Photovoltaic inverter system and photovoltaic energy storage device
By introducing impedance balanced resistors into the photovoltaic inverter and determining the resistance value using the voltage divider resistor, the problem of static impedance imbalance in the photovoltaic inverter is solved, and a low-cost static impedance balance is achieved without affecting the working efficiency of the equipment.
Patent Information
- Application Number
- CN202422104186.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-28
- Publication Date
- 2025-06-27
- Estimated Expiration
- 2034-08-28
AI Technical Summary
The multiple access to the MPPT function in the photovoltaic inverter leads to the static impedance imbalance of the positive and negative DC buses, causing voltage deviations, and affecting the normal operation of the photovoltaic inverter.
An impedance balance resistor is introduced between the positive end of the busbar of the photovoltaic inverter and the controlled ground, and the resistance value is determined by setting a voltage divider resistor to achieve static impedance balance.
The static impedance balance of the photovoltaic inverter is realized, which reduces the cost and does not affect the working efficiency of the photovoltaic inverter.
Smart Images
Figure CN223039656U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of photovoltaic inverters, and particularly relates to a photovoltaic inverter system and a photovoltaic energy storage device. Background Art
[0002] With the increasing power of photovoltaic inverters, the access methods, types of photovoltaic modules are gradually increasing. In actual use, in order to enhance the adaptability of the photovoltaic inverter to each connected photovoltaic module, each path connected to the photovoltaic module in the photovoltaic inverter is connected with an MPPT (Maximum Power Point Tracking) function. However, the multi-path access to the MPPT function will cause the static impedance imbalance of the positive and negative DC buses (i.e., positive and negative BUS) of the photovoltaic inverter, thereby bringing voltage deviation and affecting the normal operation of the photovoltaic inverter.
[0003] Currently, it is common to balance the static impedance of the positive and negative DC buses of the photovoltaic inverter by adding more circuit components in the photovoltaic inverter or adding two high-cost and high-energy-consuming high-power resistors. This not only has a high implementation cost, but also reduces the working efficiency of the photovoltaic inverter. Summary of the Utility Model
[0004] The main purpose of the utility model is to provide a photovoltaic inverter system, aiming to achieve the static impedance balance of the photovoltaic inverter at low cost without affecting the working efficiency of the photovoltaic inverter.
[0005] To achieve the above purpose, the utility model proposes a photovoltaic inverter system, which includes:
[0006] A photovoltaic inverter;
[0007] Multiple MPPT branches, the photovoltaic inverter is connected to each MPPT branch;
[0008] An impedance balancing resistor, which is connected between the positive end of the bus of the photovoltaic inverter and the control ground to eliminate the impedance deviation existing in the photovoltaic inverter.
[0009] In one embodiment, a voltage dividing resistor is arranged on each MPPT branch to determine the resistance value of the impedance balancing resistor.
[0010] In one embodiment, the resistance values of all the voltage dividing resistors are the same.
[0011] In one embodiment, the photovoltaic inverter system further includes a plurality of rectification modules, and the number of the rectification modules is the same as the number of the MPPT branches;
[0012] One end of the rectification module is connected to the MPPT branch, and the other end of the rectification module is connected to the positive terminal of the bus of the PV inverter.
[0013] In one embodiment, the rectification module is a diode;
[0014] The anode of the diode is connected to the MPPT branch, and the cathode of the diode is connected to the positive terminal of the bus of the PV inverter.
[0015] In one embodiment, the PV inverter system further includes a plurality of branch discharge modules, and the number of the branch discharge modules is the same as the number of the MPPT branches;
[0016] One end of the branch discharge module is connected to the MPPT branch, and the other end of the branch discharge module is connected to the power ground.
[0017] In one embodiment, the branch discharge module is a branch discharge resistor.
[0018] In one embodiment, the PV inverter system further includes a bus capacitor discharge module;
[0019] The first end of the bus capacitor discharge module is connected to the positive terminal of the bus of the PV inverter, the second end of the bus capacitor discharge module is connected to the bus capacitor of the PV inverter, and the third end of the bus capacitor discharge module is connected to the power ground.
