Method and apparatus for controlling busbar voltage in a photovoltaic power generation system

Abstract

The present application relates to a method for controlling busbar voltage in a photovoltaic power generation system. The photovoltaic power generation system includes a DC / DC converter and a DC / AC converter. The DC / DC converter, the DC / AC converter, and an energy storage battery are connected via a busbar. The DC / DC converter is connected to a photovoltaic DC source and performs maximum power point tracking for input power from the photovoltaic DC source. A load connected to the DC / AC converter has a load power. The energy storage battery has a maximum charge power and a maximum discharge power. The method includes controlling the busbar voltage to a plurality of different discrete voltage intervals based on different results of a comparison between the maximum photovoltaic power and the load power, the maximum charge power, and the maximum discharge power. The plurality of different discrete voltage intervals corresponds to different operating states of an inverter.

Description

[Technical field]

[0001] The present application relates to power electronics technology, and in particular to a method and apparatus for controlling busbar voltage in a photovoltaic power generation system. [Background technology]

[0002] New energy technologies such as photovoltaic power generation have developed rapidly. Photovoltaic power generation refers to converting solar radiation energy into electrical energy by utilizing the photovoltaic power effect of semiconductor materials. For example, direct current is generated when a solar cell module is exposed to light. The solar cell module is the core part of the photovoltaic power system. Several solar cells are connected in series and parallel and packaged into a single module to convert solar energy into electrical energy. Multiple solar cell modules are connected in series and parallel to form a photovoltaic array.

[0003] In a photovoltaic system, a photovoltaic array provides energy to a load. Due to light and environmental factors, the energy provided by the photovoltaic array may fluctuate, and the maximum power point tracking (MPPT) technique may be used to track the output voltage and current to obtain maximum photovoltaic power. Furthermore, when there is excess energy provided by the photovoltaic array, the excess energy may be stored or sent to the AC grid. When there is insufficient solar radiation or when there is insufficient energy provided by the photovoltaic array, an energy storage device provides energy to the load of the system. Therefore, a photovoltaic system needs to control the charging / discharging power of the energy storage device to match the change in the load.

[0004] In the conventional technology, the charge / discharge power of the energy storage device is calculated based on the busbar voltage, and there is a linear relationship between the busbar voltage and the charge power, and between the busbar voltage and the discharge power. In order to maximize the charge / discharge efficiency, the busbar voltage needs to be gradually adjusted in a certain range due to the fact that the busbar capacitor of the inverter usually has a large value. However, this results in a wide adjustment range and slow dynamic response of the busbar voltage. As a result, the conversion efficiency of the inverter is not high, which not only reduces the revenue of the system, but also does not lead to a quick adjustment of the busbar voltage to control the charge / discharge power to match the change of the load. Summary of the Invention

[0005] The objective of the present application is to provide a method for controlling a busbar voltage of a photovoltaic power generation system. The photovoltaic power generation system includes a DC / DC converter and a DC / AC converter. The DC / DC converter, the DC / AC converter, and the energy storage battery are connected through a busbar, the DC / DC converter is connected to a photovoltaic DC source and performs maximum power point tracking MPPT on the input power from the photovoltaic DC source, a load connected to the DC / AC converter has a load power, and the energy storage battery has a maximum charging power and a maximum discharging power. The method includes: controlling the busbar voltage to a plurality of different discrete voltage intervals according to different results of the comparison between the maximum photovoltaic power generation power and the load power, the maximum charging power, and the maximum discharging power, the plurality of different discrete voltage intervals corresponding to different inverter operating states. Thus, the busbar voltage is controlled to a plurality of different discrete voltage intervals to realize the switching of the inverter operating states, promoting stability and flexibility. In addition, the busbar voltage is controlled based on different results of comparison between the maximum solar power generation and load power, the maximum charging power, and the maximum discharging power, which realizes fast power balance in the scenario of rapid change in load and fast response to changes in the charging / discharging power of the energy storage battery, thereby improving the conversion efficiency of the inverter, narrowing the operating range of the inverter, further improving the efficiency of the inverter, and increasing the system revenue.

[0006] According to a first aspect, an embodiment of the present application provides a method for controlling a busbar voltage of a photovoltaic power generation system, the photovoltaic power generation system includes a DC / DC converter and a DC / AC converter, the DC / DC converter, the DC / AC converter and an energy storage battery are connected via a busbar, the DC / DC converter is connected to a photovoltaic power generation source and performs maximum power point tracking MPPT on an input power from the photovoltaic power generation source, a load connected to the DC / AC converter has a load power, and the energy storage battery has a maximum charging power and a maximum discharging power. The method includes: controlling the busbar voltage to be in a plurality of different discrete voltage intervals based on different results of a comparison between the maximum photovoltaic power generation power and the load power, the maximum charging power and the maximum discharging power, the plurality of different discrete voltage intervals corresponding to different operating states of an inverter.

[0007] According to the technical solution described in the first aspect, the busbar voltage is controlled to be a plurality of different discontinuous voltage intervals to realize inverter working state switching, promoting stability and flexibility. Also, the busbar voltage is controlled based on different results of comparison between the maximum photovoltaic power and the load power, the maximum charging power, and the maximum discharging power, which realizes fast power balance in the scenario of fast response to sudden changes in load and changes in the charging / discharging power of the energy storage battery, thereby improving the conversion efficiency of the inverter, narrowing the working range of the inverter, and further improving the efficiency of the inverter and increasing the system profit.

[0008] According to a first aspect, in a possible implementation, the step of controlling the busbar voltage to be in a plurality of different discontinuous voltage intervals based on different results of a comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a first voltage interval when the maximum solar generated power is greater than the load power and the maximum solar generated power minus the load power is greater than the maximum charging power, the first voltage interval corresponds to a reference value of the busbar voltage on the BST side, and when the operating state of the inverter is in a state corresponding to the reference value of the busbar voltage on the BST side, the energy storage battery is in a charging state, the charging power of the energy storage battery reaches the maximum charging power, the solar generated output power of the solar power DC source is less than the maximum solar generated power, and the solar generated output power of the solar power DC source is equal to the sum of the load power and the maximum charging power.

[0009] Thereby, the busbar voltage is controlled to a specific voltage interval in order to switch the inverter to a corresponding operating state.

[0010] According to a first aspect, in a possible implementation, the step of controlling the busbar voltage to be in a plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a second voltage interval when the maximum solar generated power is greater than the load power and the maximum solar generated power minus the load power is less than the maximum charging power, the second voltage interval corresponding to a reference value of the busbar voltage for charging the energy storage battery, and when the operating state of the inverter is in a state corresponding to the reference value of the busbar voltage for charging the energy storage battery, the energy storage battery is in a charging state, the charging power of the energy storage battery is less than the maximum charging power, the solar power output power supplied by the solar power DC source reaches the maximum solar generated power, and the charging power of the energy storage battery is equal to the maximum solar generated power minus the load power.

[0011] Thereby, the busbar voltage is controlled to a specific voltage interval in order to switch the inverter to a corresponding operating state.

[0012] According to a first aspect, in a possible implementation, the step of controlling the busbar voltage to be in a plurality of different discontinuous voltage intervals based on different results of the comparison between the maximum photovoltaic power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a third voltage interval when the maximum photovoltaic power is smaller than the load power and the maximum photovoltaic power minus the load power is smaller than the maximum discharging power, the third voltage interval corresponds to a reference value of the INV side busbar voltage, when the operating state of the inverter is in a state corresponding to the reference value of the INV side busbar voltage, the energy storage battery is in a discharging state, the discharging power of the energy storage battery reaches the maximum discharging power, the photovoltaic output power supplied by the photovoltaic DC source reaches the maximum photovoltaic power, and the load obtains compensation power from the AC grid, and the compensation power is equal to the load power minus the maximum photovoltaic power plus the maximum discharging power.

[0013] Thereby, the busbar voltage is controlled to a specific voltage interval in order to switch the inverter to a corresponding operating state.

[0014] According to a first aspect, in a possible implementation, the step of controlling the busbar voltage to be in a plurality of different discontinuous voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a fourth voltage interval when the maximum solar generated power is smaller than the load power and the maximum solar generated power minus the load power is greater than the maximum discharging power, the fourth voltage interval corresponds to a reference value of the busbar voltage for discharging the energy storage battery, and when the operating state of the inverter is in a state corresponding to the reference value of the busbar voltage for discharging the energy storage battery, the energy storage battery is in a discharging state, the discharging power of the energy storage battery is greater than the maximum discharging power, the solar power output power supplied by the solar power DC source reaches the maximum solar generated power, and the discharging power of the energy storage battery is equal to the maximum solar generated power minus the load power.

[0015] Thereby, the busbar voltage is controlled at specific voltage intervals to switch the inverter to a corresponding operating state.

[0016] According to a first aspect, in a possible implementation, the steps of controlling the busbar voltage to a plurality of different discontinuous voltage intervals based on different results of a comparison between the maximum photovoltaic power and the load power, the maximum charging power, and the maximum discharging power include: controlling the busbar voltage to operate in a first voltage interval when the maximum photovoltaic power is greater than the load power and the maximum photovoltaic power minus the load power is greater than the maximum charging power, the first voltage interval corresponding to a reference value of the busbar voltage on the BST side; controlling the busbar voltage to operate in a second voltage interval when the maximum photovoltaic power is greater than the load power and the maximum photovoltaic power minus the load power is less than the maximum charging power, the second voltage interval corresponding to a reference value of the busbar voltage for charging the energy storage battery; controlling the busbar voltage to operate at a third voltage interval when the solar power minus the load power is smaller than the maximum discharge power, the third voltage interval corresponding to a reference value of the INV side busbar voltage; or controlling the busbar voltage to operate at a fourth voltage interval when the maximum solar power generation power is smaller than the load power and the maximum solar power generation power minus the load power is greater than the maximum discharge power, the fourth voltage interval corresponding to a reference value of the busbar voltage for discharging the energy storage battery, wherein the reference value of the BST side busbar voltage is greater than the reference value of the busbar voltage for charging the energy storage battery, the reference value of the busbar voltage for charging the energy storage battery is greater than the reference value of the busbar voltage for discharging the energy storage battery, and the reference value of the busbar voltage for discharging the energy storage battery is greater than the reference value of the INV side busbar voltage.

[0017] In this way, the busbar voltage is controlled to be in different voltage intervals based on different results of the comparison between the maximum solar power generation and the load power, the maximum charging power, and the maximum discharging power to switch the inverter to a corresponding operating state.

[0018] According to the first aspect, in a possible implementation, the method further includes: generating a loop control command for the BST-side busbar voltage based on the sampled value of the busbar voltage of the inverter and the reference value of the busbar voltage of the BST side to control the output power of the inverter such that the busbar voltage is stabilized at the reference value of the busbar voltage of the BST side; generating a loop control command for the INV-side busbar voltage based on the sampled value of the busbar voltage and the reference value of the busbar voltage of the INV side to control the output power of the inverter such that the busbar voltage is stabilized at the reference value of the busbar voltage of the INV side; generating a loop control command for a busbar voltage for charging the energy storage battery based on the sampled values ​​of the busbar voltage and the reference value of the busbar voltage for charging the energy storage battery, in order to control the charging power of the energy storage battery so that the busbar voltage is stabilized at the reference value of the busbar voltage for charging the energy storage battery; and generating a loop control command for a busbar voltage for discharging the energy storage battery based on the sampled values ​​of the busbar voltage and the reference value of the busbar voltage for discharging the energy storage battery, in order to control the discharging power of the energy storage battery so that the busbar voltage is stabilized at the reference value of the busbar voltage for discharging the energy storage battery.

