Single-point multi-port power concentrator and control method thereof

Abstract

The application relates to a single-point multi-port power energy concentrator and a control method thereof, comprising a high-voltage DC bus, two voltage source converters, a bidirectional DC / DC converter, a boost converter and a buck converter; the DC sides of the two voltage source converters are connected in parallel with the high-voltage DC bus, and the AC sides of the two voltage source converters are connected with a power grid or an AC load; the application can accurately control the power flow of the distributed power supply, energy storage and flexible load after the distributed power supply, energy storage and flexible load are connected with the power grid through the converters and the converters, the efficiency of the control and management of the distributed power supply, energy storage and flexible load is improved, and meanwhile, the distributed power supply, energy storage and flexible load can be used immediately.

Description

Technical Field

[0001] This invention relates to the field of energy interconnection technology, specifically to a single-point multi-port power collector and its control method. Background Technology

[0002] With the introduction of the Energy Internet strategy, new energy sources are developing rapidly. New energy power generation typically exhibits intermittent, random, and uncontrollable characteristics. To achieve peak shaving and valley filling and provide energy buffers for fluctuations in new energy power generation, a large number of energy storage devices are being connected to the grid. The rapid development of new energy grid connection and energy storage technologies has led to a transition in power system generation from traditional centralized to distributed generation, resulting in a coexistence of centralized and distributed generation, with distributed generation accounting for an increasingly larger proportion. Simultaneously, flexible loads, represented by electric vehicles, are also being connected to the grid in large numbers, leading to a coexistence of "source, grid, and load" in the power system, and the flow of electricity is gradually changing from a traditional unidirectional flow to a multidirectional flow.

[0003] Microgrids are an effective method for connecting distributed generation sources and flexible loads to the distribution network. Their typical construction model involves each distributed generation source, energy storage unit, and flexible load connecting to the grid using its own power electronic converter. While this approach solves the source-load connection problem to a certain extent, the complexity of the microgrid structure stems from the need for various power electronic devices to address both source-load connection and energy transfer while also ensuring grid-friendly interaction. This leads to difficulties in control and management, hinders coordination and optimization, results in system inefficiency, and makes it difficult to achieve plug-and-play functionality. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a single-point multi-port power collector and its control method, which solves the problem of low control and management efficiency after distributed power sources, energy storage and flexible loads are connected to the grid, enabling distributed power sources, energy storage and flexible loads to be used immediately.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] The present invention provides a single-point multi-port power collector, which is improved in that it includes: a high-voltage DC bus, two voltage source converters, a bidirectional DC / DC converter, a boost converter and a buck converter;

[0007] The DC side of the two voltage source converters is connected in parallel with the high voltage DC bus, and the AC side of the two voltage source converters is connected to the power grid or AC load.

[0008] The high-voltage sides of the bidirectional DC / DC converter, boost converter, and buck converter are connected in parallel with the high-voltage DC bus;

[0009] The low-voltage side of the bidirectional DC / DC converter is connected to the energy storage system, the low-voltage side of the boost converter is connected to the photovoltaic system, and the low-voltage side of the buck converter is connected to the DC load.

[0010] Based on the same inventive concept, the present invention also provides a control method for the aforementioned power collector, the improvement of which includes:

[0011] When one voltage source converter is connected to the grid and the other is connected to an AC load, the switching transistors in the voltage source converter connected to the grid are controlled based on the voltage of the high-voltage DC bus; the switching transistors in the voltage source converter connected to the AC load are controlled based on the active power command value of the high-voltage DC bus; the switching transistors in the bidirectional DC / DC converter are controlled based on the low-voltage side voltage of the bidirectional DC / DC converter and the active power command value of the high-voltage DC bus; the switching transistors in the boost converter are controlled based on the output power of the photovoltaic system; and the switching transistors in the buck converter are controlled based on the voltage of the DC load.

