An inverter architecture with power factor regulation function

Abstract

The application discloses an inverter architecture with power factor regulation function, comprising at least one inverter, each inverter comprising a DC / DC unit, a first DC / AC unit and a second DC / AC unit; the DC / DC unit performs MPPT tracking, the first DC / AC unit is adapted to output MPPT power as active power, and simultaneously outputs zero reactive power; the second DC / AC unit is connected in parallel with the first DC / AC unit, the second DC / AC unit is connected in parallel with the first DC / AC unit, and the second DC / AC unit outputs corresponding reactive power by tracking the reactive power instruction required for power factor regulation. The application has the beneficial effects that two DC / AC units are arranged to respectively realize only active power and reactive power, so that the power factor of the grid-connected port can be ensured to be above 0.95. The two DC / AC units can be completely decoupled, so that the design of the whole architecture is relatively simple; meanwhile, the two DC / AC units can be redundant to each other, so as to improve the working reliability of the architecture.

Description

Technical Field

[0001] This application relates to the field of new energy power generation technology, and in particular to an inverter architecture with power factor regulation function. Background Technology

[0002] Power companies have specific requirements for the power factor at the grid connection points of various industrial parks or factories. To ensure that the power factor of a factory is greater than 0.95, a certain capacity SVG device is usually installed.

[0003] like Figure 1 As shown, when a factory or industrial park installs a photovoltaic (PV) power generation device, the active power P at the grid connection point decreases, while the reactive power Q remains unchanged. This leads to a decrease in the power factor; specifically, a power factor < 0.95, which does not meet safety regulations. In this case, the factory or industrial park will have to purchase a large-capacity SVG (Static Var Generator) device to meet the power factor requirements, which will inevitably increase the factory's or industrial park's electricity costs. Traditional inverters typically have a reactive power range of -0.8 to 0.8, and when the apparent power exceeds the rated value, the system will operate at a reduced rate, resulting in a loss of some active power. Therefore, existing inverters cannot meet the power factor requirements of factories or industrial parks. Summary of the Invention

[0004] One objective of this application is to provide an inverter architecture with power factor regulation that can solve at least one of the defects in the aforementioned background art.

[0005] To achieve at least one of the above objectives, the technical solution adopted in this application is as follows: an inverter architecture with power factor regulation function, comprising at least one inverter, each inverter comprising a DC / DC unit, a first DC / AC unit, and a second DC / AC unit; the DC / DC unit performs MPPT tracking, the first DC / AC unit is adapted to output the MPPT power tracked by the DC / DC unit as active power, while outputting zero reactive power; the second DC / AC unit is connected in parallel to the first DC / AC unit, and the second DC / AC unit tracks the reactive power command required for power factor regulation to output the corresponding reactive power.

[0006] Preferably, the DC side of the second DC / AC unit is connected to the DC side of the first DC / AC unit via a connection switch; when the second DC / AC unit outputs reactive power, the connection switch is in the open state, and at this time the second DC / AC unit is adapted to maintain the DC side voltage through the bus voltage loop.

[0007] Preferably, the control loop of the first DC / AC unit includes a bus voltage loop as an outer loop and a current loop as an inner loop; the bus voltage loop is adapted to take the bus voltage on the DC side and the bus voltage command value corresponding to the MPPT power as input, and then output the d-axis current setpoint value to the current loop; the current loop is adapted to take the dq-axis current component of the phase current and the dq-axis current setpoint value as input, and the output of the current loop is modulated to obtain the drive signal for controlling the first DC / AC unit; wherein, the q-axis current setpoint value is zero.

[0008] Preferably, the control loop of the second DC / AC unit includes a bus voltage loop and a reactive power loop as the outer loop, and a current loop as the inner loop; the bus voltage loop is adapted to take the DC-side bus voltage and the bus voltage setpoint as inputs to maintain the DC-side bus voltage of the second DC / AC unit at the bus voltage setpoint; the reactive power loop is adapted to take the reactive power command and reactive power as inputs, and then input the q-axis current setpoint to the current loop; the current loop is adapted to take the dq-axis current component of the phase current and the dq-axis current setpoint as inputs, and the output of the current loop is modulated to obtain the drive signal for controlling the second DC / AC unit; wherein, the d-axis current setpoint is zero.

