Aiming at the security risks of power grid frequency oscillations caused by the external transmission line faults from the eastern developed area,the architecture of automatic generation control between power grid and power plant is analyzed,and a method of online monitoring of the characteristics of primary frequency regulation (PFR) in thermal power units is proposed.Based on the hybrid energy management system,the schematic diagram of PFR online monitoring is designed.According to the engineering practice,the effect of PFR is measured in terms of different evaluation indexes.Considering the performance of ultra-supercritical units and the technology of time division,the control strategy of PFR online monitoring is established.The test results demonstrate satisfactory performance of the proposed online monitoring system.In addition,improvement is made by replacing the original post-faults analysis with pre-faults supervision,and the parameters of PFR can meet all the requirements of dispatching procedures.

二次再热技术以其较高的经济性正得到越来越广泛的应用,我国目前尚无二次再热机组工程投产的实例,相关启动运行经验较为缺乏.以国内第1台660MW等级超超临界二次再热锅炉为研究对象,介绍了机组锅炉的主要特点,并从冷态通风试验、新型吹管工艺、低负荷稳燃、燃烧初调整等方面阐述了二次再热锅炉关键调试技术.针对机组试运行期间出现的燃烧器、风机、控制逻辑等问题给出了解决办法.经过调整优化,机组运行稳定、性能可靠,各项参数均达到了投产要求.

In an ultra supercritical 1000 MW double-reheat unit, the control strategy of water-coal ratio is coal follows water. To adapt the dramatic increase in the unit's thermal inertia, the coal-water ratio control strategy was changed into the one that coal follows water mainly in the dynamic process and water follows coal mainly in the steady process. The two control strategies cross each other, which not only can adjust the intermediate point temperature quickly to ensure the safe and stability of the unit, but also can reduce the deviation of the main steam pressure to satisfy the requirements of AGC and the primary frequency control. The research provides a new idea for control strategy of coal-water ratio for the double-reheat units.

To explore suitable pipe-blowing methods for ultra supercritical double-reheat units, a decompression combined pipe-blowing method was proposed and put into practice on the domestic first double-reheat boiler. This new method is a combination of "one section pipe-blowing" method's structure and "two-section pipe-blowing" method's operating characteristics. The superheater, primary reheater, secondary reheater and its associated pipelines were connected in series in one time. The whole system is divided into three parts, and each part is purged and targeted separately. For the problem that the steam purge coefficient does not satisfy the standard, field test and theoretical analysis were carried out. Some measures, such as increasing the separator outlet steam pressure, opening multiple valves simultaneously, were taken into practice to eliminate the blocking flow effect and guarantee the purging quality. The final target plate tests results show that, the depression combined pipe-blowing method completed the purging of double-reheat boiler heating surfaces with high quality. This method can provide practical reference for other similar units.

In the first and third stage superheater and two-stage high temperature reheater in a 1000 MW double-reheat unit tower-type boiler, the tube wall temperature is far away over the limit temperature. To solve this problem, many measures related to optimization and modification of the heating surfaces have been proposed, on the basis of the site operation data and simulation thermodynamic calculation results. By cutting two outboard tubes on the secondary superheater, the heat absorption area of the superheater decreased by 28％. By installing throttle short tubes on both sides of the high pressure and low pressure reheaters, the coolant flow rate of the central tube group increased. For some of the seriously over-temperature tubes, part of the high pressure high temperature reheater tubes were cut short and the low pressure high temperature reheater was painted with thermal insulation material. These measures greatly reduced heat absorption of the relevant tubes and the tube wall temperature reduced dramatically. After the comprehensive retrofitting and adjustment, the over-temperature problem of the superheater was basically solved during the boiler load change process. Under full load working conditions, the superheated steam temperature and two-stage reheat steam temperature approached the design value. No metal tube wall temperature alarmed. The comprehensive renovation plan greatly improves the safety and economy of the boiler operation.

