Analysis of Coordinated Control Technology for 300MW Generator Sets Han Zhihong (Shanxi Sunshine Power Generation Co., Ltd., Pingding 045200, China) The advantages and disadvantages of coordinated control and the problems of coordinated control are analyzed. The abnormal working conditions occurred during operation are analyzed. The corrective measures were taken, and the suggestions or solutions for solving the problems were elaborated from the actual situation.
1994 The original principle of work 4 (learning thermal professional a: drumalElectronicPublish dust unchanged Us should be specified in one range. h after the operation summary i, n negative 1 system introduction Shanxi Sunshine Power Generation Co., Ltd. 300MW generator set coordinated control system Since the implementation in gradual implementation in 1998, it has been more than 3 years. With the unit from commissioning to stable operation, the primary equipment of various majors such as machine, electric furnace and heat have been comprehensively improved and rectified, achieving a more reliable effect. From the original 50% to the current 100%, the protection input rate is 100%, the unit control is within the load of 180MW~300MW, CCS (coordinated control) is realized, and even AGC (scheduling control) is realized, which greatly improves the automation of the system. The degree has reduced the labor intensity of the staff, which has greatly improved the efficiency of the power plant and the safe and civilized production. However, in terms of coordinated control technology, it is still affected and restricted by many factors, and there are many problems in its use. Threatening the safety of the unit, it has caused many abnormalities, obstacles and even accidents. Therefore, it is against the actual problems of the Sunshine Power Generation Company. Adjust the control technology for some discussion.
2 Problems in operation and suggestions for rectification measures 2.1 Poor adjustment characteristics of coal mills Double-input and double-out coal mills are used in the powder production system of No. 1 and No. 2 furnaces of Sunshine Power Generation Company. Each furnace is equipped with 4 sets of milling powder. In the positive pressure direct blowing type, the adjustment of the grinding force is performed by the action of the load regulating baffle. In the case of manual operation, the operator can make artificial adjustment according to the amount of coal and the pressure of the coal mill barrel. However, under the coordinated control, the adjustment characteristics of each coal mill are poor and different. When the coordination is put into operation, the phenomenon of adjustment of each mill will occur. As a result, the deviations of the A, B, C, and D mill parameters are serious, and some of the milled air has exceeded the protection value. The coal supply is greater than 50t/h. (Specified less than 40t / h) and some of the primary air volume is significantly lower, the cylinder pressure is less than 3kPa, the powder is obviously difficult to discharge, especially during the lifting load, the dynamic adjustment is more inappropriate and will cause partial wear blockage. Part of the grinding can not turn out the powder, so that the combustion will deteriorate, and even if the fire is not adjusted, it will cause adverse consequences from both safety and economic aspects. According to the coordinated control input conditions, any coal mill load control system is put into automatic and the primary air volume is milled. The signal is normal. However, in actual operation, the equipment cannot be accurately operated due to grinding, and the tracking is slow or over-adjusted, which makes it difficult to coordinate the investment. According to the above, in order to make the coordination system smoothly input, it is necessary to first solve the adjustment characteristics of the coal mill, and make great efforts in the rectification of the equipment. The performance of the four milling machines is synchronized and excellent. Only in this way can the conditions for the normal operation of the coordination system be created, and the safety and economic benefits of the power plant enterprises can be guaranteed. The impact of the load set value and the load lifting rate of the 2.2 unit is coordinated and controlled. On the unit, the first step of load lifting is the load setting. This operation is manually intervened by the operator. If there is a slight negligence, such as changing the 250MW to 25MW when the value is changed, the unit will load the original load. Up to 25 MW, resulting in a load dump accident, causing a large loss. This is the wrong command, leading to serious consequences. In order to prevent this from happening, in addition to strengthening the quality of the operators and the responsibility of safety, it should also consider from the coordination setting that if the instructions larger than 20MW are used, the blocking will be performed without executing, that is, the coordinated control will only accept less than 20MW (including 20MW) instructions, so that it will be foolproof, so as not to cause unnecessary loss. The load-lifting rate refers to the rate of load change, the unit is MW / min. The set value of the load-lifting rate of the solar power company is 6MW/min. The determination of the rate of lifting and lowering cannot be affected by the following factors: It can be seen that only the operator can change the rate of lifting and lowering according to the actual situation to adapt to the requirements of variable working conditions. 