Principle of primary frequency modulation and secondary frequency modulation

The principles of primary frequency modulation and secondary frequency modulation are as follows:

1, primary frequency modulation: refers to the inherent ability of the frequency characteristics of the speed control system of the generator set to automatically adjust the frequency with the frequency change.

Secondary frequency modulation: refers to the frequency modulation method adopted when the load or power output of the power system changes greatly and the frequency cannot be restored to the specified range by primary frequency modulation. Secondary frequency modulation is divided into manual frequency modulation and automatic frequency modulation.

2. Relationship between primary frequency modulation and secondary frequency modulation: primary frequency modulation is differential regulation, which cannot keep the grid frequency unchanged, while secondary frequency modulation can accurately keep the grid frequency unchanged.

3. The primary frequency modulation is completed by the governor actions of multiple generators, aiming at the very frequent small load fluctuations; The secondary frequency modulation is aimed at the load fluctuation with large change amplitude and slow frequency change, and is completed by the frequency modulator of the frequency modulation power plant.

4. Primary frequency modulation is differential regulation. Theoretically, the secondary frequency modulation can realize the deadbeat adjustment. People who undertake the task of frequency modulation are different, one is the governor and the other is the frequency modulator; According to the different load changes, one is a very frequent load with small load fluctuation, and the other is a load with large change range and slow change frequency. It is to ensure the frequency stability of power system.

5. Primary frequency modulation is usually spontaneous. When the active power output by the system is less than the active power required by the load, the frequency of the system will be reduced, because there are a large number of motor loads in the system, and with the reduction of frequency, the load consumption will be reduced.

6. Secondary frequency modulation means that the system automatically tracks the frequency of 50Hz or the dispatcher manually adjusts the active output, so as to adjust the system frequency and return to 50Hz.