[0019] In this way, corresponding loop control commands are generated based on the sampled values ​​of the busbar voltage and the voltage reference values.

[0020] According to the first aspect, in a possible implementation, the loop control command for the busbar voltage on the BST side, the loop control command for the busbar voltage on the INV side, the loop control command for the busbar voltage for charging the energy storage battery, and the loop control command for the busbar voltage for discharging the energy storage battery all use PI controllers.

[0021] Thus, the use of a PI controller helps to improve the conversion efficiency of the inverter, narrow the inverter operating range, and further improve the inverter efficiency and increase system revenue.

[0022] According to a first aspect, in a possible implementation, the step of controlling the busbar voltage to be in a plurality of different discontinuous voltage intervals based on different results of the comparison between the maximum photovoltaic power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a fifth voltage interval when the maximum photovoltaic power is smaller than the load power and the maximum photovoltaic power minus the load power is greater than the maximum discharging power, or when the maximum photovoltaic power is greater than the load power and the maximum photovoltaic power minus the load power is smaller than the maximum charging power, the fifth voltage interval corresponding to a reference value of the busbar voltage for charging / discharging the energy storage battery, and when the operating state of the inverter is in a state corresponding to the reference value of the busbar voltage for charging / discharging the energy storage battery, the photovoltaic output power supplied by the photovoltaic DC source reaches the maximum photovoltaic power, and the maximum photovoltaic power minus the load power is smaller than the maximum charging power and greater than the maximum discharging power.

[0023] In this way, the busbar voltage is controlled to be in different voltage intervals based on different results of the comparison between the maximum solar power generation and the load power, the maximum charging power, and the maximum discharging power in order to switch the inverter into a corresponding operating state.

[0024] According to the first aspect, in a possible implementation, the step of controlling the busbar voltage to a plurality of different discontinuous voltage intervals based on different results of the comparison between the maximum photovoltaic power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a first voltage interval when the maximum photovoltaic power is greater than the load power and the maximum photovoltaic power minus the load power is greater than the maximum charging power, the first voltage interval corresponding to a reference value of the busbar voltage on the BST side; controlling the busbar voltage to operate in a third voltage interval when the maximum photovoltaic power is less than the load power and the maximum photovoltaic power minus the load power is less than the maximum discharging power, the third voltage interval corresponding to a reference value of the busbar voltage on the BST side; or controlling the busbar voltage to operate in a fifth voltage interval when the maximum solar power generation power is smaller than the load power and the maximum solar power generation power minus the load power is greater than the maximum discharge power, or when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is smaller than the maximum charge power, wherein the fifth voltage interval corresponds to a reference value of the busbar voltage for charging / discharging the energy storage battery, the reference value of the BST side busbar voltage is greater than the reference value of the busbar voltage for charging / discharging the energy storage battery, and the reference value of the busbar voltage for charging / discharging the energy storage battery is greater than the reference value of the INV side busbar voltage.

[0025] In this way, the busbar voltage is controlled to be in different voltage intervals based on different results of the comparison between the maximum solar power generation and the load power, the maximum charging power, and the maximum discharging power to switch the inverter to a corresponding operating state.

[0026] According to the first aspect, in a possible implementation, the method further includes: generating a loop control command for the BST side busbar voltage based on the sampled value of the busbar voltage of the inverter and the reference value of the busbar voltage on the BST side to control the output power of the inverter such that the busbar voltage is stabilized at the reference value of the busbar voltage on the BST side; generating a loop control command for the INV side busbar voltage based on the sampled value of the busbar voltage and the reference value of the busbar voltage on the INV side to control the output power of the inverter such that the busbar voltage is stabilized at the reference value of the busbar voltage on the INV side; and generating a loop control command for the busbar voltage for charging / discharging the energy storage battery based on the sampled value of the busbar voltage and the reference value of the busbar voltage for charging / discharging the energy storage battery to control the charge / discharge power of the energy storage battery such that the busbar voltage is stabilized at the reference value of the busbar voltage for charging / discharging the energy storage battery.

[0027] In this way, corresponding loop control commands are generated based on the sampled values ​​of the busbar voltage and the voltage reference values.

[0028] According to the first aspect, in a possible implementation, the loop control command of the busbar voltage on the BST side, the loop control command of the busbar voltage on the INV side, and the loop control command of the busbar voltage for charging / discharging the energy storage battery all use PI controllers.

[0029] Thus, the use of a PI controller helps to increase the conversion efficiency of the inverter, narrow the inverter operating range, further increasing the inverter efficiency and increasing system revenue.

[0030] According to the first aspect, in a possible implementation, the maximum charging power and the maximum discharging power are preset.

[0031] In this way, by setting the maximum charging power and the maximum discharging power in advance, the configuration is adjusted as necessary.

[0032] According to a second aspect, an embodiment of the present application provides a photovoltaic power generation system. The photovoltaic power generation system includes: a DC / DC converter; a DC / AC converter, where the DC / DC converter, the DC / AC converter, and the energy storage battery are connected via a busbar, the DC / DC converter is connected to a photovoltaic DC source and performs maximum power point tracking MPPT on an input power from the photovoltaic DC source, a load connected to the DC / AC converter has a load power, and the energy storage battery has a maximum charging power and a maximum discharging power; and a busbar voltage controller; The busbar voltage controller is configured to: control the busbar voltage to a plurality of different discrete voltage intervals based on different results of a comparison between the maximum photovoltaic power and the load power, the maximum charging power, and the maximum discharging power, where the plurality of different discrete voltage intervals correspond to different operating states of the inverter.

[0033] According to the technical solution described in the second aspect, the busbar voltage is controlled to be a plurality of different discontinuous voltage intervals to realize inverter working state switching, promoting stability and flexibility. Also, the busbar voltage is controlled based on different results of comparison between the maximum photovoltaic power and the load power, the maximum charging power, and the maximum discharging power, which realizes fast power balance in the scenario of fast response to sudden changes in load and changes in the charging / discharging power of the energy storage battery, thereby improving the conversion efficiency of the inverter, narrowing the working range of the inverter, and further improving the efficiency of the inverter and increasing the system profit.

[0034] According to a second aspect, in a possible implementation, controlling the busbar voltage to be in a plurality of different discontinuous voltage intervals based on different results of a comparison between the maximum solar power generated and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a first voltage interval when the maximum solar power generated is greater than the load power and the maximum solar power minus the load power is greater than the maximum charging power, the first voltage interval corresponds to a reference value of the BST side busbar voltage, and when the operating state of the inverter is in a state corresponding to the reference value of the BST side busbar voltage, the energy storage battery is in a charging state, the charging power of the energy storage battery reaches the maximum charging power, the solar power output of the solar power DC source is less than the maximum solar power generated, and the solar power output power of the solar power DC source is equal to the sum of the load power and the maximum charging power.

[0035] Thereby, the busbar voltage is controlled to a specific voltage interval to switch the inverter to a corresponding operating state.

[0036] According to a second aspect, in a possible implementation, controlling the busbar voltage to be in a plurality of different discrete voltage intervals based on different results of a comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a second voltage interval when the maximum solar generated power is greater than the load power and the maximum solar generated power minus the load power is less than the maximum charging power, the second voltage interval corresponding to a reference value of the busbar voltage for charging the energy storage battery, and when the operating state of the inverter is in a state corresponding to the reference value of the busbar voltage for charging the energy storage battery, the energy storage battery is in a charging state, the charging power of the energy storage battery is less than the maximum charging power, the solar power output power supplied by the solar power DC source reaches the maximum solar generated power, and the charging power of the energy storage battery is equal to the maximum solar generated power minus the load power.

[0037] Thereby, the busbar voltage is controlled to be at a specific voltage interval in order to switch the inverter to a corresponding operating state.

[0038] According to a second aspect, in a possible implementation, controlling the busbar voltage to be in a plurality of different discontinuous voltage intervals based on different results of the comparison between the maximum photovoltaic power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a third voltage interval when the maximum photovoltaic power is smaller than the load power and the maximum photovoltaic power minus the load power is smaller than the maximum discharging power, the third voltage interval corresponds to a reference value of the INV side busbar voltage, when the operating state of the inverter is in a state corresponding to the reference value of the INV side busbar voltage, the energy storage battery is in a discharging state, the discharging power of the energy storage battery reaches the maximum discharging power, the photovoltaic output power supplied by the photovoltaic DC source reaches the maximum photovoltaic power, and the load obtains compensation power from the AC grid, and the compensation power is equal to the load power minus the maximum photovoltaic power plus the maximum discharging power.

[0039] Thereby, the busbar voltage is controlled to a specific voltage interval in order to switch the inverter to a corresponding operating state.

[0040] According to a second aspect, in a possible implementation, controlling the busbar voltage to be in a plurality of different discontinuous voltage intervals based on different results of a comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a fourth voltage interval when the maximum solar generated power is less than the load power and the maximum solar generated power minus the load power is greater than the maximum discharging power, the fourth voltage interval corresponding to a reference value of the busbar voltage for discharging the energy storage battery, and when the operating state of the inverter is in a state corresponding to the reference value of the busbar voltage for discharging the energy storage battery, the energy storage battery is in a discharging state, the discharging power of the energy storage battery is greater than the maximum discharging power, the solar power output power supplied by the solar power DC source reaches the maximum solar generated power, and the discharging power of the energy storage battery is equal to the maximum solar generated power minus the load power.

[0041] Thereby, the busbar voltage is controlled to a specific voltage interval in order to switch the inverter to a corresponding operating state.

[0042] According to a second aspect, in a possible implementation, controlling the busbar voltage to a plurality of different discontinuous voltage intervals based on different results of a comparison between the maximum photovoltaic power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a first voltage interval when the maximum photovoltaic power is greater than the load power and the maximum photovoltaic power minus the load power is greater than the maximum charging power, the first voltage interval corresponding to a reference value of the busbar voltage on the BST side; controlling the busbar voltage to operate in a second voltage interval when the maximum photovoltaic power is greater than the load power and the maximum photovoltaic power minus the load power is less than the maximum charging power, the second voltage interval corresponding to a reference value of the busbar voltage for charging the energy storage battery; controlling the busbar voltage to operate in a first voltage interval when the maximum photovoltaic power is greater than the load power and the maximum photovoltaic power minus the load power is less than the maximum charging power, the first voltage interval corresponding to a reference value of the busbar voltage for charging the energy storage battery; controlling the busbar voltage to operate at a third voltage interval when the photovoltaic power minus the load power is smaller than the maximum discharge power, the third voltage interval corresponding to a reference value of the INV side busbar voltage; or controlling the busbar voltage to operate at a fourth voltage interval when the maximum photovoltaic power is smaller than the load power and the maximum photovoltaic power minus the load power is greater than the maximum discharge power, the fourth voltage interval corresponding to a reference value of the busbar voltage for discharging the energy storage battery, wherein the reference value of the BST side busbar voltage is greater than the reference value of the busbar voltage for charging the energy storage battery, the reference value of the busbar voltage for charging the energy storage battery is greater than the reference value of the busbar voltage for discharging the energy storage battery, and the reference value of the busbar voltage for discharging the energy storage battery is greater than the reference value of the INV side busbar voltage.

