Distributed power generation systems use various available resources for small-scale distributed power generation, and there are many classification methods. From the perspective of energy used, it can be classified into the use of renewable energy, the use of fossil energy, and the use of secondary energy and garbage fuel. Among them, the renewable energy sources used mainly include wind energy, solar energy, biomass, water energy, ocean energy, geothermal energy, etc.; fossil energy sources include natural gas, methane, gasoline, diesel, etc., and their combustion power devices include micro gas turbines and gas turbines, Internal combustion engines, conventional diesel generators, fuel cells, etc.; secondary energy sources such as hydrogen energy. From the classification of user needs, it can be divided into simple power supply mode, combined heat and power, and combined heat, power and cooling.
1. Wind power generation
Wind power generation resources are widely distributed and the technology is mature. It is the fastest growing and most widely used power generation technology in recent years. The wind blows the impeller, the wind turbine rotates, and the generator generates electricity through the drive shaft. Wind power generation generally uses asynchronous generators, but synchronous generators can also be used. For a wind power generation system, the output active power is determined by the wind speed and will change with the change of the wind speed, and the reactive power absorbed by the generator will also change. In order to stabilize the output power, the wind power generation system can adopt constant pitch stall control or variable pitch control, so that the wind turbine can output stable power in a wide range of wind speed. At present, among all kinds of renewable energy power generation, wind power has the lowest cost and will be able to compete with conventional energy power generation in the near future.
2. Solar power generation
Solar power technology mainly includes two types, namely solar thermal power generation and solar photovoltaic power generation. Solar thermal power generation technology refers to the use of large-scale mirrors to collect heat energy radiated by sunlight, provide steam through heat exchange devices, and combine with traditional steam turbine generator technology to achieve the purpose of power generation. It is mainly suitable for centralized power generation. The energy conversion device of solar photovoltaic power generation technology is a solar cell, also called a photovoltaic cell, which is composed of semiconductor materials. Solar cells directly convert light energy into electrical energy through the photovoltaic effect of semiconductors. Photovoltaic power generation is basically not restricted by region, with flexible construction scale and site selection, convenient installation, simple maintenance, and environmental protection. However, its energy density is relatively low, and it is greatly affected by meteorological conditions, and the initial construction cost is relatively high. In recent years, solar photovoltaic power generation technology has developed extremely rapidly, and its applications are also very extensive, ranging from spacecraft to household power sources, as large as megawatt power stations to toys, and photovoltaic power sources are everywhere.
3. Fuel cell
The fuel cell does not need to be combusted, but is an electrochemical device that converts chemical energy into direct current electricity. It can directly chemically react the hydrogen in the fuel (natural gas, coal gas, petroleum, etc.) with the oxygen in the air through the electrolyte. Among them, hydrogen releases electrons to carry positive charges, and oxygen obtains electrons from hydrogen to carry negative charges, and the two combine to become neutral water. The transfer of electrons is added to the externally connected load to realize power supply to the load. The process is simple, efficient, noiseless, clean and environmentally friendly. At present, the cost of fuel cells is still relatively high and has not yet been widely commercialized.
