Primary frequency modulation control strategy analysis in order to ensure the safety and reliability of unit and power network operation, primary frequency modulation function is set up in both pure power modulation mode and coordination mode. In CCS system, under load control mode, the network frequency signal is received. For CCS low frequency signal acquisition precision, and do not agree with DEH collection cycle, unable to meet the control requirements, so the adoption of DEH slip signal as a frequency modulation control signal of CCS, plus or minus 50 420 r/min of DEH slip signal corresponding to ma analog signal control precision is relatively high, basic can meet the requirements of CCS a frequency modulation of the control signal. When the set value of speed is subtracted from the actual speed of the unit, the deviation passes through the signal of success rate of conversion from dead zone to power function, and the signal is processed by high-low amplitude limiting, which is superimposed on the CCS load instruction to form a loop. The instruction is sent to the main control loop of the boiler to make the combustion system respond. Compared with the turbine power reference, the order gives the power increase or decrease pulse signal to the DEH system, and coordinates with the DEH power regulation system to complete the primary frequency modulation of the power grid.

　　When primary frequency modulation input is made on CCS side, primary frequency modulation excision is made on DEH side to avoid over-modulation due to the superposition of correction power and excessive disturbance of the unit. To reduce jitter phenomenon, power adjustment frequency offset is to ensure a stable, FM in the process of rapid increase rate of primary frequency limitations: the rate of 200 mw/min delay rate of steam turbine hydraulic governing system delay rate is in the work within the scope of speed adjustment system of hysteresis/hysteresis response speed, load or oil motivation when ascending and descending of the static relationship. It reflects the insensitivity of speed regulation system to speed fluctuation. The delay rate of units over 200MW shall be less than 0.06%. Setting of frequency difference function the frequency difference correction function of CCS side grid shall adopt the same dead zone and parameters as that of DEH side. The speed variation rate of the primary frequency modulation setting is 4.5%, dead band of frequency modulation plus or minus 2r/min, load limit plus or minus 20MW, frequency difference adjustment range plus or minus 14.5r/min. Load regulation limit: + / - 20MW.

　　In order to ensure the stability of the unit in a frequency modulation operation, the output instruction in CCS system is limited, and its limit value is set in the test. (1) the base value of speed adjustment in the DEH system was 2990.3r/min(when the actual speed of the turbine was 3000r/min). (2) when the load of the unit is 180MW, the load in the DEH system or the regulating stage pressure is in the automatic mode. At this time, according to the frequency difference -- power curve load instruction of the unit should be reduced by 12.7mw, and the actual load of the unit oscillates around 167.3mw. (3) record the response lag time of primary frequency modulation, the stability time of primary frequency modulation and the load variation amplitude of primary frequency modulation of the unit. (4) observe whether the main steam pressure, drum water level, superheater steam temperature, reheater steam temperature and other parameters are in the normal range.

　　The measured value of recovery speed is the actual speed. If the test evaluation value does not meet the requirements, adjust the slope of frequency difference -- power on the engineer station, and then carry out the above test; If all the above tests are normal and the unit load and speed are stable, the following tests can be conducted :(1) after the unit load is stable, the base speed value in the DEH system is adjusted to 3009.7r/min(when the actual speed of the turbine is 3000r/min). (2) according to the load instruction of the unit based on frequency difference-power curve, 12.7mw should be added, and the actual load of the unit oscillates around 192.7mw. (3) record the response lag time of primary frequency modulation, the stability time of primary frequency modulation and the load variation amplitude of primary frequency modulation of the unit. (4) observe whether the main steam pressure, drum water level, superheater steam temperature, reheater steam temperature and other parameters are in the normal range.