[0012] When two voltage source converters are connected to the grid, the switching transistors in the voltage source converter connected to the grid are controlled based on the voltage of the high-voltage DC bus, and the switching transistors in the bidirectional DC / DC converter are controlled based on the low-voltage side voltage of the bidirectional DC / DC converter and the active power command value of the high-voltage DC bus. The switching transistors in the boost converter are controlled based on the output power of the photovoltaic system, and the switching transistors in the buck converter are controlled based on the voltage of the DC load.

[0013] When both voltage source converters are connected to AC loads, the switching transistors in the voltage source converter connected to the AC load are controlled based on the active power command value of the high-voltage DC bus. The switching transistors in the bidirectional DC / DC converter are also controlled based on the low-voltage side voltage of the bidirectional DC / DC converter and the voltage of the high-voltage DC bus. The switching transistors in the boost converter are controlled based on the output power of the photovoltaic system. The switching transistors in the buck converter are controlled based on the voltage of the DC load.

[0014] Preferably, the switching on or off of the switching transistor in the voltage source converter connected to the power grid based on the voltage control of the high-voltage DC bus includes:

[0015] The difference between the voltage of the high-voltage DC bus and the voltage command value is used as the input of the first PI controller;

[0016] The output of the first PI controller, the AC side capacitor voltage and inductor current of the voltage source converter connected to the power grid are used as the input of the virtual synchronous machine control algorithm to obtain the first voltage amplitude and the first phase angle output by the virtual synchronous machine control algorithm.

[0017] Based on the first voltage amplitude E1 and the first phase angle θ1, the first three-phase voltage reference signal is determined by the following formula:

[0018]

[0019] In the formula, E a,1 E is the reference signal for the voltage of the first phase a. b,1 E is the reference signal for the first phase b voltage. c,1 This is the reference signal for the first c-phase voltage;

[0020] The first three-phase voltage reference signal is used as the input of the first PWM modulator, and the modulation signal output by the first PWM modulator is used to control the opening or closing of the switching transistors in the voltage source converter connected to the power grid.

[0021] Preferably, the control of the switching transistors in the voltage source converter connected to the AC load based on the active power command value of the high-voltage DC bus includes:

[0022] The active power command value of the high-voltage DC bus, the AC side capacitor voltage and inductor current of the voltage source converter connected to the AC load are used as inputs to the virtual synchronous machine control algorithm to obtain the third voltage amplitude and third phase angle output by the virtual synchronous machine control algorithm.

[0023] Based on the third voltage amplitude E3 and the third phase angle θ3, the third three-phase voltage reference signal is determined by the following formula:

[0024]

[0025] In the formula, E a,3 E is the reference signal for the third phase a voltage. b,3 E is the reference signal for the third phase b voltage. c,3 This is the reference signal for the third c-phase voltage;

[0026] The third three-phase voltage reference signal is used as the input of the third PWM modulator, and the modulation signal output by the third PWM modulator is used to control the opening or closing of the switching transistors in the voltage source converter connected to the AC load.

[0027] Preferably, controlling the switching transistors in the bidirectional DC / DC converter to open or close based on the low-voltage side voltage of the bidirectional DC / DC converter and the active power command value of the high-voltage DC bus includes:

[0028] The active power on the low-voltage side of the bidirectional DC / DC converter is obtained based on the low-voltage side voltage and the inductor current of the bidirectional DC / DC converter.

[0029] The difference between the active power on the low-voltage side of the bidirectional DC / DC converter and the active power command value of the high-voltage DC bus is used as the input of the third PI controller.

[0030] The output of the third PI controller is used as the input of the fifth PWM modulator, and the modulation signal output of the fifth PWM modulator is used to control the switching transistors in the bidirectional DC / DC converter to turn on or off.

[0031] Preferably, controlling the switching transistors in the bidirectional DC / DC converter to open or close based on the low-voltage side voltage and the high-voltage DC bus voltage includes:

[0032] The active power on the low-voltage side of the bidirectional DC / DC converter is obtained based on the low-voltage side voltage and the inductor current of the bidirectional DC / DC converter.

