at the series connection point of the positive and negative power electronic components using the first positive AC voltage component and the first negative AC voltage component. The first energy deviation is eliminated by the AC circulating current to maintain the energy balance between the positive and negative power electronic components.

[0077] In this implementation, the absorbed power of the positive and negative power electronic components can be collected in real time, and the difference between the two is taken as the first deviation power. Based on this first deviation power, the controller can use an AC circulating current injection strategy to superimpose AC components of the same amplitude but opposite polarity onto the original DC reference voltage of the positive and negative power electronic components. Since the positive and negative power electronic components are electrically connected in series, the two opposite AC voltage components will generate a potential difference at the series connection point. This potential difference drives the AC circulating current to flow between the positive and negative power electronic components instead of flowing through the external DC line, thus achieving energy balance.

[0078] For example, the AC injection strategy can be a common-mode and differential-mode separation injection strategy. Under this strategy, the controller measures the current of the positive and negative power electronic components and separates the common-mode current and differential-mode current. Based on the first deviation power, the common-mode current reference value is calculated by proportional-integral control. The voltage reference values ​​of the positive and negative power electronic components are generated by vector current control. The differential-mode current is decoupled to control the energy balance of the AC blocking device.

[0079] When implementing the aforementioned AC circulating current injection strategy, it is necessary to prevent the generated AC voltage and current from leaking into the external power grid, especially preventing them from flowing into the third terminal, to avoid overheating of the grounding system, malfunction of protection systems, or deterioration of power quality. The blocking characteristics of the first set of AC blocking devices can also be used for isolation. For example, the blocking characteristics of the first set of AC blocking devices in the interconnection device can also be used to isolate the AC voltage and current generated by the positive and negative AC voltage components from flowing into the third terminal of the interconnection device.

[0080] In this example, the high AC impedance characteristics of the first set of AC blocking devices ensure that the fluctuating voltage at the series connection point falls almost entirely across the two ends of the device and is not transmitted to the third end. Furthermore, the high and low impedance switching of the device can also isolate AC circulating current components that attempt to flow to the third segment.

[0081] To further eliminate the problems of uneven voltage distribution or lag in dynamic response of capacitors in sub-modules within the positive and negative power electronic components, one implementation may further include: Monitor the second energy deviation between the positive and negative power electronic components; Based on the second energy deviation, the positive electrode power electronic component is controlled to output a second positive AC voltage component superimposed at the first intermediate lead-out point, and the negative electrode power electronic component is controlled to output a second negative AC voltage component superimposed at the second intermediate lead-out point. By utilizing the second positive AC voltage component and the second negative AC voltage component, an AC current is generated at the first set of energy balancing devices of the interconnected device to eliminate the second energy deviation and maintain the energy balance between the positive and negative power electronic components.

[0082] In this implementation, the average submodule capacitor voltage of the upper and lower half-bridge arms of the positive and negative power electronic components, or the current distribution flowing through specific nodes within the components, can be monitored. For example, the energy difference between the average submodule capacitor voltage of the upper half-bridge arm (first positive power electronic component) of the positive power electronic component and the lower half-bridge arm (second negative power electronic component) of the negative power electronic component can be used as a second energy deviation. This energy deviation may cause overvoltage or undervoltage lockout of some submodules, affecting the operational stability of the device.

[0083] Based on the second energy deviation, the controller can use a distributed intermediate point injection strategy to locally excite the positive and negative power electronic components. It adjusts the modulation waves of the sub-modules in the upper and lower half-bridge arms of the positive power electronic component, causing a second positive AC voltage component to be generated at the first intermediate lead-out point relative to the DC neutral point. Similarly, the negative power electronic component generates a second negative AC voltage component at the second intermediate lead-out point relative to the DC neutral point. The second positive and second negative AC voltage components typically have equal amplitudes but opposite phases to create the maximum driving potential difference. This potential difference is directly applied to the equivalent impedance of the first energy balancing device, which can induce a large AC current within it. By adjusting the phase relationship between this AC current and voltage, the direction of active power flow can be controlled, thus eliminating the second energy deviation.

