State Grid Corporation of China has developed a draft of the technical requirements for the distribution of distributed power to the grid on the basis of research on the related technologies of distributed power access to the power grid. At present, this regulation has been submitted to the National Energy Administration. After the approval of the Energy Bureau, the regulation will become a national standard to guide the development of the distributed energy industry.
It is understood that the regulation clearly defines the distribution of the system from nine aspects including access system principles, power quality, power control and voltage regulation, voltage and current and frequency response characteristics, relay protection and safety automatic devices, communications, electric energy measurement, and grid detection. The technical requirements that the power supply should meet the voltage level of 35kV and below.
Among them, the principle of distributed power supply access to the power grid system is that the principle of the grid connection point is to effectively transfer power after the power supply is integrated into the power grid and to ensure the safe and stable operation of the power grid. When more than one power supply is incorporated at the public connection point, The overall impact should be taken into account. In principle, the total power supply capacity should not exceed 25% of the maximum load in the power supply area of ​​the upper transformer.
The distributed power supply access voltage level is: 200kW and below distributed power access to 0.38kV voltage level power grid; more than 200kW distributed power access to 10kV and above voltage level power grid. After a technical and economic comparison, when the distributed power supply is accessed with a lower voltage rating than the high-voltage rating, it can be accessed at a lower voltage level.
According to relevant persons from the State Grid, the standard fully takes into account the technical and economic characteristics of the distributed power system, and on the premise of ensuring the safe operation of the system and the distribution network, it appropriately simplifies the standards requirements for measurement, automation, protection and communication systems. For example, the distributed power supply connected to the grid with 6kV-35kV voltage level must have the ability to communicate with the grid for data communication and to receive power grid dispatch adjustment commands. However, it does not require the use of optical fiber access methods, which will help reduce investment.
More specific technical standards and specifications, including series standards for distributed power supply grid-connection characteristics testing, distributed power grid-connected operation control series standards, distributed power monitoring system series functional specifications, and distributed power supply monitoring equipment, have been formulated and planned. Separated and published in 2011-2013.
For a long time, due to the lack of relevant technical regulations, distributed power grid-connected power can only be connected to the grid according to conventional power grids, causing a series of problems such as the difficulty of distributed power grid connection. According to statistics from Wang Zhenming, a senior advisor to the Hot Special Committee of the China Electrical Engineering Society, at present, China has built up 5 million kilowatts of distributed energy, most of which face difficulties in grid connection. State Grid's development of relevant technical regulations will facilitate the integration of future distributed power sources into the power grid and improve the efficiency of social energy use.
Entrusted by the National Energy Administration, the State Grid Energy Research Institute has also carried out special research work on distributed energy policies and regulations. At present, the first draft of the report has been completed. The first draft includes planning and project management, grid management, operation model, electricity pricing mechanism, and preferential treatment. The package of policy recommendations, including policies, has been basically approved by the energy authorities.