Power conversion system and method of controlling the same, power conversion system

Abstract

The application discloses a power conversion system and a control method thereof, and belongs to the field of power electronics. The power conversion system comprises a first direct current conversion module, a direct current bus and an alternating direct current conversion module. A first direct current side of the first direct current conversion module is used for connecting a first direct current power supply. A second direct current side of the first direct current conversion module and a third direct current side of the alternating direct current conversion module are respectively connected to the direct current bus. An alternating current side of the alternating direct current conversion module is used for being connected to an alternating current source network. The power conversion system is configured to: in response to a first preset working condition, stop driving one of power switching tubes in the first direct current conversion module and power switching tubes in the alternating direct current conversion module, and control the other of the power switching tubes in the first direct current conversion module and the power switching tubes in the alternating direct current conversion module to perform power conversion, so as to maintain a bus voltage of the direct current bus. The power conversion system can reduce the overall power consumption of the system and improve the working efficiency of the system.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically to a power conversion system and its control method, and a power conversion system. Background Technology

[0002] A photovoltaic (PV) energy storage system typically comprises a photovoltaic (PV) DC power source, an energy storage DC power source, and a power conversion system. The power conversion system, such as residential energy storage inverters and integrated PV-energy storage units, not only generates electricity when connected to the grid but also has the capability to operate independently with load during grid outages. The power conversion system may include multiple power conversion modules, such as a first DC-DC converter for converting the DC voltage output from the PV DC power source, a second DC-DC converter for converting the DC voltage output from the energy storage DC power source, and a DC / AC converter for AC-DC conversion. When the grid is normally connected and there is a certain load or dispatch demand, the power conversion system can coordinate the operation of each power conversion module according to energy management strategies to meet power supply or grid connection requirements. The power conversion system typically operates continuously; however, under certain specific operating conditions, this mode of operation can lead to higher overall system power consumption, thereby reducing the efficiency of the PV-energy storage system. Summary of the Invention

[0003] This application provides a power conversion system and its control method, aiming to reduce the overall power consumption of the system and improve the system's working efficiency.

[0004] In a first aspect, embodiments of this application provide a power conversion system, the power conversion system including a first DC conversion module, a DC bus, and an AC-DC conversion module, wherein a first DC side of the first DC conversion module is used to connect to a first DC power supply, and a second DC side of the first DC conversion module and a third DC side of the AC-DC conversion module are respectively connected to the DC bus; the AC side of the AC-DC conversion module is used to connect to an AC source network; The power conversion system is configured as follows: In response to a first preset operating condition, one of the power switches in the first DC-DC converter module and the power switches in the AC-DC converter module is stopped from driving, and the other of the power switches in the first DC-DC converter module and the power switches in the AC-DC converter module is controlled to perform power conversion in order to maintain the bus voltage of the DC bus.

[0005] In some embodiments, the first preset operating condition includes: the first DC side of the first DC conversion module has a DC power input, and the AC power output requirement of the AC-DC conversion module is zero power; The step of stopping the driving of one of the power switches in the first DC-DC converter module and the power switches in the AC-DC converter module, and controlling the other of the power switches in the first DC-DC converter module and the power switches in the AC-DC converter module to perform power conversion, includes: Stop driving the power switching transistors in the AC / DC conversion module; The power switching transistors in the first DC-DC conversion module are controlled to output a preset first bus voltage from the second DC side.

[0006] In some embodiments, the AC source network includes a power grid and loads; The AC power output requirement of the AC-DC conversion module is zero power, including: The power dispatching power of the power grid is zero, and the load demand power of the load is zero.

[0007] In some embodiments, the first preset operating condition includes: the input power of the first DC side of the first DC conversion module is less than or equal to a preset power threshold. The step of stopping the driving of one of the power switches in the first DC-DC converter module and the power switches in the AC-DC converter module, and controlling the other of the power switches in the first DC-DC converter module and the power switches in the AC-DC converter module to perform power conversion, includes: Stop driving the power switch in the first DC-DC converter module; The power switching transistors in the AC / DC conversion module are controlled to output a preset second bus voltage from the third DC side.

[0008] In some embodiments, the input power on the first DC side of the first DC conversion module is less than or equal to a preset power threshold, including at least one of the following: The output power of the first DC power supply is less than or equal to the preset power threshold. The dispatch power of the first DC power supply is zero power; The output power of the first DC power supply is greater than the preset power threshold, and the AC power output requirement of the AC-DC conversion module is zero power.

[0009] In some embodiments, the power conversion system further includes a second DC-DC conversion module, wherein a fourth DC side of the second DC-DC conversion module is used to connect to the first energy storage power source, and a fifth DC side of the second DC-DC conversion module is connected to the DC bus. The power conversion system is further configured as follows: In response to the non-charging condition of the first energy storage power supply, the power switching transistor in the second DC-DC conversion module is stopped from being driven. Alternatively, in response to the charging condition of the first energy storage power source, the power switching transistor in the second DC-DC conversion module is controlled to draw power from the DC bus to charge the first energy storage power source.

[0010] In some embodiments, the power conversion system is further configured to: Before stopping the driving of one of the power switches in the first DC-DC converter module and the power switches in the AC-DC converter module, a power module to be maintained for the DC bus voltage is determined as the target power module; the power module to be maintained for the DC bus voltage is: the power module among the first DC-DC converter module, the AC-DC converter module, and the second DC-DC converter module that has the ability to establish the DC bus voltage; When the second DC-DC conversion module is used as the target power module, at least one of the power switching transistors in the first DC-DC conversion module and the AC-DC conversion module is stopped from driving, and the power switching transistors in the second DC-DC conversion module are controlled to perform power conversion in order to maintain the bus voltage of the DC bus. If the second DC-DC converter is not used as the target power module, the step of stopping the driving of one of the power switches in the first DC-DC converter and the power switches in the AC-DC converter is performed.

[0011] In some embodiments, the power conversion system further includes a third DC conversion module, wherein a sixth DC side of the third DC conversion module is used to connect to a second DC power supply, and a seventh DC side of the third DC conversion module is connected to the DC bus. The power conversion system is further configured as follows: If the power switching transistor in the first DC-DC conversion module is stopped from being driven, and the bus voltage of the DC bus is maintained by the AC-DC conversion module, then the power switching transistor in the third DC-DC conversion module is stopped from being driven, or the second DC power supply is controlled to output power to the DC bus.

[0012] In some embodiments, the power conversion system is further configured to: In response to the non-charging condition of the second DC power supply, the power switching transistor in the third DC conversion module is stopped from being driven. Alternatively, in response to the charging condition of the second DC power supply, the power switch in the third DC conversion module is controlled to output the fourth bus voltage from the seventh DC side to the DC bus.

[0013] In some embodiments, the power conversion system is further configured to: After stopping the driving of one of the power switches in the first DC-DC converter module and the power switches in the AC-DC converter module, in response to a power scheduling requirement on the first DC power supply or the AC side of the AC-DC converter module, the power switch in the first DC-DC converter module and the power switch in the AC-DC converter module that was stopped from driving are controlled to resume power conversion.