[0020] In one embodiment, the bus capacitor discharge module includes a first discharge resistor and a second discharge resistor;
[0021] One end of the first discharge resistor is connected to the positive terminal of the bus of the PV inverter, the other end of the first discharge resistor is connected to one end of the second discharge resistor and the bus capacitor of the PV inverter, and the other end of the second discharge resistor is connected to the power ground.
[0022] In addition, to achieve the above object, the present invention further provides a PV energy storage device, and the PV energy storage device includes the above PV inverter system.
[0023] The present invention provides a PV inverter system, which includes a PV inverter, various MPPT branches connected to the PV inverter, and an impedance balancing resistor connected between the positive terminal of the bus of the PV inverter and the control ground; since the resistance value of the impedance balancing resistor is the target resistance value, and the target resistance value is the resistance value required for the impedance balancing resistor to eliminate the impedance deviation existing in the PV inverter, so by using the impedance balancing resistor with the resistance value of the target resistance value, the impedance deviation existing in the PV inverter can be eliminated to achieve the static impedance balance of the PV inverter.
[0024] Therefore, the present utility model only needs to set an impedance balancing resistor with a suitable resistance value in the photovoltaic inverter to balance the static impedance of the photovoltaic inverter. Compared with the conventional method of using too many circuit components or using two high-cost and high-energy-consuming high-power resistors to balance the static impedance of the photovoltaic inverter, the present utility model not only has a low cost for realizing the static impedance balance of the photovoltaic inverter, but also does not affect the working efficiency of the photovoltaic inverter. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following-described drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.
[0026] Figure 1 FIG. is a schematic circuit diagram of a conventional structure for realizing the static impedance balance of a photovoltaic inverter provided by an embodiment of the present utility model;
[0027] Figure 2 FIG. is another schematic circuit diagram of a conventional structure for realizing the static impedance balance of a photovoltaic inverter provided by an embodiment of the present utility model;
[0028] Figure 3 FIG. is a schematic structural diagram of a photovoltaic inverter system provided by the first embodiment of the present utility model;
[0029] Figure 4 FIG. is a schematic structural diagram of a photovoltaic inverter system when voltage-dividing resistors are provided on each MPPT branch provided by the first embodiment of the present utility model;
[0030] Figure 5 FIG. is a schematic structural diagram of a photovoltaic inverter system provided by the second embodiment of the present utility model;
[0031] Figure 6 FIG. is a schematic structural diagram of a photovoltaic inverter system provided by the third embodiment of the present utility model;
[0032] Figure 7 FIG. is a schematic structural diagram of a photovoltaic inverter system provided by the fourth embodiment of the present utility model;
[0033] Figure 8 FIG. is a schematic structural diagram of a photovoltaic inverter system after combining the embodiments provided by the present utility model.
[0034] The realization of the object, functional features, and advantages of the present utility model will be further described in conjunction with the embodiments and with reference to the drawings.
[0035] Description of the attached reference numerals:
[0036] 10. Photovoltaic inverter; 20. Rectification module; 30. Branch discharge module; 40. Bus capacitor discharge module; PV1 - PVn. MPPT branches; Rx. Impedance balancing resistor; Ra. Voltage dividing resistor; Rb1 - Rb3. Branch discharge resistors; D1 - D3. Diodes; R1. First discharge resistor; R2. Second discharge resistor; C1 - C2. Bus capacitors; GND. Control ground; GNDD. Power ground. Specific embodiments
[0037] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0039] It should be noted that the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of the technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.
[0040] As the power of the photovoltaic inverter is getting larger and larger, the ways, methods, and types of photovoltaic module access are gradually increasing. In actual use, in order to enhance the adaptability of the photovoltaic inverter to each connected photovoltaic module, the MPPT function is connected to each path of the photovoltaic inverter where the photovoltaic module is connected. However, the multi-path access of the MPPT function will cause the static impedance imbalance of the positive and negative DC buses (i.e., positive and negative BUS) of the photovoltaic inverter, thereby bringing voltage deviation and affecting the normal operation of the photovoltaic inverter.
