Photovoltaic anti-reflux device

Abstract

The invention relates to the technical field of photovoltaic power supply, in particular to a photovoltaic countercurrent prevention device. The photovoltaic countercurrent prevention device comprises an acquisition circuit which is used for acquiring load power at a load circuit; the booster circuit is used for boosting the electric energy at the photovoltaic module and outputting the boosted electric energy; the main control circuit is used for generating a driving signal based on the load power; and a DSP circuit for converting the driving signal into a DSP signal for driving the boost circuit. According to the invention, the load power of the load can be monitored at the load circuit in real time in the photovoltaic power generation system, and the boost circuit is driven to work based on the load power, so that the output power of the photovoltaic module can be adjusted to be not higher than the load power in real time, and the occurrence of a'countercurrent 'phenomenon can be better avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power supply, and in particular to a photovoltaic backflow prevention device. Background Art

[0002] In the power system, electricity is generally sent from the grid to the user load, which is called forward current. However, in the photovoltaic system, when the power of the photovoltaic system is greater than the power of the local load, the unabsorbed electric energy will be sent to the grid. Since the flow direction of this energy is opposite to the normal direction of the grid system, it is called "reverse flow". "Reverse flow" has the following adverse effects: (1) The reverse flow will send the generated electricity to the public grid, which will cause harmonic pollution to the grid and easily cause grid voltage fluctuations and flicker. If there are many such power generation sources transmitting electricity to the grid, it will cause a serious decline in the quality of grid power; (2) Reverse flow may cause damage to other equipment in the grid, especially when the wires are old or the system stability is insufficient.

[0003] At present, general backflow prevention technology requires real-time acquisition of the voltage, current and real-time power of the inverter at the switch, and complex calculations and judgments to achieve dynamic closed-loop regulation. This technology is relatively complex to implement and has high requirements for equipment and systems. Efficient and reliable backflow prevention technology often requires the use of advanced equipment and systems, which may increase costs. Summary of the invention

[0004] The present invention provides a photovoltaic backflow prevention device, which can overcome certain defects of the prior art.

[0005] A photovoltaic backflow prevention device according to the present invention comprises:

[0006] A collection circuit, which is used to collect load power at the load circuit;

[0007] A boost circuit is used to boost and output the electric energy at the photovoltaic module; wherein the electric energy generated by the photovoltaic module is sequentially supplied to the load circuit through the boost circuit, the rectifier circuit and the inverter circuit;

[0008] a main control circuit for generating a driving signal based on load power; and

[0009] A DSP circuit is used to convert a driving signal into a DSP signal for driving a boost circuit; wherein the boost circuit is constructed based on a MOS tube, and the DSP signal is used to keep the power output of the boost circuit not higher than the load power.

[0010] Based on the above, the load power of the load can be monitored in real time at the load circuit in the photovoltaic power generation system. By driving the boost circuit based on the load power, the output power of the photovoltaic module can be adjusted in real time to not be higher than the load power, thereby better preventing the occurrence of "reverse current" phenomenon.

[0011] The boost circuit can adopt a conventional boost circuit constructed based on, for example, 8 MOS tubes, the rectifier circuit can adopt a conventional rectifier circuit constructed based on, for example, 8 common-cathode and common-anode diodes, and the inverter circuit can adopt an H-bridge circuit.

[0012] Preferably, the acquisition circuit includes:

[0013] A sampling circuit, which is used to collect the voltage value and current value of the load circuit and to output a load power signal;

[0014] A processing circuit, which is used to process the load power signal to obtain a communication signal;

[0015] A communication circuit, which is used to transmit the communication signal to the main control circuit; and

[0016] The power supply circuit is used to supply power to the sampling circuit, the processing circuit and the communication circuit.

[0017] Based on the above, real-time collection of load power can be better achieved.

[0018] Preferably, the sampling circuit includes a power collection chip, which is used to collect current signals and voltage signals at the load circuit and output a load power signal, so that the load power can be collected better.

[0019] Preferably, the processing circuit includes a processing chip, so that the processing of the relevant signals can be better realized.

[0020] Preferably, the communication circuit includes a 485 chip, so that data communication can be better achieved.

[0021] Preferably, the power supply circuit includes an AC-DC chip, so that a DC power supply voltage can be outputted preferably.