Due to the higher thermal efficiency and the lower pollutant emissions,the double-reheat cycle technology is getting moreapplied in the industry..Therefore,the steam blowing process for the new units with double-reheat cycle calls for urgent study.In this paper,an ultra-supercritical 660 MW double-reheat boiler is taken as the study object.Based on the routine one-staged and two-staged pipe-blowing techniques,the three-staged pipe-blowing with pressure-reduction steam is proposed in accordance with the arrangement of the boiler heating surfaces.The results of the target plate test show that the number of the flushed spots are less than 5 and the diameters of the spots are all smaller than 0.5 mm,which completely meets the requirements of the national codes.The three-staged pressure-reduction pipe-blowing method,which produces good blowing quality,can provide practical reference for subsequent units with double reheat technology.

The reheat steam temperature of China's firstly built double-reheat boiler is sharply lower than the design value. To solve this problem, the quality of coal as fired and the heat absorption capacity of the boiler heating surface was analyzed. Moreover, the flue gas recirculation thermal control scheme was improved. On this basis, the comprehensive temperature improvement scheme was proposed, including optimizing the coal mill combination type, regulating the burner elevation angle, increasing the over fired air volume, improving the soot-blower's putting-in-service mode and adjusting the flue gas recirculation amount. Furthermore, the condition test to explore the effect of burner's swinging angle and flue gas recirculation fan speed on temperature of the first reheat and second reheat steam were carried out. After debugging optimization , the reheat steam temperature of the boiler can reach 610～620℃at high load and 590～590℃ at low and medium loads, which are similar with the design value, indicating the problem of low reheat steam temperature was solved well. The debugging experience has project reference value for subsequent similar units.

目前,国内对二次再热超超临界机组再热蒸汽温度控制研究仅限于仿真研究,国内首台投产的二次再热超超临界机组基于国外二次再热超超临界机组的再热蒸汽温度控制,结合成熟的超临界机组再热蒸汽温度控制策略及燃用褐煤机组再热蒸汽温度的烟气再循环控制策略的特点,构建了再热蒸汽温度控制策略.以华能安源电厂二次再热超超临界660 MW机组为对象,探讨和研究其再热蒸汽温度控制策略,并分析了控制难点.结果表明:对于二次再热超超临界机组的再热蒸汽温度控制,在主蒸汽压力、中间点温度投入自动控制方式后,再投入烟气挡板、烟气再循环系统控制,可提高各种扰动下控制系统对再热蒸汽温度的调节品质,且能够满足机组运行的要求;尽管该控制策略以华能安源电厂二次再热超超临界660 MW机组再热蒸汽温度控制为对象,但其仍可为不同再热系统结构的二次再热超超临界机组再热蒸汽温度控制策略设计提供参考.

In the No.1and No.2supercritical 600 MW units in Huaneng Shanghai Shidongkou Second Power Plant,under the unit automatic generation control(AGC),large control deviation of the main steam temperature,main steam pressure and superheating ratio at steam separator intermediate point resulted in low input ratio of the AGC.Combining with the operation situation of the unit,optimization on control logic of several subsystems was performed,such as the unit coordinated control system,the main and reheat steam temperature control system,and the feed flow rate control system.The variable load test with load variation rate of 1.5%/min was conducted on the optimized control system.The results show that,the absolute values of the main steam temperature deviation of the two units during load variation are both below 5 ℃,that of the reheat steam temperature are below 10℃,and that of the superheating ratio at steam separator intermediate point are below 6superheating ratio at steam separator intermediate point.Moreover,the absolute value of the main steam pressure deviation of the two units are both less than 0.6MPa,and that of the power are less than 2MW,indicating the optimized control system makes the fluctuation of the steam turbine regulating valve opening small,and the load response quick,which satisfies the AGC'requirements.

In order to reduce power consumption rate of the unit,the steam-driven induced draft fan(ID fan)was applied to replace the electricity driven ID fan and desulfurization booster fan.Combining with the control requirements like automatic control,rapid runback(RB)and others,the control strategies for furnace pressure of backpressure steam driven ID fan and RB were optimized.The improved control strategies were applied on an ultra supercritical 660MW unit,and good control effect was achieved.

Small capacity of Hainan power grid causes several problems,like frequent primary frequency reg-ulation of the units,long time and large amplitude of single direction movement during primary frequency regulation,and others.Furthermore,as the power grid has two operation modes (networking and isolated grid),the primary frequency control is relatively complex.Therefore,on the basis of analyzing the opera-tion characteristics of Hainan power grid,the primary frequency control strategy of a 350 MW unit was op-timized,to solve the frequent small amplitude primary frequency regulation problem and improve control quality of the primary frequency control.In addition,corresponding optimization on coordinated control system was also conducted to enhance the safety and stability of the unit operation,on the premise of ensu-ring the primary frequency control.