[0014] In some embodiments, the power conversion system further includes a filter connected between the AC side of the AC-DC conversion module and the AC source network, the filter being used to connect the AC source network via a first switch; the power conversion system is further configured to: The first switch remains closed when the power switching transistors in the AC-DC conversion module are stopped from being driven, and the AC source network allows the capacitors of the filter to enter reactive power. Disconnect the first switch when the power switching transistors in the AC / DC conversion module are stopped from being driven and the AC source network prevents the capacitors of the filter from receiving reactive power.

[0015] In some embodiments, the filter is connected to the AC side of the AC / DC conversion module via a second switch; the power conversion system is further configured to: If the first switch is disconnected, then the second switch is disconnected.

[0016] In some embodiments, the power conversion system is further configured to: After stopping the power switching transistors in the AC / DC conversion module, and before controlling the power switching transistors in the AC / DC conversion module to resume power conversion, the first switch is controlled to close.

[0017] Secondly, embodiments of this application provide a control method for a power conversion system. The power conversion system includes a first DC-DC conversion module, a DC bus, and an AC-DC conversion module. A first DC side of the first DC-DC conversion module is connected to a first DC power supply. A second DC side of the first DC-DC conversion module and a third DC side of the AC-DC conversion module are respectively connected to the DC bus. The AC side of the AC-DC conversion module is connected to an AC source network. The control method includes: In response to a first preset operating condition, one of the power switches in the first DC-DC converter module and the power switches in the AC-DC converter module is stopped from driving, and the other of the power switches in the first DC-DC converter module and the power switches in the AC-DC converter module is controlled to perform power conversion in order to maintain the bus voltage of the DC bus.

[0018] Thirdly, embodiments of this application provide a power conversion system, the power conversion system comprising: First DC power supply; A power conversion system includes a first DC conversion module, a DC bus, an AC-DC conversion module, and a first controller. The first DC side of the first DC conversion module is used to connect to a first DC power supply. The second DC side of the first DC conversion module and the third DC side of the AC-DC conversion module are respectively connected to the DC bus. The AC side of the AC-DC conversion module is used to connect to an AC source network. The first controller is connected to both the first DC-DC conversion module and the AC-DC conversion module, and is configured to: in response to a first preset operating condition, stop driving one of the power switches in the first DC-DC conversion module and the power switches in the AC-DC conversion module, and control the other of the power switches in the first DC-DC conversion module and the power switches in the AC-DC conversion module to perform power conversion in order to maintain the bus voltage of the DC bus.

[0019] In some embodiments, the power conversion system further includes: An energy storage system includes a fourth DC-DC converter module, a second energy storage power supply, and a second controller. The eighth DC side of the fourth DC-DC converter module is connected to the second energy storage power supply, and the ninth DC side of the fourth DC-DC converter module is connected to the DC bus. The fourth DC-DC converter module is also connected to the second controller. The second controller is communicatively connected to the first controller and is configured to send the status of the second energy storage power supply to the first controller. The first controller is further configured to: in response to a non-charging condition of the second energy storage power supply, stop driving the power switching transistor in the fourth DC-DC conversion module via the second controller; Alternatively, in response to the charging condition of the second energy storage power supply, the power switch in the fourth DC-DC conversion module is controlled to draw power from the DC bus to charge the second energy storage power supply.

[0020] In some embodiments, the first controller is further configured to: Before stopping the driving of one of the power switches in the first DC-DC converter module and the power switches in the AC-DC converter module, a power module to be maintained for the DC bus voltage is determined as the target power module; the power module to be maintained for the DC bus voltage is: the power module among the first DC-DC converter module, the AC-DC converter module, and the fourth DC-DC converter module that has the ability to establish the DC bus voltage; When the fourth DC-DC conversion module is the target power module, at least one of the power switching transistors in the first DC-DC conversion module and the AC-DC conversion module is stopped from driving, and the power switching transistors in the fourth DC-DC conversion module are controlled by the second controller to perform power conversion in order to maintain the bus voltage of the DC bus. If the fourth DC-DC converter is not used as the target power module, the step of stopping the driving of one of the power switches in the first DC-DC converter and the power switches in the AC-DC converter is performed.

[0021] In this embodiment of the application, when the first preset operating condition is met, the power conversion system enters a hot standby state, stops driving one of the power switches in the first DC conversion module and the power switches in the AC-DC conversion module, and controls the other of the power switches in the first DC conversion module and the power switches in the AC-DC conversion module to perform power conversion in order to maintain the bus voltage of the DC bus, thereby reducing the ineffective energy consumption when there is no power scheduling requirement in each module of the power conversion system, reducing the overall power consumption of the system, and improving the overall energy utilization efficiency of the system. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a power conversion system provided in an embodiment of this application; Figure 2 This is another schematic diagram of the power conversion system provided in the embodiments of this application; Figure 3 This is a bus voltage control topology diagram of the DC bus provided in the embodiments of this application; Figure 4 This is a control schematic diagram of another structure of the power conversion system provided in the embodiments of this application under the condition that the second DC conversion module is the target module; Figure 5 This is a control schematic diagram of another structure of the power conversion system provided in the embodiments of this application, under the condition that the first DC-DC conversion module is the target module; Figure 6 This is another structural schematic diagram of the power conversion system provided in the embodiments of this application; Figure 7This is a control schematic diagram of another structure of the power conversion system provided in this application embodiment under the condition that the third DC conversion module has not stopped driving; Figure 8 This is another structural schematic diagram of the power conversion system provided in the embodiments of this application; Figure 9 This is a schematic diagram of the control flow for the power conversion system to enter hot standby state provided in an embodiment of this application; Figure 10 This is a schematic diagram of the control flow for the power conversion system to exit hot standby state provided in an embodiment of this application; Figure 11 This is a schematic diagram of a power conversion system provided in an embodiment of this application; Figure 12 This is another structural schematic diagram of the power conversion system provided in the embodiments of this application.

[0024] Explanation of reference numerals in the attached figures: 100. Power conversion system; 101. First DC-DC conversion module; 102. Second DC-DC conversion module; 103. Third DC-DC conversion module; 104. AC-DC conversion module; 105. DC bus; 106. First controller; 107. Filter; 108. First switch; 109. Second switch; a. First DC side; b. Second DC side; c. Third DC side; d. AC side; e. Fourth DC side; f. Fifth DC side; g. Sixth DC side; h. Seventh DC side; i. Eighth DC side; j. Ninth DC side; s. Power switch transistor; 200. First DC power supply; 300. Second DC power supply; 400. First energy storage power source; 500, AC source network; 501, power grid; 502, load.

[0025] 600. Energy storage system; 601. Fourth DC-DC conversion module; 602. Second energy storage power supply; 603. Second controller. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0029] The use of "applies to" or "configured to" in this application implies open and inclusive language, which does not exclude the applicability to or configuration to devices performing additional tasks or steps. Additionally, the use of "based on" implies openness and inclusivity, because processes, steps, calculations, or other actions "based on" one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0030] In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0031] like Figure 1As shown in the figure, this application embodiment provides a power conversion system 100, which includes a first DC conversion module 101, a DC bus 105, and an AC / DC conversion module 104. The first DC side a of the first DC conversion module 101 is used to connect to a first DC power supply 200, and the second DC side b of the first DC conversion module 101 and the third DC side c of the AC / DC conversion module 104 are respectively connected to the DC bus 105; the AC side d of the AC / DC conversion module 104 is used to connect to an AC power source network 500.