[0009] Preferably, the inverter further includes a DC / DC unit connected to the DC side of the first DC / AC unit; the AC side of the first DC / AC unit is connected to the power grid via a circuit breaker; the startup of the inverter includes the following process: first, closing the connection switch and starting the DC / DC unit to establish the bus voltage; then starting the first DC / AC unit to output voltage until the output voltage is in the same frequency, phase, and voltage as the grid voltage, and then closing the circuit breaker; after the circuit breaker completes closing, blocking the first DC / AC unit and simultaneously disconnecting the connection switch; finally, starting the first DC / AC unit and the second DC / AC unit, so that the first DC / AC unit controls active power and the second DC / AC unit controls reactive power.

[0010] Preferably, in scenarios where there are multiple inverters, the inverter architecture further includes a control module; the control module is communicatively connected to multiple inverters; the control module is adapted to collect power at the grid connection location and send corresponding reactive power commands to each inverter based on the collected data.

[0011] Preferably, the control module includes a networking unit, a CPU unit, and a power acquisition unit connected in sequence; the power acquisition unit is adapted to acquire power at the grid connection location, the CPU unit is adapted to receive the power data acquired by the acquisition unit and generate reactive power commands corresponding to each of the inverters, and the networking unit is adapted to send the reactive power commands generated by the CPU unit to each of the inverters.

[0012] Preferably, the generation of reactive power commands by the control module includes the following process: calculating the required total reactive power based on the power collected at the grid connection location; dividing the calculated total reactive power by the total number of inverters to obtain the reactive power command corresponding to each inverter.

[0013] Preferably, the control module generates reactive power commands through the following process: calculating the required total reactive power Q based on the power collected at the grid connection location; setting priorities #1 to #N for all N inverters; and setting the upper limit of reactive power output by each inverter to Q. max If the total reactive power Q satisfies: (k-1)Q max ≤Q<kQ max A reactive power command is sent to the inverters with priorities #1 to #k, and the reactive power command for each of the k inverters is Q / k; where k≤N.

[0014] Preferably, the priority of the N inverters is adapted to be rotated in reverse order at set intervals, with the priority change being at least one level each time.

[0015] Compared with the prior art, the beneficial effects of this application are as follows:

[0016] By setting up two DC / AC units to generate active and reactive power respectively, the power factor at the grid connection port can be guaranteed to be above 0.95. Furthermore, the two DC / AC units can achieve complete power decoupling, simplifying the overall architecture design; simultaneously, the two DC / AC units can provide redundancy for each other, improving the architecture's operational reliability. Attached Figure Description

[0017] Figure 1 A schematic diagram of the power supply for a factory or industrial park that has traditionally installed photovoltaic (PV) power generation devices.

[0018] Figure 2 This is a schematic diagram of the architecture of a traditional string photovoltaic inverter system.

[0019] Figure 3 This is a schematic diagram of the overall architecture of this application.

[0020] Figure 4This is a schematic diagram of the inverter architecture of this application in a steady-state operating state.

[0021] Figure 5 This is a schematic diagram of the control loop operating state of the inverter architecture in this application under steady state.

[0022] Figure 6 This is a schematic diagram of the control flow during startup for the inverter architecture of this application.

[0023] Figure 7 A schematic diagram of one example of the communication architecture for reactive power command allocation in this application.

[0024] Figure 8 A schematic diagram of another example of the communication architecture for reactive power command allocation in this application. Detailed Implementation

[0025] The present application will now be further described in conjunction with specific embodiments. It should be noted that, in the description of this specification, the use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0026] In the description of this application, it should be noted that the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., which indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of this application.

