Numerical and experimental investigation of leakage behavior at null position of high-pressure electro-pneumatic servo valve

The high-pressure electro-pneumatic servo valve(HESV)is a core element of the high-pressure pneumatic servo system.The annular clearance and the rounded corner of the spool-sleeve can cause the leakage at null position,thereby affecting high-precision control and stability of the servo system.This paper investigates the effects of the clearance structure on leakage behavior at null position of the HESV.A numerical approach was employed to evaluate the effects,and then a mathematical model was established to obtain the variation law of leakage flow rate at null position.The results indicate that the leakage flow rate at null position varies linearly with supply pressure and rounded corner radius,and is nonlinear as a quadratic concave function with annular clearance.The leakage flow rate of the annular clearance and the rounded corner varies with the valve opening in an invariable−nonlinear−linear trend.A test rig system of leakage behavior at null position of the HESV was built to confirm the validity of the numerical model,which agrees well with the conducted experimental study.

Development of a Novel Parallel-spool Pilot Operated High-pressure Solenoid Valve with High Flow Rate and High Speed

High-pressure solenoid valve with high flow rate and high speed is a key component in an underwater driving system.However,traditional single spool pilot operated valve cannot meet the demands of both high flow rate and high speed simultaneously.A new structure for a high pressure solenoid valve is needed to meet the demand of the underwater driving system.A novel parallel-spool pilot operated high-pressure solenoid valve is proposed to overcome the drawback of the current single spool design.Mathematical models of the opening process and flow rate of the valve are established.Opening response time of the valve is subdivided into 4 parts to analyze the properties of the opening response.Corresponding formulas to solve 4 parts of the response time are derived.Key factors that influence the opening response time are analyzed.According to the mathematical model of the valve,a simulation of the opening process is carried out by MATLAB.Parameters are chosen based on theoretical analysis to design the test prototype of the new type of valve.Opening response time of the designed valve is tested by verifying response of the current in the coil and displacement of the main valve spool.The experimental results are in agreement with the simulated results,therefore the validity of the theoretical analysis is verified.Experimental opening response time of the valve is 48.3 ms at working pressure of 10 MPa.The flow capacity test shows that the largest effective area is 126 mm2 and the largest air flow rate is 2320 L/s.According to the result of the load driving test,the valve can meet the demands of the driving system.The proposed valve with parallel spools provides a new method for the design of a high-pressure valve with fast response and large flow rate.

Simulation research on dynamic performance of the new type high-pressure solenoid valve

To improve energy density,the transportation,storage,and operations of hydrogen,methane,and compressed air vehicles currently require high-pressure compression.High-pressure solenoid valve becomes the vital element to above system.In order to reduce leakage and aerodynamic force influence,a new type high-pressure solenoid valve was proposed.The simulation model which included electromagnetic model,aerodynamic force model was established by means of the nonlinear mathematic models.Using the software MATLAB/Simulink for simulation,the dynamic response characteristics of high-pressure pneumatic solenoid valve were obtained under different pulse width modulation(PWM)input control signals.Results show that,first of all,the new type of high-pressure solenoid valve can meet the switch requirement.Secondly,the opening movement and closing movement of the spool lags the PWM rising signal,and the coil current fluctuates significantly during the movement of the spool.Lastly,on/off status of high-pressure valve cannot be represented by the duty cycle.This research can be referred in the design of the high-pressure solenoid valve..

单喷嘴挡板电液阀关键参数正交试验优化设计

介绍了一种电液调速器及该调速器上使用的单喷嘴挡板电液阀的工作原理,并以此建立AMESim模型。对单喷嘴挡板电液阀的5个关键结构参数采用正交试验分析方法,仿真分析其对性能的影响,优选出这些关键结构参数的组合方案。此方法可确定电液调速器用电液阀的关键结构参数的最优值。

功阁水电站3^(#)机调速器异响的故障分析

功阁水电站调速器操作油压由4 MPa改为16 MPa后,在运行的过程中,特别是在微调减出力时,调速器液压系统内部发出异响,调节过程有一定的波动,且给运行人员造成一定的心理压力。经分析是导叶接力器、水轮机重锤和导叶控制阀三者不匹配造成的。测试表明,通过减轻重锤重量和减小开腔背压都可以达到消除异响的效果,最终采取了在调速器液压锁开腔下部增加一个平衡阀组使开腔的背压与关腔压力保持平衡,从而异响消除,机组稳定运行。这种现象在多个水电站出现过,具有一定的普遍性,故在此撰文以飨读者。