[0032] The power conversion system 100 is configured as follows: In response to the first preset operating condition, one of the power switch s in the first DC-DC conversion module 101 and the power switch s in the AC-DC conversion module 104 is stopped from driving, and the other of the power switch s in the first DC-DC conversion module 101 and the power switch s in the AC-DC conversion module 104 is controlled to perform power conversion in order to maintain the bus voltage of the DC bus 105.

[0033] Specifically, the first DC-DC conversion module 101 is used to convert and transmit the DC power provided by the first DC power supply 200, and the AC-DC conversion module 104 is used to convert the DC power output by the first DC-DC conversion module 101 to obtain AC power for connection to the AC power source network 500, thereby meeting the needs of the AC power source network 500. The DC bus 105 is used for the transfer and transmission of DC power. It is necessary to maintain the bus voltage of the DC bus 105 at the target value through either the first DC-DC conversion module 101 or the AC-DC conversion module 104, so that the power conversion system 100 can restore power dispatch output at any time in hot standby mode.

[0034] In some examples, the power conversion system 100 also includes a first controller 106. The first controller 106 is used to execute control actions on the power switches s in each module.

[0035] In some examples, the first DC power supply 200 is a photovoltaic DC power source or an energy storage DC power source. That is to say, the first DC conversion module 101 can convert the DC power output from the photovoltaic DC power source into DC power, or it can convert the DC power output from the energy storage DC power source into DC power.

[0036] In some examples, the first DC-DC conversion module 101 and the AC-DC conversion module 104 are semiconductor modules, each containing a corresponding power switch s, such as an IGBT. The power switch s is driven to turn on and off at a specific switching frequency via an output PWM signal.

[0037] In this embodiment, stopping the drive of the power switch s is not a shutdown or waiting, but rather turning off the pulse width modulation (PWM) drive of the corresponding module, reducing the switching and conduction losses of the corresponding module to 0W. At this time, the module that stops driving the power switch s is still in operation and does not require power-on or self-testing when resuming operation; it is considered a running state. The normal operation of either the first DC-DC conversion module 101 or the AC-DC conversion module 104 can maintain the bus voltage of the DC bus 105, providing energy for the module that stops driving the power switch s to resume operation. The module that stops driving the power switch s can start at any time, responding to power scheduling, shortening the response time, and improving the efficiency of power scheduling.

[0038] The first preset operating condition is a pre-set operating condition, such as the operating condition where the power conversion system 100 meets the low-power condition, or the subsequent corresponding actions are executed when the power conversion system 100 meets the low-power condition. Whether the power conversion system 100 meets the first preset operating condition is determined based on the DC power input of the first DC side a of the first DC conversion module 101 and the AC power output demand of the AC side d of the AC-DC conversion module 104. If the power conversion system 100 meets the first preset operating condition, it enters a hot standby state. The hot standby state is the low-power operating state of the power conversion system 100. In the hot standby state, the power conversion system 100 is not completely shut down, and one of the first DC conversion module 101 or the AC-DC conversion module 104 can stop outputting power, thereby reducing the overall power consumption of the system.

[0039] In the first preset operating condition, the power conversion system 100 enters a hot standby state, stops driving one of the power switches s in the first DC-DC conversion module 101 and the power switches s in the AC-DC conversion module 104, and controls the other of the power switches s in the first DC-DC conversion module 101 and the power switches s in the AC-DC conversion module 104 to perform power conversion in order to maintain the bus voltage of the DC bus 105, thereby reducing the ineffective energy consumption when there is no power scheduling requirement in each module of the power conversion system 100 and improving the overall energy utilization efficiency.

[0040] In some examples, the first preset operating condition includes: the first DC side a of the first DC conversion module 101 has a DC power input, and the AC power output requirement of the AC-DC conversion module 104 is zero power.

[0041] For example, the AC source network 500 includes a power grid 501 and a load 502. The AC power output demand of the AC-DC conversion module 104 is zero power, including: the grid dispatch power of the power grid 501 is zero power, and the load demand power of the load 502 is zero power.

[0042] The first DC side a of the first DC conversion module 101 has a DC power input, including: the output power of the first DC power supply 200 is greater than zero, or the dispatch power of the first DC power supply 200 is greater than zero.

[0043] In this context, the grid dispatch power of grid 501 is the power that the AC / DC conversion module 104 is allowed to output to grid 501, and the load demand power is the actual power consumption demand of load 502. A zero grid dispatch power indicates that the output power of the first DC power supply 200 cannot be transmitted to grid 501 through the AC / DC conversion module 104. A zero load demand power of load 502 indicates that no electrical equipment is currently operating on load 502, and there is no demand for electrical energy consumption.

[0044] Based on the above example, stopping the driving of one of the power switch s in the first DC-DC conversion module 101 and the power switch s in the AC-DC conversion module 104, and controlling the other of the power switch s in the first DC-DC conversion module 101 and the power switch s in the AC-DC conversion module 104 to perform power conversion includes: Stop driving the power switch S in the AC / DC conversion module 104; The power switch s in the first DC-DC conversion module 101 is controlled to output a preset first bus voltage from the second DC side b.

[0045] Specifically, when the first DC side a has a DC power input and the AC power output requirement of the AC-DC conversion module 104 is zero, the power switch s in the AC-DC conversion module 104 is stopped from being driven, and the bus voltage is maintained through the first DC conversion module 101. At this time, the first DC conversion module 101 can convert the output power of the first DC power supply 200 into DC power and output the first bus voltage from the second DC side b to the DC bus 105.

[0046] For example, taking the first DC power supply 200 as a photovoltaic DC power source, when the photovoltaic DC power source has energy and the AC power output demand of the AC-DC conversion module 104 is zero, the power switch s in the AC-DC conversion module 104 is stopped from being driven, and the bus voltage is maintained through the first DC conversion module 101. Taking the first DC power supply 200 as an energy storage DC power source, when the energy storage DC power source has energy and the energy storage dispatch power is greater than zero and the AC power output demand of the AC-DC conversion module 104 is zero, the power switch s in the AC-DC conversion module 104 is stopped from being driven, and the bus voltage is maintained through the first DC conversion module 101.

[0047] In some examples, the first preset operating condition includes: the input power of the first DC side a of the first DC conversion module 101 is less than or equal to a preset power threshold.

[0048] For example, the input power of the first DC side a of the first DC conversion module 101 is less than or equal to a preset power threshold, including at least one of the following: The output power of the first DC power supply 200 is less than or equal to a preset power threshold. The dispatch power of the first DC power supply 200 is zero. The output power of the first DC power supply 200 is greater than the preset power threshold, and the AC power output requirement of the AC-DC conversion module 104 is zero power.

