第十一章 压缩机控制.doc

11 COMPRESSOR CONTROLS压缩机控制11.1 GENERAL DESCRIPTION概述11.1.1 Antisurge Control System反喘振控制系统The antisurge control system prevents compressor surge by recycling process gas, reducing head and increasing flow through the compressor.反喘振控制系统通过循环处理气，减少压差和增加流过压缩机的流量来防止压缩机喘振。The antisurge control system consists of pressure transmitters and temperature detectors at the suction and discharge sides of the compressor, a flow transmitter across the suction line orifice, an algorithm in the control system, and a recycle control valve with accessories.反喘振控制系统由压缩机入口和出口侧的压力变送器和温度探测器，入口管线上有一个流量变送器，控制系统里的一个运算法则，和一个再循环控制阀及其附件。When conditions fall below the surge protection margin, the control system opens the recycle valve. When conditions return to greater than the surge protection margin, the control system closes the recycle valve. Figure 11.1.1 is an antisurge system diagram.当条件降到喘振保护极限，控制系统打开再循环阀。当条件回到大于喘振保护极限，控制系统关闭再循环阀。图11.1.1是一个反喘振系统图。Figure 11.1.1 Antisurge Control System Diagram图11.1.1反喘振控制系统图View graphic看图SURGE DETECTOR喘振探测器Rapid decreases in compressor flow indicate compressor surge. The surge detector in the antisurge system monitors flow through the compressor and counts flow rate pulses. A pulse is a 25 percent decrease in flow. Each pulse opens the recycle valve 15 percent. Five pulses in ten seconds shuts down the engine.压缩机流量迅速减少显示压缩机喘振。反喘振系统里的喘振探测器监视流过压缩机的流量和计算流度脉冲。一个脉冲是25%的流量减少。每个脉冲打开再循环阀15%。十秒五个脉冲将关闭引擎。11.1.2 Process Control System过程控制系统Process control maintains control parameter(s) at selected setpoint(s) by modifying the turbines gas producer speed (Ngp), and if necessary by opening the recycle valve.过程控制通过修改透平压气机的速度(Ngp)来在选择的设定点维护控制参数，如果需要打开再循环阀。The three-loop process control system regulates engine speed and recycle valve position to control suction pressure, discharge pressure, and suction flow process variables. The antisurge system works with process control and overrides it when necessary.三回路过程控制系统调节引擎速度和再循环阀位置来控制入口压力，出口压力，和入口流量工艺参数。反喘振系统可过程控制一起运行，必要时优先于过程控制。For settings and operating design values not discussed in this chapter refer to the Balance of Plant Specification.设置和操作的设计值在本章节内没有进行讨论，查阅设备平衡规范。11.2 FUNCTIONAL DESCRIPTION功能描述11.2.1 Antisurge Control System反喘振控制系统MEASURED PARAMETERS测量参数The antisurge system monitors:反喘振系统监控： Pressure drop across a flow measuring element (hw)流量测量元件的压力(hw) Suction and discharge pressures (P2 and P1)入口和出口压力(P2 和 P1) Suction and discharge temperatures (T2 and T1)入口和出口温度(T2 和 T1)THE SURGE LIMIT MODEL喘振限制模型The compressors surge limit is modeled over the compressors operating speed. 在压缩机运行速度上建立压缩机喘振限制模型。The Y-axis and X-axis are (P2 / P1)(n-1)/n)-1 / (n-1) / n versus hw/P11/2. The foregoing are termed reduced head and reduced flow as the common factors (T, Z, and SG) in the head and flow calculation equations are cancelled.Y轴和X轴是(P2 / P1)(n-1)/n)-1 / (n-1) / n与hw/P11/2 相对。前面的减少压差和减少流量做为公因数(T, Z, 和 SG)在压差和流量计算方程式里被删除。X and Y values are expressed as 0 to 100 percent.X和Y值表示成百分之0到100。The polytropic exponent (n-1) / n equals (log (T2 / T1) / log (P2 / P1).