Against such problems as high and variable heating load in co-generation units with reheat steam heating,the coordination control,water/coal ratio control and coal-fired calorific value correction loop (BTU)control were optimized.Moreover,the intercept valve pressure regulating function was added in the turbine digital electro-hydraulic control system (DEH).Thus,the unit load and heat load regulation in the coordination mode was realized,which ensures the security,stability,economic operation of the units.

The circulating fluidized bed(CFB)boiler has good adaptability and variable load capacity,but its large thermal inertia and hysteresis and strong coupling relations between parameters lead to difficulty in putting the automatic control function into service.Therefore,the 330 MW CFB unit manufactured by Harbin Boiler Factory was regarded as the control object,optimization on the major analog coordinated control system was performed,on the basis of ensuring the balance of material,heat and energy between the machine and furnace and so on.After the optimization,the response speed of fuel amount variation on the main steam pressure deviation was improved,and the strong coupling,large inertia and nonlinear of the main steam pressure,bed temperature and bed pressure were overcome.Moreover,the temperature and bed pressure of the CFB with double feet and double grid-plates structure were balanced.

Aiming at decreasing the unit auxiliary power consumption rate,some newly built generator units combined induced draft fan(IDF) with desulphurization booster fan,and adopted steam turbine to drive the IDF.However,this caused changing of IDF closed loop control(stator blade + speed control),and variation of the unit run back(RB) control strategy.According to the problems occurred during the debugging and operation process of the steam turbine driven IDF control for a 1 000 MW unit,optimization measurements such as reserving speed control in the original variable structure,and changing static blade control into liner or manual way were proposed.Application results show that,the optimized control strategy for turbine driven IDF can satisfy the requirements,and has good control effect with unit auxiliary power consumption rate at less than 3%.

Along with the steam turbine-driven IDF gradually applied in 1 000 MW turbine generator units, the related runback (RB) test has received more and more attention. Based on the analysis and summary of the debugging and RB test problems in a 1 000 MW turbine generator unit using steam turbine-driven IDF, this paper suggested the optimization strategy for the control logic of FDF and IDF. The RB test result proves the feasibility of the optimization strategy, which can provide reference for other units that use the steam turbine-driven IDF.

随着汽动引风机在新建1000 MW级汽轮发电机组中被逐步应用,相关的辅机故障减负荷(run back,RB)试验受到了越来越多的关注.基于对某台采用汽动引风机的1000 MW级汽轮发电机组在调试、RB试验中出现问题的分析和总结,提出了送、引风机控制逻辑的优化策略.通过RB试验的严峻考验,证明了该优化策略的可行性,可为其他采用汽动引风机的机组提供相关借鉴.

With the coal-fired units large-scale in China and for reducing auxiliary power rate,the draft fan and the booster fan for desulfurization are combined firstly in 1 000 MW unit and driven by the steam turbine.The operation mode,sequential control and automatic adjustment(including stationary blade control,speed control and RB control) change for the turbine-driven fan under various operation conditions of units.Therefore,from the engineering application point of view,the traditional control strategies must be modified by field tests,for achieving the above control and ensuring the safe and stable operation of the units.After repeated trials and optimizations,the auxiliary power rate is reduced 1.27%.The difficulties,key points,problems and solutions during the control are summarized,providing references for other units saving energy.

随着大型循环流化床机组的投产,流化床机组自身存在的热惯性大、迟滞性大、参数间耦合关系强烈的特点,使机组的自动控制及自动发电量控制(automatic generation control,AGC)功能的投入存在很大困难.通过对首台国产化300 MW外置循环流化床机组协调控制策略等的优化,克服流化床机组热惯性问题,在保证运行过程的物料平衡、能量平衡以及两侧床压平衡(防止翻床)的基础上,优化协调控制系统,通过控制燃料量变化来提高对主汽压力偏差的响应速度,优化上、下层二次风量的控制来提高流化床锅炉的燃烧率,克服主蒸汽压力、床温、床压的强耦合,适应炉内大量床料的存在所产生的大惯性、非线性,最终投入AGC功能,取得满意的效果.