Black-start cooperative control system and method for optical storage DC micro-grid

Abstract

The invention discloses a black-start cooperative control system and method for an optical storage DC micro-grid, and the system is characterized in that an electric energy router is connected with a power grid through a grid-connected port, is connected with an energy storage unit through an energy storage port, is connected with a photovoltaic unit through a photovoltaic port, and is connected with a load through a DC load port; a grid-connected port adopts a constant-voltage control mode, an energy storage port adopts a constant-voltage control mode, and a photovoltaic port adopts a constant-power mode and a maximum power point tracking mode; and a direct current load port adopts constant power control, and under the adjustment of a PI controller, a black-start light storage coordination control strategy of the light storage direct current micro-grid is finally obtained according to an active power balance expression between a power supply and a load. According to the invention, on the basis of a coordinated control strategy scheme of active power balance and time limit power and maximum power point tracking between a power supply and a load, an efficient black-start process is realized, and a theoretical basis and technical support are provided for efficient operation of the optical storage micro-grid.

Description

Technical Field

[0001] The present invention belongs to the technical field of power electronics and relates to a black start collaborative control system and method for a photovoltaic-storage DC microgrid. Background Art

[0002] Microgrids can improve energy efficiency, promote the integration of renewable energy, and enhance the resilience of power systems. DC microgrids have significant advantages in the application of photovoltaic storage systems. In the prior art, microgrids are generally studied through the collaboration of power routers to achieve black start with the support of large power grids. However, after a power grid failure, the microgrid cannot achieve the black start capability in an isolated operating state, and cannot further improve the power supply reliability of the system. Therefore, it is urgent to propose a collaborative control strategy for microgrids to achieve black start without relying on large power grids. Summary of the invention

[0003] The purpose of the present invention is to solve the problem that the existing microgrid cannot start automatically, and disclose a photovoltaic storage DC microgrid black start collaborative control system and method.

[0004] The object of the present invention can be achieved by the following scheme:

[0005] In the first aspect, the present invention constructs a photovoltaic-storage DC microgrid black start collaborative control system, including a photovoltaic-storage DC microgrid black start collaborative control system, including an energy router (EER), the energy router includes a grid-connected port, an energy storage port, a photovoltaic port, and a DC load port, the energy router is connected to the grid through the grid-connected port, is connected to the energy storage unit through the energy storage port, is connected to the photovoltaic unit through the photovoltaic port, and is connected to the load through the DC load port; each unit is flexibly switched on the DC bus through a circuit breaker; the voltage construction and control of each port of the EER are simulated, the grid-connected port adopts a constant voltage control mode, the energy storage port adopts a constant voltage control mode, and the photovoltaic port adopts a constant power (CP) mode and a maximum power point tracking (MPPT) mode; the DC load port adopts CP control, and under the adjustment of the PI controller, the photovoltaic-storage coordinated control strategy of the photovoltaic-storage DC microgrid black start is finally obtained based on the active power balance expression between the power supply and the load.

[0006] Further preferably, the photovoltaic-storage DC microgrid black start collaborative control strategy includes:

[0007] Based on the active power balance expression between power source and load: P pv +P Bat -P Load -P e =0,P pv is the active power output of the photovoltaic unit, P Loadis the active power consumed by the controllable load, P Bat is the active output of the energy storage unit, P e It is the active power loss of the power router. Based on the basic principle of the conductance increment method, a CP and MPPT coordinated control strategy is adopted to effectively track the load changes when the photovoltaic unit output is sufficient, and there is power surplus to charge the energy storage unit. When it is insufficient, the maximum power output is achieved, and the power shortage is borne by the energy storage unit.

[0008] Further preferably, the CP and MPPT coordinated control strategy includes:

[0009] The output voltage U of the photovoltaic unit is monitored pv The photovoltaic unit output current I pv Calculate the real-time active output of the photovoltaic unit P pv , by comparing the active output of the photovoltaic unit P pv The active power consumed by the controllable load P Load size, select its working mode. pv >P Load When it works in CP mode, when P pv <P Load When the power is turned on, it works in MPPT mode.