多变指数(n-1) / n等于(log (T2 / T1) / log (P2 / P1)。T1 and T2 are suction and discharge temperatures.T1和T2是入口和出口温度。P1 and P2 are suction and discharge pressures.P1和P2是入口和出口压力。SG is gas specific gravity.SG是气体比重。Z is gas compressibility.Z是气体可压缩性。Flow differential pressure (DP) in inches of water is expressed as hw.水流量压差（DP）微动用hw表示。The surge limit model is a third-order polynomial of the form:喘振限制模型是一个三次多项式形式：X = AY3 + BY2 + CY + DNOTE注意The foregoing equation is written unconventionally to show that the independent variable in the calculation is reduced head, or the Y axis value. The dependent variable is reduced flow, or the X axis value. Reduced head is input, and reduced flow is calculated.上面写出的方程式不依惯例，显示计算中的自变量是减少压差或Y轴值。因变量是减少流量，或X轴值。减少压差是输入，减少流量是计算出的。From the operating point Y value (reduced head), the X value (reduced flow), at surge (Xs), can be calculated using the polynomial. Then Xs is multiplied by the sum of one (1) plus the desired protection margin (typically 10 percent) to get the control point Xc. Then Xc (control) is subtracted from X (operating) to find the error.从运行点Y值(减少压差)，X值（减少流量），喘振(Xs)，利用多项式可以计算出来。Xs被乘上1加预期保护极限（一般为10%）的和便得到控制点Xc。这时Xc（控制）被从X（运行）里减去来发现错误。P+I ALGORITHM P+I算法The Solar antisurge controller combines proportional plus integral control modes. The controller function used in the Solar antisurge control loop is:索拉反喘振控制器是比例加积分控制模式。在索拉反喘振控制回路中的控制器函数是：Proportional Term = OP + KP(E0-E1) 比例项 = OP + KP(E0-E1)Integral Term = 0.5(KI)(T)(E0+E1) 积分项 = 0.5(KI)(T)(E0+E1)Derivative Term = (KD)(E0-2E1+E2)/(T) 微分项 = (KD)(E0-2E1+E2)/(T)Then,于是Output = P+I+D 输出 = P+I+DWhere:这里：OP = Output输出KP = Proportional Gain比例增益KI = Integral Gain积分增益KD = Derivative Gain微分增益E0 = Current Error电流错误E1 = Immediately past Error立即通过错误E2 = Error before E1 E1前的错误The control algorithm is described in the following figures.控制算法在下图中有描述Figure 11.2.1 depicts the top control function which takes output from each of the following subroutines, and which dispatches control commands.图11.2.1描述了顶部控制功能，从下面每个子程序获得输出，分派控制命令。Figure 11.2.1 Head versus Flow Antisurge Control Flow Diagram图11.2.1与流量相对的压差反喘振控制流程图View graphic 1图1View graphic 2图2View graphic 3图3Figure 11.2.2 is the filter subroutine to the programmable logic controller (PLC) where process variables are filtered to remove excessive signal noise. From a process variable, FLTR_PV, the last filtered process variable, FLTR_PVF, and the filter constant, FLTR_KF, a new filtered process variable, FLTR_PVF, is generated based on a filter gain FLTR_KF. Maximum and minimum values for the process variable are also generated. The filter constant must be between 0 and +1, or the unfiltered value is returned, indicating the signal was not excessively noisy.图11.2.2是可编程逻辑控制器(PLC)的过滤器子程序，工艺参数被过滤除去额外的信号噪音。从工艺参数FLTR_PV，最后过滤的工艺参数FLTR_PVF，和过滤器常量FLTR_KF，新过滤的工艺参数FLTR_PVF，基于过滤器增益FLTR_KF产生。同样产生工艺参数的最大和最小值。过滤器常量必须在0到+1间，否则没有过滤的值将返回，说明信号不是非常地吵杂。