Safe and reliable component-level photovoltaic turn-off system
By using magnetic relays and diodes in the photovoltaic power generation system, the problem that the photovoltaic power generation system is difficult to safely and reliably perform component-level shutdown in emergency situations is solved, and a safe, low-cost and reliable photovoltaic shutdown system is realized.
Patent Information
- Application Number
- CN202411544310.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-31
- Publication Date
- 2025-02-28
AI Technical Summary
It is difficult for existing photovoltaic power generation systems to safely and reliably perform component-level shutdown in emergencies such as fires, resulting in a safety threat to rescue when a fire occurs. The switches of traditional shutdown systems are easily damaged due to excessive voltage, and the presence of contact resistance leads to power loss.
A component-level photovoltaic shutdown system is designed, using a magnetic relay as a switch in the shutdown box, which consumes power only when operating, and consumes 0 in the release state, and uses diodes to replace the high-voltage switch to achieve safe shutdown and re-energy of the series.
It realizes safe and reliable component-level shutdown in emergency situations such as fires, avoids the problem of switch damage due to excessive voltage, reduces power loss, and improves system reliability and safety.
Smart Images
Figure CN119543052A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of photovoltaic power generation technology, and in particular to a safe and reliable component-level photovoltaic shutdown system. Background Art
[0002] Due to the large-scale application of rooftop photovoltaic power generation, the safety of rooftop power stations has become an important topic. Because photovoltaic modules generate electricity when exposed to light, multiple strings are connected in series to form a high-voltage DC power supply of 800 volts or more. This power supply cannot be cut off by shutting off the mains supply on the user side, which poses a safety threat to rescue in the event of a fire. A safe, reliable and low-cost module-level shutdown system is urgently needed.
[0003] This urgent need has given rise to a number of photovoltaic shutdown systems. The most representative one is the following Figure 1 In the main circuit system shown, a switch is connected between every two components. In case of emergency such as fire, K01, K02... Kn are turned off through instructions. In this way, the series components are separated, and the operating voltage of each component is only 30~40V, which is safe for the human body.
[0004] Problems with traditional shutdown systems: like Figure 1 As shown, it seems feasible in principle, but there are the following problems in practical application: 1. Since K01, K02...Kn are connected in series, they jointly bear the total voltage of the string. However, after the shutdown command is issued, these more than 10 switches have a more or less order of shutdown. The first switch to be activated will withstand hundreds of volts. If a low-voltage switch is used, it may arc and burn out, and lose its function. Then, the second one will also be in the same situation; among current industrial products, there are very few switches that can withstand 800V / 10A, or they are expensive.
[0005] 2. K01, K02...Kn switches all have contact resistance. With the current level of relay industry or the performance of electronic devices, this contact resistance is generally 10 milliohms or above. Taking the current high-power components as an example, during normal operation, each switch will lose several watts of power, and each string will lose tens or hundreds of watts. The harm is not only the loss of electrical power. Due to the long-term passage of current, the electric shock life of the switch will not be very long. For high-reliability photovoltaic systems, this will become a serious shortcoming. Summary of the invention
[0006] The technical problem to be solved by the present invention is to provide a safe and reliable component-level photovoltaic shutdown system which solves the problem of controllable shutdown of photovoltaic power generation and has the advantages of safety, low price and reliability.
[0007] To achieve the above object, the present invention provides the following technical solutions: A safe and reliable component-level photovoltaic shutdown system comprises photovoltaic components (M1, M2, M3, Mn), a shutdown box, a command box, a photovoltaic cable, and an inverter, wherein the photovoltaic components (M1, M2, M3, Mn) are connected in series to form a string through wires, a shutdown box is connected in parallel to each output end of the photovoltaic components, the photovoltaic components (M1, M2, M3, Mn) are connected to the inverter through photovoltaic cables, the inverter is connected to the command box, and one of the photovoltaic components in the string is connected to the command box through a wire.
[0008] Furthermore, the command box includes a main switch (JB0), a current probe (C) and a control unit (CPU). Furthermore, the shut-off box includes a shut-off switch (K12, K13, K1n) and a control terminal, and the control terminal is connected to the instruction box.