[0043] In this way, the busbar voltage is controlled to be in different voltage intervals based on different results of the comparison between the maximum photovoltaic power and the load power, the maximum charging power, and the maximum discharging power in order to switch the inverter into a corresponding operating state.

[0044] According to the second aspect, in a possible implementation, the busbar voltage controller further: generates a loop control command for the BST side busbar voltage based on the sampled value of the busbar voltage of the inverter and the reference value of the busbar voltage on the BST side to control the output power of the inverter such that the busbar voltage is stabilized at the reference value of the busbar voltage on the BST side; generates a loop control command for the INV side busbar voltage based on the sampled value of the busbar voltage of the inverter and the reference value of the busbar voltage on the INV side to control the output power of the inverter such that the busbar voltage is stabilized at the reference value of the busbar voltage on the INV side; generate a loop control command for a busbar voltage for charging the energy storage battery based on the sampled values ​​of the busbar voltage and the reference value for the busbar voltage for charging the energy storage battery, in order to control the charging power of the energy storage battery so that the busbar voltage is stabilized at the reference value of the busbar voltage for charging the energy storage battery; and generate a loop control command for a busbar voltage for discharging the energy storage battery based on the sampled values ​​of the busbar voltage and the reference value for the busbar voltage for discharging the energy storage battery, in order to control the discharging power of the energy storage battery so that the busbar voltage is stabilized at the reference value of the busbar voltage for discharging the energy storage battery.

[0045] In this way, corresponding loop control commands are generated based on the sampled values ​​of the busbar voltage and the voltage reference values.

[0046] According to the second aspect, in a possible implementation, the loop control command for the busbar voltage on the BST side, the loop control command for the busbar voltage on the INV side, the loop control command for the busbar voltage for charging the energy storage battery, and the loop control command for the busbar voltage for discharging the energy storage battery all use PI controllers.

[0047] Thus, the use of a PI controller helps to improve the conversion efficiency of the inverter, narrow the inverter operating range, further improving the inverter efficiency and increasing system revenue.

[0048] According to a second aspect, in a possible implementation, controlling the busbar voltage to be in a plurality of different discontinuous voltage intervals based on different results of the comparison between the maximum photovoltaic power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a fifth voltage interval when the maximum photovoltaic power is smaller than the load power and the maximum photovoltaic power minus the load power is greater than the maximum discharging power, or when the maximum photovoltaic power is greater than the load power and the maximum photovoltaic power minus the load power is smaller than the maximum charging power, the fifth voltage interval corresponding to a reference value of the busbar voltage for charging / discharging the energy storage battery, and when the operating state of the inverter is in a state corresponding to the reference value of the busbar voltage for charging / discharging the energy storage battery, the photovoltaic output power supplied by the photovoltaic DC source reaches the maximum photovoltaic power, and the maximum photovoltaic power minus the load power is smaller than the maximum charging power and greater than the maximum discharging power.

[0049] In this way, the busbar voltage is controlled to different voltage intervals based on different results of the comparison between the maximum solar power generation and the load power, the maximum charging power, and the maximum discharging power to switch the inverter to a corresponding operating state.

[0050] According to a second aspect, in a possible implementation, controlling the busbar voltage to a plurality of different discontinuous voltage intervals based on different results of a comparison between the maximum photovoltaic power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a first voltage interval when the maximum photovoltaic power is greater than the load power and the maximum photovoltaic power minus the load power is greater than the maximum charging power, the first voltage interval corresponding to a reference value of the busbar voltage on the BST side; controlling the busbar voltage to operate in a third voltage interval when the maximum photovoltaic power is less than the load power and the maximum photovoltaic power minus the load power is less than the maximum discharging power, the third voltage interval corresponding to a reference value of the busbar voltage on the INV side. controlling the busbar voltage to operate in a fifth voltage interval when the maximum solar power generation power is smaller than the load power and the maximum solar power generation power minus the load power is greater than the maximum discharge power, or when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is smaller than the maximum charge power, wherein the fifth voltage interval corresponds to a reference value of the busbar voltage for charging / discharging the energy storage battery, and the reference value of the busbar voltage on the BST side is greater than the reference value of the busbar voltage for charging / discharging the energy storage battery, and the reference value of the busbar voltage for charging / discharging the energy storage battery is greater than the reference value of the busbar voltage on the INV side.

[0051] In this way, the busbar voltage is controlled to be in different voltage intervals based on different results of the comparison between the maximum solar power generation and the load power, the maximum charging power, and the maximum discharging power in order to switch the inverter into a corresponding operating state.

[0052] According to the second aspect, in a possible implementation, the busbar voltage controller is further configured to: generate a loop control command for the BST side busbar voltage based on the sampled value of the inverter busbar voltage and the reference value of the BST side busbar voltage to control the output power of the inverter such that the busbar voltage is stabilized at the reference value of the BST side busbar voltage; generate a loop control command for the INV side busbar voltage based on the sampled value of the busbar voltage and the reference value of the INV side busbar voltage to control the output power of the inverter such that the busbar voltage is stabilized at the reference value of the INV side busbar voltage; and generate a loop control command for the busbar voltage for charging / discharging the energy storage battery based on the sampled value of the busbar voltage and the reference value of the busbar voltage for charging / discharging the energy storage battery to control the charge / discharge power of the energy storage battery such that the busbar voltage is stabilized at the reference value of the busbar voltage for charging / discharging the energy storage battery.

[0053] In this way, corresponding loop control commands are generated based on the sampled values ​​of the busbar voltage and the voltage reference values.

[0054] According to the second aspect, in a possible implementation, the loop control command of the busbar voltage on the BST side, the loop control command of the busbar voltage on the INV side, and the loop control command of the busbar voltage for charging / discharging the energy storage battery all use PI controllers.

[0055] Thus, the use of a PI controller helps to increase the conversion efficiency of the inverter, narrow the inverter's operating range, further increasing the inverter's efficiency and increasing system revenue.

[0056] According to the second aspect, in a possible implementation, a maximum charging power and a maximum discharging power are preset.

[0057] In this way, by setting the maximum charging power and the maximum discharging power in advance, the configuration is adjusted as necessary. [Brief description of the drawings]

[0058] In order to describe the technical solutions in the embodiments or background of the present application, the following briefly describes the accompanying drawings for describing the embodiments or background of the present application.

[0059] [Figure 1] FIG. 1 is a block diagram of the structure of a photovoltaic power generation system including a busbar voltage controller of an inverter according to an embodiment of the present application.

[0060] [Diagram 2] 1 is a schematic flowchart of a method for controlling a busbar voltage of an inverter according to a first implementation of an embodiment of the present application.

[0061] [Diagram 3] FIG. 3 is a schematic diagram of a busbar voltage control of an inverter based on the method shown in FIG. 2 according to an embodiment of the present application.

[0062] [Figure 4] 11 is a schematic flowchart of a method for controlling a busbar voltage of an inverter according to a second implementation of an embodiment of the present application.

[0063] [Diagram 5] FIG. 5 is a schematic diagram of a busbar voltage control of an inverter based on the method shown in FIG. 4 according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0064] An embodiment of the present application provides a method for controlling a busbar voltage of a photovoltaic power generation system. The photovoltaic power generation system includes a DC / DC converter and a DC / AC converter. The DC / DC converter, the DC / AC converter, and an energy storage battery are connected through a busbar, the DC / DC converter is connected to a photovoltaic power generation DC source, and performs maximum power point tracking MPPT on an input power from the photovoltaic power generation DC source, a load connected to the DC / AC converter has a load power, and the energy storage battery has a maximum charging power and a maximum discharging power. The method includes: controlling the busbar voltage to be a plurality of different discrete voltage intervals according to different results of a comparison between the maximum photovoltaic power generation power and the load power, the maximum charging power, and the maximum discharging power, the plurality of different discrete voltage intervals corresponding to different operating states of an inverter. Thus, the busbar voltage is controlled to be a plurality of different discrete voltage intervals to realize switching of the operating state of the inverter, promoting stability and flexibility. In addition, the busbar voltage is controlled based on different results of comparison between the maximum solar power generation and the load power, the maximum charging power, and the maximum discharging power, which realizes fast power balance in the scenario of rapid load change and fast response to the change in the charging / discharging power of the energy storage battery, thereby improving the conversion efficiency of the inverter, narrowing the inverter operating range, and further improving the inverter efficiency and increasing the system revenue.

[0065] This embodiment of the present application may be applied to application scenarios including, but not limited to, photovoltaic inverters, photovoltaic power generation systems, and other application scenarios that require fast balancing of load power and implementation of fast response to energy storage batteries.

[0066] The present embodiment of the present application may be adjusted and improved based on a particular application environment, which is not specifically limited herein.

[0067] In order to enable those skilled in the art to better understand the solutions of the present application, the following describes the embodiments of the present application with reference to the accompanying drawings of the embodiments of the present application.

[0068] Please refer to FIG. 1. FIG. 1 is a block diagram of a structure of a photovoltaic power generation system including a busbar voltage controller of an inverter according to an embodiment of the present application. As shown in FIG. 1, the photovoltaic power generation system 100 includes a photovoltaic power generation array 102, an inverter 120, an energy storage battery 108, a load 110, and an energy meter 112. The photovoltaic power generation array 102 is composed of a plurality of solar cell modules connected in series and parallel. Each solar cell module converts solar radiation energy into direct current according to the effect of photovoltaic power generation. The inverter 120 includes a DC / DC converter 104 and a DC / AC converter 106. The DC / DC converter 104 is located on the BST side of the inverter 120, i.e., corresponds to the DC-to-DC conversion part of the inverter 120. The DC / AC converter 106 is located on the INV side of the inverter 120, i.e., corresponds to the DC-to-AC conversion part of the inverter 120. It should be noted that the DC / DC converter 104 and the DC / AC converter 106 may be integrated into one device or may be multiple separate devices. The present application does not limit the specific physical form of the DC / DC converter and the DC / AC converter. Specifically, the inverter can be one device that contains at least one DC / DC converter and at least one DC / AC converter inside; or it can be multiple devices, one of which is a DC / DC converter and another is a DC / AC converter, and the at least one DC / DC converter and the at least one DC / AC converter together form the inverter. In certain embodiments of the present application, the inverter is composed of a DC / DC converter and a DC / AC converter. These can be adjusted and improved based on the actual situation, which is not specifically limited in the present application. In some embodiments, the DC / DC converter 104 can function completely as a solar power optimizer and be connected between a solar power DC source (including a solar power DC source such as a solar power panel and a solar power array) and the inverter as an independent optimizer product.

