Photovoltaic inverter and photovoltaic power generation system

Abstract

The utility model provides a photovoltaic inverter and a photovoltaic power generation system. The photovoltaic inverter comprises an MPPT circuit, a bus capacitor module, an inverter circuit, a power grid side switch, a temperature sensor and a controller. The input end of the MPPT circuit is connected with a photovoltaic module, the output end of the MPPT circuit is connected with the input end of the bus capacitor module, the output end of the bus capacitor module is connected with the input end of the inverter circuit, and the output end of the inverter circuit is connected with a power grid through a power grid side switch; the MPPT circuit is used for adjusting the output voltage of the photovoltaic module so as to track the maximum power working point of the photovoltaic module during normal working; the inverter circuit is used for converting direct current into alternating current; and the temperature sensor is used for detecting the temperature of the bus capacitor module, so that the controller controls the on or off of the power grid side switch according to the temperature of the bus capacitor module. The heat condition of the bus capacitor module is monitored through the temperature sensor, and temperature data is fed back in real time, so that the working condition of the inverter is regulated and controlled, and power grid resonance is weakened or avoided.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic power generation technology, and in particular to a photovoltaic inverter and a photovoltaic power generation system. Background Art

[0002] With the development of the photovoltaic industry, the number of photovoltaic grid-connected inverters has continued to increase, increasing the complexity of the power grid and causing more inverter resonance problems. The resonance of the power grid also threatens the safety of electrical equipment. How to effectively suppress or weaken the resonance is an issue that needs to be urgently addressed. Utility Model Content

[0003] The present application provides a photovoltaic inverter and a photovoltaic power generation system to accurately identify whether a photovoltaic inverter resonates, and to suppress or weaken the resonance when the photovoltaic inverter resonates.

[0004] On one hand, the present application provides a photovoltaic inverter, including: an MPPT circuit, a bus capacitor module, an inverter circuit, a grid-side switch, a temperature sensor, and a controller;

[0005] The input end of the MPPT circuit is connected to the photovoltaic module, the output end of the MPPT circuit is connected to the input end of the bus capacitor module, the output end of the bus capacitor module is connected to the input end of the inverter circuit, and the output end of the inverter circuit is connected to the grid through the grid-side switch;

[0006] The MPPT circuit is used to adjust the output voltage of the photovoltaic module to track the maximum power operating point of the photovoltaic module during normal operation; the inverter circuit is used to convert direct current into alternating current;

[0007] The temperature sensor is used to detect the temperature of the bus capacitor module, so that the controller controls the on or off of the grid-side switch according to the temperature of the bus capacitor module.

[0008] In one example, the bus capacitor module includes a PCB board, and a bus capacitor and a filter inductor are arranged on the PCB.

[0009] In one example, the temperature sensor is disposed on the PCB, or on the bus capacitor, or on the filter inductor.

[0010] In one example, the temperature sensor is disposed on the PCB or on the bus capacitor or on the filter inductor by means of an adhesive or structural fixing method.

[0011] In one example, the filter inductor includes a first filter inductor and a second filter inductor, and the bus capacitor includes a first bus capacitor and a second bus capacitor;

[0012] The first filter inductor is arranged on the positive DC bus, one end of the first filter inductor is connected to the output end of the MPPT circuit, and the other end of the first filter inductor is connected to the input end of the inverter circuit;

[0013] The second filter inductor is arranged on the negative DC bus, one end of the second filter inductor is connected to the output end of the MPPT circuit, and the other end of the second filter inductor is connected to the input end of the inverter circuit;

[0014] One end of the first bus capacitor is connected to the positive DC bus, and the other end of the first bus capacitor is connected to the neutral line; one end of the second bus capacitor is connected to the negative DC bus, and the other end of the second bus capacitor is connected to the neutral line.

[0015] In one example, the temperature sensor includes at least one of a temperature switch, a negative temperature coefficient (NTC) sensor, and an optical fiber.

[0016] In one example, a DC side switch is also provided at the output end of the MPPT circuit and the input end of the bus capacitor module;

[0017] The controller is further configured to control the on or off of the DC side switch according to the temperature of the bus capacitor module.

[0018] On the other hand, the present application provides a photovoltaic power generation system, which includes a photovoltaic component and the photovoltaic inverter, wherein the output port of the photovoltaic component is connected to the input port of the photovoltaic inverter, and the output port of the photovoltaic inverter is connected to a power grid. The photovoltaic component is used to generate direct current, and the photovoltaic inverter is used to invert the direct current and input the alternating current obtained by the inversion process into the power grid.