[0049] Specifically, taking the first DC power supply 200 as a photovoltaic DC power supply as an example, when the energy of the photovoltaic DC power supply is less than or equal to a first threshold so that the output power is less than or equal to a preset power threshold, or when the energy of the photovoltaic DC power supply is greater than the first threshold so that the output power is greater than the preset power threshold, and the AC power output demand of the AC-DC conversion module 104 is zero, the input power of the first DC side a of the first DC conversion module 101 is determined to be less than or equal to the preset power threshold. Taking the first DC power supply 200 as an energy storage DC power supply as an example, when the state of charge (SOC) of the energy storage DC power supply is less than or equal to a second threshold so that the output power is less than or equal to the preset power threshold, or when the dispatch power of the energy storage DC power supply is zero, the input power of the first DC side a of the first DC conversion module 101 is determined to be less than or equal to the preset power threshold.

[0050] The energy of the photovoltaic DC source is used to characterize the output power parameter. The first threshold is a pre-set critical value at which the photovoltaic DC source has no effective energy. When the energy of the photovoltaic DC source is lower than the first threshold, it means that the photovoltaic DC source cannot provide DC power to the photovoltaic side. At this time, the input power of the first DC side a is less than or equal to the preset power threshold.

[0051] The state of charge (SOC) is the percentage of the battery's remaining charge in the energy storage DC power source relative to its rated capacity. The second threshold is a pre-set critical value for the battery in the energy storage DC power source to be discharged. When the SOC of the battery in the energy storage DC power source is lower than the second threshold, it means that the energy storage DC power source cannot output DC power from the energy storage side. At this time, the input power of the first DC side a is less than or equal to the preset power threshold.

[0052] The fact that the dispatch power of the first DC power supply 200 is zero indicates that the first DC power supply 200 has not received a charging or discharging command. Even if the state of charge of the energy storage DC source is higher than the second threshold, it does not need to participate in power interaction.

[0053] Based on the above example, stopping the driving of one of the power switch s in the first DC-DC conversion module 101 and the power switch s in the AC-DC conversion module 104, and controlling the other of the power switch s in the first DC-DC conversion module 101 and the power switch s in the AC-DC conversion module 104 to perform power conversion includes: Stop driving the power switch S in the first DC-DC converter module 101; The power switch s in the AC / DC conversion module 104 is controlled to output a preset second bus voltage from the third DC side c.

[0054] Specifically, when the input power on the first DC side a is less than or equal to a preset power threshold, the power switch s in the first DC-DC conversion module 101 is stopped from driving, and the bus voltage is maintained through the third DC side c of the AC-DC conversion module 104. At this time, the AC-DC conversion module 104 can draw power from the power grid 501 for AC-DC conversion, and then output the second bus voltage from the third DC side c to the DC bus 105.

[0055] like Figure 2 As shown, in some examples, the power conversion system 100 further includes a second DC conversion module 102, the fourth DC side e of the second DC conversion module 102 is used to connect to the first energy storage power supply 400, and the fifth DC side f of the second DC conversion module 102 is connected to the DC bus 105.

[0056] The power conversion system 100 is also configured as follows: In response to the non-charging condition of the first energy storage power supply 400, the power switching transistor s in the second DC-DC conversion module 102 is stopped from being driven. Alternatively, in response to the charging condition of the first energy storage power supply 400, the power switch s in the second DC-DC conversion module 102 is controlled to draw power from the DC bus 105 to charge the first energy storage power supply 400.

[0057] In some examples, the second DC-DC conversion module 102 is a semiconductor module, which contains a corresponding power switch s, such as an IGBT. The power switch s is driven to turn on and off at a specific switching frequency by the output PWM signal.

[0058] For example, the non-charging state of the first energy storage power source 400 includes either the first energy storage power source 400 being prohibited from charging or the first energy storage power source 400 being fully charged. A fully charged state of charge indicates that the first energy storage power source 400 has no charging requirement; the first energy storage power source 400 being prohibited from charging indicates that the first energy storage power source 400 is prohibited from receiving electrical energy, for example, due to a battery malfunction. The charging state of the first energy storage power source 400 includes a partially charged state of charge. A partially charged state of charge indicates that the first energy storage power source 400 has a charging requirement and there is no restriction prohibiting charging, and it can normally receive electrical energy.

[0059] In some examples, the power conversion system 100 is also configured as follows: Before stopping the power switch s in the first DC-DC converter module 101 and the power switch s in the AC-DC converter module 104, the power module to be maintained for the DC bus voltage is determined as the target power module; the power module to be maintained for the DC bus voltage is: the power module in the first DC-DC converter module 101, the AC-DC converter module 104, and the second DC-DC converter module 102 that has the ability to establish the DC bus voltage 105; When the second DC-DC conversion module 102 is used as the target power module, at least one of the power switch s in the first DC-DC conversion module 101 and the power switch s in the AC-DC conversion module 104 is stopped from driving, and the power switch s in the second DC-DC conversion module 102 is controlled to perform power conversion in order to maintain the bus voltage of the DC bus 105. If the second DC-DC converter module 102 is not used as the target power module, the step of stopping the driving of one of the power switches s in the first DC-DC converter module 101 and the power switches s in the AC-DC converter module 104 is executed.

[0060] like Figure 3The diagram shows the bus voltage control topology for DC bus 105. Specifically, it determines whether any one of the following modules—the first DC conversion module 101, the AC / DC conversion module 104, and the second DC conversion module 102—can establish the bus voltage for DC bus 105 during normal operation. Specifically, this can be achieved by obtaining the bus voltage command and bus voltage sampling feedback through a control regulator, calculating the first difference between the bus voltage command and the bus voltage sampling feedback, and obtaining the first, second, and third current sampling feedbacks. The first current sampling feedback is the current sampling feedback from the first DC power supply 200, the second current sampling feedback is the current sampling feedback from the first energy storage power supply 400, and the third current sampling feedback is the inverter current sampling feedback from the AC side d of the AC / DC control module. The module corresponding to the current sampling feedback that can compensate for the first difference among the first, second, and third current sampling feedbacks is selected as the target module. The control regulator can be, for example, a proportional-integral (PI) controller.

[0061] Once the target module capable of establishing the bus voltage of DC bus 105 is determined, the power switch S of at least one of the two remaining modules can be stopped from driving. For example, if the second DC-DC converter module 102 is the target module, one or both of the first DC-DC converter module 101 and the AC-DC converter module 104 can be stopped from driving; if the first DC-DC converter module 101 is the target module, one or both of the second DC-DC converter module 102 and the AC-DC converter module 104 can be stopped from driving; if the AC-DC converter module 104 is the target module, one or both of the second DC-DC converter module 102 and the first DC-DC converter module 101 can be stopped from driving.

[0062] like Figure 4 and Figure 5 As illustrated, exemplarily, when the second DC-DC conversion module 102 serves as the target power module, the power conversion system 100 may, in response to the non-charging condition of the first energy storage power supply 400 or the first DC power supply 200 having no energy, and the AC power output demand of the AC-DC conversion module 104 being zero, stop driving the power switch s in the first DC-DC conversion module 101 and the power switch s in the AC-DC conversion module 104. The power conversion system 100 may also, in response to the charging condition of the first energy storage power supply 400, and the first DC power supply 200 having energy and the AC power output demand being zero, stop driving the power switch s in the AC-DC conversion module 104, and control the first DC-DC conversion module 101 to find its maximum operating point, so that the output power of the first DC power supply 200 is converted to DC and fed into the DC bus 105, and then charged to the first energy storage power supply 400 through the DC bus 105.