[0069] The DC input side of the DC / DC converter 104 is connected to the solar power array 102 to convert the DC output from the solar power array 102 into a suitable DC that meets the operating requirements of the DC / AC converter 106. Furthermore, a maximum power point tracking MPPT control strategy is performed on the DC provided by the solar power array 102 to obtain the maximum solar power of the solar power array 102, which is then output from the DC output side of the DC / DC converter 104. The DC output side of the DC / DC converter 104 is connected to the DC input side of the DC / AC converter 106. The DC / AC converter 106 converts the received DC into AC, and then outputs AC from the AC output side of the DC / AC converter 106. The connection point between the DC output side of the DC / DC converter 104 and the DC input side of the DC / AC converter 106 is a bus bar (hereinafter referred to as BUS). As an external energy storage device, an energy storage battery 108 can be connected to the bus bar of the inverter 120. That is, an energy storage battery 108 may be connected between the DC / DC converter 104 and the DC / AC converter 106. The inverter 120 outputs electrical energy to the load 110 and is connected to the AC grid 114 via the power meter 112. The load 110 may be powered by the inverter 120, or may be powered by the AC grid 114, or may be powered by both the inverter 120 and the AC grid 114. The power meter 112 is configured to measure the power available from the AC grid 114. When the solar power system 100 is configured to be on-grid with zero power, the solar power system 100 is not feeding back power to the AC grid 114, indicating a reading of the power meter 112 equal to or greater than zero.

[0070] Please continue to refer to FIG. 1. The DC / DC converter 104, the DC / AC converter 106, and the energy storage battery 108 are coupled to the busbars of the inverter 120. It should be understood that the DC busbar is the positive and negative terminal wiring between the DC / DC converter 104 and the DC / AC converter 106, the DC busbar capacitor is the capacitor between the DC busbars, and the DC busbar voltage is the voltage between the positive and negative terminal wiring of the DC busbar, i.e., the voltage applied to the two terminals of the DC busbar capacitor. The connecting lines shown in FIG. 1 are used to indicate the flow direction of the electrical energy. The notation explanation is as follows: PV denotes the photovoltaic output power, i.e., the actual output power of the photovoltaic array 102. P PV_MPP (not shown) denotes the maximum photovoltaic power, which is also the maximum power that can be output from the photovoltaic array 102 based on the MPPT control strategy, i.e., the maximum MPPT-based photovoltaic power that can be obtained by the DC / DC converter 104. P BAT indicates the charge / discharge power of the energy storage battery 108 and may be expressed as a value having a positive and negative sign, where a positive sign indicates charging and a negative sign indicates discharging. P INV denotes the output power of the inverter 120, which is also the AC output power provided by the DC / AC converter 106. LOAD indicates the load power of the load 110. Meter represents the power drawn from the AC grid and measured by the power meter 112, which may be represented as a value with a positive and negative sign, with a positive sign indicating drawing power from the AC grid and a negative sign indicating sharing power with the AC grid. The inverter 120 converts the solar power output P PV Receives power P INV When the solar power generation system 100 is configured to be on-grid with zero power, the watt-hour meter power P Meter is greater than or equal to zero, and no power is fed into the grid. PV_MPP , load power P LOAD, and based on the result of the comparison between the maximum charging power and the maximum discharging power of the energy storage battery 108, a loop contention strategy can be executed to achieve power matching. The inverter 120 further includes a busbar voltage controller 122 to achieve the loop contention strategy. The busbar voltage controller 122 can be disposed within the inverter 120 or disposed separately. The busbar voltage controller 122 has a necessary hardware structure to communicate with the energy storage battery 108 to control the charging / discharging power of the energy storage battery 108 and to obtain a sampled value of the busbar voltage. It should be understood that the busbar voltage controller 122 has a basic structure of a processor and memory to perform the necessary detection and control functions and to store program codes for the loop contention strategy, or has the necessary circuits and components to perform the control functions. The specific structure and function of the busbar voltage controller 122 can be set or improved based on a specific application scenario, which is not particularly limited here.

[0071] Please refer to Figure 1. The change in load is the load power P LOAD Changes in solar radiation and other conditions also cause changes in the solar power generation output P PV Therefore, the inverter 120 needs to control the charging / discharging power of the energy storage battery 108 based on the power data of the power meter 112 to match these changes. The inverter 120 also performs MPPT of the photovoltaic power generation array to determine the maximum photovoltaic power generation input power P PV_MPP Obtain the power P INV The busbar voltage controller 122 further includes a busbar voltage controller 122 that is communicatively connected to the energy storage battery 108 and outputs a charge / discharge power P BATThe busbar voltage controller 122 obtains sampled values ​​of the busbar voltage of the inverter 120 and performs a loop contention strategy to determine the control of the busbar voltage and perform energy management accordingly. It should be understood that the busbar voltage controller 122 has a processor and memory architecture for performing the required detection and control functions and storing the program code of the loop contention strategy, or has the necessary circuits and components to perform the control functions. The busbar voltage controller 122 obtains sampled values ​​of the busbar voltage and controls the output power P of the inverter 120 using any suitable technical means in the prior art, which is not particularly limited here. INV can be measured.

[0072] In some example embodiments, the solar array 102 may be any DC source capable of obtaining maximum power based on MPPT control strategies, which may be adjusted and improved based on the particular application environment, which is not particularly limited here.

[0073] In some exemplary embodiments, the DC / DC converter 104 implements MPPT control on the DC input provided by the photovoltaic array 102 using a constant voltage method, a perturb and observe method, or an incremental conductance method to obtain maximum photovoltaic power. In some exemplary embodiments, the DC / DC converter 104 may use a pulse width modulation scheme, may include necessary elements such as a control chip, an inductor, and a capacitor, and may be of boost, buck, or boost-buck type. These may be adjusted and improved based on the specific application environment, which is not limited here.

[0074] In some exemplary embodiments, the DC / AC converter 106 may be a single-phase inverter, or may be a three-phase inverter, or may be another type of inverter circuit capable of converting direct current to alternating current, which may be adjusted and improved based on the particular application environment, which is not particularly limited here.

[0075] Please refer to Figure 2. Figure 2 is a schematic flowchart of a method for controlling a busbar voltage of an inverter according to a first implementation of an embodiment of the present application. As shown in Figure 2, the control method includes the following steps:

[0076] Step S200: Generate a loop control command for the busbar voltage on the BST side based on the sampling value of the busbar voltage of the inverter and the reference value of the busbar voltage on the BST side, in order to control the output power of the inverter so that the busbar voltage is stabilized at the reference value of the busbar voltage on the BST side.

[0077] The inverter includes a DC / DC converter and a DC / AC converter. DC The DC input side of the converter is connected to the photovoltaic array, and the DC / DC The connection point between the DC output side of the converter and the DC input side of the DC / AC converter is the busbar. DC The DC input side of the converter is connected to the solar array and DC The DC output from the photovoltaic array is converted into a suitable DC to meet the operating requirements of the converter. Furthermore, a maximum power point tracking MPPT control strategy is executed on the DC provided by the photovoltaic array to obtain the maximum photovoltaic power of the photovoltaic array. As an external energy storage device, an energy storage battery can be connected to the busbar of the inverter. That is, the energy storage battery can be connected between the DC / DC converter and the DC / AC converter. It should be understood that the photovoltaic array is any DC source that can obtain maximum power based on the MPPT control strategy. These can be adjusted and improved based on a specific application environment, which is not particularly limited here.

[0078] The loop control command for the busbar voltage on the BST side is a proportional-integral controller. In the form of a PWM Integral Controller (PI), the PWM can be generated according to the following equations (1) and (2).

number

[0079] t indicates time, U REF_BST indicates the reference value of the busbar voltage on the BST side, and U BUS (t) denotes the sampled value of the busbar voltage, e(t) denotes the difference between the reference value of the busbar voltage on the BST side and the sampled value of the busbar voltage, and P BST (t) is the reference value U of the busbar voltage on the BST side. REF_BST indicates the inverter output power under the loop control command of the busbar voltage on the BST side so that it is stable at K p is the proportional adjustment coefficient, and K i denotes the integral regulation coefficient. It should be understood that the busbar voltage being stable at the reference value of the busbar voltage on the BST side means that the fluctuations, jitter, ripple or multiple different voltage values ​​of the busbar voltage are limited within a certain interval. There is a measurable difference between the upper or lower limit of each interval and the lower or upper limit of another interval, and the intervals have a clear definition and limit. The busbar voltage may be sampled by directly detecting and measuring the voltage using a sampling resistor or using another suitable technical means. Also, the use of a PI controller can be achieved by regulating the reference value U of the busbar voltage on the BST side. REF_BST The busbar voltage can be stabilized by the PI controller, which promotes improving the conversion efficiency of the inverter, narrowing the operating range of the inverter, further improving the efficiency of the inverter, and increasing the system profit. It should be understood that in the embodiment of the present application, the controller is not necessarily a PI controller, and other controllers may be used as necessary.

[0080] Step S202: In order to control the output power of the inverter so that the busbar voltage is stabilized at the reference value of the INV side busbar voltage, a loop control command for the INV side busbar voltage is generated based on the sampled value of the busbar voltage and the reference value of the INV side busbar voltage.

[0081] The loop control command for the INV side busbar voltage can be generated in the form of a PI controller according to the following equations (3) and (4).

number

[0082] t indicates time, U REF_INV indicates the reference value of the INV side busbar voltage, and U BUS (t) denotes the sampled value of the busbar voltage, e(t) denotes the difference between the reference value of the INV side busbar voltage and the sampled value of the busbar voltage, and P INV (t) is the reference value U of the busbar voltage on the INV side REF_INV indicates the inverter output power under the loop control command for the INV side busbar voltage that is stabilized at K p is the proportional adjustment coefficient, and K i indicates the integral adjustment coefficient. The busbar voltage is the reference value U of the INV side busbar voltage. REF_INV It should be understood that being stable at 1000 Hz means that the jitter or ripple of the busbar voltage is below a threshold value, or that the average or root-mean-square value of the busbar voltage remains somewhat constant. The busbar voltage may be sampled by directly detecting and measuring the voltage using a sampling resistor, or by using another suitable technical means. Also, the use of a PI controller can be used to compare the busbar voltage with the reference value U of the INV side busbar voltage. REF_INV , which promotes improving the conversion efficiency of the inverter, narrowing the inverter operating range, and further improving the efficiency of the inverter and increasing the system profit. It should be understood that in the embodiments of the present application, the controller is not necessarily a PI controller, and other controllers may be used as necessary.

[0083] Step S204: Generate a loop control command for the busbar voltage for charging the energy storage battery based on the sampled value of the busbar voltage and the reference value of the busbar voltage for charging the energy storage battery, in order to control the charging power of the energy storage battery so that the busbar voltage is stabilized at the reference value of the busbar voltage for charging the energy storage battery.

