1. Program Name:
A new scheme for boosting power distribution design for "0.1MW unit inverter-box change integrated device" for photovoltaic power generation.
2. Background art and defects and deficiencies of the prior art:
I. Background technology: The principle of photovoltaic power generation is to convert light energy into electrical energy. After DC power distribution, the combiner box is sent to the inverter and becomes AC, and then boosted and delivered to the distribution network. There are currently three types of power distribution design, centralized, string, and distributed.
The centralized type uses 1MW as a design unit to convert light energy into electrical energy from the photovoltaic power generation board, through the DC combiner box, and then to the 2*500KW centralized inverter, which becomes 0.315KV AC and is sent to the booster.
The distributed type is a design unit of 1MW, which is the same as the centralized type. Only the MPPT module is added in the combiner box to balance the voltage regulation effect. The DC of the combiner box becomes 800V, which is sent to the inverter and then to 520V. , after boosting to the grid.
The string type is a design unit of 28-50KW, which is firstly inverted to AC 480V, and then transferred to the 1MW box to be boosted by the AC combiner box.
Second, the defects and deficiencies of the existing technology:
1. Advantages: The current centralized boost power distribution, the normal capacity is 1000KW, the inverter is 2*500KW, and the power generation system efficiency is about 78%-80%. Distributing and string-type than centralized boosting power distribution, the nearby MPPT configuration can solve the phenomenon of different voltage pull-down of photovoltaic panels, which is about 3% higher than centralized. The string inverter scheme improves the power generation efficiency by 5-8% in the mountain photovoltaic project, and the installation is convenient, and the fault impact surface is small.
2. Disadvantages: centralized and distributed type is 1. Large area, 2. Power generation efficiency is limited. 3. Large-scale mountain transportation and installation is difficult. 4. Civil construction costs are high. 5. The AC and DC transmission system has a large loss. 6, the impact of the face is large
The string type feature is that although there is already a certain market application, it still needs time to verify the operational reliability. Expensive.
3. Specific technical solution description:
The technical problem to be solved by this solution is to provide a relatively obvious solution for improving power generation efficiency. Its principle is as shown in Figure 1:
1. Adopt centralized inverter 3 or string inverter, 100KW set, 8 sets of MPPT, DC voltage is about 660V~720V, 16 strings (each group is 6.24KW, 22~24 PV) The board is a string), each group shares one MPPT, 16 sets of DC switch cabinets, which can reduce the voltage drop caused by blocking or dusting, and near and far photovoltaic panel combiner box. The 660V~720V DC voltage inverter is AC three-phase power. The string inverter can save the DC cabinet.
2, AC power through 100KVA transformer 1, directly boost to 35KV, transformers, high-voltage isolating switch fuses, inverters, lightning arresters, etc. are installed in a box change.
3, 200 units are divided into 5 circuits, 40 units form a tree-like structure distribution system, and 4MW is a high-voltage line, which is sent to the 35KV power distribution room of the photovoltaic power plant for grid connection. The cable between the centralized inverter-box change and the DC cable between the combiner box and the inverter are reduced. Reduced the intermediate combiner box link.
figure 1
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