[0063] When the second DC-DC conversion module 102 is not used as the target power module, the bus voltage is maintained by the first DC-DC conversion module 101 or the AC-DC conversion module 104. The second DC-DC conversion module 102 can maintain the drive when the first energy storage power supply 400 is in charging mode, and stop the drive when the first energy storage power supply 400 is in non-charging mode.

[0064] For example, when the first DC-DC conversion module 101 is the target module, the power conversion system 100 can stop driving the power switch s in the second DC-DC conversion module 102 and the power switch s in the AC-DC conversion module 104 in response to the zero power AC power output demand of the AC-DC conversion module 104 and the non-charging condition of the first energy storage power source 400. At this time, the first DC-DC conversion module 101 maintains the bus voltage by injecting power into the DC bus 105. The power conversion system 100 can also stop driving the power switch s in the AC-DC conversion module 104 in response to the zero power AC power output demand of the AC-DC conversion module 104 and the charging condition of the first energy storage power source 400, and control the power switch s in the second DC-DC conversion module 102 to perform power conversion so as to draw power from the DC bus 105 to charge the first energy storage power source 400.

[0065] For example, when the AC / DC conversion module 104 is the target module, the power conversion system 100 can stop driving the power switch s in the first DC conversion module 101 and the power switch s in the second DC conversion module 102 in response to the input power of the first DC side a of the first DC conversion module 101 being less than or equal to a preset power threshold and the dispatch power of the first energy storage power supply 400 being zero power. The power conversion system 100 can also stop driving the power switch s in the second DC conversion module 102 in response to the input power of the first DC side a being greater than or equal to a preset power threshold and the dispatch power of the first energy storage power supply 400 being zero power, and control the power switch s in the first DC conversion module 101 to perform power conversion in order to find the maximum operating point. After the output power of the first DC power supply 200 is converted to DC power, it is charged into the DC bus 105. At this time, when the voltage of the DC bus 105 exceeds the voltage of the third bus, the AC / DC conversion module 104 will supply the bus voltage to the grid 501 to maintain the stability of the bus voltage.

[0066] like Figure 6 As shown, in some examples, the power conversion system 100 also includes a third DC conversion module 103, the sixth DC side g of the third DC conversion module 103 being connected to the second DC power supply 300, and the seventh DC side h of the third DC conversion module 103 being connected to the DC bus 105.

[0067] The power conversion system 100 is also configured as follows: If the power switch s in the first DC-DC conversion module 101 is stopped from being driven, and the bus voltage of the DC bus 105 is maintained by the AC-DC conversion module 104, the power switch s in the third DC-DC conversion module 103 is stopped from being driven, or the second DC power supply 300 is controlled to output power to the DC bus 105.

[0068] In some examples, the third DC-DC conversion module 103 is a semiconductor module, which contains a corresponding power switch s, such as an IGBT. The power switch s is driven to turn on and off at a specific switching frequency by the output PWM signal.

[0069] In some examples, the second DC power supply 300 is a photovoltaic DC power source or an energy storage DC power source. That is to say, the third DC conversion module 103 can convert the DC power output from the photovoltaic DC power source into DC power, or it can convert the DC power output from the energy storage DC power source into DC power.

[0070] like Figure 7 As shown, in some examples, the power conversion system 100 is also configured as follows: In response to the non-charging condition of the second DC power supply 300, the power switching transistor s in the third DC conversion module 103 is stopped from being driven. Alternatively, in response to the charging condition of the second DC power supply 300, the power switch s in the third DC conversion module 103 is controlled to draw power from the DC bus 105 to charge the second DC power supply 300.

[0071] For example, the non-charging condition of the second DC power supply 300 indicates a condition in which the second DC power supply 300 is prohibited from outputting electrical energy. For example, the second DC power supply 300 is prohibited from charging or the energy state of the second DC power supply 300 is not fully charged. The charging condition of the second DC power supply 300 indicates a condition in which the second DC power supply 300 can output electrical energy normally. For example, the energy state of the second DC power supply 300 is fully charged.

[0072] When the power switch s in the first DC-DC converter module 101 is stopped from driving and the bus voltage of the DC bus 105 is maintained by the AC-DC converter module 104, the power switch s in the third DC-DC converter module 103 can be stopped from driving in response to the non-charging condition of the second DC power supply 300. In response to the charging condition of the second DC power supply 300, the power switch s in the third DC-DC converter module 103 can be controlled to output the fourth bus voltage from the seventh DC side h to the DC bus 105. At this time, the AC-DC converter module 104 draws power from the grid 501 to maintain the bus voltage of the DC bus 105, and can also output the excess voltage output by the third DC-DC converter module 103 to the grid 501.

[0073] In some embodiments, the power conversion system 100 is further configured to: After stopping the driving of one of the power switches s in the first DC-DC converter module 101 and the power switches s in the AC-DC converter module 104, in response to a power scheduling demand in the first DC power supply 200 or the AC side d of the AC-DC converter module 104, the power switch s in the first DC-DC converter module 101 and the power switch s in the AC-DC converter module 104 that was stopped from driving is controlled to resume power conversion.

[0074] Specifically, when the power conversion system 100 has entered the hot standby state, if there is a power scheduling requirement on either the AC side d of the first DC power supply 200 or the AC side d of the AC-DC conversion module 104, the power conversion system 100 is triggered to exit the hot standby state, so that one of the power switching transistors s in the first DC conversion module 101 and the AC-DC conversion module 104 that was stopped from driving can quickly resume driving.

[0075] For example, when the power switch s in the first DC-DC converter module 101 is stopped from being driven, if the energy state of the first DC power supply 200 is detected to be higher than the first threshold and the AC power output demand of the AC side d is not zero, or if the dispatch power of the first DC power supply 200 is detected to be not zero, the hot standby state is immediately exited and the driving of the power switch s in the first DC-DC converter module 101 is resumed.

[0076] If the power switch s in the AC-DC converter module 104 is stopped from driving, and the AC power output demand on the AC side d is detected to be non-zero (e.g., the load 502 power is non-zero, the dispatch power is non-zero, or the feeder status permission changes from prohibited to permitted), the hot standby state is immediately exited and the driving of the power switch s in the AC-DC converter module 104 is resumed.

[0077] Since only the pulse width modulation (PWM) drive is turned off when the power switching transistor s in the first DC-DC converter module 101 or AC-DC converter module 104 is stopped, the switching / conduction loss of the corresponding module is reduced to 0W. At this time, the first DC-DC converter module 101 or AC-DC converter module 104 is still in operation, and at least one of the modules in the first DC-DC converter module 101 or AC-DC converter module 104 is used to maintain the bus voltage of the DC bus 105. Therefore, the module whose drive has been stopped can quickly resume normal operation, achieve millisecond-level response, quickly restore output, and improve power dispatch efficiency.