[0084] For example, the above-mentioned distributed intermediate point injection strategy can be a circulating current injection strategy based on AC / DC separation. In this strategy, a constant AC voltage is first superimposed on the first and second intermediate leads. The instantaneous voltages of the first and second intermediate leads are collected and decomposed into DC and AC voltages. Unipolar operation leads to the generation of a second deviation power. The second deviation power is used as a negative feedback signal and input to the proportional-integral controller in real time to continuously generate the reference current of the first set of energy balancing devices. Based on the reference current, an AC voltage correction amount is dynamically generated through vector current control to adjust and correct the AC voltages of the first and second intermediate leads. Finally, the AC voltage correction amount and the constant AC voltage amount are superimposed on the DC voltage to generate the reference voltages of the first and second intermediate leads, so as to control the superimposed output of a second positive AC voltage component and a second negative AC voltage component.

[0085] In one implementation, the embodiments of the present invention may further include: During the transition of a true bipolar system from normal operation to unipolar operation, the transmission power from the pseudo bipolar system is monitored. If the transmission power exceeds the power limit of the single pole operating in a true bipolar system, at least one set of controllable resistors in the interconnect device is connected to consume the extra power exceeding the power limit.

[0086] In this implementation, if the transmitted power exceeds the power limit of the operating unipolar pole (i.e., the pole that has not been deactivated), the difference is used as additional power. One or more sets of controllable resistors are selected based on the power dissipation of each set of reliable resistors, ensuring that the total rated power dissipation is not less than this additional power. Then, a switching signal is sent to the selected resistors, and the additional power is directed to the activated resistors, where it is dissipated as heat. When the true bipolar system stabilizes in unipolar operation, these selected resistors can be disconnected, completing the protection during this transition process.

[0087] Example 3: Based on the same inventive concept, this invention also provides an interconnection operation system for interconnection devices based on true and false bipolar systems, as shown in the schematic diagram below. Figure 11 As shown, it includes: The monitoring module is used to monitor the operating status of the true bipolar system; The control module is used to control the transmission of current between the true bipolar system and the pseudo bipolar system through the positive and negative lines when the operating state is normal, and the interconnection device is unloaded; when the operating state is unipolar, it controls the positive and negative power electronic components in the interconnection device to output the same DC voltage to maintain the symmetry of the positive and negative voltages of the pseudo bipolar system.

[0088] In one specific implementation, the monitoring module is also used to monitor the first energy deviation between the positive and negative power electronic components; The control module is also used to control the positive power electronic component to output a first positive AC voltage component and the negative power electronic component to output a first negative AC voltage component based on the first energy deviation; and to use the first positive AC voltage component and the first negative AC voltage component to generate an AC circulating current at the series connection point of the positive and negative power electronic components, thereby eliminating the first energy deviation and maintaining the energy balance between the positive and negative power electronic components.

[0089] In one specific implementation, the control module is also used to utilize the blocking characteristics of the first set of AC blocking devices in the interconnecting device to isolate the AC voltage and AC current generated by the positive AC voltage component and the negative AC voltage component from flowing into the third terminal of the interconnecting device.

[0090] In one specific implementation, the monitoring module is also used to monitor a second energy deviation between the positive and negative power electronic components; The control module is also used to control the positive power electronic component to output a second positive AC voltage component superimposed at the first intermediate lead point, and the negative power electronic component to output a second negative AC voltage component superimposed at the second intermediate lead point, based on the second energy deviation; using the second positive AC voltage component and the second negative AC voltage component, an AC current is generated at the first set of energy balancing devices of the interconnection device to eliminate the second energy deviation and maintain the energy balance between the positive power electronic component and the negative power electronic component.

[0091] In one specific implementation, the monitoring module is also used to monitor the transmission power from the pseudo-bipolar system during the transition of the true bipolar system from normal operation to unipolar operation. The control module is also used to, if the transmission power exceeds the power limit of the single pole operating in the true bipolar system, to connect at least one set of controllable resistors in the interconnect device to consume the extra power exceeding the power limit of the transmission power.

