Customized smart photovoltaic power distribution box
Customized smart photovoltaic power distribution box
The purpose of photovoltaic combiner box
The solar photovoltaic industry has become one of the most concerned emerging industries in the world today. Photovoltaic power generation is a direct power generation method that uses solar energy and semiconductor electronic devices to effectively absorb solar radiation energy and convert it into electrical energy. It is the mainstream solar power generation method today. Photovoltaic power generation does not require fuel and has no gas emissions. It is a "green" industry. It has the characteristics of no pollution, safety, long life, simple maintenance, inexhaustible resources, and wide distribution of resources. It is regarded as the most important new energy in the 21st century. It can be widely used in aerospace, communications, energy, agriculture, office facilities, transportation, and residential areas. It is worth noting that the places where the solar photovoltaic industry develops the fastest are often the places where natural disasters suffer the most. This paper proposes a design method for the smart photovoltaic combiner box in view of the large number of photovoltaic array components of photovoltaic power generation system, wiring troubles, high inverter cost, and heavy lightning damage. It has a wide range of applicability and application prospects.
The smart photovoltaic combiner box is used to connect the photovoltaic array and the inverter, provide lightning protection and overcurrent protection, and monitor the single string current, voltage, temperature in the photovoltaic array, the state of the lightning protection device, and the state of the circuit breaker. Our intelligence The photovoltaic combiner box is added with the function of tripping the main circuit breaker when the temperature is over or the photovoltaic string current is too large, which can effectively prevent the damage caused by the external short circuit. In the solar photovoltaic power generation system, in order to reduce the connection between the solar photovoltaic cell array and the inverter, the user can connect a certain number of photovoltaic cells with the same specifications in series to form a photovoltaic series, and then connect several photovoltaic cells. Connected in series and parallel to the smart photovoltaic combiner box, after converging in the smart photovoltaic combiner box, it is output through the DC circuit breaker and used with the photovoltaic inverter to form a complete photovoltaic power generation system and realize grid connection with the mains. In order to improve the reliability and practicability of the system, a dedicated photovoltaic DC lightning protection module, DC fuse, circuit breaker, etc. can be configured in the smart photovoltaic combiner box, and working status indicators, lightning counters, etc. can be set to facilitate users to grasp timely and accurately The working conditions of the photovoltaic cells ensure that the solar photovoltaic power generation system exerts its maximum efficiency.
For large-scale photovoltaic grid-connected power generation systems, in order to reduce the connection lines between photovoltaic modules and inverters, facilitate maintenance, and improve reliability, it is generally necessary to add a DC bus device between the photovoltaic modules and the inverter. Using the photovoltaic combiner box, the user can connect a certain number of photovoltaic modules with the same specifications in series to form a photovoltaic module string according to the DC voltage range input by the inverter, and then connect several strings to the photovoltaic array lightning protection combiner box. Through the rear output of the lightning protection device and the circuit breaker, it is convenient to connect the rear-stage inverter.
Structural design
The structure of the combiner box and the manufacturing quality of the cabinet itself, the main circuit connection, the secondary line and the installation of electrical components, etc. should meet the following requirements:
1) The relevant parts and components of the frame assembly should meet their respective technical requirements;
2) The box body should be firm and flat, and the surface should be smooth and flat, without peeling, rusting, cracks, etc.;
3) The rack panel should be flat, and the text and symbols should be clear, tidy, standardized and correct;
4) Signs, signs and markings should be complete and clear;
5) Various switches should be easy to operate, flexible and reliable.
The design of the smart photovoltaic combiner box should have the following characteristics:
1) Meet the requirements of outdoor installation
2) 16 channels of photovoltaic array can be connected at the same time, each channel is equipped with 15A, 1000Vdc fuse (other grades can be replaced)
3) Equipped with a special high-voltage lightning protection device for photovoltaics, both positive and negative electrodes have lightning protection functions
4) Four-pole DC circuit breaker with positive and negative poles connected in series; (improving DC withstand voltage)
5) Current monitoring of the input array, local LED display and output current value through RS485
6) Monitor the voltage after confluence, the local LED display and the output voltage value through RS485