[0078] like Figure 8As shown, in some examples, the power conversion system 100 also includes a filter 107 connected between the AC side d of the AC-DC conversion module 104 and the AC source network 500. The filter 107 is used to connect the AC source network 500 via a first switch 108.

[0079] The power conversion system 100 is also configured as follows: The first switch 108 remains closed when the power switch s in the AC-DC conversion module 104 is stopped and the AC source network 500 allows the capacitor of the filter 107 to enter reactive power. When the power switch S in the AC / DC conversion module 104 is stopped and the AC source network 500 prevents the capacitor of the filter 107 from entering reactive power, the first switch 108 is disconnected.

[0080] Specifically, filter 107 is used to suppress power harmonics on the AC side of AC-DC converter module 104, making the input or output AC waveform smoother. First switch 108 is used to control the connection and disconnection between filter 107 and load 502 and power grid 501. When AC-DC converter module 104 stops outputting, the capacitor in filter 107 may output reactive power to power grid 501. Therefore, when power grid 501 allows reactive power from filter 107 to enter, keeping first switch 108 closed avoids additional switching operations, reducing switching and conduction losses. When power grid 501 does not allow reactive power from filter 107 to enter, opening first switch 108 isolates filter 107 from power grid 501, reducing the consumption of reactive power by the capacitor in power grid 501.

[0081] In some examples, filter 107 is connected to the AC side d of AC / DC conversion module 104 via second switch 109; power conversion system 100 is also configured to: With the first switch 108 disconnected, the second switch 109 is disconnected.

[0082] Specifically, the second switch 109 is used to control the connection and disconnection between the filter 107 and the AC side d of the AC-DC conversion module 104. In this way, by disconnecting the first switch 108 to isolate the filter 107 from the power grid 501, and then disconnecting the second switch 109, the isolation between the AC-DC conversion module 104 and the filter 107 can be further achieved, avoiding the conduction of reactive power capacitance in the filter 107 and reducing losses.

[0083] In some examples, the power conversion system 100 is also configured as follows: After stopping the power switch s in the AC / DC conversion module 104, and before controlling the power switch s in the AC / DC conversion module 104 to resume power conversion, the first switch 108 is closed.

[0084] Specifically, after stopping the power switch S in the AC / DC converter module 104, the first switch 108 is in the open state due to the grid 501 disabling the reactive power input of the filter 107 capacitor. If the drive of the power switch S in the AC / DC converter module 104 is directly restored at this time, the AC side d-circuit will be blocked, resulting in the inability to transmit power and causing problems such as overvoltage on the DC bus 105 and module idling. Controlling the first switch 108 to close first and then restoring the output of the AC / DC converter module 104 can effectively avoid the problem of the AC side d-circuit being blocked.

[0085] like Figure 9 As shown, taking the power conversion system 100, which includes a first DC conversion module 101, a second DC conversion module 102, and an AC / DC conversion module 104, as an example, when the power conversion system 100 enters the hot standby state, the module that needs to be stopped is determined according to the preset low power consumption conditions. If the module to be stopped is the first DC conversion module 101 or the second DC conversion module 102, the output can be stopped directly. If the module to be stopped is the AC / DC conversion module 104, it is determined whether the first switch 108 needs to be disconnected based on whether the power grid 501 prohibits the reactive power input of the capacitor of the filter 107. If the first switch 108 needs to be disconnected, a command to disconnect the first switch 108 is sent to disconnect the first switch 108. If the first switch 108 does not need to be disconnected, the first switch 108 is kept closed.

[0086] like Figure 10 As shown, taking the power conversion system 100 including a first DC conversion module 101, a second DC conversion module 102, and an AC / DC conversion module 104 as an example, when the power conversion system 100 exits the hot standby state, the stopped modules are restored. If the stopped modules are the first DC conversion module 101 and the second DC conversion module 102, the output can be directly restored. If the stopped module is the AC / DC conversion module 104, it is determined whether the first switch 108 is open. If the first switch 108 is open, a command to close the first switch 108 is sent to close the first switch 108. If the first switch 108 is closed, the output of the AC / DC conversion module 104 is restored.

[0087] The above are only specific examples of implementation methods in some embodiments. They can be flexibly combined and matched according to product design, power grid 501 requirements or user needs to meet the needs of different power conversion systems 100.

[0088] In this embodiment of the power conversion system 100, when a first preset operating condition is met, the power conversion system 100 enters a hot standby state, stops driving one of the power switches s in the first DC-DC conversion module 101 and the power switches s in the AC-DC conversion module 104, and controls the other of the power switches s in the first DC-DC conversion module 101 and the power switches s in the AC-DC conversion module 104 to perform power conversion in order to maintain the bus voltage of the DC bus 105, thereby reducing the ineffective energy consumption when there is no power scheduling requirement in each module of the power conversion system 100, reducing the overall power consumption of the system, and improving the overall energy utilization efficiency of the system.

[0089] Accordingly, this application also provides a control method for a power conversion system 100, applied to the power conversion system 100 of this application embodiment. Specifically, the control method is applied to a first controller 106 and includes: In response to the first preset operating condition, one of the power switch s in the first DC-DC conversion module 101 and the power switch s in the AC-DC conversion module 104 is stopped from driving, and the other of the power switch s in the first DC-DC conversion module 101 and the power switch s in the AC-DC conversion module 104 is controlled to perform power conversion in order to maintain the bus voltage of the DC bus 105.

[0090] For the specific control switching logic, please refer to the corresponding descriptions in the foregoing embodiments, which will not be repeated here.

[0091] Through the above technical solution, under the condition of satisfying the first preset working condition, the power conversion system 100 is controlled to enter the hot standby state, and one of the power switches s in the first DC conversion module 101 and the AC-DC conversion module 104 is stopped from driving, and the other of the power switches s in the first DC conversion module 101 and the AC-DC conversion module 104 is controlled to perform power conversion in order to maintain the bus voltage of the DC bus 105, thereby reducing the ineffective energy consumption when there is no power scheduling requirement in each module of the power conversion system 100, reducing the overall power consumption of the system, and improving the overall energy utilization efficiency of the system.

[0092] Accordingly, embodiments of this application also provide a power conversion system. For example... Figure 11 As shown, the power conversion system includes a first DC power supply 200 and a power conversion system 100.

[0093] The power conversion system 100 includes a first DC conversion module 101, a DC bus 105, an AC / DC conversion module 104, and a first controller 106. The first DC side a of the first DC conversion module 101 is used to connect to a first DC power supply 200. The second DC side b of the first DC conversion module 101 and the third DC side c of the AC / DC conversion module 104 are respectively connected to the DC bus 105. The AC side d of the AC / DC conversion module 104 is used to connect to an AC power source network 500. The first controller 106 is connected to the first DC-DC conversion module 101 and the AC-DC conversion module 104 respectively, and is configured to: in response to a first preset operating condition, stop driving one of the power switch s in the first DC-DC conversion module 101 and the power switch s in the AC-DC conversion module 104, and control the other of the power switch s in the first DC-DC conversion module 101 and the power switch s in the AC-DC conversion module 104 to perform power conversion in order to maintain the bus voltage of the DC bus 105.