[0019] The photovoltaic inverter and photovoltaic power generation system provided in the present application monitor the thermal condition of the bus capacitor module through a temperature sensor and provide real-time feedback of temperature data, thereby regulating the working condition of the inverter and further weakening or avoiding grid resonance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0021] Figure 1 is a schematic diagram of a photovoltaic inverter provided in an embodiment of the present application;

[0022] Figure 2 It is another schematic diagram of a photovoltaic inverter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the present application. The terms used in this specification in the specification of the present application are only for the purpose of describing specific embodiments and are not used to limit the present application. The term "and / or" used in this specification includes any and all combinations of one or more related listed items.

[0024] like Figure 1 As shown, a photovoltaic inverter provided in an embodiment of the present application includes an MPPT circuit, a bus capacitor module T1, an inverter circuit, a grid-side switch K1, a temperature sensor J1, and a controller;

[0025] The input end of the MPPT circuit is connected to a photovoltaic module (not shown in the figure), the output end of the MPPT circuit is connected to the input end of the bus capacitor module T1, the output end of the bus capacitor module T1 is connected to the input end of the inverter circuit, and the output end of the inverter circuit is connected to the grid through the grid-side switch K1;

[0026] The MPPT circuit is used to adjust the output voltage of the photovoltaic module to track the maximum power operating point of the photovoltaic module during normal operation; the inverter circuit is used to convert direct current into alternating current;

[0027] The temperature sensor J1 is used to detect the temperature of the bus capacitor module T1, so that the controller controls the on or off of the grid-side switch K1 according to the temperature of the bus capacitor module T1.

[0028] In one example, the bus capacitor module T1 includes a PCB board, a bus capacitor and a filter inductor arranged on the PCB. The temperature sensor J1 is arranged on the filter inductor (the filter inductor L2 in the figure, and may also be arranged on the filter inductor L1 in other examples).

[0029] In one example, the temperature sensor J1 is disposed on the filter inductor by adhesive or structural fixing.

[0030] Exemplarily, the adhesive may be epoxy resin, polyethylene glue, acrylic polyurethane, ultraviolet rays (UV) glue and other high temperature resistant glues, or the adhesive may be a mixture of at least one of the above epoxy resin, polyethylene glue, acrylic polyurethane and UV glue.

[0031] Exemplarily, the temperature sensor J1 may be held on the filter inductor by a holding structure.

[0032] In one example, the filter inductor includes a first filter inductor L1 and a second filter inductor L2, and the bus capacitor includes a first bus capacitor C1 and a second bus capacitor C2; the first bus capacitor C1 and the second bus capacitor C2 can be composed of multiple bus capacitors connected in series and / or in parallel.

[0033] The first filter inductor L1 is arranged on the positive DC bus, one end of the first filter inductor L1 is connected to the output end of the MPPT circuit, and the other end of the first filter inductor L1 is connected to the input end of the inverter circuit;

[0034] The second filter inductor L2 is arranged on the negative DC bus, one end of the second filter inductor L2 is connected to the output end of the MPPT circuit, and the other end of the second filter inductor L2 is connected to the input end of the inverter circuit;

[0035] One end of the first bus capacitor C1 is connected to the positive DC bus, and the other end of the first bus capacitor C1 is connected to the neutral line; one end of the second bus capacitor C2 is connected to the negative DC bus, and the other end of the second bus capacitor C2 is connected to the neutral line.

[0036] In one example, the temperature sensor J1 includes at least one of a temperature switch, a negative temperature coefficient (NTC) sensor, and an optical fiber.

[0037] In a specific implementation, when the temperature sensor J1 is a negative temperature coefficient NTC sensor or an optical fiber, the temperature sensor J1 transmits data to the controller. When the data received by the controller is greater than a set threshold, the grid-side switch K1 is controlled to be disconnected; when the data received by the controller is less than or equal to the set threshold, the grid-side switch K1 is controlled to be turned on.

[0038] When the temperature sensor J1 is a temperature switch, when the controller senses that the temperature switch has a signal jump, the controller controls the grid-side switch K1 to be disconnected; when the controller senses that the temperature switch has a signal that returns to an initial state, the controller controls the grid-side switch K1 to be turned on.