[0022] In the present invention, the acquisition circuit can be integrated into an acquisition device, so it is easy to implement.

[0023] Preferably, a sampling interface for accessing a current / voltage transformer can be formed at the sampling circuit, so that the current signal and the voltage signal at the load circuit can be collected better.

[0024] Preferably, a communication interface can be formed at the communication circuit, thereby facilitating signal transmission.

[0025] Preferably, a power interface can be formed at the power supply circuit, so as to facilitate the access of the power supply.

[0026] In addition, a photovoltaic backflow prevention device of the present invention can also include a switch circuit arranged in series between the photovoltaic module and the load circuit, and the switch circuit is used to accept the control of the main control circuit to disconnect when the load power is zero. This makes it possible to keep the photovoltaic module and the load circuit in a disconnected state when the load circuit does not use electrical energy, thereby effectively preventing current backflow. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a system block diagram of a photovoltaic backflow prevention device in Example 1;

[0028] Figure 2 is a system block diagram of the acquisition circuit in Example 1;

[0029] Figure 3 is an electrical schematic diagram of the sampling circuit in Example 1;

[0030] Figure 4 is an electrical schematic diagram of the processing circuit in Example 1;

[0031] Figure 5 is an electrical schematic diagram of the communication circuit in Example 1;

[0032] Figure 6 This is the electrical schematic diagram of the power supply circuit in Example 1. DETAILED DESCRIPTION

[0033] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with the embodiments. It should be understood that the embodiments are only for explaining the present invention and are not intended to limit it.

[0034] Example 1

[0035] See Figure 1 , this embodiment provides a photovoltaic backflow prevention device, which includes:

[0036] A collection circuit, which is used to collect load power at the load circuit;

[0037] A boost circuit is used to boost and output the electric energy at the photovoltaic module; wherein the electric energy generated by the photovoltaic module is sequentially supplied to the load circuit through the boost circuit, the rectifier circuit and the inverter circuit;

[0038] a main control circuit for generating a driving signal based on load power; and

[0039] A DSP circuit is used to convert a driving signal into a DSP signal for driving a boost circuit; wherein the boost circuit is constructed based on a MOS tube, and the DSP signal is used to keep the power output of the boost circuit not higher than the load power.

[0040] Based on the above, the load power of the load can be monitored in real time at the load circuit in the photovoltaic power generation system. By driving the boost circuit based on the load power, the output power of the photovoltaic module can be adjusted in real time to not be higher than the load power, thereby better preventing the occurrence of "reverse current" phenomenon.

[0041] The boost circuit can adopt a conventional boost circuit constructed based on, for example, 8 MOS tubes, the rectifier circuit can adopt a conventional rectifier circuit constructed based on, for example, 8 common-cathode and common-anode diodes, and the inverter circuit can adopt an H-bridge circuit.

[0042] See Figure 2 , the acquisition circuit includes:

[0043] A sampling circuit, which is used to collect the voltage value and current value of the load circuit and to output a load power signal;

[0044] A processing circuit, which is used to process the load power signal to obtain a communication signal;

[0045] A communication circuit, which is used to transmit the communication signal to the main control circuit; and

[0046] The power supply circuit is used to supply power to the sampling circuit, the processing circuit and the communication circuit.

[0047] Based on the above, real-time collection of load power can be better achieved.

[0048] See Figure 3 The sampling circuit includes a power collection chip, which is used to collect current signals and voltage signals at the load circuit and output a load power signal. Therefore, the load power can be collected better.

[0049] See Figure 4 The processing circuit includes a processing chip. Therefore, the processing of the relevant signal can be better realized.

[0050] See Figure 5 The communication circuit includes a 485 chip. Therefore, data communication can be better achieved.

[0051] See Figure 6 The power supply circuit includes an AC-DC chip, so it can output a DC power supply voltage preferably.

[0052] In this embodiment, the acquisition circuit can be integrated into an acquisition device, so it is convenient to implement.

[0053] The sampling circuit can form a sampling interface CON6 for accessing the current / voltage transformer, so that the current signal and the voltage signal at the load circuit can be collected better.

[0054] Wherein, the communication circuit can form a communication interface CON5, so it is beneficial to signal transmission.