Seal contact performance analysis of soft seals on high-pressure hydrogen charge valves

The charge valve is an important element in the charging port of a high-pressure hydrogen storage cylinder(HP-HSC).It is normally closed after the HP-HSC is filled with hydrogen.If the seal of the charge valve is damaged,it will seriously affect the stable operation of the hydrogen supply system and may even cause safety problems.Therefore,the seal performance of the charge valve is important.In this paper,finite element analysis(FEA)is carried out to analyze the seal contact performance of hydrogenated nitrile rubber(HNBR)gaskets in the seal pair of a charge valve.The effects of different pre-compressions,seal widths,and hydrogen pressures on the seal contact performance of the charge valve are analyzed.The contact pressure on the seal surface increases with the increase of pre-compression.With a pre-compression of 2.5 mm,the maximum contact pressure without and with hydrogen pressure are 68.51 and 107.38 MPa,respectively.A contact gap appears in the inner ring of the seal surface with pre-compression below 0.15 mm.The contact gap occurs between the entire seal surface with a seal width of1 mm.The contact pressure on the seal surface and the width of the separation area between the seal surfaces increase with the increase of the seal width.The contact gap between the seal surfaces is zero with a width of 2.5 mm.The width of the separation area between the seal surfaces decreases with the decrease of the hydrogen pressure.The width of the separation area is reduced from 0.5 mm at 35 MPa to 0.17 mm at 15 MPa.This work can be useful for improvement of the seal performance and of the design of the charge valve used in the HP-HSC.

SWT Microcomputer-Based Hydro-Turbine Governor

This paper presents a new microcomputer-based hydro-turbine governor type SWT and introduces the system structure and the main function of the governor. By comparison with other governors used at present, the paper expounds the merits of the SWT microcomputer-based governor.

基于PLC的水轮机微机调速器设计

水轮机调速器是水电站实现自动化控制的主要设备之一。它的结构及其控制方式合理与否直接影响着电站输出的交流电的品质,关系着电站设备的运行安全。本文介绍了一种基于PLC采用PID控制算法的水轮机调速器的系统结构设计,利用PLC主单元内置的计时器、V/F转换器设计模拟测频电路,编写了PLC控制程序,输出两路PWM脉冲信控制随动系统的两个高速开关阀动作,优化了水轮机微机调速器的调节和控制功能,减少了程序执行时间,增强了调速器的实时性和可靠性。

某水电厂水轮机调速器紧急停机装置迭代升级研究

水轮机调速器紧急停机装置既要满足二十五项反措中“失电动作”的要求,又要避免装置电磁阀线圈长期带电易烧损带来的机组非计划停运隐患。介绍了某大型水电厂水轮机调速器紧急停机装置从双电磁铁两位电磁阀、单电磁铁弹簧复位二位电磁阀到基于双电磁阀搭配联动阀的三代技术改进历程,阐述其工作原理,对比其各自优劣。证实基于双电磁阀搭配联动阀的水轮机调速器紧急停机装置是实用可靠的调速系统急停控制优化方案,在水电厂极具推广价值。

某大型水力发电厂油压装置异常情况分析

油压装置是水轮发电机组调速器、筒阀等设备的重要组成部分,为其工作提供必要的清洁压力油和接受操作后的回油。油压装置故障将直接影响调速器、筒阀等设备的正常工作,故障严重时将迫使机组停运。掌握油压装置常见异常,提前发现异常,处理异常,是控制事故扩大的根源。根据油压装置故障历史事件,结合监控系统历史数据服务器记录数据,总结油压装置常见异常情况,辅助运行值班人员掌握油压装置运行工况。

大型水轮机组调速器比例伺服阀故障报警分析与处理

介绍了梨园电厂SAFR-2000H型调速器在机组运行过程中报比例伺服阀2故障,停机后对故障原因进行逐步排查,最终确定为主配位移传感器2异常,引起调速器机械柜内综合控制模块2与功放板2控制比例伺服阀2长期单端带电,达到一定电压值后引起上位机频繁报警,更换主配位移传感器2后调速器报警消失。

某电站3号机调速器油泵频繁启动原因及处置

调速器是水电站的重要设备,调速器压油泵频繁启动威胁机组正常运行。通过对某水电站3号机调速器压油泵频繁启动的现象进行收集,分析出频繁启动的原因,给出相应处置建议,成功保障机组的安全稳定运行,也为其他水电站处置类似故障提供借鉴。