[0084] The loop control command of the busbar voltage for charging the energy storage battery may be generated in the form of a PI controller according to the following equations (5) and (6):

number

[0085] t indicates time, U REF_CHARGE denotes the reference value of the busbar voltage for charging the energy storage battery, and U BUS (t) denotes the sampled value of the busbar voltage, e(t) denotes the difference between the reference value of the busbar voltage for charging the energy storage battery and the sampled value of the busbar voltage, and P BAT_CHARGE (t) is the reference value U of the busbar voltage for charging the energy storage battery. REF_CHARGE Denote the charging power of the energy storage battery under the loop control command of the busbar voltage for charging the energy storage battery so that it is stabilized at K p is the proportional adjustment coefficient, and K i indicates the integral regulation coefficient. The busbar voltage is the reference value U of the busbar voltage for charging the energy storage battery. REF_CHARGE It should be understood that being stable at 1000 Hz means that the jitter or ripple of the busbar voltage is below a threshold value, or that the average or root-mean-square value of the busbar voltage remains somewhat constant. The busbar voltage may be sampled by directly detecting and measuring the voltage using a sampling resistor, or by using another suitable technical means. The use of a PI controller may also be used to determine the reference value U of the busbar voltage for charging the energy storage battery. REF_CHARGEThe busbar voltage can be stabilized by the PI controller, which promotes improving the conversion efficiency of the inverter, narrowing the operating range of the inverter, and further improving the efficiency of the inverter and increasing the system profit. It should be understood that in the embodiment of the present application, the controller is not necessarily a PI controller, and other controllers may be used as necessary.

[0086] Step S206: Generate a loop control command for the busbar voltage for discharging the energy storage battery based on the sampled value of the busbar voltage and the reference value of the busbar voltage for discharging the energy storage battery, in order to control the discharge power of the energy storage battery so that the busbar voltage is stabilized at the reference value of the busbar voltage for discharging the energy storage battery.

[0087] The loop control command of the busbar voltage for discharging the energy storage battery can be generated in the form of a PI controller according to the following equations (7) and (8).

number

[0088] t indicates time, U REF_DISCHARGE denotes the reference value of the busbar voltage for discharging the energy storage battery, and U BUS (t) denotes the sampled value of the busbar voltage, e(t) denotes the difference between the reference value of the busbar voltage for discharging the energy storage battery and the sampled value of the busbar voltage, and P BAT_DISCHARGE (t) is the reference value U of the busbar voltage for discharging the energy storage battery. REF_DISCHARGE Denote the discharge power of the energy storage battery under the loop control command of the busbar voltage for discharging the energy storage battery so that it is stabilized at K p is the proportional adjustment coefficient, and K i indicates the integral adjustment coefficient. Note that the busbar voltage is the reference value U REF_DISCHARGEIt should be understood that being stable at u means that the jitter or ripple of the busbar voltage is below a threshold value, or that the average or root-mean-square value of the busbar voltage remains somewhat constant. The busbar voltage may be sampled by directly detecting and measuring the voltage using a sampling resistor, or by using another suitable technical means. The use of a PI controller may also be used to determine the reference value U of the busbar voltage for the discharge of the energy storage battery. REF_DISCHARGE The busbar voltage can be stabilized by the PI controller, which promotes improving the conversion efficiency of the inverter, narrowing the operating range of the inverter, and further improving the efficiency of the inverter and increasing the system profit. It should be understood that in the embodiment of the present application, the controller is not necessarily a PI controller, and other controllers may be used as necessary.

[0089] Step S208: Based on the result of the comparison between the maximum photovoltaic power generation, the load power, and the maximum charging power and maximum discharging power of the energy storage battery, select to execute a loop control command of the busbar voltage on the BST side, a loop control command of the busbar voltage on the INV side, a loop control command of the busbar voltage for charging the energy storage battery, or a loop control command of the busbar voltage for discharging the energy storage battery.

[0090] The maximum charging power of the energy storage battery indicates the maximum value of the charging power of the energy storage battery when the energy storage battery is in a charging state, and the maximum discharging power of the energy storage battery indicates the maximum value of the discharging power of the energy storage battery when the energy storage battery is in a discharging state. The maximum charging power and the maximum discharging power are preset, for example, preset based on the application scenario of the inverter, or preset based on the design limit or factory setting of the energy storage battery. The loop contention strategy in step S208 may be implemented by the controller or the control circuit of the inverter. The above loop control command may be generated by the controller. In this way, the control of the busbar voltage is determined based on the result of the loop contention, and the corresponding energy management is implemented. For example, the output power of the inverter or the charging / discharging power of the energy storage battery is controlled based on the result of the loop contention, and the change in the load power due to the sudden change in the load is taken into account. Therefore, fast power balancing in the scenario of a sudden change in the load can be realized. In addition, compared with the case of the change of the busbar voltage and the limited response speed of the busbar capacitor, the loop competition strategy directly controls the related power and stabilizes the busbar voltage at a reference voltage value based on the result of the loop competition, thus realizing a fast response to the change of the charge / discharge power of the energy storage battery, thereby improving the conversion efficiency of the inverter, narrowing the operating range of the inverter, further improving the efficiency of the inverter, and increasing the system revenue.

[0091] Specifically, in step S208, the loop contention strategy can be represented by making a series of decisions based on the maximum solar power generation power, the load power, the maximum charging power, and the maximum discharging power to select the loop control command to be executed: Selecting to execute a loop control command of the busbar voltage on the BST side when the maximum photovoltaic power generation is greater than the load power and the maximum photovoltaic power generation minus the load power is greater than the maximum charging power of the energy storage battery; selecting to execute a loop control command of the busbar voltage for charging the energy storage battery when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is less than the maximum charging power of the energy storage battery; Selecting to execute a loop control command of the INV side busbar voltage when the maximum photovoltaic power generation is less than the load power and the maximum photovoltaic power generation minus the load power is less than the maximum discharge power of the energy storage battery; and Selecting to execute a loop control command of the busbar voltage for discharging the energy storage battery when the maximum solar power generation power is smaller than the load power and the maximum solar power generation power minus the load power is greater than the maximum discharge power of the energy storage battery.

[0092] In step S208, if the loop control command of the busbar voltage on the BST side is selected to be executed, the energy storage battery is in a charging state, the charging power of the energy storage battery reaches the maximum charging power, the photovoltaic power generation output is smaller than the maximum photovoltaic power generation power, and the photovoltaic power generation output is equal to the sum of the load power and the maximum charging power of the energy storage battery. Referring to steps S200 and S208, the photovoltaic power generation power is calculated according to the following equations (9) and (10).

number

[0093] P LOAD indicates the load power, and P BAT_CHARGE_MAX indicates the maximum charging power, and P PV_MPP indicates the maximum solar power generation, and P PVindicates the PV output power under the loop control command of the busbar voltage on the BST side. Thus, if the maximum PV power is exceeded even after satisfying the power supply to the load and the maximum charging power of the energy storage battery, and the system needs to be on-grid with 0 power, that is, the surplus energy is not allowed to be supplied to the AC grid, the output power of the DC source may be smaller than the maximum PV power, and only the load power required for power supply to the load and the maximum charging power of the energy storage battery are satisfied, thereby realizing fast power balance and improving the system efficiency.

[0094] In S208, if the loop control command of the busbar voltage on the INV side is selected to be executed, the energy storage battery is in a discharging state, the discharging power of the energy storage battery reaches the maximum discharging power, the photovoltaic power output power reaches the maximum photovoltaic power, and the inverter obtains compensation power from the grid connected to the inverter, and the compensation power is equal to the load power minus the maximum photovoltaic power plus the maximum discharging power. Referring to S202 and S208, the compensation power is calculated according to the following equations (11) and (12).

number

[0095] P Meter denotes the compensation power, and P LOAD indicates the load power, and P PV_MPP indicates the maximum solar power generation, and P PV indicates the photovoltaic power output, and P BAT_DISCHARGE_MAX indicates the maximum discharge power. Thus, the maximum solar power generation Add When the sum of the maximum discharge power of the energy storage batteries still does not meet the requirements of power supply to the load, the compensation power is supplied by the AC grid. In this case, the DC source supplies the maximum photovoltaic power, and the energy storage batteries discharge at the maximum discharge power. And the corresponding compensation power is obtained from the AC grid to meet the load power required for power supply to the load, thereby realizing fast power balance and improving the system efficiency.

[0096] In step S208, if the loop control command of the busbar voltage for charging the energy storage battery is selected to be executed, the energy storage battery is in a charging state, the charging power of the energy storage battery is less than the maximum charging power, the photovoltaic power generation output power reaches the maximum photovoltaic power generation, and the charging power is equal to the maximum photovoltaic power generation power minus the load power. Referring to steps S204 and S208, the charging power is calculated according to the following equations (13) and (14).

number

[0097] P BAT_CHARGE indicates the charging power, and P PV indicates the photovoltaic power output, and P LOAD indicates the load power, and P PV_MPP denotes the maximum photovoltaic power generation. In this way, after the maximum photovoltaic power generation meets the power supply to the load, the remaining power is used to charge the energy storage battery. In this case, the charging power of the energy storage battery is controlled to preferably meet the load power required for power supply to the load, thereby realizing fast power balance and improving system efficiency.

[0098] In step S208, if the loop control command of the busbar voltage for discharging the energy storage battery is selected to be executed, the energy storage battery is in a discharging state, the discharging power of the energy storage battery is greater than the maximum discharging power, the photovoltaic power generation output power reaches the maximum photovoltaic power generation power, and the discharging power is equal to the maximum photovoltaic power generation power minus the load power. Referring to steps S206 and S208, the discharging power is calculated according to the following equations (15) and (16):

number

[0099] P BAT_DISCHARGE indicates the discharge power, and P PV indicates the photovoltaic power output, and PLOAD indicates the load power, and P PV_MPP denotes the maximum photovoltaic power generation. In this way, when the maximum photovoltaic power generation is not enough to supply power to the load, the compensating power is supplied by discharging the energy storage battery. In this case, the discharge power of the energy storage battery is controlled to preferably satisfy the load power required to supply power to the load, thereby realizing fast power balance and improving system efficiency.

[0100] It should be understood that the order of step S200, step S202, step S204, and step S206 may be adjusted or rearranged. The order of the four steps is not limited in the embodiment of the present application. Steps S200 to S206 may be performed synchronously or rearranged and combined in any order. The present application and the embodiment of FIG. 2 will describe steps S200 to S206 one by one for ease of description.

