Wuxi Lanhai Electric Motor Co.,Ltd
Add: 4#, Tianshi Road Shitangwan Town, Wuxi, Jiangsu, China
In order to ensure the safe and reliable operation of the unit and power network, the primary frequency modulation function is set up in the pure electric control mode and the coordination mode. In the CCS system, the load control mode accepts the network frequency signal. 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. The set value of the rotating speed is reduced by the actual rotating speed of the unit. The deviation passes through the slip of the dead zone -- the conversion success rate signal of the power function, and after the high and low amplitude limit is processed, it is superimposed to 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. This instruction is compared with the reference power of steam turbine, and the power increase or decrease pulse signal is given to the DEH system, which coordinates with the DEH system to complete the primary frequency modulation of the grid.
When the primary FM of CCS side is input, the primary FM of DEH side is excised to avoid the superposition of correction power and over-regulation, causing 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 above 200MW is required to be less than 0.06%. Setting the frequency difference function of CCS side grid frequency difference correction function takes the same dead zone and parameters as that of DEH side. The speed change rate was set at 4.5% in the primary FM setting, plus or minus 2r/min in the FM dead zone, plus or minus 20MW in load limitation, plus or minus 14.5r/min in frequency difference adjustment range. Load regulation: limited-range: 20MW.
In order to ensure the stability of the unit during the primary frequency modulation operation, the output instruction in the CCS system is restricted, and the limit value is set in the test. (1) adjust speed reference value of 2990.3r/min in the DEH system (at that time, the actual speed of the turbine was 3000r/min). (2) when the unit load is 180MW, the load in the DEH system is automatically or the adjusted stage pressure is in the automatic mode. At this time, 12.7mw should be reduced according to the load instruction of the power curve unit, and the actual load of the unit oscillates around 167.3mw. (3) the response lag time of the unit's primary frequency modulation, the stable time of primary frequency modulation and the load variation range of primary frequency modulation are recorded. (4) observe whether the parameters of main steam pressure, drum water level, superheater steam temperature and reheater steam temperature are in the normal range.
The measured value of restoring speed is the actual speed. If the test assessment value does not meet the requirements, adjust the slope of frequency difference - power at the engineer station and carry out the above test again; If all the above tests are normal, the following tests can be performed after the unit load and speed are stable :(1) after the unit load is stable, adjust the speed reference value of the DEH system to 3009.7r/min(at that time, the actual speed of the turbine is 3000r/min). (2) according to the load instruction of frequency difference - power curve unit, 12.7MW should be increased, and the actual load of unit oscillates around 192.7MW. (3) the response lag time of the unit's primary frequency modulation, the stable time of primary frequency modulation and the load variation range of primary frequency modulation are recorded. (4) observe whether the parameters of main steam pressure, drum water level, superheater steam temperature and reheater steam temperature are in the normal range.