[0027] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0028] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0030] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0031] To facilitate understanding of the technical solution of this application, the specific architecture of the photovoltaic (PV) power generation device used in a factory or industrial park will be described below. Generally, the PV power generation device adopts a string photovoltaic inverter system, such as... Figure 2 As shown, a string photovoltaic inverter system comprises N photovoltaic strings, N DC / DC units, and a DC / AC unit. The N photovoltaic strings can be labeled PV#1 to PV#N, and the N DC / DC units can be labeled DC / DC#1 to DC / DC#N. The N photovoltaic strings can be connected in parallel to the DC side of the corresponding DC / DC units. The AC side of the DC / AC units is connected to the power grid via circuit breaker K. By closing circuit breaker K, the string photovoltaic inverter system can be connected to the grid, thereby supplying power to the loads in the factory or industrial park.

[0032] It is understood that the specific structure and working principle of DC / DC and DC / AC units are well known to those skilled in the art, and therefore will not be described in detail here. For example, a DC / DC unit can use a Boost circuit, and a DC / AC unit can use a T-type three-level circuit. Since a traditional string photovoltaic inverter system has only one DC / AC unit, when the DC / AC unit generates reactive power, if the apparent power output exceeds the rated power, some active power must be lost, which will cause a decrease in the power factor.

[0033] To ensure that the inverter architecture meets power factor requirements during grid connection, this application provides an inverter architecture with power factor regulation function, such as... Figure 3 As shown, one preferred embodiment includes at least one inverter. Each inverter includes a DC / DC unit and a first DC / AC unit and a second DC / AC unit connected in parallel. The DC / DC unit performs MPPT tracking, and the first DC / AC unit can output the MPPT power tracked by the DC / DC unit as active power, while outputting zero reactive power. The second DC / AC unit is connected in parallel with the first DC / AC unit, and the second DC / AC unit tracks the reactive power command required for power factor adjustment to output the corresponding reactive power.

[0034] It is understood that the technical solution of this application is equivalent to adding a DC / AC unit, namely the second DC / AC unit, to the traditional string photovoltaic inverter system architecture. Based on the added second DC / AC unit, the control loops of the two DC / AC units are appropriately adjusted so that the first DC / AC unit focuses solely on generating active power, specifically the MPPT power of the preceding photovoltaic string, ensuring no load derating during grid connection. The second DC / AC unit focuses solely on generating reactive power, and by adjusting the reactive power, the power factor at the grid connection port can be guaranteed to reach above 0.95. Furthermore, since the first and second DC / AC units can achieve complete power decoupling, the design of the entire inverter architecture is simplified. Simultaneously, functional redundancy can be achieved between the first and second DC / AC units, effectively improving the operational stability of the inverter architecture.

[0035] It should be understood that because the first DC / AC unit and the second DC / AC unit are connected in parallel, but each performs different power outputs, fluctuations in the DC-side bus voltage may occur, thus affecting the balance of the bus midpoint voltage. Therefore, the connection method between the first DC / AC unit and the second DC / AC unit needs to be improved so that their DC-side voltages do not interfere with each other when outputting power.

[0036] In this embodiment, as Figure 3 and Figure 4 As shown, the DC side of the second DC / AC unit is connected to the DC side of the first DC / AC unit via a connection switch. When the second DC / AC unit outputs reactive power, the connection switch is in the open state, and the second DC / AC unit can maintain the DC side voltage through the bus voltage loop.

[0037] Understandably, the second DC / AC unit only needs to control the disconnection of its DC-side positive and negative buses from the first DC / AC unit via connection switches. That is, as follows... Figure 3 and Figure 4 As shown, the positive DC bus of the second DC / AC unit is connected to the positive DC bus of the first DC / AC unit via a connecting switch T1, and the negative DC bus of the second DC / AC unit is connected to the negative DC bus of the first DC / AC unit via a connecting switch T2. The midpoint of the DC bus of the second DC / AC unit is directly connected to the midpoint of the DC bus of the first DC / AC unit. The specific structural types of connecting switches T1 and T2 are well known to those skilled in the art. For example, connecting switches T1 and T2 can be relay switches, MOSFETs, or thyristors. In this embodiment, bidirectional thyristors are preferred.