[0101] Please refer to Figure 3. Figure 3 is a schematic diagram of the busbar voltage control of the inverter based on the method shown in Figure 2 according to an embodiment of the present application. As shown in Figure 3, the Y-axis represents the charging / discharging power of the energy storage battery; the positive direction, i.e., the upper half of the Y-axis, represents the charging power; the negative direction, i.e., the lower half of the Y-axis, represents the discharging power; the maximum value of the charging / discharging power is 3kW / -3kW. The X-axis represents the corresponding busbar voltages and various voltage reference values. Specifically, the reference value of the busbar voltage on the BST side is represented as F, which corresponds to 430V, also called the first voltage interval; the reference value of the busbar voltage for charging the energy storage battery is represented as C, which corresponds to 410V, also called the second voltage interval; the reference value of the busbar voltage for discharging the energy storage battery is represented as D, which corresponds to 390V, also called the third voltage interval; the reference value of the busbar voltage on the INV side is represented as G, which corresponds to 370V, also called the fourth voltage interval. The voltage interval is simplified as a single voltage value, and the difference between any two adjacent voltage values ​​is 20V, so the interval has a clear definition and limits. Also, the central voltage is represented as E, which corresponds to 400V. As shown in FIG. 3, the reference value of the busbar voltage on the BST side is greater than the reference value of the busbar voltage for charging the energy storage battery, the reference value of the busbar voltage for charging the energy storage battery is greater than the reference value of the busbar voltage for discharging the energy storage battery, and the reference value of the busbar voltage for discharging the energy storage battery is greater than the reference value of the busbar voltage on the INV side. Thus, with reference to FIG. 2 and FIG. 3, the correspondence relationship between the busbar voltage and the charge / discharge power shown in FIG. 3 can be obtained by setting the voltage reference value. In this way, the energy storage battery has a stable charging power between C and F, and the energy storage battery has a stable discharging power between G and D. In addition, the related power is directly controlled and the busbar voltage is stabilized at the reference voltage value, which realizes a fast response to the changes in the charge / discharge power of the energy storage battery, thereby improving the conversion efficiency of the inverter, narrowing the operating range of the inverter, further improving the efficiency of the inverter and increasing the system revenue.

[0102] In some example embodiments, the maximum value of the charge / discharge power may be another value such as 4kW / -4kW, or 5kW / -5kW, etc. These can be adjusted and improved based on the specific application environment, which is not limited here.

[0103] In some example embodiments, the voltage reference values ​​may be other values, which may be adjusted and refined based on the particular application environment, not limited herein.

[0104] 4 is a schematic flowchart of a method for controlling a busbar voltage of an inverter according to a second implementation of an embodiment of the present application. As shown in FIG. 4, the method for controlling includes the following steps:

[0105] Step S400: In order to control the output power of the inverter so that the busbar voltage is stabilized at the reference value of the busbar voltage on the BST side, generate a loop control command for the busbar voltage on the BST side based on the sampling value of the busbar voltage of the inverter and the reference value of the busbar voltage on the BST side.

[0106] The inverter includes a DC / DC converter and a DC / AC converter. The DC input side of the DC / AC converter is connected to the photovoltaic array, and the connection point between the DC output side of the DC / AC converter and the DC input side of the DC / AC converter is a busbar. direct current The busbar voltage is called busbar voltage for short. direct currentThe sampled value of the busbar voltage is referred to as the sampled value of the busbar voltage for short. The DC input side of the DC / AC converter is connected to the photovoltaic power array to convert the DC output from the photovoltaic power array into a suitable DC to meet the operating requirements of the DC / AC converter. Furthermore, a maximum power point tracking MPPT control strategy is executed on the DC provided by the photovoltaic power array to obtain the maximum photovoltaic power of the photovoltaic power array. As an external energy storage device, an energy storage battery can be connected to the busbar of the inverter. That is, the energy storage battery can be connected between the DC / DC converter and the DC / AC converter. It should be understood that the photovoltaic power array can be any DC source that can obtain the maximum power based on the MPPT control strategy. These can be adjusted and improved based on a specific application environment, which is not particularly limited here.

[0107] For generating the loop control command for the busbar voltage on the BST side, refer to step S200, and the details will not be described again here.

[0108] Step S402: In order to control the output power of the inverter so that the busbar voltage is stabilized at the reference value of the INV side busbar voltage, a loop control command for the INV side busbar voltage is generated based on the sampled value of the busbar voltage and the reference value of the INV side busbar voltage.

[0109] For generation of the loop control command for the INV side busbar voltage, refer to step S202, and the details will not be described again here.

[0110] Step S404: Generate a loop control command for the busbar voltage for charging / discharging the energy storage battery based on the sampled value of the busbar voltage and the reference value of the busbar voltage for charging / discharging the energy storage battery, in order to control the charging / discharging power of the energy storage battery so that the busbar voltage is stabilized at the reference value of the busbar voltage for charging / discharging the energy storage battery.

[0111] The loop control commands of the busbar voltage for charging / discharging the energy storage battery may be generated in the form of a PI controller according to the following equations (17) and (18):

number

[0112] t indicates time, U REF_BAT indicates the reference value of the busbar voltage for charging / discharging the energy storage battery, which is also called the reference value of the busbar voltage on the energy storage battery side, and U BUS (t) denotes the sampled value of the busbar voltage, e(t) denotes the difference between the reference value of the busbar voltage for charging / discharging the energy storage battery and the sampled value of the busbar voltage, and P BAT (t) is the reference value U of the busbar voltage for charging / discharging the energy storage battery. REF_BAT indicates the charge / discharge power of the energy storage battery under the loop control command of the busbar voltage for charging / discharging the energy storage battery so that it is stabilized at K p is the proportional adjustment coefficient, and K i indicates the integral regulation coefficient. The busbar voltage is the reference value U of the busbar voltage for charging / discharging the energy storage battery. REF_BAT It should be understood that being stable at 1000 Hz means that the jitter or ripple of the busbar voltage is below a threshold value, or that the average or root-mean-square value of the busbar voltage remains somewhat constant. The busbar voltage may be sampled by directly detecting and measuring the voltage using a sampling resistor, or by using another suitable technical means. Also, the use of a PI controller can be used to determine the reference value U of the busbar voltage for charging / discharging the energy storage battery. REF_BAT The busbar voltage can be stabilized by the PI controller, which promotes improving the conversion efficiency of the inverter, narrowing the inverter operating range, and further improving the efficiency of the inverter and increasing the system profit. It should be understood that in the embodiment of the present application, the controller is not necessarily a PI controller, and other controllers may be used as necessary. 。

[0113] Step S406: Based on the result of the comparison between the maximum photovoltaic power generation, the load power, and the maximum charging power and maximum discharging power of the energy storage battery, select to execute a loop control command of the busbar voltage on the BST side, a loop control command of the busbar voltage on the INV side, or a loop control command of the busbar voltage of charging / discharging the energy storage battery.

[0114] The maximum charging power of the energy storage battery is used to indicate the maximum value of the charging power of the energy storage battery when the energy storage battery is in a charging state, and the maximum discharging power of the energy storage battery is used to indicate the maximum value of the discharging power of the energy storage battery when the energy storage battery is in a discharging state. The maximum charging power and the maximum discharging power are preset, for example, preset based on the application scenario of the inverter, or preset based on the design limit or factory setting of the energy storage battery. The loop competition strategy in step S406 may be implemented by the controller or the control circuit of the inverter. The above loop control command may be generated by the controller. Thereby, the control of the busbar voltage is determined based on the result of the loop competition, and the corresponding energy management is realized. For example, the output power of the inverter or the charging / discharging power of the energy storage battery is controlled based on the result of the loop competition, and the change in the load power due to the sudden change in the load is taken into account. Therefore, a fast power balance in the scenario of a sudden change in the load can be realized. In addition, compared with the case of the change of the busbar voltage and the limited response speed of the busbar capacitor, the loop competition strategy directly controls the related power and stabilizes the busbar voltage around the reference voltage value based on the result of the loop competition, thus realizing a fast response to the change of the charge / discharge power of the energy storage battery, thereby improving the conversion efficiency of the inverter, narrowing the operating range of the inverter, further improving the efficiency of the inverter, and increasing the system revenue.

[0115] Specifically, in step S406, the loop contention strategy may be represented by making a series of decisions based on the maximum solar power generation power, the load power, the maximum charging power, and the maximum discharging power to select the loop control command to be executed: Selecting to execute a loop control command of the busbar voltage on the BST side when the maximum photovoltaic power generation power is greater than the load power and the maximum photovoltaic power generation power minus the load power is greater than the maximum charging power of the energy storage battery; Selecting to execute a loop control command of the INV side busbar voltage when the maximum photovoltaic power generation is less than the load power and the maximum photovoltaic power generation minus the load power is less than the maximum discharge power of the energy storage battery; and Select to execute a loop control command of the busbar voltage for charging / discharging the energy storage battery when the maximum solar power generation power is smaller than the load power and the maximum solar power generation power minus the load power is greater than the maximum discharge power of the energy storage battery, or when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is smaller than the maximum charge power of the energy storage battery.

[0116] In step S406, if a loop control command of the busbar voltage on the BST side is selected to be executed, the relevant details are similar to those in step S208, and the details will not be described again here.In step S406, if a loop control command of the busbar voltage on the INV side is selected to be executed, the relevant details are similar to those in step S208, and the details will not be described again here.

[0117] In step S406, when the loop control command of the busbar voltage for charging / discharging the energy storage battery is selected to be executed, the DC source provides the maximum photovoltaic power, and the maximum photovoltaic power minus the load power is less than the maximum charging power of the energy storage battery and greater than the maximum discharging power of the energy storage battery. Referring to steps S404 and S406, the charging / discharging power of the energy storage battery is the actual output power of the DC source, i.e., between the photovoltaic power output power and the load power, and is the charging power or discharging power according to the actual situation. Under the loop control command of the busbar voltage for charging / discharging the energy storage battery, the busbar voltage is equal to or greater than the reference value U of the busbar voltage for charging / discharging the energy storage battery. REF_BAT and the DC source operates at maximum solar power.

[0118] It should be understood that the order of step S400, step S402, and step S404 can be adjusted or rearranged. In the embodiment of the present application, the order of the three steps is not limited. Steps S400 to S404 can be performed synchronously, or can be rearranged and combined in any order. For ease of explanation, the present embodiment of the present application and FIG. 4 describe steps S400 to S404 one by one.

[0119] FIG. 5 is a schematic diagram of the busbar voltage control of the inverter based on the method shown in FIG. 4 according to an embodiment of the present application. As shown in FIG. 5, the Y-axis represents the charge / discharge power of the energy storage battery; the positive direction, i.e., the upper half of the Y-axis, represents the charge power; the negative direction, i.e., the lower half of the Y-axis, represents the discharge power; the maximum value of the charge / discharge power is 3kW / -3kW. The X-axis represents the corresponding busbar voltages and various voltage reference values ​​according to the first configuration. Specifically, the reference value of the busbar voltage on the BST side is represented as F, which corresponds to 430V, also called the fifth voltage interval; the reference value of the busbar voltage on the energy storage battery side is represented as E, which corresponds to 400V, also called the sixth voltage interval; the reference value of the busbar voltage on the INV side is represented as G, which corresponds to 370V, also called the seventh voltage interval. The configuration of FIG. 5 shows that the reference value of the busbar voltage on the BST side is greater than the reference value of the busbar voltage on the energy storage battery side, and the reference value of the busbar voltage on the energy storage battery side is greater than the reference value of the busbar voltage on the INV side. Thus, referring to Figures 4 and 5, the corresponding relationship between the busbar voltage and the charge / discharge power shown in Figure 5 can be obtained by setting the voltage reference value. And the related power is directly controlled, and the busbar voltage is stabilized around the reference voltage value, thereby improving the conversion efficiency of the inverter, narrowing the operating range of the inverter, further improving the efficiency of the inverter, and increasing the system profitability.