[0010] Further preferably, the grid-connected port adopts the DC bus voltage for closed-loop control; when the photovoltaic storage DC microgrid system runs stably and the black start process is completed, the grid is connected to the photovoltaic storage DC microgrid system. At this time, the grid-connected port adopts grid-following constant voltage control and automatically balances the power to stabilize the DC voltage. The grid-connected port is responsible for stabilizing the DC bus voltage and regulating the charging and discharging power of the energy storage device by controlling the current of the energy storage port through the power loop. At this time, the energy storage port adopts a constant power control mode; the grid-connected module is incorporated into the system under the condition that the constraints allow, including:

[0011] When connected to the grid, the grid-connected port maintains a constant DC bus voltage. The reference value of the DC bus voltage is input, and the PWM control signal is generated after the voltage outer loop and current inner loop control. The DC bus voltage is closed-loop controlled, and the grid-connected port automatically balances the power to stabilize the DC voltage.

[0012] The energy storage port stabilizes the DC bus voltage through the DC voltage outer loop, and the current inner loop tracks and controls the current. The energy storage unit is incorporated into the system under the constraints allowed, including:

[0013] When connected to the grid, the current of the energy storage port is controlled by the power ring to adjust the charging and discharging power of the energy storage unit. At this time, the energy storage port adopts the CP control mode, and the grid side is responsible for stabilizing the DC bus voltage.

[0014] Further preferably, the photovoltaic port is based on a Boost circuit, and its output side is connected to the DC bus. There are two working modes of the photovoltaic unit: constant power (CP) mode and maximum power point tracking (MPPT) mode. The photovoltaic unit first provides the set power to the load end in the CP mode, and after stable operation, the photovoltaic working mode is converted to the MPPT mode according to the load increase.

[0015] Further preferably, the DC load port uses a Buck converter for voltage conversion: the control target of the DC load port is to output a DC voltage of a specified amplitude and keep it stable. In order to achieve the control target, a closed-loop feedback is performed on the output DC voltage, and the output voltage U d With reference voltage reference value As the control input, the PI regulator outputs the control signal to the DC load port to realize the constant power control of the DC load; the DC load module is incorporated into the system under the condition that the constraints allow, including:

[0016] After the photovoltaic unit is connected to the photovoltaic storage DC microgrid system, the load power connected to the DC load port becomes larger, and the voltage and current dual closed-loop control of the same different voltage levels is used to match the transmission power of the photovoltaic working mode from CP mode to MPPT mode.

[0017] In the second aspect, the present invention provides a photovoltaic and DC microgrid black start collaborative control method, which relies on the constructed photovoltaic and DC microgrid black start collaborative control system to realize the photovoltaic and DC microgrid black start process and the startup process and sequence of each port of the EER. The startup process and sequence are the self-starting stage of the energy storage unit, the stage of the photovoltaic unit connecting to and supplying power to the load, the load recovery stage and the grid-connected operation stage.

[0018] In the energy storage unit self-starting stage, the energy storage unit starts from zero voltage and charges the EER DC bus. At the same time, it provides starting power to the photovoltaic unit so that it can start successfully. In this stage, the photovoltaic DC microgrid has active power constraints: P Bat >P PVLoad +P e , where P Bat is the active output of the energy storage unit, P PVLoad is the starting load of the photovoltaic unit, P e is the active power loss of the power router.

[0019] During the PV unit startup phase, the PV unit outputs active power while the energy storage unit maintains the DC bus voltage and provides the power required by the base load and ensures the stable operation of the photovoltaic storage DC microgrid system. To ensure that the system does not fail to start due to the impact of PV access, there is a power constraint: P Bat +P pv >P Load +PPVLoad +P e .

[0020] Where: P pv is the active power output of the photovoltaic unit, P Load Consume active power for controllable load.

[0021] The load recovery phase uses the started power supply to quickly start other loads and maintain the stability of the system DC bus voltage during the recovery process. In this phase, there are controllable load cut-in and cut-out. To ensure that the system does not experience a secondary power outage, the microgrid has a power constraint at this time: P Bat +P pv -P Load -P e >P m .

[0022] Where: P m It is the active margin of the recovery process.