[0038] To facilitate understanding, the following will provide a detailed description of the entire inverter architecture's operation in steady state.

[0039] When the inverter architecture is in a steady state, such as Figure 5 As shown, the control loop of the DC / DC unit includes an MPPT loop, a voltage loop, and a current loop. The voltage value v output from the photovoltaic string is... PV and current value i PV The data is fed into the MPPT loop, and then the corresponding MPPT algorithm can output the target voltage value v. PV * Target voltage value v PV * In the voltage loop, with voltage value v PV By comparing, the corresponding target current value i can be obtained. PV *And output to the current loop; target current value i PV * In the current loop, with current value i PV By comparing the duty cycles, the corresponding duty cycle d can be obtained, and then the DC / DC unit can be driven and controlled through the duty cycle d.

[0040] like Figure 5 As shown, the control loop of the first DC / AC unit includes a bus voltage loop as the outer loop and a current loop as the inner loop, and also includes a phase-locked loop. The grid voltage v ga v gb and vgc Phase locking is achieved using a phase-locked loop (PLL). In the outer loop of the bus voltage, the real-time acquired DC-side bus voltage V can be... dc_sum That is, the voltage V of the upper and lower half of the bus. dc1 and V dc2 The sum of the bus voltage command value V corresponding to the MPPT power dc_sum * After being compared as input, the current is passed through a PI controller and limited before the d-axis current setpoint i can be output to the current loop. d1 * Simultaneously, the three-phase grid-connected current i on the AC side of the first DC / AC unit can be... a1 i b1 and i c1 Perform an abc / dq0 transformation to obtain the dq0-axis current component i. d1 i q1 and i 01 In the current loop, the obtained dq-axis current component i can be... d1 and i q1 The current values ​​i along the dq axes are respectively related to the given values ​​of the currents along the d and q axes. d1 * and i q1 * The signals are compared, then limited by a PI controller, and then dq0 / abc transformation is performed to obtain the corresponding duty cycle signal. After the duty cycle signal is modulated by SPWM, the drive signal for controlling the first DC / AC unit can be obtained.

[0041] like Figure 5 As shown, the control loop of the second DC / AC unit includes a bus voltage loop and a reactive power loop as the outer loop, a current loop as the inner loop, and a phase-locked loop. The grid voltage v ga v gb and vgc Phase locking is achieved using a phase-locked loop (PLL). In the outer loop of the bus voltage, the DC-side bus voltage V can be acquired in real time. dc With the set bus voltage setpoint V dc *After being compared as input, the voltage is passed through a PI controller and limited to maintain the DC-side bus voltage at the bus voltage setpoint V. dc * In the reactive power loop, the reactive power command Q can be used. * After comparing the reactive power Q collected in real time with the input, and then passing through a PI controller and being limited, the q-axis current setpoint i can be output from the current loop input. q2 * Simultaneously, the three-phase grid-connected current i on the AC side of the second DC / AC unit can be... a2 i b2 and i c2 Perform an abc / dq0 transformation to obtain the dq0-axis current component i. d2 i q2 and i 02 In the current loop, the obtained dq-axis current component i can be... d2 and i q2 The current values ​​i along the dq axes are respectively related to the given values ​​of the currents along the d and q axes. d2 * and i q2 * The signals are compared, then limited by a PI controller, and then dq0 / abc transformation is performed to obtain the corresponding duty cycle signal. After the duty cycle signal is modulated by SPWM, the drive signal for controlling the second DC / AC unit can be obtained.

[0042] It should be understood that the d-axis current component is mainly used to control active power, while the q-axis current component is mainly used to control reactive power. Therefore, in the control loop of the first DC / AC unit, the q-axis current setpoint i is... q1 * The value is limited to zero; in the control loop of the second DC / AC unit, the d-axis current setpoint i is set to zero. d2 * Limited to zero.