[0041] Currently, circuits such as Figure 1 shown or circuits such as Figure 2 shown are often used to balance the static impedance of the positive and negative DC buses of the photovoltaic inverter. However, Figure 1 the circuit shown requires the use of multiple circuit components to balance the static impedance, and its implementation cost is relatively high;Figure 2 The shown circuit needs to use two high-power resistors to balance the static impedance. However, high-power resistors have a high cost and consume more energy. Therefore, not only is its implementation cost high, but it also reduces the working efficiency of the photovoltaic inverter.
[0042] Based on this, the present utility model provides a photovoltaic inverter system. In the first embodiment of the present utility model, please refer to Figure 3 , the photovoltaic inverter system may include a photovoltaic inverter 10, multiple MPPT branches PV1 - PVn, and an impedance balancing resistor Rx; the photovoltaic inverter 10 is connected to each MPPT branch PV1 - PVn, and the impedance balancing resistor Rx is connected between the positive bus terminal of the photovoltaic inverter 10 and the control ground GND; wherein, the resistance value of the impedance balancing resistor Rx is the target resistance value, used to eliminate the impedance deviation existing in the photovoltaic inverter 10.
[0043] It should be noted that the MPPT branch refers to the control channel with the MPPT function accessed. The target resistance value refers to the resistance value that the impedance balancing resistor Rx needs to reach to eliminate the impedance deviation existing in the photovoltaic inverter 10. The impedance balancing resistor Rx is a resistor with a fixed resistance value of the target resistance value, not a resistor with a variable resistance value. The target resistance value can be determined according to the design specifications of each MPPT branch PV1 - PVn.
[0044] In a feasible implementation manner, in order to be able to determine the target resistance value using the design specifications of each MPPT branch PV1 - PVn, please refer to Figure 4 , a voltage-dividing resistor Ra needs to be set on each of the MPPT branches PV1 - PVn, so as to determine the target resistance value by using the resistance value of the voltage-dividing resistor Ra and the input voltage range of each MPPT branch PV1 - PVn.
[0045] It should be noted that in the process of determining the target resistance value by using the resistance value of the voltage-dividing resistor Ra and the input voltage range of each MPPT branch PV1 - PVn, each MPPT branch PV1 - PVn can first select an input voltage value from its respective input voltage range as the target voltage value, or directly use the voltage-dividing resistor Ra to collect the input voltage value of each MPPT branch PV1 - PVn under the static working condition of the photovoltaic inverter 10 as the target voltage value; then substitute the target voltage values of each MPPT branch PV1 - PVn and the resistance value of the voltage-dividing resistor Ra into the following formula to achieve the determination of the target resistance value. Generally speaking, the input voltage ranges of each MPPT branch PV1 - PVn are the same, for example, they can all be 450 - 820V; the resistance values of the voltage-dividing resistors Ra on each MPPT branch PV1 - PVn are also the same.
[0046]
[0047] Wherein, X(Vpv1,..., Vpvn) is the target resistance value, Vpv1 is the maximum voltage value among the target voltage values, Vpv2 to Vpvn are the other target voltage values except the maximum voltage value among the target voltage values respectively, and R is the resistance value of the voltage-dividing resistor Ra.
[0048] This embodiment provides a photovoltaic inverter system, which includes a photovoltaic inverter 10, each MPPT branch PV1 to PVn connected to the photovoltaic inverter 10, and an impedance balancing resistor Rx connected between the positive bus terminal of the photovoltaic inverter 10 and the control ground GND; since the resistance value of the impedance balancing resistor Rx is the target resistance value, and the target resistance value is the resistance value that the impedance balancing resistor Rx needs to reach to eliminate the impedance deviation existing in the photovoltaic inverter 10, so by using the impedance balancing resistor Rx with the resistance value of the target resistance value, the impedance deviation existing in the photovoltaic inverter 10 can be eliminated to achieve the static impedance balance of the photovoltaic inverter 10.