[0120] In some example embodiments, the maximum value of the charge / discharge power may be another value such as 4kW / -4kW, or 5kW / -5kW, etc. These can be adjusted and improved based on the specific application environment, which is not limited here.

[0121] In some example embodiments, the voltage reference values ​​may be other values, which may be adjusted and refined based on the particular application environment, not limited herein.

[0122] Certain embodiments provided in this application may be implemented using any one or combination of hardware, software, firmware, or solid-state logic circuitry, and may be implemented in combination with signal processing, and control and / or special purpose circuitry. Devices or apparatuses provided in certain embodiments of this application may include one or more processors (microprocessors, controllers, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), etc.). These processors process various computer-executable instructions to control the operation of the device or apparatus. Devices or apparatuses provided in certain embodiments of this application may include a system bus or data transmission system that couples various components. The system bus may include any one or combination of different bus structures, such as a memory bus or memory controller, a peripheral bus, a universal serial bus, and / or a processor or local bus utilizing any one of a number of bus architectures. Devices or apparatuses provided in certain embodiments of this application may be provided separately, may be part of a system, or may be part of another device or apparatus.

[0123] The embodiments provided herein may include or be combined with a computer-readable storage medium, e.g., one or more storage devices capable of providing non-transitory data storage. The computer-readable storage medium / storage device may be configured to store data, programmers, and / or instructions that, when executed by a processor of a device or apparatus provided herein, cause the device or apparatus to perform operations associated with the device or apparatus. The computer-readable storage medium / storage device may include one or more of the following characteristics: volatile, non-volatile, dynamic, static, readable / writable, read-only, random access, sequential access, location addressability, file addressability, and content addressability. In one or more exemplary embodiments, the computer-readable storage medium / storage device may be integrated into or belong to a common system with a device or apparatus provided herein in certain embodiments. The computer readable storage medium / storage device may include optical, semiconductor and / or magnetic storage devices, including random access memory (RAM), flash memory, read only memory (ROM), erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), registers, hard disks, removable hard disks, recordable and / or rewritable compact disks (CDs), digital versatile disks (DVDs), and mass media storage devices or any other form of suitable storage medium.

[0124] The above is an implementation of the embodiments of the present application. It should be noted that the steps of the methods described in the specific embodiments of the present application may be subject to sequence adjustment, combination, and omission based on the actual requirements. The above embodiments focus on the description of the embodiments, respectively. For parts not described in detail in one embodiment, please refer to the related descriptions of other embodiments. It can be understood that the structures shown in the embodiments and accompanying drawings of the present application do not constitute specific limitations of the related apparatus or system. In some other embodiments of the present application, the related apparatus or system may include more or less components than those shown in the specific embodiments and accompanying drawings, or some components may be combined, or some components may be divided, or different component arrangements may be used. Those skilled in the art should understand that various modifications or changes may be made to the arrangement, operation, and details of the methods and apparatuses recorded in the specific embodiments without departing from the spirit and scope of the specific embodiments of the present application; Some improvements and modifications may further be made without departing from the principles of the embodiments of the present application, and these improvements and modifications shall also be construed as falling within the scope of protection of the present application.

Claims

1. A method for controlling a busbar voltage of a photovoltaic power system, the photovoltaic power system having an inverter having a DC / DC converter and a DC / AC converter, the DC / DC converter, the DC / AC converter and an energy storage battery are connected via a busbar, the DC / DC converter is connected to a photovoltaic power source and performs maximum power point tracking MPPT on an input power from the photovoltaic power source, a load connected to the DC / AC converter has a load power, and the energy storage battery has a maximum charging power and a maximum discharging power; the method includes: controlling the busbar voltage into a plurality of different discrete voltage intervals based on different results of a comparison between a maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power; the plurality of different discrete voltage intervals corresponding to different operating conditions of the inverter. method.

2. Controlling the busbar voltage into the plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power comprises: controlling the busbar voltage to operate in a first voltage interval when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is greater than the maximum charging power; the first voltage interval corresponds to a reference value of a busbar voltage on the DC / DC converter side of the inverter; When the operating state of the inverter is a state corresponding to the reference value of the busbar voltage on the DC / DC converter side, the energy storage battery is in a charging state, the charging power of the energy storage battery reaches the maximum charging power, the photovoltaic output power of the photovoltaic DC source is smaller than the maximum photovoltaic power, and the photovoltaic output power of the photovoltaic DC source is equal to the sum of the load power and the maximum charging power; The method of claim 1.

3. Controlling the busbar voltage into the plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power comprises: controlling the busbar voltage to operate in a second voltage interval when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is less than the maximum charging power; the second voltage interval corresponds to a reference value of a busbar voltage for charging the energy storage battery; When the operating state of the inverter is a state corresponding to the reference value of the busbar voltage for charging the energy storage battery, the energy storage battery is in a charging state, the charging power of the energy storage battery is less than the maximum charging power, the photovoltaic output power provided by the photovoltaic DC source reaches the maximum photovoltaic power, and the charging power of the energy storage battery is equal to the maximum photovoltaic power minus the load power. The method of claim 1.

4. Controlling the busbar voltage into the plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power comprises: controlling the busbar voltage to operate in a third voltage interval when the maximum solar power generation power is less than the load power and the maximum solar power generation power minus the load power is less than the maximum discharge power; the third voltage interval corresponds to a reference value of a busbar voltage on the DC / AC converter side of the inverter; when the operating state of the inverter is a state corresponding to the reference value of the busbar voltage on the DC / AC converter side, the energy storage battery is in a discharging state, the discharging power of the energy storage battery reaches the maximum discharging power, the photovoltaic output power provided by the photovoltaic DC source reaches the maximum photovoltaic power, the load obtains compensation power from the AC grid, and the compensation power is equal to the load power minus the maximum photovoltaic power plus the maximum discharging power; The method of claim 1.

5. Controlling the busbar voltage into the plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power comprises: controlling the busbar voltage to operate in a fourth voltage interval when the maximum solar power generation power is less than the load power and the maximum solar power generation power minus the load power is greater than the maximum discharge power; the fourth voltage interval corresponds to a reference value of a busbar voltage for discharging the energy storage battery; When the operating state of the inverter is a state corresponding to the reference value of the busbar voltage for discharging of the energy storage battery, the energy storage battery is in a discharging state, the discharge power of the energy storage battery is greater than the maximum discharge power, the photovoltaic output power provided by the photovoltaic DC source reaches the maximum photovoltaic power, and the discharge power of the energy storage battery is equal to the maximum photovoltaic power minus the load power. The method of claim 1.

6. Controlling the busbar voltage into the plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power comprises: A method for controlling the busbar voltage so as to operate at a first voltage interval when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is greater than the maximum charging power, the first voltage interval corresponding to a reference value of a busbar voltage on the DC / DC converter side of the inverter, the steps of: controlling the busbar voltage to operate at a second voltage interval when the maximum solar generated power is greater than the load power and the maximum solar generated power minus the load power is less than the maximum charging power, the second voltage interval corresponding to a reference value of the busbar voltage for charging the energy storage battery; controlling the busbar voltage to operate at a third voltage interval when the maximum solar power generation power is smaller than the load power and the maximum solar power generation power minus the load power is smaller than the maximum discharge power, the third voltage interval corresponding to a reference value of the busbar voltage on the DC / AC converter side of the inverter; or controlling the busbar voltage to operate in a fourth voltage interval when the maximum solar power generated is less than the load power and the maximum solar power minus the load power is greater than the maximum discharge power, the fourth voltage interval corresponding to a busbar voltage reference value for discharging the energy storage battery; the reference value of the busbar voltage on the DC / DC converter side is greater than the reference value of the charging busbar voltage of the energy storage battery, the reference value of the charging busbar voltage of the energy storage battery is greater than the reference value of the discharging busbar voltage of the energy storage battery, and the reference value of the discharging busbar voltage of the energy storage battery is greater than the reference value of the busbar voltage on the DC / AC converter side; The method of claim 1.

7. The method further comprises: generating a loop control command for the busbar voltage on the DC / DC converter side based on the sampled value of the busbar voltage of the inverter and the reference value of the busbar voltage on the DC / DC converter side, in order to control the output power of the inverter so that the busbar voltage is stabilized at the reference value of the busbar voltage on the DC / DC converter side; generating a loop control command for the busbar voltage on the DC / AC converter side based on the sampled value of the busbar voltage and the reference value of the busbar voltage on the DC / AC converter side to control the output power of the inverter so that the busbar voltage is stabilized at the reference value of the busbar voltage on the DC / AC converter side; generating a loop control command for the charging busbar voltage of the energy storage battery based on the sampled value of the busbar voltage and the reference value of the charging busbar voltage of the energy storage battery to control the charging power of the energy storage battery such that the busbar voltage is stabilized at the reference value of the charging busbar voltage of the energy storage battery; and generating a loop control command for the discharging busbar voltage of the energy storage battery based on the sampled value of the busbar voltage and the reference value of the discharging busbar voltage of the energy storage battery to control a discharge power of the energy storage battery such that the busbar voltage is stabilized at the reference value of the discharging busbar voltage of the energy storage battery; The method according to claim 6.

8. The loop control command of the busbar voltage on the DC / DC converter side, the loop control command of the busbar voltage on the DC / AC converter side, the loop control command of the busbar voltage for charging the energy storage battery, and the loop control command of the busbar voltage for discharging the energy storage battery all use a PI controller. The method according to claim 7.

9. Controlling the busbar voltage into the plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power comprises: controlling the busbar voltage to operate in a fifth voltage interval when the maximum solar power generation power is less than the load power and the maximum solar power generation power minus the load power is greater than the maximum discharge power, or when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is less than the maximum charge power; the fifth voltage interval corresponds to a reference value of a busbar voltage for charging / discharging the energy storage battery; When the operating state of the inverter is in a state corresponding to the reference value of the busbar voltage for charging / discharging the energy storage battery, the photovoltaic output power provided by the photovoltaic DC source reaches the maximum photovoltaic power, and the maximum photovoltaic power minus the load power is smaller than the maximum charging power and larger than the maximum discharging power. The method of claim 1.

10. Controlling the busbar voltage into the plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power comprises: controlling the busbar voltage to operate at a first voltage interval when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is greater than the maximum charging power, the first voltage interval corresponding to a reference value of a busbar voltage on the DC / DC converter side of the inverter; controlling the busbar voltage to operate at a third voltage interval when the maximum solar power generation power is smaller than the load power and the maximum solar power generation power minus the load power is smaller than the maximum discharge power, the third voltage interval corresponding to a reference value of the busbar voltage on the DC / AC converter side of the inverter; or if the maximum solar power generation power is less than the load power and the maximum solar power generation power minus the load power is greater than the maximum discharge power, or if the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is less than the maximum charge power, controlling the busbar voltage to operate in a fifth voltage interval, the fifth voltage interval corresponding to a reference value of the busbar voltage for charging / discharging the energy storage battery; the reference value of the busbar voltage on the DC / DC converter side is greater than the reference value of the busbar voltage for charging / discharging the energy storage battery, and the reference value of the busbar voltage for charging / discharging the energy storage battery is greater than the reference value of the busbar voltage on the DC / AC converter side; The method of claim 1.