Figure 11.2.2 Filter Diagram图11.2.2过滤器图View graphic看图In the antisurge control logic diagram Figure 11.2.3, X values, ASC_XAXIS, and Y values, ASC_YAXIS, are calculated using the input parameters suction pressure, ASC_SUCPRS, discharge pressure, ASC_DISPRS, suction temperature, ASC_SUCTMP, discharge temperature ASC_DISTMP, and differential pressure across the flow meter, ASC_FLOWDP. Pressures are in psi, temperatures are in degrees F, and flow meter differential pressure is in inches of water. Global parameters, that is, values which are used in the calculation, but not returned as output are polytropic exponent, ASC_PLYEXP, pressure ratio, ASC_PR, and temperature ratio, ASC_TR. The polytropic exponent is a function of gas properties and the efficiency of the compression process. It is the exponent that directly relates the actual temperature rise to the pressure rise.反喘振控制逻辑图11.2.3，X值ASC_XAXIS，和Y值ASC_YAXIS，利用输入参数入口压力ASC_SUCTMP,出口压力ASC_DISPRS,入口温度ASC_SUCTMP，出口温度ASC_DISTMP,和流过流量计的压差ASC_FLOWDP可以计算出来。压力单位psi，温度单位是F，流量计压差是水的英寸数。全局参数在计算中使用，但作为输出返回，是多变指数ASC_PLYEX，压力比率ASC_PR,和温度比率ASC_TR。多变指数是气体道具和压缩机处理效率的一个函数。它是直接联系实际温度上升和压力上升的指数。Figure 11.2.3 Antisurge System Control Logic Diagram图11.2.3反喘振系统控制逻辑图View graphic图In the polynomial equation subroutine (Figure 11.2.4), surge margins are determined by analysis of the X and Y values generated by the routine depicted in Figure 11.2.4. A Y value, POLYEQNY, is calculated using the input variable X, POLYEQNX, and the input coefficients POLYEQNA, POLYEQNB, POLYEQNC, and POLYEQND. The constant factors POLYFCTA, POLYFCTB, and POLYFCTC are used in the calculation but are not returned as output. The result is limited by POLYMAX and POLYMIN, values which approximately define the upper 50 percent of the compressors operating speed.多项式方程子程序里（图11.2.4），喘振极限由分析图11.2.4里描述的程序产生的X和Y值决定。Y值POLYEQNY是利用输入变量X POLYEQNX和输入系数POLYEQNA, POLYEQNB, POLYEQNC, 和 POLYEQND计算出来的。常因子POLYFCTA, POLYFCTB, 和 POLYFCTC在计算中使用但不作为输出返回。结果受POLYMAX 和 POLYMIN的限制，值大约是压缩机运行速度的50%以上。Figure 11.2.4 Polynomial Equation Diagram图11.2.4多项式方程图View graphic图The controller function in the PLC acts to reduce the process error by opening the recycle control valve. PLC里的控制器函数通过打开再循环控制阀减少过程错误。The routine depicted in Figure 11.2.5, similar to the preceding figure, calculates errors and returns them without modification.图11.2.5里描述的程序同前面的图相似，计算错误并没有修改就返回。Figure 11.2.5 Error Flow Diagram图11.2.5错误流程图View graphic图The routine depicted in Figure 11.2.6 selects gains based on the operating position relative to the control line. The gains move the recycle control valve. High gains are output when the compressor has a insufficient surge margin, in which case, the operating point is shown on the surge display X:Y plot to the left of the desired range, and the recycle valve is opened. Low gains are output when the compressor has a large surge margin, in which case, the operating point is shown on the surge display X:Y plot to the right of the desired range, and the recycle valve is closed. Inputs are the previous output, PID_OP, and proportional, integral, and derivative gains, PID_KP, PID_KI, and PID_KD. Errors, PID_E0, PID_E1, PID_E2, are also input. A new gain output, PID_OP, between 0 and 100, is output.