Briefly describe the composition and safety protection of solar grid connected photovoltaic power ge

1) It can regulate the peak of the power grid, improve the voltage stability at the end of the power grid, improve the power factor of the power grid, and eliminate the clutter of the power grid. The generated energy can be fed back to the power grid, and the grid is used as an energy storage device, eliminating the need for batteries. (3) The perfect combination of photovoltaic cells and buildings is quiet, which can not only generate electricity, but also can be used as building materials and decorative materials, so that resources can be fully utilized and play a variety of functions.

4) Flexible access to the power grid, which is not only conducive to improving the load balance of the power system, but also reducing line loss.

Summary. 1.The design of photovoltaic power station should comprehensively consider factors such as sunshine conditions, land and building conditions, installation and transportation conditions, and should meet the requirements of safety, reliability, economic application, environmental protection, beauty, and easy installation and maintenance.

2.While satisfying safety and reliability, the design of photovoltaic power stations should give priority to the use of new technologies, new processes, new equipment and new materials.

Photovoltaic power stations should be established in line with the actual photovoltaic power station () aSafety Procedure BOverhaul regulations.

1.The design of photovoltaic power station should comprehensively consider factors such as sunshine conditions, land and building conditions, installation and transportation conditions, and should meet the requirements of safety, reliability, economic application, environmental protection, beauty, and easy installation and maintenance. 2.

While satisfying safety and reliability, the design of photovoltaic power stations should give priority to the use of new technologies, new processes, new equipment, and new materials.

3.Large and medium-sized photovoltaic power stations should be equipped with solar radiation on-site observation devices. 4.

The system configuration of photovoltaic power stations should ensure that the power quality of the output power meets the current relevant national standards. 5.The photovoltaic power station connected to the public power grid shall be installed with a liquid energy metering device approved by the local quality and technical regulatory agency, and put into operation after passing the calibration.

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The silo effect. <>

The so-called islanding effect refers to the fact that if a power generation device is integrated into the public power grid, in the event of a power grid failure, the power generation device cannot detect or does not have the corresponding detection means at all, and still feeds electricity to the public power grid.

Due to the potential danger of islanding and the damage to equipment, owners of social public works and power generation equipment have long been concerned about the anti-islanding control of photovoltaic grid-connected inverters. Therefore, the islanding effect must be prevented in the application of photovoltaic grid-connected power generation systems.

The principle of silos.

In a circuit in which a capacitor is connected in series, only two plates connected to the outer circuit (note: plates that are not the same capacitor) have current flow (charge exchange), and the total charge of the other plates is constant, so it is called islanding. Islanding is an electrical phenomenon that occurs when a part of the grid is disconnected from the main grid, which is powered entirely by photovoltaic systems.

This is still a point of contention on the topic of international PV grid connection standardization, because islanding can compromise the safety of the public and power company maintenance personnel and the quality of power supply, and there is a risk of damaging equipment when automatically or manually re-closing the power supply switch to re-supply power to the island grid. Therefore, inverters are usually equipped with anti-islanding devices.

Extended Materials. The islanding effect can adversely affect the entire power distribution system equipment and the equipment at the user end

1. Endanger the life safety of power maintenance personnel;

2. Affect the action program of the protection switch on the power distribution system;

3. The unstable nature of power supply voltage and frequency in the isolated area will cause damage to the electrical equipment;

4. When the power supply is restored, the voltage phase is not synchronized, which will produce inrush current, which may cause re-tripping or damage to the photovoltaic system, load and power supply system;

5. The photovoltaic grid-connected power generation system causes the problem of under-phase power supply of the three-phase load of the system due to the single-phase power supply.

It can be seen that as a safe and reliable grid-connected inverter, it must be able to detect the islanding effect in time and avoid the harm caused by it.

The solar grid-connected power generation system is divided into four modes of operation:

1. Grid-connected power generation with countercurrent.

2. Grid-connected power generation without countercurrent.

3. Switching grid-connected power generation.

4. Grid-connected power generation with energy storage device.

I need to tell you what they mean again.

Composition and principle of photovoltaic system.