11. The method further comprises: generating a loop control command for the busbar voltage on the DC / DC converter side based on the sampled value of the busbar voltage of the inverter and the reference value of the busbar voltage on the DC / DC converter side, in order to control the output power of the inverter so that the busbar voltage is stabilized at the reference value of the busbar voltage on the DC / DC converter side; generating a loop control command for the busbar voltage on the DC / AC converter side based on the sampled value of the busbar voltage and the reference value of the busbar voltage on the DC / AC converter side to control the output power of the inverter so that the busbar voltage is stabilized at the reference value of the busbar voltage on the DC / AC converter side; and generating a loop control command for the busbar voltage for charging / discharging the energy storage battery based on the sampled value of the busbar voltage and the reference value of the busbar voltage for charging / discharging the energy storage battery to control the charge / discharge power of the energy storage battery so that the busbar voltage is stabilized at the reference value of the busbar voltage for charging / discharging the energy storage battery; The method of claim 10.

12. The loop control command of the busbar voltage on the DC / DC converter side, the loop control command of the busbar voltage on the DC / AC converter side, and the loop control command of the busbar voltage for charging / discharging the energy storage battery all use a PI controller; The method of claim 11.

13. The maximum charging power and the maximum discharging power are preset.

13. The method according to any one of claims 1 to 12.

14. A photovoltaic power generation system having an inverter, comprising: the inverter comprises a DC / DC converter, a DC / AC converter, and a busbar voltage controller; The DC / DC converter, the DC / AC converter, and an energy storage battery are connected via a bus bar, the DC / DC converter is connected to a solar power generation DC source and performs maximum power point tracking MPPT on the input power from the solar power generation DC source, a load connected to the DC / AC converter has a load power, and the energy storage battery has a maximum charging power and a maximum discharging power; The busbar voltage controller: configured to control the busbar voltage into a plurality of different discrete voltage intervals based on different results of the comparison between the maximum photovoltaic power and the load power, the maximum charging power, and the maximum discharging power; the plurality of different discrete voltage intervals corresponding to different operating conditions of the inverter. Photovoltaic power generation system.

15. Controlling the busbar voltage into the plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a first voltage interval when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is greater than the maximum charging power; the first voltage interval corresponds to a reference value of a busbar voltage on the DC / DC converter side of the inverter; When the operating state of the inverter is a state corresponding to the reference value of the busbar voltage on the DC / DC converter side, the energy storage battery is in a charging state, the charging power of the energy storage battery reaches the maximum charging power, the photovoltaic output power of the photovoltaic DC source is smaller than the maximum photovoltaic power, and the photovoltaic output power of the photovoltaic DC source is equal to the sum of the load power and the maximum charging power; The solar power generation system according to claim 14.

16. Controlling the busbar voltage into the plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a second voltage interval when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is less than the maximum charging power; the second voltage interval corresponds to a reference value of a busbar voltage for charging the energy storage battery; When the operating state of the inverter is a state corresponding to the reference value of the busbar voltage for charging the energy storage battery, the energy storage battery is in a charging state, the charging power of the energy storage battery is less than the maximum charging power, the photovoltaic output power provided by the photovoltaic DC source reaches the maximum photovoltaic power, and the charging power of the energy storage battery is equal to the maximum photovoltaic power minus the load power. The solar power generation system according to claim 14.

17. Controlling the busbar voltage into the plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a third voltage interval when the maximum solar power generation power is less than the load power and the maximum solar power generation power minus the load power is less than the maximum discharge power; the third voltage interval corresponds to a reference value of a busbar voltage on the DC / AC converter side of the inverter; when the operating state of the inverter is a state corresponding to the reference value of the busbar voltage on the DC / AC converter side, the energy storage battery is in a discharging state, the discharging power of the energy storage battery reaches the maximum discharging power, the photovoltaic output power provided by the photovoltaic DC source reaches the maximum photovoltaic power, the load obtains compensation power from the AC grid, and the compensation power is equal to the load power minus the maximum photovoltaic power plus the maximum discharging power; The solar power generation system according to claim 14.

18. Controlling the busbar voltage into the plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a fourth voltage interval when the maximum solar power generation power is smaller than the load power and the maximum solar power generation power minus the load power is greater than the maximum discharge power; the fourth voltage interval corresponds to a reference value of a busbar voltage for discharging the energy storage battery; When the operating state of the inverter is a state corresponding to the reference value of the busbar voltage for discharging of the energy storage battery, the energy storage battery is in a discharging state, the discharge power of the energy storage battery is greater than the maximum discharge power, the photovoltaic output power provided by the photovoltaic DC source reaches the maximum photovoltaic power, and the discharge power of the energy storage battery is equal to the maximum photovoltaic power minus the load power; The solar power generation system according to claim 14.

19. Controlling the busbar voltage into the plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage so as to operate at a first voltage interval when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is greater than the maximum charging power, the first voltage interval corresponding to a reference value of a busbar voltage on the DC / DC converter side of the inverter; controlling the busbar voltage to operate at a second voltage interval when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is less than the maximum charging power, the second voltage interval corresponding to a reference value of the busbar voltage for charging the energy storage battery; When the maximum solar power generation power is smaller than the load power and the maximum solar power generation power minus the load power is smaller than the maximum discharge power, controlling the busbar voltage to operate at a third voltage interval, the third voltage interval corresponding to a reference value of the busbar voltage on the DC / AC converter side of the inverter; or controlling the busbar voltage to operate in a fourth voltage interval when the maximum solar power generated is less than the load power and the maximum solar power minus the load power is greater than the maximum discharge power, the fourth voltage interval corresponding to a reference value of the busbar voltage for discharging the energy storage battery; the reference value of the busbar voltage on the DC / DC converter side is greater than the reference value of the charging busbar voltage of the energy storage battery, the reference value of the charging busbar voltage of the energy storage battery is greater than the reference value of the discharging busbar voltage of the energy storage battery, and the reference value of the discharging busbar voltage of the energy storage battery is greater than the reference value of the busbar voltage on the DC / AC converter side; The solar power generation system according to claim 14.

20. The busbar voltage controller further comprises: generating a loop control command for the busbar voltage on the DC / DC converter side based on the sampled value of the busbar voltage of the inverter and the reference value of the busbar voltage on the DC / DC converter side, in order to control the output power of the inverter so that the busbar voltage is stabilized at the reference value of the busbar voltage on the DC / DC converter side; generating a loop control command for the busbar voltage on the DC / AC converter side based on the sampled value of the busbar voltage and the reference value of the busbar voltage on the DC / AC converter side, in order to control the output power of the inverter so that the busbar voltage is stabilized at the reference value of the busbar voltage on the DC / AC converter side; generating a loop control command for the charging busbar voltage of the energy storage battery based on the sampled value of the busbar voltage and the reference value of the charging busbar voltage of the energy storage battery to control the charging power of the energy storage battery such that the busbar voltage is stabilized at the reference value of the charging busbar voltage of the energy storage battery; and generating a loop control command for the discharging busbar voltage of the energy storage battery based on the sampled value of the busbar voltage and the reference value of the discharging busbar voltage of the energy storage battery to control a discharge power of the energy storage battery such that the busbar voltage is stabilized at the reference value of the discharging busbar voltage of the energy storage battery; 20. The solar power generation system according to claim 19.

21. The loop control command of the busbar voltage on the DC / DC converter side, the loop control command of the busbar voltage on the DC / AC converter side, the loop control command of the busbar voltage for charging the energy storage battery, and the loop control command of the busbar voltage for discharging the energy storage battery all use a PI controller. The solar power generation system according to claim 20.

22. Controlling the busbar voltage into the plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage to operate in a fifth voltage interval when the maximum solar power generation power is smaller than the load power and the maximum solar power generation power minus the load power is greater than the maximum discharge power, or when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is smaller than the maximum charge power; the fifth voltage interval corresponds to a reference value of a busbar voltage for charging / discharging the energy storage battery; When the operating state of the inverter is in a state corresponding to the reference value of the busbar voltage for charging / discharging the energy storage battery, the photovoltaic output power supplied by the photovoltaic DC source reaches the maximum photovoltaic power, and the maximum photovoltaic power minus the load power is smaller than the maximum charging power and larger than the maximum discharging power. The solar power generation system according to claim 14.

23. Controlling the busbar voltage into the plurality of different discrete voltage intervals based on different results of the comparison between the maximum solar generated power and the load power, the maximum charging power, and the maximum discharging power includes: controlling the busbar voltage so as to operate at a first voltage interval when the maximum solar power generation power is greater than the load power and the maximum solar power generation power minus the load power is greater than the maximum charging power, the first voltage interval corresponding to a reference value of a busbar voltage on the DC / DC converter side of the inverter; When the maximum solar power generation power is smaller than the load power and the maximum solar power generation power minus the load power is smaller than the maximum discharge power, controlling the busbar voltage to operate at a third voltage interval, the third voltage interval corresponding to a reference value of the busbar voltage on the DC / AC converter side of the inverter; or controlling the busbar voltage to operate at a fifth voltage interval when the maximum solar power is less than the load power and the maximum solar power minus the load power is greater than the maximum discharge power, or when the maximum solar power is greater than the load power and the maximum solar power minus the load power is less than the maximum charge power, the fifth voltage interval corresponding to a reference value of the busbar voltage for charging / discharging the energy storage battery; the reference value of the busbar voltage on the DC / DC converter side is greater than the reference value of the busbar voltage for charging / discharging the energy storage battery, and the reference value of the busbar voltage for charging / discharging the energy storage battery is greater than the reference value of the busbar voltage on the DC / AC converter side; The solar power generation system according to claim 14.

24. The busbar voltage controller further comprises: generating a loop control command for the busbar voltage on the DC / DC converter side based on the sampled value of the busbar voltage of the inverter and the reference value of the busbar voltage on the DC / DC converter side, in order to control the output power of the inverter so that the busbar voltage is stabilized at the reference value of the busbar voltage on the DC / DC converter side; generating a loop control command for the busbar voltage on the DC / AC converter side based on the sampled value of the busbar voltage and the reference value of the busbar voltage on the DC / AC converter side to control the output power of the inverter so that the busbar voltage is stabilized at the reference value of the busbar voltage on the DC / AC converter side; and generating a loop control command for the charging / discharging busbar voltage of the energy storage battery based on the sampled value of the busbar voltage and the reference value of the charging / discharging busbar voltage of the energy storage battery to control the charging / discharging power of the energy storage battery so that the busbar voltage is stabilized at the reference value of the charging / discharging busbar voltage of the energy storage battery; It is configured as follows: The solar power generation system according to claim 23.

25. The loop control command of the busbar voltage on the DC / DC converter side, the loop control command of the busbar voltage on the DC / AC converter side, and the loop control command of the busbar voltage for charging / discharging the energy storage battery all use a PI controller; The solar power generation system according to claim 24.

26. The maximum charging power and the maximum discharging power are preset. The photovoltaic power generation system according to any one of claims 14 to 25.

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