[0023] Beneficial effects of the present invention: The photovoltaic storage DC microgrid black start collaborative control system disclosed by the present invention makes full use of the plug-and-play characteristics of the power router, and can realize the self-start of the DC microgrid based on the power router when the main network fails. It has the black start capability in an isolated operation state, so that the photovoltaic storage system can achieve black start, and access multiple types of loads through EER, thereby achieving rapid networking and autonomous black start. It realizes the black start of the microgrid without relying on the large power grid, and further improves the power supply reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] The present invention will be further described below in conjunction with the accompanying drawings.

[0026] Figure 1 It is the topological structure diagram of the black start collaborative control system of the photovoltaic energy storage DC microgrid.

[0027] Figure 2 It is a schematic diagram of the startup sequence of each port of the EER in the present invention;

[0028] Figure 3 It is a schematic diagram of the port control of the energy storage unit;

[0029] Figure 4 It is a schematic diagram of DC load port control;

[0030] Figure 5 It is a schematic diagram of PV port control;

[0031] Figure 6 It is a schematic diagram of the coordinated control process of MPPT and CP;

[0032] Figure 7 It is a schematic diagram of PV port control. DETAILED DESCRIPTION

[0033] The present invention and its implementation methods are described below, which are not restrictive and the actual implementation methods are not limited thereto. In short, if ordinary technicians in the field are inspired by it and design structural methods and embodiments similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.

[0034] Example 1

[0035] like Figure 1 As shown, the photovoltaic-storage DC microgrid black start collaborative control system includes an energy router (EER), which includes a grid-connected port, an energy storage port, a photovoltaic port, and a DC load port. The energy router is connected to the grid through the grid-connected port, connected to the energy storage unit through the energy storage port, connected to the photovoltaic unit through the photovoltaic port, and connected to the load through the DC load port; each unit can be flexibly switched on the DC bus through a circuit breaker; the voltage construction and control of each port of the EER are simulated, the grid-connected port adopts a constant voltage control mode, the energy storage port adopts a constant voltage control mode, and the photovoltaic port adopts a constant power (CP) mode and a maximum power point tracking (MPPT) mode; the DC load port adopts CP control, and under the adjustment of the PI controller, the photovoltaic-storage coordinated control strategy for the black start of the photovoltaic-storage DC microgrid is finally obtained based on the active power balance expression between the power supply and the load. The photovoltaic-storage DC microgrid black start collaborative control strategy includes:

[0036] Based on the active power balance expression between power source and load: P pv +P Bat -P Load -P e =0,P pv is the active power output of the photovoltaic unit, P Load is the active power consumed by the controllable load, P Bat is the active output of the energy storage unit, P eIt is the active power loss of the power router. Based on the basic principle of the conductance increment method, a CP and MPPT coordinated control strategy is adopted to effectively track the load changes when the photovoltaic unit output is sufficient, and there is power surplus to charge the energy storage unit. When it is insufficient, the maximum power output is achieved, and the power shortage is borne by the energy storage unit.

[0037] The CP and MPPT coordinated control strategy includes:

[0038] The output voltage U of the photovoltaic unit is monitored pv The photovoltaic unit output current I pv Calculate the real-time active output of the photovoltaic unit P pv , by comparing the active output of the photovoltaic unit P pv The active power consumed by the controllable load P Load size, select its working mode. pv >P Load When it works in CP mode, when P pv <P Load When the power is turned on, it works in MPPT mode.

[0039] The grid-connected port uses the DC bus voltage for closed-loop control; when the photovoltaic storage DC microgrid system is running stably and the black start process is completed, the grid is connected to the photovoltaic storage DC microgrid system. At this time, the grid-connected port adopts grid-following constant voltage control and automatically balances the power to stabilize the DC voltage. The grid-connected port is responsible for stabilizing the DC bus voltage and regulating the charging and discharging power of the energy storage device by controlling the current of the energy storage port through the power loop. At this time, the energy storage port adopts a constant power control mode. The grid-connected module is incorporated into the system under the constraints allowed, including:

[0040] When connected to the grid, the grid-connected port maintains a constant DC bus voltage. The reference value of the DC bus voltage is input, and the PWM control signal is generated after the voltage outer loop and current inner loop control. The DC bus voltage is closed-loop controlled, and the grid-connected port automatically balances the power to stabilize the DC voltage.