[0033] The voltage of the high-voltage DC bus and the voltage command value are used as the input of the fourth PI controller;

[0034] The product of the output of the fourth PI controller and the voltage of the high-voltage DC bus is obtained, and the difference between this product and the active power on the low-voltage side of the bidirectional DC / DC converter is used as the input of the fifth PI controller.

[0035] The output of the fifth PI controller is used as the input of the sixth PWM modulator, and the modulation signal output by the sixth PWM modulator is used to control the switching transistors in the bidirectional DC / DC converter to turn on or off.

[0036] Preferably, the switching on or off of the switching transistor in the photovoltaic system-based output power control boost converter includes:

[0037] The duty cycle signal for the next moment is determined based on the current output power of the photovoltaic system.

[0038] The duty cycle signal at the next moment is used to control the switching transistors in the boost converter to turn on or off at the next moment.

[0039] Preferably, determining the duty cycle signal for the next moment based on the current output power of the photovoltaic system includes:

[0040] When P PV,k =P PV,k-1 When, then D(k+1)=D(k);

[0041] When P PV,k <P PV,k-1At that time, if U PV,k >U PV,k-1 If so, then D(k+1) = D(k) - ΔD; otherwise, D(k+1) = D(k) + ΔD.

[0042] When P PV,k >P PV,k-1 At that time, if U PV,k >U PV,k-1 If so, then D(k+1) = D(k) + ΔD; otherwise, D(k+1) = D(k) - ΔD.

[0043] Among them, P PV,k Let P be the output power of the photovoltaic system at time k. PV,k-1 Let U be the output power of the photovoltaic system at time k-1. PV,k Let U be the output voltage of the photovoltaic system at time k. PV,k-1 Let D(k+1) be the output voltage of the photovoltaic system at time k-1, D(k+1) be the duty cycle signal at time k+1, D(k) be the duty cycle signal at time k, and ΔD be the perturbation step size.

[0044] Preferably, the switching on or off of the switching transistor in the DC load-based voltage-controlled buck converter includes:

[0045] The difference between the DC load voltage and the DC load voltage command value is used as the input to the sixth PI controller.

[0046] The difference between the output of the sixth PI controller and the inductor current in the buck converter is used as the input of the seventh PI controller.

[0047] Use the output of the seventh PI controller as the input of the seventh PWM modulator;

[0048] The control signal output from the seventh PWM modulator is used to control the switching transistors in the Buck converter to turn on or off.

[0049] Compared with the closest existing technology, the present invention has the following advantages:

[0050] This invention provides a single-point multi-port power collector and its control method, comprising: a high-voltage DC bus and two voltage source converters, a bidirectional DC / DC converter, a boost converter, and a buck converter connected in parallel with the high-voltage DC bus; the DC side of the two voltage source converters is connected in parallel with the high-voltage DC bus, and the AC side of the two voltage source converters is connected to the power grid or AC load; the bidirectional DC / DC converter, boost converter, and buck converter of this invention serve as the output / input ports of the power collector, enabling plug-and-play functionality for distributed power sources, energy storage, and flexible loads;

[0051] In this invention, the control method achieves precise regulation of power flow for distributed power sources, energy storage, and flexible loads by controlling the switching of each converter and transformer, thereby improving the efficiency of control and management of distributed power sources, energy storage, and flexible loads.

[0052] The parallel connection of the DC side of the voltage source converter with the high voltage DC bus ensures high reliability and stability of AC power supply. The virtual synchronous control method can achieve smooth switching between AC side on-grid and off-grid operation. It can also resist rapid system fluctuations caused by small external disturbances and respond to grid anomalies and actively participate in grid regulation.

[0053] Based on the output power control of the photovoltaic system, the switching transistors in the boost converter are turned on or off to realize the local consumption of distributed power sources.

[0054] By controlling the switching transistors in a bidirectional DC / DC converter, the charging and discharging of stored energy can be used to control the DC bus voltage, achieving the effects of self-support and improved power quality.