图11.2.6里描述的程序选择基于相对于控制线的运行位置的增益。这些增益移动再循环控制阀。当压缩机喘振极限不足时输出高增益，这种情况下，运行点在预置范围的左边喘振显示X：Y区域出现，并且再循环阀打开。当压缩机喘振极限足够时输出低增益，这种情况下，运行点在预置范围的右边喘振显示X：Y区域出现，并且再循环阀关闭。输入优先于输出PID_OP，比例，积分和微分增益PID_KP, PID_KI, 和 PID_KD。错误PID_E0, PID_E1, PID_E2也是输入。在0到100之间的一个新增益输出PID_OP，是输出。Figure 11.2.6 PID Controller Flow Diagram图11.2.6PID控制器流程图View graphic图CONSTANTS常数Table 11.2.1 describes operator-set constant values, Kvals, which are used in the programmable logic controller (PLC) algorithm.表11.2.1描述了操作员设置常量值Kvals,在可编程逻辑控制器(PLC)运算中使用。Table 11.2.1 Operator-Set Constant Values, Kvals表11.2.1操作员设定常量值KvalsSymbol符号Description描述HPC KPFASTProportional gain limit比例增益极限HPC KIFASTIntegral gain limit积分增益极限HPC KPSLOWProportional gain limit比例增益极限HPC KISLOWIntegral gain limit积分增益极限Table 11.2.2 describes programmed constant values, Kvals, which are used in the PLC.表11.2.2描述了在PLC中使用的编程常量值Kvals。Table 11.2.2 Programmed Constant Values, Kvals编程常量值KvalsSymbol符号Description描述HPC KCLFCTSurge margin喘振极限HPC KDBFCTDeadband width死区宽度HPC SCVOPNManual opening rate手动打开比率HPC SCVCLSManual closing rate手动关闭比率HPC QXMTRFlow transmitter range流量变送器范围HPCSUCPXMTSuction pressure transmitter range入口压力变送器范围HPCDISPXMTDischarge pressure transmitter range出口压力变送器范围NGPLOADSPNgp load speed NGP负荷速度HPCASC_ACoefficient, 3rd order polynomial三次多项式系数HPCASC_BCoefficient, 3rd order polynomial三次多项式系数HPCASC _CCoefficient, 3rd order polynomial三次多项式系数HPCASC _DCoefficient, 3rd order polynomial三次多项式系数HPCASCXMAXEquation range limit方程范围限制HPCASCYMINEquation range limit方程范围限制HPCASCYMAXEquation range limit方程范围限制LPCASC_KFFilter constant过滤器常数SURGE DETECTOR喘振探测器The surge detector operates as part of the antisurge system. The differential pressure across the flow orifice is used to compute the rate-of-decrease of flow through the compressor and is compared to a preset value. If the maximum value exceeds the minimum value by a preset amount (typically 25 percent), one pulse is counted, and the recycle valve is opened 20 percent. If five pulses occur within ten seconds, the engine is shut down and a message indicating that the compressor is in surge appears on the display terminal.喘振探测器是反喘振系统的一部分。通过流量孔的压差用来计算流过压缩机的流量的减少比率，并与预置值进行比较。如果最大值超过最小值的百分数（一般为25%），计算为一个脉冲，再循环阀打开20%。如果十秒内产生五个脉冲，引擎将关闭并在终端显示器上出现压缩机在喘振的信息。For single pulses or less than five pulses in a ten-second period, the recycle valve closes comparatively slowly. Closure from fully open requires about a minute, while opening requires milliseconds.因为单个或十秒内少于五个脉冲，再循环阀关闭相当慢。从全开到关闭大概需要一分钟，打开需要几毫秒。SYSTEM OPERATION系统运行The antisurge control loop is disabled until engine speed is greater than a preset value. Below this value, the recycle control valve is fully open to allow maximum gas flow through the compressor.反喘振控制回路直到引擎速度高于预置值时才起作用。在这个值下时，再循环控制阀全开来让做大气体量流入压缩机。