[0041] The energy storage port stabilizes the DC bus voltage through the DC voltage outer loop, and the current inner loop tracks and controls the current. The energy storage unit is incorporated into the system under the constraints allowed, including:

[0042] When connected to the grid, the current of the energy storage port is controlled by the power ring to adjust the charging and discharging power of the energy storage unit. At this time, the energy storage port adopts the CP control mode, and the grid side is responsible for stabilizing the DC bus voltage.

[0043] The photovoltaic port is based on the Boost circuit, and its output side is connected to the DC bus. There are two working modes of the photovoltaic unit: constant power (CP) mode and maximum power point tracking (MPPT) mode. The photovoltaic unit first provides the set power to the load end in the CP mode. After stable operation, the photovoltaic working mode is converted to the MPPT mode according to the load increase.

[0044] The DC load port uses a Buck converter for voltage conversion: the control target of the DC load port is to output a DC voltage of a specified amplitude and keep it stable. In order to achieve the control target, the output DC voltage is fed back in a closed loop and the output voltage U d With reference voltage reference value As the control input, the PI regulator outputs the control signal to the DC load port to realize the constant power control of the DC load; the DC load module is incorporated into the system under the condition that the constraints allow, including:

[0045] After the photovoltaic unit is connected to the photovoltaic storage DC microgrid system, the load power connected to the DC load port becomes larger, and the voltage and current dual closed-loop control of the same different voltage levels is used to match the transmission power of the photovoltaic working mode from CP mode to MPPT mode.

[0046] According to the black start collaborative control strategy of photovoltaic storage DC microgrid based on power router, the fluctuation range of DC bus voltage is always kept within 5% during black start and grid-connected conversion, and the output voltage stability results of each port are generated. The operation test results of each port module are coordinated and integrated to generate collaborative test results.

[0047] During the black start process, the energy storage unit first starts from zero voltage to charge the EER DC bus and provide starting power to the photovoltaic unit to enable it to start. When the EER DC bus voltage gradually stabilizes, the photovoltaic unit outputs active power and is incorporated into the photovoltaic DC microgrid system under power constraints. At the same time, the photovoltaic DC microgrid system can quickly start other loads to ensure that there will be no second power outage when connected to the photovoltaic DC microgrid system. To implement the black start collaborative control strategy of the photovoltaic DC microgrid, the voltage construction and control of each port of the EER are simulated, the constant power (CP) control mode is adopted, and the PI controller is used for adjustment to ensure the stability and response speed of the photovoltaic DC microgrid system.

[0048] Example 2

[0049] In the second aspect, the present invention provides a photovoltaic and DC microgrid black start collaborative control method, which relies on the constructed photovoltaic and DC microgrid black start collaborative control system to realize the photovoltaic and DC microgrid black start process and the startup process and sequence of each port of the EER. The startup process and sequence are the self-starting stage of the energy storage unit, the stage of the photovoltaic unit connecting to and supplying power to the load, the load recovery stage and the grid-connected operation stage.

[0050] In the energy storage unit self-starting stage, the energy storage unit starts from zero voltage and charges the EER DC bus. At the same time, it provides starting power to the photovoltaic unit so that it can start successfully. In this stage, the photovoltaic DC microgrid has active power constraints: P Bat >P PVLoad +P e , where P Bat is the active output of the energy storage unit, P PVLoad is the starting load of the photovoltaic unit, P e is the active power loss of the power router.

[0051] During the PV unit startup phase, the PV unit outputs active power while the energy storage unit maintains the DC bus voltage and provides the power required by the base load and ensures the stable operation of the photovoltaic storage DC microgrid system. To ensure that the system does not fail to start due to the impact of PV access, there is a power constraint: P Bat +P pv >P Load +P PVLoad +P e .

[0052] Where: P pv is the active power output of the photovoltaic unit, P Load Consume active power for controllable load.

[0053] The load recovery phase uses the started power supply to quickly start other loads and maintain the stability of the system DC bus voltage during the recovery process. In this phase, there are controllable load cut-in and cut-out. To ensure that the system does not experience a secondary power outage, the microgrid has a power constraint at this time: P Bat +P pv -P Load -P e >P m .