[0055] AC and DC loads are connected to the system through corresponding converters and transformers, which improves the flexibility of power supply to the loads. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the single-point multi-port power collector structure of the present invention;

[0057] Figure 2 This is a schematic diagram of the controller of a voltage source converter connected to the power grid in an embodiment of the present invention;

[0058] Figure 3 This is a schematic diagram of the controller of a voltage source converter connected to an AC load in an embodiment of the present invention;

[0059] Figure 4 This is a schematic diagram of the first controller of the bidirectional DC / DC converter in an embodiment of the present invention;

[0060] Figure 5 This is a schematic diagram of the second controller of the bidirectional DC / DC converter in an embodiment of the present invention;

[0061] Figure 6 This is a schematic diagram of the controller of the buck converter in an embodiment of the present invention. Detailed Implementation

[0062] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0063] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] This invention provides a single-point multi-port power collector, such as... Figure 1 As shown, it includes: a high-voltage DC bus, two voltage source converters, a bidirectional DC / DC converter, a boost converter, and a buck converter;

[0065] The DC sides of the two voltage source converters are connected in parallel with the high-voltage DC bus, and the AC sides of the two voltage source converters are connected to the power grid or AC load.

[0066] The high-voltage sides of the bidirectional DC / DC converter, boost converter, and buck converter are connected in parallel with the high-voltage DC bus;

[0067] The low-voltage side of the bidirectional DC / DC converter is connected to the energy storage system, the low-voltage side of the boost converter is connected to the photovoltaic system, and the low-voltage side of the buck converter is connected to the DC load.

[0068] Based on the same inventive concept, the present invention also provides a control method for the power collector, comprising:

[0069] When one voltage source converter is connected to the grid and the other is connected to an AC load, the switching transistors in the voltage source converter connected to the grid are controlled based on the voltage of the high-voltage DC bus; the switching transistors in the voltage source converter connected to the AC load are controlled based on the active power command value of the high-voltage DC bus; the switching transistors in the bidirectional DC / DC converter are controlled based on the low-voltage side voltage of the bidirectional DC / DC converter and the active power command value of the high-voltage DC bus; the switching transistors in the boost converter are controlled based on the output power of the photovoltaic system; and the switching transistors in the buck converter are controlled based on the voltage of the DC load.

[0070] When two voltage source converters are connected to the grid, the switching transistors in the voltage source converter connected to the grid are controlled based on the voltage of the high-voltage DC bus, and the switching transistors in the bidirectional DC / DC converter are controlled based on the low-voltage side voltage of the bidirectional DC / DC converter and the active power command value of the high-voltage DC bus. The switching transistors in the boost converter are controlled based on the output power of the photovoltaic system, and the switching transistors in the buck converter are controlled based on the voltage of the DC load.

[0071] When both voltage source converters are connected to AC loads, the switching transistors in the voltage source converter connected to the AC load are controlled based on the active power command value of the high-voltage DC bus. The switching transistors in the bidirectional DC / DC converter are also controlled based on the low-voltage side voltage of the bidirectional DC / DC converter and the voltage of the high-voltage DC bus. The switching transistors in the boost converter are controlled based on the output power of the photovoltaic system. The switching transistors in the buck converter are controlled based on the voltage of the DC load.

[0072] In embodiments of the present invention, such as Figure 2 As shown, the opening or closing of the switching transistors in the voltage source converter connected to the power grid based on the voltage control of the high-voltage DC bus includes:

[0073] The difference ΔU between the voltage of the high-voltage DC bus and the voltage command value is used as the input of the first PI controller;

[0074] The output of the first PI controller, the AC side capacitor voltage and inductor current of the voltage source converter connected to the power grid are used as inputs to the virtual synchronous machine control algorithm to obtain the first voltage amplitude and first phase angle output by the virtual synchronous machine control algorithm; where u C,a,1 ,u C,b,1 ,u C,c,1 These represent the phase voltages (a, b, and c) of the AC side capacitor of the voltage source converter connected to the power grid, i. L,a,1 i L,b,1 i L,c,1 These are the a, b, and c phase currents of the AC side inductor of the voltage source converter connected to the power grid, respectively.

