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55-56 Configuration of Large Centralized Grid - connected Solar Power Station

Author: Source: Datetime: 2016-12-22 17:21:09
PV grid-connected power generation system can be divided into two types: grid connection on the user side and grid connection on the power generation side. The former is generally in the low-voltage side (380 / 220V), mainly for spontaneous use; or medium voltage side (10kV, 35kV), mainly to the nearest consumption. Usually reversible photovoltaic grid-connected system, and some systems require the establishment of reverse power protection (ie, irreversible current grid-connected PV system). Large-scale centralized grid-connected PV power plant users side of the grid and the generation side of both types of network, 10MWp level and more power for the power generation side of the grid, the "irreversible" grid, Not spontaneous use and "net meter", can only give the price of electricity. Usually connected to 110kV or 220kV high-voltage output power, the output characteristics of the grid frequency and voltage changes with the current source, the power factor of 1, does not provide reactive power.

Large-scale centralized grid-connected PV power plant is mainly composed of solar PV array, inverter power control device and power network access system (step-up transformer, AC circuit breaker and metering equipment). The configuration is shown in Figure 4-3. The figure shows that, in addition to the main equipment, the photovoltaic power plant configuration also has a square square of the DC lightning protection, cross-DC distribution system, detection, measurement, data acquisition and transmission, AC and DC cables. Figure 4-4 Department of a 20MWp grid-connected photovoltaic power generation system block diagram.

As shown in Figure 4-4, the DC power generation system consists of solar battery modules, PV arrays, DC lightning protection converters, DC lightning protection power distribution cabinets, PV grid-connected inverters, and L-connected inverters. Voltage transformer and the connection between the cable and so on.


The Design of Photovoltaic Array

Large-scale centralized grid-connected PV power plant DC part of the design, the first is the design of photovoltaic arrays, because the main part of the field in the power plant is the PV array. It is arranged by the orderly matrix, while the square is a certain number of PV modules by the string, in parallel. Therefore, the design sequence should be from the component selection to the square array design and then to the square array and the corresponding bracket, foundation, connecting cables and other design.

Selection of solar cell module

Currently, commercial solar cell module types and efficiency are shown in Figure 4-5. Large-scale centralized grid-connected photovoltaic power plants use high-efficiency crystalline silicon solar modules. Efficiency, performance is relatively stable thin-film solar cells have also been demonstrated applications.

In particular, monolithic components power 280Wp, the battery efficiency of 17% to 18%, through the ISO 9001 quality system certification and UL, the United States and the United States and the United States and the United States, TUV, IEC and a series of international certification, to ensure that PV modules output power of more than 25 years, battery efficiency and stability are in the world's advanced level. In the construction of large-scale photovoltaic power generation systems, often also use the commercial high-quality 240Wp or 2600Wp polysilicon solar modules, such components are characterized by: ① high-quality solid aluminum alloy frame can resist strong winds, frozen and deformation; ② new special frame Design and thus strengthen the glass and the border seal; ③ aluminum alloy frame with the length of the short side with mounting holes to meet the requirements of different installation methods; ④ high transmittance of low-iron ultra-transparent glass to enhance the impact resistance; ⑤ high-quality EVA material And a back electrode material. The technical parameters are listed in Table 4-1.

Here to emphasize that for the use of the beach, the island's photovoltaic power plant construction of solar modules, to go through the necessary technical feasibility studies and take the necessary measures to prevent the sea breeze, salt erosion and other impact on power generation and service life.

It should be noted that, with the large-scale use of PV modules, found that the main existence of hot spots, crack and power decay and other quality problems in the selection of PV modules should be good off, not only concerned about the price. In particular, some PV power plants induced by the "potential induced decay" (PVP) of photovoltaic modules are obviously decayed after a certain period of operation, which has led to more and more researches on PID causes and prevention methods in PV industry. Many countries and regions have gradually begun to PID as one of the key components of the request.Many users in Japan explicitly require the anti-PID write to the contract on the real reason for the PID phenomenon until now there is no clear conclusion, it is clear that PID phenomenon is related to the reflective layer on the surface of the cell, and the improvement of the refractive index of the reflective layer can effectively reduce the occurrence of PID phenomenon.



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