[0009] Compared with the prior art, the present invention has the following beneficial effects: 1. The switch in the shut-off box uses a magnetic latching relay, which consumes only a small amount of power at the moment of action; 2. The switch in the shutdown box is usually in the released state and consumes 0 power; 3. When the switch in the shut-off box is in action, it does not bear voltage and there is no requirement for the contact pressure resistance; 4. In the entire string, only one switch (JBO in the command box) bears the voltage and current. You can choose a DC relay with a higher withstand voltage, and the cost is controllable; 5. The diode has reverse blocking performance. The diode can replace the more expensive high-voltage switch JB0, which can also meet the use requirements and also play the role of string reverse protection; 6. The present invention solves the problem of controllable shutdown of photovoltaic power generation and has the advantages of safety, low price and reliability. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 It is a schematic diagram of the structure of a traditional photovoltaic shutdown system; Figure 2 It is a schematic diagram of the structure of the present invention; Figure 3 It is a structural diagram of embodiment 2 of the present invention. DETAILED DESCRIPTION
[0011] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention. Example
[0012] See also Figure 2 As shown, a safe and reliable component-level photovoltaic shutdown system includes photovoltaic components M1, M2, M3, Mn, a shutdown box, a command box, a photovoltaic cable, and an inverter. The photovoltaic components M1, M2, M3, and Mn are connected in series to form a group string through wires, and each photovoltaic component output end is connected in parallel with a shutdown box. The photovoltaic components M1, M2, M3, and Mn are connected to the inverter through photovoltaic cables, and the inverter is connected to the command box. One of the photovoltaic components in the group string is connected to the command box through a wire. The command box includes a main switch JB0, a current probe C, and a control unit CPU. The shutdown box includes shutdown switches K12, K13, K1n and control terminals. The control terminals are connected to the command box. The switch in the shutdown box is designed with a magnetic latching relay. Working principle of the present invention: When an emergency such as a fire occurs, the user sends a shutdown command through the command box. The command box first disconnects the internal JB0 to cut off the component current, and then sends a positive pulse to the shutdown box 1, shutdown box 2...shutdown box n; after the shutdown box 1, shutdown box 2...shutdown box n receives the positive pulse, the internal K12, K13...K1n switches are closed and connected, connecting the output ends of the corresponding components together, the output of each component is short-circuited, and the voltage drops to 0; in this way, except for M1, the voltage of other components is 0, and the entire string is in a safe state; When power needs to be restored after the danger is eliminated, the user only needs to send a connection command to the command box, and the command box sends a negative pulse to the shutdown box. The magnetic latching relay in the shutdown box is released. After waiting for about 30ms, the command box turns on the internal JB0 and the string resumes power generation. Example
[0013] See also Figure 3 As shown, a diode is used to replace the high-voltage switch JB0. Due to the reverse blocking performance of the diode, the diode can be used to replace the more expensive high-voltage switch JB0, which can also meet the use requirements and also play the role of string reverse protection.
[0014] In summary, the present invention solves the problem of controllable shutdown of photovoltaic power generation and has the advantages of safety, low price and reliability.
[0015] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. Any equivalent modifications or changes made by ordinary technicians in this field based on the contents disclosed by the present invention should be included in the protection scope recorded in the claims.
Claims
1. A safe and reliable module-level photovoltaic shutdown system, including photovoltaic modules (M1, M2, M3, Mn), a shutdown box, a command box, a photovoltaic cable, and an inverter, characterized in that: The photovoltaic components (M1, M2, M3, Mn) are connected in series to form a string through wires, a shut-off box is connected in parallel to the output end of each photovoltaic component, the photovoltaic components (M1, M2, M3, Mn) are connected to an inverter through a photovoltaic cable, the inverter is connected to a command box, and one of the photovoltaic components in the string is connected to the command box through a wire.
2. A safe and reliable module-level photovoltaic shutdown system according to claim 1, characterized in that: The command box includes a main switch (JB0), a current probe (C) and a control unit (CPU).
3. A safe and reliable module-level photovoltaic shutdown system according to claim 1 or claim 2, characterized in that: The shutoff box comprises a shutoff switch (K12, K13, K1n) and a control terminal, wherein the control terminal is connected to the command box, and the switch in the shutoff box is designed as a magnetic latching relay.