[0075] Based on the first voltage amplitude E1 and the first phase angle θ1, the first three-phase voltage reference signal is determined by the following formula:

[0076]

[0077] In the formula, E a,1 E is the reference signal for the voltage of the first phase a. b,1 E is the reference signal for the first phase b voltage. c,1 This is the reference signal for the first c-phase voltage;

[0078] The first three-phase voltage reference signal is used as the input of the first PWM modulator, and the modulation signal output by the first PWM modulator is used to control the switching transistors in the voltage source converter connected to the power grid to open or close, so as to realize the real-time regulation of the voltage of the high voltage DC bus.

[0079] In embodiments of the present invention, such as Figure 3 As shown, the opening and closing of the switching transistors in the voltage source converter connected to the AC load, which controls the active power command value based on the high-voltage DC bus, includes:

[0080] The active power command value P of the high-voltage DC bus set The AC side capacitor voltage and inductor current of the voltage source converter connected to the AC load are used as inputs to the virtual synchronous machine control algorithm to obtain the third voltage amplitude and third phase angle output by the virtual synchronous machine control algorithm.

[0081] Based on the third voltage amplitude E3 and the third phase angle θ3, the third three-phase voltage reference signal is determined by the following formula:

[0082]

[0083] In the formula, E a,3 E is the reference signal for the third phase a voltage. b,3 E is the reference signal for the third phase b voltage. c,3 This is the reference signal for the third c-phase voltage;

[0084] The third three-phase voltage reference signal is used as the input of the third PWM modulator, and the modulation signal output by the third PWM modulator is used to control the opening or closing of the switching transistors in the voltage source converter connected to the AC load, so as to realize the real-time regulation of the active power of the high voltage DC bus.

[0085] In embodiments of the present invention, such as Figure 4 As shown, the control of the switching transistors in the bidirectional DC / DC converter to open or close based on the low-voltage side voltage and the active power command value of the high-voltage DC bus includes:

[0086] The active power P on the low-side of the bidirectional DC / DC converter is obtained based on the low-side voltage and the inductor current of the bidirectional DC / DC converter. output ;

[0087] The difference between the active power on the low-voltage side of the bidirectional DC / DC converter and the active power command value of the high-voltage DC bus (the output of the first subtractor) is used as the input of the third PI controller.

[0088] The output of the third PI controller is used as the input of the fifth PWM modulator, and the modulation signal output of the fifth PWM modulator is used to control the switching transistors in the bidirectional DC / DC converter to regulate the low-voltage side voltage of the DC / DC converter.

[0089] Specifically, when the active power on the low-voltage side of the bidirectional DC / DC converter is positive, the bidirectional DC / DC converter operates in buck mode; when the active power on the low-voltage side of the bidirectional DC / DC converter is negative, the bidirectional DC / DC converter operates in boost mode.

[0090] In embodiments of the present invention, such as Figure 5 As shown, the above-mentioned control of the switching transistors in the bidirectional DC / DC converter to open or close based on the low-voltage side voltage and the high-voltage DC bus voltage includes:

[0091] The active power on the low-side of the bidirectional DC / DC converter is obtained based on the low-side voltage and the inductor current of the bidirectional DC / DC converter; second subtractor

[0092] The voltage U of the high-voltage DC bus dc With voltage command value U dc,ref As the input to the fourth PI controller;

[0093] The product of the output of the fourth PI controller and the voltage of the high-voltage DC bus is obtained, and the difference between this and the active power on the low-voltage side of the bidirectional DC / DC converter (the output of the second subtractor) is used as the input of the fifth PI controller.

[0094] The output of the fifth PI controller is used as the input of the sixth PWM modulator, and the modulation signal output of the sixth PWM modulator is used to control the switching transistors in the bidirectional DC / DC converter to regulate the low-voltage side voltage of the DC / DC converter.