[0039] Figure 2 is another schematic diagram of a photovoltaic inverter provided in an embodiment of the present application. Figure 1 The difference from the example is that the temperature sensor J1 is arranged on the bus capacitor (in the figure, it is the bus capacitor C2, in other examples, it can also be arranged on the bus capacitor C1). Figure 1 Similarly, the temperature sensor J1 can be disposed on the bus capacitor by adhesive or structural fixing.

[0040] and Figure 1 The difference is that a DC side switch K2 is further provided between the output end of the MPPT circuit and the input end of the bus capacitor module T1. The controller can also control the on or off of the DC side switch K2 according to the temperature of the bus capacitor module T1.

[0041] It should be noted that Figure 1 or Figure 2 The difference from the example is that the temperature sensor J1 is arranged on the PCB, which is also feasible. Similar to the above, the temperature sensor J1 can be arranged on the PCB by means of adhesive or structural fixing.

[0042] It should be noted that the preferred embodiments of the present application are given in the specification and drawings of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described in the specification. These embodiments are not used as additional limitations on the content of the present application. The purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. In addition, the above-mentioned technical features continue to be combined with each other to form various embodiments not listed above, which are all regarded as the scope of the description of the present application; further, for ordinary technicians in this field, they can be improved or transformed according to the above description, and all these improvements and transformations should belong to the scope of protection of the claims attached to the present application.

Claims

1. A photovoltaic inverter, characterized in that: include: MPPT circuit, bus capacitor module, inverter circuit, grid-side switch, temperature sensor and controller; The input end of the MPPT circuit is connected to the photovoltaic module, the output end of the MPPT circuit is connected to the input end of the bus capacitor module, the output end of the bus capacitor module is connected to the input end of the inverter circuit, and the output end of the inverter circuit is connected to the grid through the grid-side switch; The MPPT circuit is used to adjust the output voltage of the photovoltaic module to track the maximum power operating point of the photovoltaic module during normal operation; the inverter circuit is used to convert direct current into alternating current; The temperature sensor is used to detect the temperature of the bus capacitor module, so that the controller controls the on or off of the grid-side switch according to the temperature of the bus capacitor module.

2. The photovoltaic inverter as claimed in claim 1, characterized in that: The busbar capacitor module includes a PCB board, a busbar capacitor and a filter inductor arranged on the PCB.

3. The photovoltaic inverter as claimed in claim 2, characterized in that: The temperature sensor is arranged on the PCB, or on the bus capacitor, or on the filter inductor.

4. The photovoltaic inverter as claimed in claim 3, characterized in that: The temperature sensor is arranged on the PCB or on the bus capacitor or on the filter inductor by means of an adhesive or a structural fixing method.

5. The photovoltaic inverter as claimed in claim 2, characterized in that: The filter inductor includes a first filter inductor and a second filter inductor, and the bus capacitor includes a first bus capacitor and a second bus capacitor; The first filter inductor is arranged on the positive DC bus, one end of the first filter inductor is connected to the output end of the MPPT circuit, and the other end of the first filter inductor is connected to the input end of the inverter circuit; The second filter inductor is arranged on the negative DC bus, one end of the second filter inductor is connected to the output end of the MPPT circuit, and the other end of the second filter inductor is connected to the input end of the inverter circuit; One end of the first bus capacitor is connected to the positive DC bus, and the other end of the first bus capacitor is connected to the neutral line; one end of the second bus capacitor is connected to the negative DC bus, and the other end of the second bus capacitor is connected to the neutral line.

6. The photovoltaic inverter as claimed in claim 1, characterized in that: The temperature sensor includes at least one of a temperature switch, a negative temperature coefficient (NTC) sensor, and an optical fiber.

7. The photovoltaic inverter as claimed in claim 1, characterized in that: A DC side switch is also provided at the output end of the MPPT circuit and the input end of the bus capacitor module; The controller is further configured to control the on or off of the DC side switch according to the temperature of the bus capacitor module.

8. A photovoltaic power generation system, characterized in that: The system includes a photovoltaic component and a photovoltaic inverter according to any one of claims 1 to 7, wherein the output port of the photovoltaic component is connected to the input port of the photovoltaic inverter, the output port of the photovoltaic inverter is connected to a power grid, the photovoltaic component is used to generate direct current, the photovoltaic inverter is used to invert the direct current, and input the alternating current obtained by the inversion process into the power grid.

Images