[0049] Therefore, in this embodiment, only an impedance balancing resistor Rx with a suitable resistance value needs to be set in the photovoltaic inverter 10 to balance the static impedance of the photovoltaic inverter 10. Compared with the conventional method of using too many circuit components or using two high-cost and high-energy-consuming high-power resistors to balance the static impedance of the photovoltaic inverter 10, this embodiment not only has a low cost for achieving the static impedance balance of the photovoltaic inverter 10, but also does not affect the working efficiency of the photovoltaic inverter 10.
[0050] Based on the above first embodiment, a second embodiment of the photovoltaic inverter system of the present utility model is proposed. In the second embodiment of the present utility model, please refer to Figure 5 , the photovoltaic inverter system may further include a plurality of rectification modules 20, and the number of the rectification modules 20 is the same as the number of MPPT branches; one end of the rectification module 20 is connected to the MPPT branch, and the other end of the rectification module 20 is connected to the positive bus terminal of the photovoltaic inverter 10.
[0051] In a feasible implementation manner, the rectification module may be a diode, the anode of the diode is connected to the MPPT branch, and the cathode of the diode is connected to the positive bus terminal of the photovoltaic inverter 10.
[0052] This embodiment improves the stability of the photovoltaic inverter system by setting a rectification module 20 between the MPPT branch and the positive bus terminal of the photovoltaic inverter 10 to prevent the current from flowing back to the MPPT branch and reducing the fluctuations caused by abnormal current direction in the photovoltaic inverter system.
[0053] Based on the above first embodiment and / or second embodiment, a third embodiment of the photovoltaic inverter system of the present invention is proposed. In the third embodiment of the present invention, please refer to Figure 6 , the photovoltaic inverter system may further include a plurality of branch discharge modules 30, and the number of the branch discharge modules 30 is the same as the number of MPPT branches; one end of the branch discharge module 30 is connected to the MPPT branch, and the other end of the branch discharge module 30 is connected to the power ground GNDD.
[0054] In a feasible implementation manner, the branch discharge module 30 may be a branch discharge resistor.
[0055] In this embodiment, by setting the branch discharge module 30 between the MPPT branch and the power ground GNDD, the discharge of the MPPT branch is realized, so as to prevent the unconsumed electric energy in the MPPT branch from flowing back into the photovoltaic inverter 10 and causing equipment damage.
[0056] Based on the above first embodiment, second embodiment and / or third embodiment, a fourth embodiment of the photovoltaic inverter system of the present invention is proposed. In the fourth embodiment of the present invention, please refer to Figure 7 , the photovoltaic inverter system may further include a bus capacitor discharge module 40; the first end of the bus capacitor discharge module 40 is connected to the positive bus terminal of the photovoltaic inverter 10, the second end of the bus capacitor discharge module 40 is connected to the bus capacitor of the photovoltaic inverter 10, and the third end of the bus capacitor discharge module 40 is connected to the power ground GNDD.
[0057] In a feasible implementation manner, the bus capacitor discharge module 40 may include a first discharge resistor and a second discharge resistor; one end of the first discharge resistor is connected to the positive bus terminal of the photovoltaic inverter 10, the other end of the first discharge resistor is connected to one end of the second discharge resistor and the bus capacitor of the photovoltaic inverter 10, and the other end of the second discharge resistor is connected to the negative bus terminal of the photovoltaic inverter 10.
[0058] In this embodiment, by setting the bus capacitor discharge module 40, the discharge of the bus capacitor of the photovoltaic inverter 10 is realized, so as to prevent the photovoltaic inverter 10 from causing an electric shock risk to maintenance personnel due to the residual charge in its internal bus capacitor after power-off, ensuring personal safety; and it can also prevent the photovoltaic inverter 10 from being affected by thermal stress due to the residual charge in its internal bus capacitor, thereby extending the service life of the photovoltaic inverter 10.
[0059] It should be noted that the rectification module 20, branch discharge module 30, and bus capacitor discharge module 40 mentioned in the above embodiments can all be flexibly set according to actual situations. Exemplarily, assuming that the rectification module 20 is a diode, the branch discharge module 30 is a branch discharge resistor, and the bus capacitor discharge module 40 includes a first discharge resistor and a second discharge resistor, taking the photovoltaic inverter system including three MPPT branches as an example, the following can be obtained as Figure 8 the structural schematic diagram of the photovoltaic inverter system shown.