[0094] like Figure 12 As shown, in some examples, the power conversion system also includes: Energy storage system 600 includes a fourth DC-DC converter module 601, a second energy storage power supply 602, and a second controller 603. The eighth DC side i of the fourth DC-DC converter module 601 is connected to the second energy storage power supply 602, and the ninth DC side j of the fourth DC-DC converter module 601 is connected to the DC bus 105. The fourth DC-DC converter module 601 is also connected to the second controller 603. The second controller 603 is communicatively connected to the first controller 106 and is configured to send the status of the second energy storage power supply 602 to the first controller 106. The first controller 106 is also configured to: in response to the non-charging condition of the second energy storage power supply 602, stop driving the power switch s in the fourth DC-DC conversion module 601 through the second controller 603; Alternatively, in response to the charging condition of the second energy storage power supply 602, the power switch s in the fourth DC-DC conversion module 601 is controlled by the second controller 603 to draw power from the DC bus 105 to charge the second energy storage power supply 602.

[0095] In some examples, the first controller 106 is also configured as follows: Before stopping the power switch s in the first DC-DC converter module 101 and the power switch s in the AC-DC converter module 104, the power module to be maintained for the DC bus voltage is determined as the target power module; the power module to be maintained for the DC bus voltage is: the power module in the first DC-DC converter module 101, the AC-DC converter module 104, and the fourth DC-DC converter module 601 that has the ability to establish the DC bus voltage 105; When the fourth DC-DC conversion module 601 is the target power module, at least one of the power switch s in the first DC-DC conversion module 101 and the power switch s in the AC-DC conversion module 104 is stopped from driving, and the power switch s in the fourth DC-DC conversion module 601 is controlled by the second controller 603 to perform power conversion in order to maintain the bus voltage of the DC bus 105. If the fourth DC-DC converter module 601 is not used as the target power module, the step of stopping the driving of one of the power switch s in the first DC-DC converter module 101 and the power switch s in the AC-DC converter module 104 is executed.

[0096] Specifically, the control logic of the fourth DC-DC conversion module 601 can be found in the second DC-DC conversion module 102 or the third DC-DC conversion module 103 of the aforementioned embodiments, and will not be repeated here.

[0097] Through the above scheme, the energy storage system 600 and the power conversion system 100 can be set up independently. In the energy storage system 600, the first controller 106 does not have direct control over the fourth DC conversion module 601. It needs to send control commands to the second controller 603, and then the second controller 603 controls the fourth DC conversion module 601 to stop output, thereby realizing the control and recovery of the hot standby state.

[0098] In the power system of this application embodiment, when the first preset operating condition is met, the power conversion system 100 enters a hot standby state, stops driving one of the power switches s in the first DC conversion module 101 and the power switches s in the AC-DC conversion module 104, and controls the other of the power switches s in the first DC conversion module 101 and the power switches s in the AC-DC conversion module 104 to perform power conversion in order to maintain the bus voltage of the DC bus 105, thereby reducing the ineffective energy consumption when there is no power scheduling requirement in each module of the power conversion system 100, reducing the overall power consumption of the system, and improving the overall energy utilization efficiency of the system.

[0099] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0100] The power conversion system 100 and its control method and power conversion system provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A power conversion system, characterized in that, The power conversion system (100) includes a first DC conversion module (101), a DC bus (105), and an AC-DC conversion module (104). The first DC side (a) of the first DC conversion module (101) is used to connect to a first DC power supply (200). The second DC side (b) of the first DC conversion module (101) and the third DC side (c) of the AC-DC conversion module (104) are respectively connected to the DC bus (105). The AC side (d) of the AC-DC conversion module (104) is used to connect to an AC source network (500). The power conversion system (100) is configured as follows: In response to a first preset operating condition, one of the power switching transistors (s) in the first DC-DC converter module (101) and the power switching transistors (s) in the AC-DC converter module (104) is stopped from driving, and the other of the power switching transistors (s) in the first DC-DC converter module (101) and the power switching transistors (s) in the AC-DC converter module (104) is controlled to perform power conversion in order to maintain the bus voltage of the DC bus (105).

2. The power conversion system according to claim 1, characterized in that, The first preset operating condition includes: the first DC side (a) of the first DC conversion module (101) has a DC power input, and the AC power output requirement of the AC-DC conversion module (104) is zero power; The step of stopping one of the power switching transistors (s) in the first DC-DC converter module (101) and the power switching transistors (s) in the AC-DC converter module (104), and controlling the other of the power switching transistors (s) in the first DC-DC converter module (101) and the power switching transistors (s) in the AC-DC converter module (104) to perform power conversion includes: Stop driving the power switch(s) in the AC / DC conversion module (104); The power switch (s) in the first DC-DC conversion module (101) is controlled to output a preset first bus voltage from the second DC side (b).

3. The power conversion system according to claim 2, characterized in that, The AC source network (500) includes a power grid (501) and a load (502); The AC power output requirement of the AC-DC conversion module (104) is zero power, including: The power dispatching power of the power grid (501) is zero, and the load demand power of the load (502) is zero.

4. The power conversion system according to claim 1, characterized in that, The first preset operating condition includes: the input power of the first DC side (a) of the first DC conversion module (101) is less than or equal to a preset power threshold; The step of stopping one of the power switching transistors (s) in the first DC-DC converter module (101) and the power switching transistors (s) in the AC-DC converter module (104), and controlling the other of the power switching transistors (s) in the first DC-DC converter module (101) and the power switching transistors (s) in the AC-DC converter module (104) to perform power conversion includes: Stop driving the power switch(s) in the first DC-DC converter module (101); The power switch (s) in the AC / DC conversion module (104) is controlled to output a preset second bus voltage from the third DC side (c).

5. The power conversion system according to claim 4, characterized in that, The input power of the first DC side (a) of the first DC conversion module (101) is less than or equal to a preset power threshold, including at least one of the following: The output power of the first DC power supply (200) is less than or equal to the preset power threshold; The dispatch power of the first DC power supply (200) is zero; The output power of the first DC power supply (200) is greater than the preset power threshold, and the AC power output requirement of the AC-DC conversion module (104) is zero power.

6. The power conversion system according to claim 1, characterized in that, The power conversion system (100) further includes a second DC conversion module (102), the fourth DC side (e) of the second DC conversion module (102) is used to connect to the first energy storage power supply (400), and the fifth DC side (f) of the second DC conversion module (102) is connected to the DC bus (105). The power conversion system (100) is further configured to: In response to the non-charging condition of the first energy storage power supply (400), the power switching transistor (s) in the second DC-DC conversion module (102) is stopped from being driven. or, In response to the charging condition of the first energy storage power supply (400), the power switch(s) in the second DC-DC conversion module (102) is controlled to draw power from the DC bus (105) to charge the first energy storage power supply (400).