[0095] In an embodiment of the present invention, the boost converter employs MPPT control. The aforementioned output power control of the photovoltaic system-based boost converter, which controls the switching transistors, includes:

[0096] The duty cycle signal for the next moment is determined based on the current output power of the photovoltaic system.

[0097] The duty cycle signal at the next moment is used to control the switching transistors in the boost converter to turn on or off, thereby regulating the output power of the photovoltaic system.

[0098] In an embodiment of the present invention, the above-mentioned determination of the duty cycle signal for the next moment based on the output power of the photovoltaic system at the current moment includes:

[0099] When P PV,k =P PV,k-1 When, then D(k+1)=D(k);

[0100] When P PV,k <P PV,k-1 At that time, if U PV,k >U PV,k-1 If so, then D(k+1) = D(k) - ΔD; otherwise, D(k+1) = D(k) + ΔD.

[0101] When P PV,k >P PV,k-1 At that time, if U PV,k >U PV,k-1 If so, then D(k+1) = D(k) + ΔD; otherwise, D(k+1) = D(k) - ΔD.

[0102] Among them, P PV,k Let P be the output power of the photovoltaic system at time k. PV,k-1 Let U be the output power of the photovoltaic system at time k-1. PV,k Let U be the output voltage of the photovoltaic system at time k. PV,k-1 Let D(k+1) be the output voltage of the photovoltaic system at time k-1, D(k+1) be the duty cycle signal at time k+1, D(k) be the duty cycle signal at time k, and ΔD be the perturbation step size.

[0103] In embodiments of the present invention, such as Figure 6 As shown, the switching of the transistor in the voltage-controlled buck converter based on the DC load described above includes:

[0104] The voltage U of the DC load dc,low Voltage command value U of DC load dc,low,ref The difference (output of the third subtractor) is used as the input of the sixth PI controller;

[0105] The output of the sixth PI controller is compared with the inductor current i in the Buck converter. L The difference (output of the fourth subtractor) is used as the input of the seventh PI controller;

[0106] Use the output of the seventh PI controller as the input of the seventh PWM modulator;

[0107] The control signal output from the seventh PWM modulator is used to control the switching transistors in the buck converter to open or close, thereby regulating the DC load voltage.

[0108] In summary, the present invention provides a single-point multi-port power collector and its control method, comprising: a high-voltage DC bus and two voltage source converters, a bidirectional DC / DC converter, a boost converter, and a buck converter connected in parallel with the high-voltage DC bus; the DC side of the two voltage source converters is connected in parallel with the high-voltage DC bus, and the AC side of the two voltage source converters is connected to the power grid or AC load; the present invention precisely controls the power flow of distributed power sources, energy storage, and flexible loads after grid connection through each converter and each transformer, thereby improving the efficiency of distributed power sources, energy storage, and flexible load control and management, and enabling distributed power sources, energy storage, and flexible loads to be used plug-and-play;

[0109] Among them, the DC side of the voltage source converter is connected in parallel with the high voltage DC bus to ensure the high reliability and stability of the AC side power supply. The virtual synchronous control method is used to control it, which can realize the smooth switching between AC side on-grid and off-grid operation modes. It can also resist the rapid system fluctuations caused by small external disturbances and can respond to grid anomalies and actively participate in grid regulation.

[0110] Based on the output power control of the photovoltaic system, the switching transistors in the boost converter are turned on or off to realize the local consumption of distributed power sources.

[0111] By controlling the switching transistors in a bidirectional DC / DC converter, the charging and discharging of stored energy can be used to control the DC bus voltage, achieving the effects of self-support and improved power quality.

[0112] AC and DC loads are connected to the system through corresponding converters and transformers, which greatly improves the flexibility of power supply to the loads.

[0113] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application 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.

[0114] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. 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... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0115] 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 1 The function specified in one or more boxes.

[0116] 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.