[0043] As can be understood from the foregoing, when the inverter architecture of this application is operating in steady state, the second DC / AC unit is connected to the first DC / AC unit on the AC side and disconnected on the DC side. Therefore, in order to ensure that the second DC / AC unit can perform reactive power control normally, the DC bus of the second DC / AC unit needs to be charged when the inverter architecture starts up, so that the DC bus of the second DC / AC unit has a stable voltage when the inverter architecture enters steady state. Since the startup process of each inverter is the same, for ease of understanding, the startup process of a single inverter will be described in detail below.

[0044] Specifically, such as Figure 6As shown, the inverter startup process includes the following steps: First, close the connection switch and start the DC / DC unit to establish the bus voltage; then, start the first DC / AC unit to output voltage until the output voltage is in the same frequency, phase, and voltage as the grid voltage, and then close the circuit breaker K; after the circuit breaker K is closed, block the first DC / AC unit and simultaneously disconnect the connection switches T1 and T2; finally, start the first DC / AC unit and the second DC / AC unit so that the first DC / AC unit controls the active power and the second DC / AC unit controls the reactive power.

[0045] In this embodiment, for a scenario with N inverters (N > 1), the N inverters can be labeled as Inverter #1 to Inverter #N. To achieve power factor regulation at the grid-connected ports of a factory or industrial park, reactive power regulation of one or more inverters is often required. This necessitates constructing a communication architecture within the inverter architecture to distribute reactive power commands to multiple inverters. Regarding the construction of the communication architecture, as follows... Figure 7 and Figure 8 As shown, the inverter architecture also includes a control module; the control module communicates with multiple inverters to form a communication architecture. The control module can collect power data at the grid connection point and send corresponding reactive power commands to each inverter based on the collected data.

[0046] In this embodiment, there are various specific structures for the control module capable of distributing reactive power commands. For ease of understanding, one such structure will be described in detail below. Figure 7 and Figure 8 As shown, the control module includes a networking unit, a CPU unit, and a power acquisition unit that are electrically connected in sequence. The power acquisition unit can acquire power at the grid-connected location. The CPU unit can receive the power data acquired by the acquisition unit and generate reactive power commands corresponding to each inverter. The networking unit can send the reactive power commands generated by the CPU unit to each inverter.

[0047] It is understood that the specific structures and working principles of the networking unit, CPU unit, and power acquisition unit are well-known technologies to those skilled in the art, and therefore will not be described in detail here. It should be noted that the specific structure of the communication architecture may differ depending on the type of networking unit. For ease of understanding, two specific examples will be used below for detailed explanation.

[0048] Example 1: such as Figure 7As shown, N inverters are connected to the load, SVG device, and power grid via power lines, enabling the inverters and grid to supply power to the load. The control module can collect the grid-connected power from the power lines through the power acquisition unit, and then the CPU unit can calculate and allocate reactive power commands based on the collected power. The networking unit can use a 485 bus; the N inverters communicate with the CPU unit via the 485 bus, thereby sending the reactive power commands allocated by the CPU unit to the N inverters via the 485 bus.

[0049] Example 2: such as Figure 8 As shown, N inverters are connected to the load, SVG device, and power grid via power lines, enabling the inverters and grid to supply power to the load. The control module can collect the grid-connected power from the power lines through the power acquisition unit, and then the CPU unit can calculate and allocate reactive power commands based on the collected power. In this case, a PLC is used as the networking unit, and the CPU unit can connect to the power lines via the PLC bus, thereby sending the reactive power commands allocated by the CPU unit to the N inverters via the PLC bus.

[0050] In this embodiment, the CPU unit can generate reactive power instructions in several ways. For ease of understanding, two specific methods will be explained in detail below.

[0051] Method 1: The CPU unit can calculate the total reactive power Q required by the inverter architecture based on the power at the grid connection location collected by the power acquisition unit. Then, the required total reactive power Q is evenly distributed to each inverter, that is, by dividing the total reactive power Q by the total number of inverters N, the reactive power command corresponding to each inverter is Q / N.