[0054] Where: P m It is the active margin of the recovery process.

[0055] Combine the following Figure 2 As shown in the figure, the photovoltaic energy storage black start sequence of the photovoltaic energy storage DC microgrid system includes:

[0056] 1. Start the power router.

[0057] In the process of realizing black start of the photovoltaic DC microgrid, starting the power router is the first step. The power router is not only responsible for the distribution and dispatching of electric energy, but also ensures the effective connection with various distributed energy sources and loads. It is connected to various components in the photovoltaic DC microgrid through the corresponding ports.

[0058] 2. Close the energy storage port and connect the energy storage unit.

[0059] The energy storage unit starts from zero voltage and charges the DC bus of the power router. At the same time, it provides starting power to the photovoltaic unit so that it can start successfully. At this stage, the energy storage unit must first meet the basic needs of the system, while also ensuring that the photovoltaic unit can start successfully. At this stage, the photovoltaic storage DC microgrid has active constraints: P Bat >P PVLoad +P e .

[0060] Energy storage port control block diagram combined Figure 3 As shown in the figure, under black start conditions, the DC bus voltage is stabilized by the energy storage unit, and the energy storage port adopts a constant voltage control mode. The DC bus voltage is stabilized by the DC voltage outer loop, and the current inner loop tracks and controls the current. That is, the output voltage U dc With reference voltage As the control input, the reference current of the energy storage unit is output through the PI regulator And compared with the actual output current I b The PI regulator outputs a control signal to the output port of the energy storage unit to achieve constant voltage control. When switching to grid-connected operation, the grid-connected port is responsible for stabilizing the DC bus voltage and regulating the charging and discharging power of the energy storage unit by controlling the current of the energy storage port through the power loop. At this time, the energy storage port adopts a constant power control mode. That is, the reference charging power of a given energy storage unit The actual charging power P b For comparison, the reference current of the energy storage unit is output through the PI regulator. The actual output current I of the energy storage unit b For comparison, the energy storage charging power control is realized by outputting the control signal through the PI regulator.

[0061] 3. Close the DC load port and connect the DC load unit.

[0062] The load recovery process is to use the started power supply to quickly start other loads and maintain the stability of the system DC bus voltage during the recovery process. In this stage, there are controllable load cut-in and cut-out. In order to ensure that the photovoltaic storage DC microgrid system will not have a secondary power outage, the photovoltaic storage DC microgrid system has a power constraint at this time: P Bat +P pv -P Load-P e >P m .

[0063] Control block diagram of DC load port combined Figure 4 As shown in the figure, the DC load port uses a Buck converter for voltage conversion. The control target of the DC load port is to output a DC voltage of a specified amplitude and keep it stable. In order to achieve the control target, the output DC voltage is fed back in a closed loop and the output voltage U d With reference voltage reference value As the control input, the DC load port reference current is output through the PI regulator And compared with the actual current I d The PI regulator outputs a control signal to the DC load port to achieve CP control of the DC load.

[0064] 4. Close the PV port and connect the PV unit.

[0065] When the EER DC bus voltage gradually stabilizes, the PV unit outputs active power. To ensure that the system does not fail to start due to the impact of PV access, there is a power constraint: P Bat +P pv >P Load +P pvLoad +P e .

[0066] The photovoltaic port is based on the Boost circuit, and its output side is connected to the DC bus. Figure 5 There are two working modes of photovoltaic units: CP mode and MPPT mode. In MPPT mode, the output voltage U pv The photovoltaic unit output current I pv As the control input, it is input into the MPPT controller and the voltage command is obtained through the conductance increment algorithm. Then the photovoltaic unit output voltage U pv Subtract, and output the control signal to the photovoltaic port through the PI regulator to realize the MPPT control of the photovoltaic unit. In CP mode, the photovoltaic unit output power detects the controllable load power, and the photovoltaic unit output voltage U pv Reference active output of photovoltaic unit As the control input, the PI regulator outputs the photovoltaic unit reference current And compared with the actual output current I pv After comparison, the PI regulator outputs a control signal to the photovoltaic port to achieve constant power control of the photovoltaic unit. Figure 6 The specific principle is to monitor the output voltage U of the photovoltaic unit pvThe photovoltaic unit output current I pv Calculate the real-time active output of the photovoltaic unit P pv , by comparing the active output of the photovoltaic unit P pv The active power consumed by the controllable load P Load Size, select its working mode. Calculate ΔP=P pv -P Load When ΔP>0, it works in constant power mode, and when ΔP<0, it works in MPPT mode.