2MW/min~ /min, otherwise it will cause the parameters to fluctuate drastically, and it may cause various accidents. 2.3 Machine side adjustment door tracking characteristics and host thrust tile working condition are in coordinated control. The machine side adjustment door is operated according to the pressure curve. Keep the pressure in front of the door so that it meets the specified value. According to this design concept, it can really guarantee the steaming. However, the load is high, especially at the full load of 300 MW, because the furnace side adjustment is not very accurate, or even very inaccurate, causing overshoot, so that the front door pressure instantaneously exceeds the maximum value of 17. 4 MPa, which will make the unit The bypass system operates, and the unit overload phenomenon occurs, which poses a great threat to the safety of the unit. In order to avoid this situation, in addition to the coordination ability of the relevant professional, the pressure curve setting considering the tracking of the host adjustment door should be smoothed, so that the adjustment of the door movement is advanced, and the pressure is not increased to the limit value, resulting in consequences. The steam turbine produced by the Dongfang Steam Turbine Plant adopted by Sunshine Power Generation Company requires that the load of the thrust block should not rise and fall suddenly, and the pressure change should be stable. If the fluctuation is severe, there will be a possibility of burning the tile and causing a vicious accident. As far as possible, the parameter curve should be smoothly transitioned to protect the host device from normal operation.
2.4 Definition of Load Area and Coordination of Retirement Method The 300MW unit of Sunshine Power Generation Company has a wide load area and is a power plant with peaking capacity. According to the manufacturer's regulations and practice, the auxiliary machines operate well between 300MW and 180MW, and the coordinated control system is applicable in this interval. If it is less than 180MW, not only the water level and combustion are difficult to control, but also the auxiliary machines, especially the coal mill, primary fan and induced draft fan, cannot be adjusted normally, which makes the coordinated control disorder and may cause accidents. Therefore, the general Sunshine Co., Ltd. coordinates the control and adapts to the load. The area should be between 180MW~300MW in case of abnormal situation. Timely exit coordination is an important part to ensure the safety of the unit, but it should be strictly observed when exiting. Firstly, the fuel main control is withdrawn, the air supply is automatically sent in turn, the coal mill is automatically withdrawn, and the main control of the boiler is automatically tripped, so that the furnace side combustion system is no longer controlled by the coordinated command and is stable under one working condition. Then, the turbine is automatically disarmed, the pressure adjustment is manually intervened, the fixed-sliding pressure switching condition is carefully checked, and the heat value correction is correct. Especially when the pressure is high near the 300MW load of the unit, the coordination should be performed urgently, manual intervention, and force protection. The unit is stable. If the tightening condition is resolutely implemented, it should never be forced to grab the 2.5 typical fault handling principle. Before the unit has no RUNBACK test, when the auxiliary machine fails, the operator removes the coordinated control system and manually intervenes to keep the unit stable. If the RUNBACK test is completed, it should be adjusted by the coordinated control system.
3 sets of grinding operation, 1 set of grinding brakes, coordination should be cut to the machine follow-up mode, the boiler main control command is reduced to 180MW, the pressure setting value is changed to 14MPa at a certain rate, and the oil-fired combustion-supporting two blowers are operated, one blower is off. After the gate, coordinate the cutting to the machine follow-up mode. If the unit is operated by 3 sets of mills, then 3 sets of mills will simultaneously reduce the load. If 4 sets of mills are run, the D-grinding will be performed. After the other 3 sets of mills simultaneously drop the load blower RB, the boiler command target The value is 200MW, and the pressure is fixed at 14. The feed pump and the primary fan should be automatically exited from the coordination system during the operation of the fan. The fuel main control system is manually intervened by the operation personnel to complete other operations. When various accidents are completed, the system is stable. When the conditions for commissioning are reached, the coordination system is re-introduced.
3 Conclusions The solar power generation company No.1 and No.2 units have used the coordinated control system more completely. The coordination ability between the furnaces is obviously higher than that of the manual state. The unit efficiency has been revealed. Because the coordinated control operates strictly according to the set curve, The parameter control is in place to ensure the safe operation of the unit. Although the benefits are obvious, there are still many unsatisfactory aspects in the actual operation. It is also necessary to solve the problem together with the staff and professionals, and conclude a more mature coordinated control method.
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