[0117] 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 it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A control method of a single-point multi-port power concentrator, characterized by, The method relates to a single-point multi-port power collector, comprising: a high-voltage DC bus, two voltage source converters, a bidirectional DC / DC converter, a boost converter and a buck converter; The DC side of the two voltage source converters is connected in parallel with the high-voltage DC bus, and the AC side of the two voltage source converters is connected with a power grid or an AC load; The high-voltage side of the bidirectional DC / DC converter, the boost converter and the buck converter is connected in parallel with the high-voltage DC bus; The low-voltage side of the bidirectional DC / DC converter is connected with an energy storage system, the low-voltage side of the boost converter is connected with a photovoltaic system, and the low-voltage side of the buck converter is connected with a DC load; The control method of the single-point multi-port power collector comprises: When one of the two voltage source converters is connected with the power grid and the other is connected with the AC load, the voltage of the high-voltage DC bus is used to control the opening or closing of the switch tube in the voltage source converter connected with the power grid, the active power instruction value of the high-voltage DC bus is used to control the opening or closing of the switch tube in the voltage source converter connected with the AC load, the low-voltage side voltage of the bidirectional DC / DC converter and the active power instruction value of the high-voltage DC bus are used to control the opening or closing of the switch tube in the bidirectional DC / DC converter, the output power of the photovoltaic system is used to control the opening or closing of the switch tube in the boost converter, and the voltage of the DC load is used to control the opening or closing of the switch tube in the buck converter; When both of the two voltage source converters are connected with the power grid, the voltage of the high-voltage DC bus is used to control the opening or closing of the switch tube in the voltage source converter connected with the power grid, and the low-voltage side voltage of the bidirectional DC / DC converter and the active power instruction value of the high-voltage DC bus are used to control the opening or closing of the switch tube in the bidirectional DC / DC converter, the output power of the photovoltaic system is used to control the opening or closing of the switch tube in the boost converter, and the voltage of the DC load is used to control the opening or closing of the switch tube in the buck converter; When both of the two voltage source converters are connected with the AC load, the active power instruction value of the high-voltage DC bus is used to control the opening or closing of the switch tube in the voltage source converter connected with the AC load, and the low-voltage side voltage of the bidirectional DC / DC converter and the voltage of the high-voltage DC bus are used to control the opening or closing of the switch tube in the bidirectional DC / DC converter, the output power of the photovoltaic system is used to control the opening or closing of the switch tube in the boost converter, and the voltage of the DC load is used to control the opening or closing of the switch tube in the buck converter.

2. The method of claim 1, wherein, The control method of the single-point multi-port power collector comprises: The difference between the voltage of the high-voltage DC bus and the voltage instruction value is used as the input quantity of the first PI controller; The output quantity of the first PI controller, the capacitor voltage and the inductor current on the AC side of the voltage source converter connected with the power grid are used as the input quantity of the virtual synchronous machine control algorithm, and the first voltage amplitude and the first phase angle output by the virtual synchronous machine control algorithm are obtained. Based on the first voltage amplitude E1 and the first phase angle θ1, the first three-phase voltage reference signal is determined by the following formula: wherein E a,1 is a first a-phase voltage reference signal, E b,1 is a first b-phase voltage reference signal, E c,1 is a first c-phase voltage reference signal; The first three-phase voltage reference signal is used as the input of the first PWM modulator, and the modulation signal output by the first PWM modulator is used to control the switching transistors in the voltage source converter connected to the power grid to be turned on or off.

3. The method of claim 1, wherein, The control of the switching transistors in the voltage source converter connected to the AC load based on the active power command value of the high-voltage DC bus includes: The active power command value of the high-voltage DC bus, the AC side capacitor voltage and inductor current of the voltage source converter connected to the AC load are used as inputs to the virtual synchronous machine control algorithm to obtain the third voltage amplitude and third phase angle output by the virtual synchronous machine control algorithm. Based on the third voltage amplitude E3 and the third phase angle θ3, the third three-phase voltage reference signal is determined by the following formula: wherein E a,3 is a third a-phase voltage reference signal, E b,3 is a third b-phase voltage reference signal, E c,3 is a third c-phase voltage reference signal; The third three-phase voltage reference signal is used as the input of the third PWM modulator, and the modulation signal output by the third PWM modulator is used to control the switching transistors in the voltage source converter connected to the AC load to be turned on or off.