[0052] It should be noted that the reactive power command for N inverters can be defined as Q1. * Q2 * Q N * Using method one, Q1 can be obtained. * =Q2 * =……=Q N * =Q / N.

[0053] Method 2: The CPU unit can calculate the total reactive power Q required by the inverter architecture based on the power at the grid connection location collected by the power acquisition unit. Priorities #1 to #N are assigned to all N inverters; the upper limit of reactive power output by each inverter is set to Q. max If the total reactive power Q satisfies: (k-1)Q max ≤Q<kQ maxThe reactive power command is sent to the inverters with priorities #1 to #k, and the reactive power command for each of the k inverters is Q / k; where k≤N.

[0054] Specifically, if the total reactive power Q satisfies: Q max ≤Q<2Q max If k is 2, then reactive power commands can be sent to inverters with priorities #1 and #2, and the reactive power command for both inverters is Q / 2. If the total reactive power Q satisfies: 2Q max ≤Q<3Q max If k is 3, then reactive power commands can be sent to inverters with priorities #1 to #3. The reactive power commands for all three inverters are Q / 3. And so on, without further details.

[0055] Understandably, for Method 1, all inverters' second DC / AC units need to be started, which may increase the heat generation of the entire inverter architecture; however, the impact of a single inverter failure on the power factor of the entire inverter architecture is relatively small. For Method 2, only the second DC / AC units of k inverters need to be started, which can appropriately reduce the heat generation of the inverter architecture; however, the failure of an inverter that transmits reactive power has a significant impact on the power factor of the entire inverter architecture. Both methods can meet the requirements of this application, and the appropriate method can be selected according to the actual needs of those skilled in the art.

[0056] It should be understood that, with the second method described above, high-priority inverters, such as priority #1 inverters, may experience longer operation times for their second DC / AC unit, while low-priority inverters, such as priority #N inverters, may experience shorter operation times or not operate at all for their second DC / AC unit. This could increase the failure rate of high-priority inverters and waste resources on low-priority inverters. Therefore, the second method described above can be improved.

[0057] Specifically, the priority of N inverters can be rotated in reverse order at set intervals, with the priority change being at least one level each time.

[0058] It is understandable that the interval for priority rotation can be set according to the actual needs of those skilled in the art, such as rotating priorities every 1 hour.

[0059] For the reverse priority rotation, taking a one-level priority change as an example, the inverter with priority #1 will have priority #N after the rotation, the inverter with priority #2 will have priority #1, the inverter with priority #3 will have priority #2, and so on. The inverter with priority #N-1 will have priority #N-2, and the inverter with priority #N will have priority #N-1. Taking a two-level priority change as an example, the inverter with priority #1 will have priority #N-1, the inverter with priority #2 will have priority #N, the inverter with priority #3 will have priority #1, and so on. The inverter with priority #N-1 will have priority #N-3, and the inverter with priority #N will have priority #N-2. The same logic applies to each priority change of X levels, and will not be detailed further.

[0060] In layman's terms, by rotating the priority in reverse order, at least one inverter's second DC / AC unit can be shut down for rest after each rotation. The specific number of second DC / AC units shut down after each rotation depends on the number of priority levels changed in each rotation; that is, if the priority changes by one level, one second DC / AC unit will be shut down after each rotation; if the priority changes by two levels, two second DC / AC units will be shut down after each rotation, and so on. By rotating the priority in reverse order, it can be ensured that the operating time of the second DC / AC unit of each inverter is basically consistent throughout the entire working cycle.