[0092] Example 4: like Figure 12 As shown, the present invention also provides an electronic device, which may be a computer device, a microcontroller device, a smart mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, processor, and transceiver component are connected via a bus; the memory can be used to store executable programs, and an exemplary executable program may include instructions; the processor is used to execute the instructions stored in the memory. The memory can also be used to store data, which can be accessed and / or modified when instructions are executed.

[0093] The processor may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, and it is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions in the storage medium to realize the corresponding method flow or corresponding function, so as to realize the steps of the interconnection operation method of an interconnection device based on a true and pseudo bipolar system in the above embodiments.

[0094] Example 5: Based on the same inventive concept, this invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory). This readable storage medium is a memory device within an electronic device used to store programs and data. It is understood that the storage medium here can include both built-in storage media within the electronic device and extended storage media supported by the electronic device. The storage medium provides storage space, which stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more executable programs (including program code). It should be noted that the storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. Loading and executing one or more instructions stored in the storage medium by the processor can implement the steps of the interconnection operation method for an interconnection device based on a true / false bipolar system in the above embodiments.

[0095] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0096] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0097] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1The function specified in one or more boxes.

[0098] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading the present invention, they can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the scope of protection of the claims pending approval.

Claims

1. An interconnection device for true and false bipolar systems, characterized in that, include: Multiple terminals, including a first terminal, a second terminal, and a third terminal; the first terminal is connected to the positive terminal of the true bipolar system and the positive terminal of the pseudo bipolar system, the second terminal is connected to the negative terminal of the true bipolar system and the negative terminal of the pseudo bipolar system, and the third terminal is grounded; A positive power electronic component and a negative power electronic component are connected in series to form a series combination, which is connected between the first end and the second end; the series connection point of the series combination is connected to the third end. A controller is electrically connected to the positive power electronic component and the negative power electronic component respectively; the controller is used to control the interconnection device to be unloaded when the true bipolar system is in normal operation. When the true bipolar system is in unipolar operation, the positive and negative power electronic components are controlled to output the same DC voltage to maintain the symmetry of the positive and negative voltages of the pseudo bipolar system.

2. The interconnection device as claimed in claim 1, characterized in that, It also includes a first set of AC blocking devices, which are connected between the series connection point and the third terminal; The first set of AC blocking devices is used to block the AC voltage and AC current generated between the positive and negative power electronic components from overflowing to the third terminal.

3. The interconnection device as claimed in claim 2, characterized in that, It also includes the first set of energy balancing devices; The positive electrode power electronic component has a first intermediate lead-out point, and the negative electrode power electronic component has a second intermediate lead-out point; The first set of energy balancing devices is connected between the first intermediate lead and the second intermediate lead; the first set of energy balancing devices is used to provide an AC path for the positive power electronic component and the negative power electronic component to maintain the AC current energy balance between the positive power electronic component and the negative power electronic component.

4. The interconnection device as claimed in claim 1, characterized in that, It also includes at least one set of controllable resistors; the at least one set of controllable resistors is connected between the first end and the second end, and is connected in parallel with the series combination; or, the at least one set of controllable resistors is connected in parallel with the capacitors of the positive power electronic component and / or the sub-modules within the negative power electronic component. The at least one set of controllable resistors is used to consume the extra power transmitted by the pseudo-bipolar system during the transition from normal operation to unipolar operation of the true bipolar system.

5. The interconnection device as claimed in claim 1, characterized in that, The interconnection device adopts a single-phase arrangement structure or a multi-phase arrangement structure; If the interconnection device adopts the single-phase arrangement structure, it further includes a capacitive filter connected between the first end and the second end, and between the second end and the third end.

6. The interconnection device as claimed in claim 3, characterized in that, If the true bipolar system and the pseudo bipolar system are at different voltage levels, then the plurality of terminals also include a fourth terminal and a fifth terminal; The fourth terminal includes a first tap terminal extending from the middle of the positive power electronic component, which is connected to the positive terminal of the pseudo-bipolar system. The first tap terminal divides the positive power electronic component into a first positive power electronic component and a second positive power electronic component. The fifth terminal includes a second tap terminal extending from the middle of the negative electrode power electronic component, which is connected to the negative electrode of the pseudo-bipolar system. The second tap terminal divides the negative electrode power electronic component into a first negative electrode power electronic component and a second negative electrode power electronic component.