[0060] Among them, D1 to D3 in the figure represent each diode, Rb1 to Rb3 represent each branch discharge resistor, R1 represents the first discharge resistor, R2 represents the second discharge resistor, and C1 and C2 represent two bus capacitors of the photovoltaic inverter 10.
[0061] The above examples are only used to assist in understanding the present invention and do not constitute a limitation to the photovoltaic inverter system of the present invention. Based on this technical concept, more forms of simple transformation are within the protection scope of the present invention.
[0062] The present invention also provides a photovoltaic energy storage device, which includes the above photovoltaic inverter system. The structure of the photovoltaic inverter system can refer to the above embodiments and will not be elaborated here. Naturally, since the photovoltaic energy storage device of this embodiment includes all the technical solutions of all the above embodiments of the photovoltaic inverter system and the achieved technical effects are exactly the same, they will not be elaborated here.
[0063] The above are only the preferred embodiments of the present invention and do not limit the patent scope of the present invention accordingly. Any equivalent structural or equivalent process transformation made by using the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are similarly included in the patent protection scope of the present invention.
Claims
1. A photovoltaic inverter system, characterized in that: The photovoltaic inverter system comprises: Photovoltaic inverter; Multiple MPPT branches, the photovoltaic inverter is connected to each MPPT branch; An impedance balancing resistor is connected between the positive end of the busbar of the photovoltaic inverter and a control ground, and the resistance value of the impedance balancing resistor is a target resistance value, so as to eliminate the impedance deviation of the photovoltaic inverter.
2. The photovoltaic inverter system according to claim 1, characterized in that: Each MPPT branch is provided with a voltage dividing resistor to determine the resistance value of the impedance balancing resistor.
3. The photovoltaic inverter system according to claim 2, characterized in that: The resistance values of the voltage-dividing resistors are all the same.
4. The photovoltaic inverter system according to any one of claims 1 to 3, characterized in that: The photovoltaic inverter system further includes a plurality of rectifier modules, the number of the rectifier modules being the same as the number of the MPPT branches; One end of the rectifier module is connected to the MPPT branch, and the other end of the rectifier module is connected to the positive end of the busbar of the photovoltaic inverter.
5. The photovoltaic inverter system according to claim 4, characterized in that: The rectifier module is a diode; The anode of the diode is connected to the MPPT branch, and the cathode of the diode is connected to the positive end of the busbar of the photovoltaic inverter.
6. The photovoltaic inverter system according to any one of claims 1 to 3, characterized in that: The photovoltaic inverter system further includes a plurality of branch discharge modules, the number of the branch discharge modules being the same as the number of the MPPT branches; One end of the branch discharge module is connected to the MPPT branch, and the other end of the branch discharge module is connected to the power ground.
7. The photovoltaic inverter system according to claim 6, characterized in that: The branch discharge module is a branch discharge resistor.
8. The photovoltaic inverter system according to any one of claims 1 to 3, characterized in that: The photovoltaic inverter system also includes a bus capacitor discharge module; The first end of the bus capacitor discharge module is connected to the bus positive end of the photovoltaic inverter, the second end of the bus capacitor discharge module is connected to the bus capacitor of the photovoltaic inverter, and the third end of the bus capacitor discharge module is connected to the power ground.
9. The photovoltaic inverter system according to claim 8, characterized in that: The busbar capacitor discharge module includes a first discharge resistor and a second discharge resistor; One end of the first discharge resistor is connected to the positive end of the busbar of the photovoltaic inverter, the other end of the first discharge resistor is connected to one end of the second discharge resistor and the busbar capacitor of the photovoltaic inverter, and the other end of the second discharge resistor is connected to the power ground.
10. A photovoltaic energy storage device, characterized in that: The photovoltaic energy storage device comprises a photovoltaic inverter system as claimed in any one of claims 1 to 9.