[0061] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. An inverter architecture with power factor regulation function, characterized in that, Includes at least one inverter, each of the inverters comprising: DC / DC unit, which performs MPPT tracking; A first DC / AC unit; the first DC / AC unit is adapted to output the MPPT power tracked by the DC / AC unit as active power, while outputting zero reactive power; and The second DC / AC unit is connected in parallel with the first DC / AC unit. The second DC / AC unit outputs the corresponding reactive power by tracking the reactive power command required for power factor adjustment. The DC side of the second DC / AC unit is connected to the DC side of the first DC / AC unit via a connection switch; When the second DC / AC unit outputs reactive power, the connection switch is in the open state. At this time, the second DC / AC unit is suitable for maintaining the DC side voltage through the bus voltage loop. The control loop of the second DC / AC unit uses the bus voltage loop as the outer loop; The bus voltage loop is adapted to take the DC-side bus voltage and the bus voltage setpoint as inputs to maintain the DC-side bus voltage of the second DC / AC unit at the bus voltage setpoint. The AC side of the first DC / AC unit is connected to the power grid via a circuit breaker; The startup process of the inverter includes the following steps: First, close the connection switch and start the DC / DC unit to establish the bus voltage; Then, the first DC / AC unit is started to output voltage until the output voltage is in the same frequency, phase and voltage as the grid voltage, and then the circuit breaker is closed. After the circuit breaker completes closing, the first DC / AC unit is blocked, and the connection switch is disconnected at the same time; Finally, the first DC / AC unit and the second DC / AC unit are activated, so that the first DC / AC unit controls the active power and the second DC / AC unit controls the reactive power.

2. The inverter architecture with power factor regulation function as described in claim 1, characterized in that, The control loop of the first DC / AC unit includes a bus voltage loop as an outer loop and a current loop as an inner loop. The bus voltage loop is adapted to take the bus voltage on the DC side and the bus voltage command value corresponding to the MPPT power as input, and then output the d-axis current setpoint to the current loop. The current loop is adapted to take the dq-axis current component of the phase current and the dq-axis current setpoint as inputs, and the output of the current loop is modulated to obtain the drive signal for controlling the first DC / AC unit; wherein, the q-axis current setpoint is zero.

3. The inverter architecture with power factor regulation function as described in claim 1, characterized in that, The control loop of the second DC / AC unit also includes a reactive power loop as an outer loop and a current loop as an inner loop; The reactive power loop is suitable for taking reactive power commands and reactive power as inputs, and then inputting the q-axis current setpoint to the current loop; The current loop is adapted to take the dq-axis current component of the phase current and the dq-axis current setpoint as inputs, and the output of the current loop is modulated to obtain the drive signal for controlling the second DC / AC unit; wherein, the d-axis current setpoint is zero.

4. The inverter architecture with power factor regulation function as described in claim 1, characterized in that, For scenarios involving multiple inverters, the inverter architecture also includes a control module; The control module is communicatively connected to multiple inverters; the control module is adapted to collect power at the grid connection location and send corresponding reactive power commands to each inverter based on the collected data.

5. The inverter architecture with power factor regulation function as described in claim 4, characterized in that, The control module includes a networking unit, a CPU unit, and a power acquisition unit that are electrically connected in sequence. The power acquisition unit is adapted to acquire power at the grid-connected location. The CPU unit is adapted to receive the power data acquired by the acquisition unit and generate reactive power commands corresponding to each inverter. The networking unit is adapted to send the reactive power commands generated by the CPU unit to each inverter.

6. The inverter architecture with power factor regulation function as described in claim 4, characterized in that, The control module generates reactive power commands through the following process: The total reactive power required is calculated based on the power collected at the grid connection location; the calculated total reactive power is divided by the total number of inverters to obtain the reactive power command corresponding to each inverter.

7. The inverter architecture with power factor regulation function as described in claim 6, characterized in that, The control module generates reactive power commands through the following process: Calculate the required total reactive power Q based on the power collected at the grid connection location; Set priority #1 to #N for all N inverters; Let Q be the upper limit of reactive power output from each inverter. max ; If the total reactive power Q satisfies: (k-1)Q max ≤Q<kQ max A reactive power command is sent to the inverters with priorities #1 to #k, and the reactive power command for each of the k inverters is Q / k; where k≤N.

8. The inverter architecture with power factor regulation function as described in claim 7, characterized in that, The priority of the N inverters is adapted to be rotated in reverse order at set intervals, with the priority change being at least one level each time.

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