水轮机分段关闭装置误投故障分析与处理

为分析中亚某水电站水轮机分段关闭装置误投故障的原因,通过介绍调速器机械液压控制系统的结构及原理,并分析机械液压系统油路,发现事故配压阀动作后由于压力油供油管内流速过快,致使分段关闭装置的控制腔压力降低而误动,因接力器关闭时间过长导致水轮发电机组转速过高。提出将分段关闭装置控制压力油的取油口从事故配压阀主压力油供油管移至调速器系统储能罐上的方案,通过效果测试证明了该方案的可行性。

某船发电柴油机飞车故障分析与处理

文章根据某船发电柴油机在运行时出现飞车的故障实例,通过分析调速器和燃油停车装置工作原理,找到故障产生的原因。调速器的转速超调是引起该故障的原因,而发电柴油机燃油停车装置故障造成了调速器转速超调。分别对调速器、燃油停车装置和控制空气系统电磁阀进行调整和修理,排除了故障。

非洲伊辛巴水电站控制设备故障分析处理

针对非洲伊辛巴水电站转子接地故障和调速器油压装置故障,详细介绍了其原因分析和排查与处理。针对电站转子接地故障,在机组长时间停运或大修后,应对励磁变外壳特别是励磁变柜子散热孔、励磁变的接头、铁芯和浇注绕组之间的双孔等处的渣滓严格清理,经测量励磁变的绝缘应满足国标要求。对调速器油压装置故障,应重点检查和处理组合阀及其内部的阀芯以及槽内的锈斑或卡阻,使组合阀回油腔的油量大小正常。

汽轮机调节汽阀阀碟螺栓故障分析与研究

针对工业汽轮机调节汽阀故障,导致汽轮机停机的问题,对工业汽轮机调节汽阀的结构特点进行了分析研究,对调节汽阀阀碟螺栓断裂和磨损,导致阀碟脱落问题的故障机理及工作环境进行了深入分析研究,提出了减少阀碟螺栓长度、对阀碟螺栓跳档使用及改进阀碟的装配工艺等措施,利用三维软件对其进行建模并利用ANSYS软件对改进前和改进后的阀碟螺栓进行了应力分析。研究结果表明,该方案可以减小阀碟螺栓承受的交变应力,提高阀碟螺栓根部的强度,可以改进因热胀不均而导致螺纹副出现相对位移的情况。结合宁夏石化机组的实际故障案例,通过将该方案应用于该机组中,彻底解决了该机组因阀碟螺栓断裂而导致机组故障问题。

汽轮机超速保护控制系统的性能优化及其对电网频率的影响分析

现代化大型机组的超速保护控制系统(over-speed protection control,OPC)的控制策略如果不当,不仅起不到应有的超速保护作用,而且会造成汽门频繁启闭,产生"乒乓"现象。文章通过对OPC振荡机理的分析,得出系统振荡的根本原因是OPC的控制参数不合理及与其它保护措施不配合。利用OPC的动作特性图得出OPC的动作时限及阀门开度的数学表达式,针对2006年7月7日贵阳南部电网事故提出3种OPC的动作修改方案,并根据实际系统,用NETOMAC程序建立了原动机、调速器和汽轮发电机过速保护的详细模型,通过仿真证明了修改方案的正确性。并提出相应的改进建议。

数字插装式水轮机调速器应用研究

数字插装式调速器作为水轮机调速器控制的一个新方向,已在工程实践中得到了较好的应用,但相关理论和工程应用研究偏少。因此,采用理论和工程应用相结合的方式,论述了数字插装式水轮机调速器在工程应用中重点关注的闭环功率调节、孤网运行、贯流式机组甩负荷低频灭磁和过速等方面的控制策略和规律,总结了数字插装式调速器的工程应用情况,对于解决调速器工程应用中的相关问题有较好借鉴意义。

全数字水轮机调速器电液随动系统的仿真研究

以自行研制的二级全数字电液伺服阀为基础,构造了一个全数字的电液随动系统,通过参数计算和数学模型的建立,以及MATLAB仿真,表明系统具有很好的动态特性,很适合于工程应用。

PWM方式控制的水轮机电液调速器研究

设计并开发了一种基于PLC并采用PID控制算法的水轮机电液调速器。该调速器的电液随动系统以高速开关阀为控制核心,采用PWM脉宽调制方法进行控制。并建立水轮机调速系统的数学模型,在MATLAB SimuLink环境下进行仿真。在实验室进行空载状态下的静特性试验及随动系统扰动试验,证明了系统在此工况下具有较优的控制性能。