The photovoltaic system consists of the following three parts: solar cell modules; Power electronic equipment such as charge and discharge controllers, inverters, test instruments and computer monitoring and storage batteries or other energy storage and auxiliary power generation equipment.

The photovoltaic system has the following characteristics:

There are no rotating parts and no noise;

No air pollution, no waste water;

There is no combustion process, no fuel is required;

Simple maintenance and low maintenance costs;

Good operation reliability and stability;

As a key component, the solar cell has a long service life, and the life of crystalline silicon solar cell can reach more than 25 years;

It is easy to scale up power generation as needed.

Photovoltaic systems are widely used, and the basic forms of photovoltaic system applications can be divided into two categories: independent power generation systems and grid-connected power generation systems. The main application areas are mainly in space aircraft, communication systems, microwave relay stations, TV differential turntables, photovoltaic water pumps and household power supply in areas without electricity and power shortage.

With the development of technology and the needs of sustainable development of the world economy, developed countries have begun to promote urban photovoltaic grid-connected power generation in a planned way, mainly the construction of household rooftop photovoltaic power generation systems and MW-level centralized large-scale grid-connected power generation systems, etc., and at the same time vigorously promote the application of solar photovoltaic systems in transportation and urban lighting.

The scale and application form of photovoltaic systems are different, such as the scale of the system spans a large range, from small solar garden lights to MW-level solar photovoltaic power stations. Its application forms are also diverse, and can be widely used in many fields such as home, transportation, communication, and space applications. Although PV systems vary in size, their composition and working principles are basically the same.

Figure 4-1 is a typical schematic diagram of a photovoltaic system with a DC load.

There is a contradiction between the surplus of power resources and the insufficient transmission capacity in the western region. The data shows that in 2016, the curtailment rate of photovoltaic power generation in the five northwestern provinces (regions) of China, Xinjiang and Gansu is more difficult, and the curtailment rate is and. The National Energy Administration held a regular press conference at the beginning of this year to announce that in 2017, 7.3 billion kilowatt-hours of PV were curtailed, with a curtailment rate of 6%, a year-on-year decrease of one percentage point.

Although there has been some improvement, there are great challenges in achieving the goal of controlling the curtailment rate of wind and solar power within 5% by 2020. An industry insider from the State Grid said.

A manager of a listed photovoltaic company said that large-scale ground-mounted power stations are mainly built in the northwest region, where the local absorption capacity is limited, and the construction of long-distance transmission and distribution facilities is not perfect, resulting in an imbalance between power supply and demand in areas with abundant sunlight resources, and between northwest inland and southeast coastal areas. The administrative manager of a listed photovoltaic company located in Taicang, Jiangsu Province, said that the amount of accumulated funds due to the construction of the power station and the failure to connect to the grid has reached billions of yuan. If they can't get on the Internet, they won't be able to repay the loans, and the banks will have to collect the loans, so they have no choice but to raise money through market institutions, with interest rates of 12 to 15 percent.

There is also a contradiction between the instability of new energy generation and the safety of grid loads. Sunlight comes and goes, and new energy power generation is easy to cause voltage instability. From January to the end of December 2017, the new installed capacity of distributed photovoltaic in China exceeded 19GW, a year-on-year increase of more than 360%, far exceeding the first five years of distributed photovoltaic capacity, accounting for more than 36% of the new installed capacity.

A large influx of distribution, undoubtedly to the power grid to increase the load, especially the country for the distribution can be consumed on the spot, can apply for grid connection at any time, without a good planning, swarming, undoubtedly increased the load in the region where it is located, changed the existing load growth model, it is obvious that the transformation and management of the distribution network will become more complicated.

Answer]: The grid-connected power generation system converts the received solar radiation energy into high-voltage direct current through high-frequency DC conversion through the side-shielded photovoltaic array, and outputs sinusoidal AC current with the same frequency and phase as the grid voltage to the grid after inverter inversion. The system structure is composed of a solar energy return board, an inverter merger, and an AC distribution cabinet.

Answer] :d Composition of grid-connected photovoltaic system: mainly composed of photovoltaic hand-cleaning battery modules, inverters of parallel and closed grids, public power grids before Bi state, and monitoring systems.