The difference between distributed photovoltaic and centralized photovoltaic

Distributed photovoltaic power generation refers to a photovoltaic power generation facility that is built near the site and is characterized by self-consumption on the user side, excess power connected to the grid, and level adjustment in the power distribution system. Distributed photovoltaic power generation follows the state-by-state regulations, which can further increase the power generation of photovoltaic power plants. After the distributed T photovoltaic power source is effectively connected to the distribution network, there is a big difference between the access method and the traditional power source, which will have an impact on many aspects of the distribution network.
Centralized large-scale grid-connected photovoltaic power station means that the country uses deserts to build large-scale photovoltaic power stations in a concentrated manner. The power generation is directly integrated into the public power grid and connected to the high-voltage transmission system to supply long-distance loads. Chinese-style large-scale grid-connected photovoltaic power plants are generally national-level power plants. The main feature is that the generated energy is directly transmitted to the power grid, and the power grid is uniformly deployed to supply power to users. However, this kind of power station has a large investment, a long construction period, and a large area. The distributed small-scale grid-connected photovoltaic system means that each household uses photovoltaic power generation on the roof for the user’s own use, and the excess electricity is incorporated into the public grid. This article will discuss in detail the differences between distributed photovoltaic power plants and centralized photovoltaic power plants.

Distributed photovoltaic power station

The basic principle of distribution: mainly based on the surface of the building, solve the user’s electricity consumption problem nearby, and realize the compensation and delivery of the power supply difference through grid connection.

1. The photovoltaic power supply is on the user side, and the power generated is supplied to the local load, which can be regarded as a load, which can effectively reduce the dependence on the grid power supply and reduce line loss.
2. By making full use of the building surface, photovoltaic cells can be used as building materials at the same time, effectively reducing the footprint of photovoltaic power plants.
3. Effective interface with smart grid and micro grid, flexible operation, and independent operation of the grid under appropriate conditions.

1. The direction of the power flow in the distribution network will change in time, and the reverse flow will cause additional losses. The relevant protections need to be re-adjusted, and the transformer taps need to be constantly changed, etc.
2. Difficulties in voltage and reactive power regulation. There are technical difficulties in the control of power factor after the connection of large-capacity photovoltaics, and the short-circuit power will also increase.
3. The energy management system at the distribution network level is required to perform the same load management in the case of large-scale photovoltaic access. New requirements are placed on secondary equipment and communications, increasing system complexity.

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Centralized photovoltaic power station

Centralized basic principles: make full use of the abundant and relatively stable solar energy resources in desert areas to build large-scale photovoltaic power plants, and connect to high-voltage transmission systems to supply long-distance loads.

1. Due to the more flexible site selection, the stability of photovoltaic output has increased, and the positive adjustment of solar radiation and electricity load has been fully utilized.
2. The operation mode is relatively flexible. Compared with distributed photovoltaics, it is more convenient to carry out reactive power and voltage control, and it is easier to realize the frequency regulation of the power grid.
3. Short construction period, strong environmental adaptability, no need for water source, coal transportation and other raw material guarantees, low operating costs, easy centralized management, small space constraints, and easy expansion.

1. It needs to rely on long-distance transmission lines to send power into the grid. At the same time, it is also a large source of interference to the power grid. Problems such as loss of transmission lines, voltage drop, and reactive power compensation will become prominent.
2. A large-capacity photovoltaic power station is realized by combining multiple conversion devices. The coordinated work of these devices requires unified management, and the technology in this area is not yet mature.
3. In order to ensure the safety of the power grid, large-capacity centralized photovoltaic access needs new functions such as LVRT. This technology often conflicts with isolated islands.

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