How to connect distributed power supply

With the optimization of energy structure and the rapid development of renewable energy, Distributed Generation (DG), as a flexible, efficient and environmentally friendly energy supply mode, is gradually becoming an important part of power system. Distributed power generation usually refers to small power generation devices with low power, close to the load center and scattered access to the distribution network, such as photovoltaic power generation, wind power generation, biomass power generation, micro gas turbines and so on.

Connecting distributed power supply to power grid is a key link to realize efficient energy utilization, improve power supply reliability and promote energy transformation. Its access process involves many aspects, such as technology, standards and management, and needs to follow scientific and reasonable principles and norms.

First of all, distributed power supply access should follow the basic requirements of safe operation of power grid. Because the output power of distributed power supply is intermittent and fluctuating, it may affect the frequency and voltage stability of power grid. Therefore, it is necessary to evaluate the carrying capacity of the power grid in detail before access, and select the appropriate access point and voltage level. Generally, small distributed power sources, such as rooftop photovoltaic, can be connected to the low-voltage distribution network (such as 380V or 220V), while large and medium-sized distributed power sources need to be connected to the medium-voltage distribution network (such as 10kV or 35kV) to ensure power quality and power grid safety.

Secondly, the access technology scheme should be scientific and reasonable. In the access design stage, factors such as power supply capacity, access mode, relay protection configuration and reactive power compensation should be considered comprehensively. For example, when photovoltaic power plants are connected, inverters and their protection devices should be configured to ensure that they can be quickly disconnected when the power grid fails or overhauls, so as to prevent islanding. In addition, it is necessary to configure necessary metering devices and automatic control systems to realize remote monitoring and dispatching of distributed power sources.

Thirdly, the access process should be standardized and orderly. The National Energy Administration and relevant electricity regulatory authorities have issued a number of technical guidelines and management measures, and defined the technical standards and approval procedures for distributed power access. The general process includes project application, access system scheme preparation, power grid enterprise review, engineering construction and grid-connected acceptance. The applicant shall submit an application for access to the local power grid enterprise, and the power grid enterprise shall issue access opinions and provide technical support within the specified time.

Finally, the operation management after access is equally important. Power grid enterprises should establish an operation monitoring platform for distributed power sources to grasp their power generation and operation status in real time; At the same time, the distributed generation is encouraged to participate in auxiliary services in the power market, such as peak shaving and frequency modulation, so as to enhance its value and role in the power system.

To sum up, the effective access of distributed power supply is not only a technical problem, but also a process of management and policy coordination. With the development of smart grid and energy internet, distributed generation will be more widely integrated into power system in the future, which will provide strong support for building a clean, low-carbon and efficient modern energy system.