[0067] 5. Close the grid-connected port and connect the grid unit.

[0068] When the black start is completed and the system is switched to grid-connected operation, the grid-connected port maintains a constant DC bus voltage and can control the bidirectional flow of power. The reference value of the DC bus voltage is input, and the PWM control signal is generated through the voltage outer loop and current inner loop control. Figure 7 As shown, the DC bus voltage is closed-loop controlled, and the grid-connected port automatically balances the power to stabilize the DC voltage. The specific principle is to use grid-following control, with the outer loop being the input grid-side reference voltage. The actual output voltage U dc For comparison, the inner loop is the current loop, and the reference current under dq coordinates and With the actual i d and i q By comparison, the value after decoupling the PI regulator and ωL and the value after the three-phase voltage is changed by coordinates are d , e q Compare and form the output voltage U d and U q The control signal is output again through the PI regulator and the coordinate converter dq / abc to achieve constant voltage control on the grid side.

[0069] Combined with the above-mentioned startup sequence and control strategy principle of the present invention, the present invention finally realizes the coordinated control strategy of microgrid black start photovoltaic storage.

[0070] Finally, it should be noted that the above embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that any person skilled in the art can still modify the technical solutions recorded in the above embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A photovoltaic storage DC microgrid black start collaborative control system, comprising an energy router, the energy router comprising a grid-connected port, an energy storage port, a photovoltaic port, and a DC load port. The energy router is connected to the grid through the grid-connected port, to the energy storage unit through the energy storage port, to the photovoltaic unit through the photovoltaic port, and to the load through the DC load port; each unit is flexibly switched on the DC bus through a circuit breaker; characterized in that, The voltage construction and control of each port of the power router are simulated. The grid-connected port adopts constant voltage control mode, the energy storage port adopts constant voltage control mode, and the photovoltaic port adopts constant power mode and maximum power point tracking mode. The DC load port adopts constant power control. Under the adjustment of the PI controller, the photovoltaic storage coordinated control strategy for the black start of the photovoltaic storage DC microgrid is finally obtained based on the active power balance expression between the power supply and the load.

2. The photovoltaic-storage DC microgrid black start collaborative control system according to claim 1 is characterized in that: The black start collaborative control strategy of the photovoltaic storage DC microgrid includes: Based on the active power balance expression between power source and load: P pv +P Bat -P Load -P e =0,P pv is the active power output of the photovoltaic unit, P Load is the active power consumed by the controllable load, P Bat is the active output of the energy storage unit, P e It is the active power loss of the power router; based on the basic principle of the conductance increment method, a constant power and maximum power tracking coordinated control strategy is adopted to effectively track the load changes when the photovoltaic unit has sufficient output, and there is power surplus to charge the energy storage unit. When it is insufficient, the maximum power output is achieved, and the power shortage is borne by the energy storage unit.

3. The photovoltaic-storage DC microgrid black start collaborative control system according to claim 2 is characterized in that: The constant power and maximum power tracking coordinated control strategy includes: The output voltage U of the photovoltaic unit is monitored pv The photovoltaic unit output current I pv Calculate the real-time active output of the photovoltaic unit P pv , by comparing the active output of the photovoltaic unit P pv The active power consumed by the controllable load P Load size, select its working mode; when P pv >P Load When P pv <P Load It works in maximum power tracking mode.