4. The method of claim 1, wherein, The control of the switching transistors in the bidirectional DC / DC converter to open or close based on the low-voltage side voltage and the active power command value of the high-voltage DC bus includes: The active power on the low-voltage side of the bidirectional DC / DC converter is obtained based on the low-voltage side voltage and the inductor current of the bidirectional DC / DC converter. The difference between the active power on the low-voltage side of the bidirectional DC / DC converter and the active power command value of the high-voltage DC bus is used as the input of the third PI controller. The output of the third PI controller is used as the input of the fifth PWM modulator, and the modulation signal output of the fifth PWM modulator is used to control the switching transistors in the bidirectional DC / DC converter to turn on or off.

5. The method of claim 1, wherein, The method of controlling the switching transistors in the bidirectional DC / DC converter to open or close based on the low-voltage side voltage and the high-voltage DC bus voltage includes: The active power on the low-voltage side of the bidirectional DC / DC converter is obtained based on the low-voltage side voltage and the inductor current of the bidirectional DC / DC converter. The voltage of the high-voltage DC bus and the voltage command value are used as the input of the fourth PI controller; The product of the output of the fourth PI controller and the voltage of the high-voltage DC bus is obtained, and the difference between this product and the active power on the low-voltage side of the bidirectional DC / DC converter is used as the input of the fifth PI controller. The output of the fifth PI controller is used as the input of the sixth PWM modulator, and the modulation signal output by the sixth PWM modulator is used to control the switching transistors in the bidirectional DC / DC converter to turn on or off.

6. The method of claim 1, wherein, The switching on or off of the switching transistors in the photovoltaic system-based output power control boost converter includes: The duty cycle signal for the next moment is determined based on the current output power of the photovoltaic system. The duty cycle signal at the next moment is used to control the switching transistors in the boost converter to turn on or off at the next moment.

7. The method of claim 6, wherein, The step of determining the duty cycle signal for the next moment based on the current output power of the photovoltaic system includes: When P PV,k = P PV,k-1 , then D(k+1) = D(k). When P PV,k <P PV,k-1 U PV,k >U PV,k-1 , then D(k+1) = D(k) - AD, otherwise, D(k+1) = D(k) + AD; When P PV,k > P PV,k-1 , if U PV,k > U PV,k-1 , then D(k+1) = D(k) + AD, otherwise, D(k+1) = D(k) - AD; where P(k) is the output power of the photovoltaic system at time k, P(k-1) is the output power of the photovoltaic system at time k-1, U(k) is the output voltage of the photovoltaic system at time k, U(k-1) is the output voltage of the photovoltaic system at time k-1, D(k+1) is the duty cycle signal at time k+1, D(k) is the duty cycle signal at time k, and ΔD is the perturbation step. PV,k PV,k-1 PV,k PV,k-1 where P(k) is the output power of the photovoltaic system at time k, P(k-1) is the output power of the photovoltaic system at time k-1, U(k) is the output voltage of the photovoltaic system at time k, U(k-1) is the output voltage of the photovoltaic system at time k-1, D(k+1) is the duty cycle signal at time k+1, D(k) is the duty cycle signal at time k, and ΔD is the perturbation step.​​​ 8. The method of claim 1, wherein, The switching of the transistors in the voltage-controlled buck converter based on the DC load includes: The difference between the DC load voltage and the DC load voltage command value is used as the input to the sixth PI controller. The difference between the output of the sixth PI controller and the inductor current in the buck converter is used as the input of the seventh PI controller. Use the output of the seventh PI controller as the input of the seventh PWM modulator; The control signal output from the seventh PWM modulator is used to control the switching transistors in the Buck converter to turn on or off.

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