[0055] Wherein, a power interface CON4 can be formed at the power supply circuit, so it is convenient for the access of the power supply.

[0056] In addition, a photovoltaic backflow prevention device of this embodiment also includes a switch circuit arranged in series between the photovoltaic module and the load circuit, and the switch circuit is used to be disconnected under the control of the main control circuit when the load power is zero. This makes it possible to keep the photovoltaic module and the load circuit in a disconnected state when the load circuit does not use electrical energy, thereby effectively preventing current backflow.

[0057] When a photovoltaic backflow prevention device of the present embodiment is actually used, the acquisition circuit can be set at the load meter of the load circuit, so the total load power can be better acquired; after the acquisition circuit acquires the load power, the main control circuit can obtain a driving signal for driving the boost circuit based on the load power, and the driving signal can control the output power of the boost circuit in the form of a DSP signal, thereby effectively ensuring that the power output of the boost circuit is not higher than the load power; at the same time, when the load power is zero, the main control circuit can also control the switch circuit to cut off the electrical connection between the photovoltaic module and the load circuit.

[0058] As an illustration, the output power of the boost circuit implemented based on the MOS tube is related to the on and off time of the MOS tube. In this embodiment, the on and off time required for the MOS tube can be calculated based on the load power as the required output power, thereby obtaining the drive signal. This means is an existing mature calculation method and can be implemented by the main control module in this embodiment; that is, this embodiment involves the content of this part and does not involve improvements to the method.

[0059] In fact, the sampling circuit of this embodiment can be separately arranged at a collection device, and the main control circuit DSP circuit, boost circuit, rectifier circuit, inverter circuit and switch circuit can be arranged at a control device. The collection device can be arranged at the load meter of the load circuit, the control device can be arranged between the photovoltaic module and the load circuit, and the collection device and the control device can communicate through the 485 bus protocol.

[0060] The present invention and its implementation methods are described schematically above, and the description is not restrictive. The embodiments shown in the embodiments are only part of the implementation methods of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by the embodiments and designs a structure and an implementation method similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A photovoltaic backflow prevention device, characterized in that: include: A collection circuit, which is used to collect load power at the load circuit; A boost circuit is used to boost and output the electric energy at the photovoltaic module; wherein the electric energy generated by the photovoltaic module is sequentially supplied to the load circuit through the boost circuit, the rectifier circuit and the inverter circuit; a main control circuit for generating a driving signal based on load power; and The DSP circuit is used to convert the driving signal into a DSP signal for driving the boost circuit; wherein the boost circuit is constructed based on a MOS tube, and the DSP signal is used to keep the power output of the boost circuit not higher than the load power.

2. A photovoltaic backflow prevention device according to claim 1, characterized in that: The acquisition circuit includes: A sampling circuit, which is used to collect the voltage value and current value of the load circuit and to output a load power signal; A processing circuit, which is used to process the load power signal to obtain a communication signal; A communication circuit, which is used to transmit the communication signal to the main control circuit; and The power supply circuit is used to supply power to the sampling circuit, the processing circuit and the communication circuit.

3. A photovoltaic backflow prevention device according to claim 2, characterized in that: The sampling circuit includes a power collection chip; wherein the power collection chip is used to collect current signals and voltage signals at the load circuit, and to output a load power signal.

4. A photovoltaic backflow prevention device according to claim 3, characterized in that: The processing circuit includes a processing chip.

5. A photovoltaic backflow prevention device according to claim 4, characterized in that: The communication circuit includes a 485 chip.

6. A photovoltaic backflow prevention device according to claim 5, characterized in that: The power supply circuit includes an AC-DC chip.

7. A photovoltaic backflow prevention device according to claim 6, characterized in that: A sampling interface for accessing a current / voltage transformer is formed at the sampling circuit.

8. A photovoltaic backflow prevention device according to claim 7, characterized in that: A communication interface is formed at the communication circuit.

9. A photovoltaic backflow prevention device according to claim 8, characterized in that: A power interface is formed at the power supply circuit.

10. A photovoltaic backflow prevention device according to claim 9, characterized in that: Also includes: The switch circuit is arranged in series between the photovoltaic module and the load circuit, and is used to be disconnected under the control of the main control circuit when the load power is zero.

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