4. The photovoltaic-storage DC microgrid black start collaborative control system according to claim 1 is characterized in that: The grid-connected port uses the DC bus voltage for closed-loop control; when the photovoltaic storage DC microgrid system is running stably and the black start process is completed, the grid is connected to the photovoltaic storage DC microgrid system. At this time, the grid-connected port adopts grid-following constant voltage control and automatically balances the power to stabilize the DC voltage. The grid-connected port is responsible for stabilizing the DC bus voltage and adjusting the charging and discharging power of the energy storage device by controlling the current of the energy storage port through the power loop. At this time, the energy storage port adopts the constant power control mode; The grid-connected module is integrated into the system under the constraints allowed, including: During grid-connected operation, the grid-connected port maintains a constant DC bus voltage; the reference value of the DC bus voltage is input, and after being controlled by the voltage outer loop and the current inner loop, a PWM control signal is generated; the DC bus voltage is closed-loop controlled, and the grid-connected port automatically balances the power to stabilize the DC voltage.

5. The photovoltaic-storage DC microgrid black start collaborative control system according to claim 1 is characterized in that: The energy storage port stabilizes the DC bus voltage through the DC voltage outer loop, and the current inner loop tracks and controls the current. The energy storage unit is incorporated into the system under the constraints allowed, including: When connected to the grid, the current of the energy storage port is controlled by the power ring to adjust the charging and discharging power of the energy storage unit. At this time, the energy storage port adopts a constant power control mode, and the grid side is responsible for stabilizing the DC bus voltage.

6. The photovoltaic-storage DC microgrid black start coordinated control system according to claim 1 is characterized in that: The photovoltaic port is based on the Boost circuit, and its output side is connected to the DC bus; the photovoltaic unit working mode is divided into two types: constant power mode and maximum power tracking mode; the photovoltaic unit first provides the set power to the load end in the constant power mode, and after stable operation, the photovoltaic working mode is converted to the maximum power tracking mode according to the load increase.

7. The photovoltaic-storage DC microgrid black start coordinated control system according to claim 1 is characterized in that: The DC load port uses a Buck converter for voltage conversion: the control target of the DC load port is to output a DC voltage of a specified amplitude and keep it stable; in order to achieve the control target, the output DC voltage is fed back in a closed loop and the output voltage U d With reference voltage reference value As the control input, the PI regulator outputs the control signal to the DC load port to realize the constant power control of the DC load; the DC load module is incorporated into the system under the condition that the constraints allow, including: After the photovoltaic unit is connected to the photovoltaic storage DC microgrid system, the load power connected to the DC load port becomes larger, and the voltage and current dual closed-loop control of the same different voltage levels is used to match the transmission power of the photovoltaic working mode from the constant power mode to the maximum power tracking mode.

8. A black start collaborative control method for a photovoltaic-storage DC microgrid, characterized in that: Relying on the photovoltaic storage DC microgrid black start collaborative control system described in any one of claims 1-7, the photovoltaic storage DC microgrid black start process and the startup process and sequence of each port of the power router are realized. The startup process and sequence are the self-starting stage of the energy storage unit, the stage of photovoltaic unit access and power supply to the load, the load recovery stage and the grid-connected operation stage.

9. A black start coordinated control method for a photovoltaic-storage DC microgrid according to claim 8, characterized in that: In the energy storage unit self-starting stage, the energy storage unit starts from zero voltage boost, charges the DC bus of the power router, and provides starting power to the photovoltaic unit to enable it to self-start successfully; in this stage, the photovoltaic DC microgrid has active power constraints: P Bat >P PVLoad +P e Among them, P Bat is the active output of the energy storage unit, P PVLoad is the starting load of the photovoltaic unit, P e is the active power loss of the power router.

10. A black start coordinated control method for a photovoltaic-storage DC microgrid according to claim 9, characterized in that: During the PV unit startup phase, the PV unit outputs active power while the energy storage unit maintains the DC bus voltage and provides the power required by the base load and ensures the stable operation of the photovoltaic storage DC microgrid system. To ensure that the system does not fail to start due to the impact of PV access, there is a power constraint: P Bat +P pv >P Load +P PVLoad +P e ; Where: P pv is the active power output of the photovoltaic unit, P Load Consume active power for controllable load; The load recovery phase uses the started power supply to quickly start other loads and maintain the stability of the system DC bus voltage during the recovery process; in this phase, there are controllable load cut-in and cut-out. To ensure that the system does not experience a secondary power outage, the photovoltaic DC microgrid has a power constraint: P Bat +P pv -P Load -P e >P m , where: P m It is the active margin of the recovery process.

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