7. The power conversion system according to claim 6, characterized in that, The power conversion system (100) is further configured to: Before stopping the power switching transistors (s) in the first DC-DC converter module (101) and the AC-DC converter module (104), a power module to maintain the DC bus voltage is determined as a target power module; the power module to maintain the DC bus voltage is: a power module in the first DC-DC converter module (101), the AC-DC converter module (104), or the second DC-DC converter module (102) that has the ability to establish the DC bus (105) voltage; When the second DC-DC converter module (102) is the target power module, at least one of the power switch(s) in the first DC-DC converter module (101) and the power switch(s) in the AC-DC converter module (104) is stopped from driving, and the power switch(s) in the second DC-DC converter module (102) is controlled to perform power conversion in order to maintain the bus voltage of the DC bus (105); If the second DC-DC converter module (102) is not the target power module, the step of stopping the driving of one of the power switch(s) in the first DC-DC converter module (101) and the power switch(s) in the AC-DC converter module (104) is performed.

8. The power conversion system according to claim 1, characterized in that, The power conversion system (100) further includes a third DC conversion module (103), the sixth DC side (g) of the third DC conversion module (103) is used to connect to the second DC power supply (300), and the seventh DC side (h) of the third DC conversion module (103) is connected to the DC bus (105). The power conversion system (100) is further configured to: If the power switching transistors (s) in the first DC-DC converter module (101) are stopped from being driven, and the bus voltage of the DC bus (105) is maintained by the AC-DC converter module (104), the power switching transistors (s) in the third DC-DC converter module (103) are stopped from being driven, or the second DC power supply (300) is controlled to output power to the DC bus (105).

9. The power conversion system according to claim 8, characterized in that, The power conversion system (100) is further configured to: In response to the non-charging condition of the second DC power supply (300), the power switching transistors (s) in the third DC conversion module (103) are stopped from being driven. or, In response to the charging condition of the second DC power supply (300), the power switch (s) in the third DC conversion module (103) is controlled to output the fourth bus voltage from the seventh DC side (h) to the DC bus (105).

10. The power conversion system according to claim 1, characterized in that, The power conversion system (100) is further configured to: After stopping the driving of one of the power switches(s) in the first DC-DC converter module (101) and the power switches(s) in the AC-DC converter module (104), in response to a power scheduling demand on the AC side (d) of the first DC power supply (200) or the AC side (d) of the AC-DC converter module (104), the power switch(s) in the first DC-DC converter module (101) and the power switches(s) in the AC-DC converter module (104) that were stopped from driving are controlled to resume power conversion.

11. The power conversion system according to any one of claims 1-10, characterized in that, The power conversion system (100) further includes a filter (107) connected between the AC side (d) of the AC-DC conversion module (104) and the AC source network (500), the filter (107) being used to connect the AC source network (500) via a first switch (108); the power conversion system (100) is further configured to: The first switch (108) remains closed when the power switching transistors (s) in the AC-DC conversion module (104) are stopped from being driven and the AC source network (500) allows the capacitor of the filter (107) to enter reactive power. When the power switching transistors (s) in the AC-DC conversion module (104) are stopped from being driven, and the AC source network (500) prevents the capacitors of the filter (107) from entering reactive power, the first switch (108) is disconnected.

12. The power conversion system according to claim 11, characterized in that, The filter (107) is connected to the AC side (d) of the AC / DC conversion module (104) via a second switch (109); the power conversion system (100) is further configured to: If the first switch (108) is disconnected, the second switch (109) is disconnected.

13. The power conversion system according to claim 11, characterized in that, The power conversion system (100) is further configured to: After stopping the power switching transistor(s) in the AC / DC conversion module (104), the first switch (108) is controlled to close before the power switching transistor(s) in the AC / DC conversion module (104) is controlled to resume power conversion.

14. A control method for a power conversion system, characterized in that, The power conversion system (100) includes a first DC conversion module (101), a DC bus (105), and an AC / DC conversion module (104). The first DC side (a) of the first DC conversion module (101) is connected to a first DC power supply (200). The second DC side (b) of the first DC conversion module (101) and the third DC side (c) of the AC / DC conversion module (104) are respectively connected to the DC bus (105). The AC side (d) of the AC / DC conversion module (104) is connected to an AC source network (500). The control method includes: In response to a first preset operating condition, one of the power switching transistors (s) in the first DC-DC converter module (101) and the power switching transistors (s) in the AC-DC converter module (104) is stopped from driving, and the other of the power switching transistors (s) in the first DC-DC converter module (101) and the power switching transistors (s) in the AC-DC converter module (104) is controlled to perform power conversion in order to maintain the bus voltage of the DC bus (105).

15. A power conversion system, characterized in that, The power conversion system includes: First DC power supply (200); A power conversion system (100) includes a first DC conversion module (101), a DC bus (105), an AC-DC conversion module (104), and a first controller (106). The first DC side (a) of the first DC conversion module (101) is used to connect to a first DC power supply (200). The second DC side (b) of the first DC conversion module (101) and the third DC side (c) of the AC-DC conversion module (104) are respectively connected to the DC bus (105). The AC side (d) of the AC-DC conversion module (104) is used to connect to an AC source network (500). The first controller (106) is connected to the first DC-DC conversion module (101) and the AC-DC conversion module (104) respectively, and is configured to: in response to a first preset operating condition, stop driving one of the power switch(s) in the first DC-DC conversion module (101) and the power switch(s) in the AC-DC conversion module (104), and control the other of the power switch(s) in the first DC-DC conversion module (101) and the power switch(s) in the AC-DC conversion module (104) to perform power conversion in order to maintain the bus voltage of the DC bus (105).

16. The power conversion system according to claim 15, characterized in that, The power conversion system also includes: An energy storage system (600) includes a fourth DC-DC converter module (601), a second energy storage power supply (602), and a second controller (603). The eighth DC side (i) of the fourth DC-DC converter module (601) is connected to the second energy storage power supply (602), and the ninth DC side (j) of the fourth DC-DC converter module (601) is connected to the DC bus (105). The fourth DC-DC converter module (601) is also connected to the second controller (603), which is communicatively connected to the first controller (106) and configured to send the status of the second energy storage power supply (602) to the first controller (106). The first controller (106) is also configured to: in response to the non-charging condition of the second energy storage power supply (602), stop driving the power switch(s) in the fourth DC-DC converter module (601) via the second controller (603). or, In response to the charging condition of the second energy storage power supply (602), the power switch(s) in the fourth DC-DC conversion module (601) is controlled by the second controller (603) to draw power from the DC bus (105) to charge the second energy storage power supply (602).

17. The power conversion system according to claim 16, characterized in that, The first controller (106) is also configured to: Before stopping the power switching transistors (s) in the first DC-DC converter module (101) and the AC-DC converter module (104), a power module to maintain the DC bus voltage is determined as the target power module; the power module to maintain the DC bus voltage is: the power module in the first DC-DC converter module (101), the AC-DC converter module (104), and the fourth DC-DC converter module (601) that has the ability to establish the DC bus (105) voltage; When the fourth DC-DC converter module (601) is the target power module, at least one of the power switch(s) in the first DC-DC converter module (101) and the power switch(s) in the AC-DC converter module (104) is stopped from driving, and the power switch(s) in the fourth DC-DC converter module (601) is controlled by the second controller (603) to perform power conversion in order to maintain the bus voltage of the DC bus (105); If the fourth DC-DC converter module (601) is not the target power module, the step of stopping the driving of one of the power switch(s) in the first DC-DC converter module (101) and the power switch(s) in the AC-DC converter module (104) is performed.

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