7. The interconnection device as claimed in claim 6, characterized in that, It also includes a second set of AC blocking devices and / or a second set of energy balancing devices; The second set of AC blocking devices includes at least one of the following connection relationships: the second set of AC blocking devices is connected between the fourth terminal and the positive terminal of the pseudo-bipolar system, and the second set of AC blocking devices is connected between the fifth terminal and the negative terminal of the pseudo-bipolar system; The second set of energy balancing devices includes at least one of the following connection relationships: the two ends of the second set of energy balancing devices are respectively connected to the first positive electrode power electronic component and the second positive electrode power electronic component, and the two ends of the second set of energy balancing devices are respectively connected to the first negative electrode power electronic component and the second negative electrode power electronic component.

8. The interconnection device as claimed in claim 7, characterized in that, The first group of AC blocking devices and the second group of AC blocking devices include bridge arms with multiple sub-modules connected in series, or reactors, or transformers, or bridge arms with multiple power devices connected in series; The first group of energy balancing devices and the second group of energy balancing devices include bridge arms with multiple sub-modules connected in series, or capacitors, or transformers, or bridge arms with multiple power devices connected in series.

9. A method for interconnecting and operating a device based on a true / false bipolar system according to any one of claims 1-8, characterized in that, include: Monitor the operating status of a true bipolar system; If the operating state is normal operating state, then the true bipolar system and the pseudo bipolar system are controlled to transmit current through the positive and negative lines, and the interconnection device is unloaded; If the operating state is a unipolar operating state, the positive and negative power electronic components in the interconnection device are controlled to output the same DC voltage to maintain the positive and negative voltage symmetry of the pseudo-bipolar system.

10. The method as described in claim 9, characterized in that, Also includes: Monitor the first energy deviation between the positive electrode power electronic component and the negative electrode power electronic component; Based on the first energy deviation, the positive electrode power electronic component is controlled to output a first positive AC voltage component, and the negative electrode power electronic component is controlled to output a first negative AC voltage component. The first positive AC voltage component and the first negative AC voltage component are used to generate an AC circulating current at the series connection point of the positive and negative power electronic components. The first energy deviation is eliminated by the AC circulating current to maintain the energy balance between the positive and negative power electronic components.

11. The method as described in claim 10, characterized in that, Also includes: By utilizing the blocking characteristics of the first set of AC blocking devices in the interconnection device, the AC voltage and AC current generated by the positive AC voltage component and the negative AC voltage component are isolated from flowing into the third terminal of the interconnection device.

12. The method as described in claim 9, characterized in that, Also includes: Monitor the second energy deviation between the positive electrode power electronic component and the negative electrode power electronic component; Based on the second energy deviation, the positive electrode power electronic component is controlled to output a second positive AC voltage component superimposed at the first intermediate lead-out point, and the negative electrode power electronic component is controlled to output a second negative AC voltage component superimposed at the second intermediate lead-out point. Using the second positive AC voltage component and the second negative AC voltage component, an AC current is generated at the first set of energy balancing devices in the interconnected device to eliminate the second energy deviation and maintain the energy balance between the positive and negative power electronic components.

13. The method according to any one of claims 9-12, characterized in that, Also includes: During the transition from normal operation to unipolar operation of the true bipolar system, the transmission power from the pseudo bipolar system is monitored. If the transmission power exceeds the power limit of the single pole in the true bipolar system, at least one set of controllable resistors in the interconnect device is connected to consume the extra power exceeding the power limit of the transmission power.

14. An electronic device, characterized in that, include: At least one processor and memory; The memory and processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, the interconnection operation method of the interconnection device based on the true and false bipolar system as described in any one of claims 9 to 13 is implemented.

15. A readable storage medium, characterized in that, It contains an executable program, which, when executed, implements the interconnection operation method of the interconnection device based on the true and false bipolar system as described in any one of claims 9 to 13.

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