Above loading speed, the antisurge control system is enabled and the recycle valve can be closed. Pressures and temperatures in the suction and discharge lines are measured and head across the compressor is calculated. Flow through the compressor is determined by measuring pressure drop across an orifice in the suction line, discharge line, or compressor impeller eye. Signals from these transmitters are processed by the control system. If the surge margin falls below a preset value, the signal to the recycle valve is reduced. The recycle valve opens a fraction proportional to the signal value. With the valve opened, a portion of the gas from the discharge side of the compressor is routed back to the suction side, and flow through the compressor increases. When the condition that caused the antisurge action disappears, the recycle control valve closes and the compressor resumes normal operation.负荷速度之上，反喘振控制系统起作用并能关闭再循环阀。测量入口和出口管线的压力和温度，计算流过压缩机的压差。通过压缩机的流量由测量通过入口管线、出口管线或压缩机叶轮入口孔板的压力决定。从这些变送器来的信号被控制系统处理。如果喘振极限降到预置值以下，去再循环阀的信号减少。再循环阀按信号值比例打开一点点。随着阀的打开，压缩机出口侧的一部分气体返回到入口侧，压缩机的流量增加。当导致反喘振动作的条件消失，再循环阀关闭并且压缩机恢复正常运行。DISPLAY显示This section describes the techniques typically used to construct the antisurge control display screen.本节描述了用于建立反喘振控制显示屏的一般技术。On the left of the screen, operating mode, operating conditions, setpoint, valve position and engine speed are displayed.屏幕左边显示有运行模式，运行状态，设定点，阀的位置和引擎速度。On the right of the screen is an X:Y plot showing surge limits and operating point. For display, X and Y values are converted to percentages. A white cross defining a point, X, Y, shows the operating point. Plus and minus one (1) are added to the operating point Y, providing Y and Y. X and X are then calculated using the polynomial equation providing Y and Y. X Y and X, Yare two points at the surge limit.屏幕右边是一个显示喘振极限和运行点的X:Y区域。为了显示，X和Y值被转换成百分数。一个白十字定义一个点，X，Y，显示运行点。运行点Y加上正负1，得到Y和 Y。利用Y和 Y多项式方程计算出X和 X。X Y 和 X, Y是喘振极限上的两个点。The displayed surge limit takes the form:显示的喘振极限变成下面形式：Y = MX + BWhere这里(X - X)/(Y - Y) = MB = Y - MXM = KSL = slope of the surge line喘振线的斜率B = SLB = Y intercept for KSL, KCL, AND KDBThe following three lines are displayed on the screen:下面三条线在屏幕上显示：KSL = slope of surge limit, SURGE LINE,喘振极限的斜率，喘振线，KCL = slope of the control line, CONTROL LINE,控制线的斜率，控制线，KDB = slope of the deadband line, DEADBAND LINE,死区线的斜率，死区线，Where这里KCL = KSL times 1 plus desired protection margin KSL时间1加期望保护的极限KDB = KCL times 1 plus desired deadband width KCL时间1加期望的死区宽度Figure 11.2.7 graphically describes the development of these control lines.图11.2.7绘出了这些控制线的走向Figure 11.2.7 Display Screen Development图11.2.7显示屏走向View graphic图Antisurge control screens are shown in Figures 11.2.8 and 11.2.9.反喘振空子屏在图11.2.8和11.2.9显示。Figure 11.2.8 Antisurge Control Screen图11.2.8反喘振控制屏View graphic图Figure 11.2.9 Antisurge Control Screen图11.2.9反喘振控制屏View graphic图Figure 11.2.10 is a flow diagram for an algorithm that develops the antisurge control screen.图11.2.10是反喘振控制屏走向的计算流程图Figure 11.2.10 Antisurge Control Screen Algorithm反喘振控制屏计算View graphic图11.2.2 Process Control System过程控制系统During operation, the process control system continually monitors and controls turbine engine/compressor speed.运行期间，过程控制系统不断监视和控制透平引擎/压缩机速度。Typical process control screens are shown in Figure 11.2.11 and 11.2.12.典型的过程控制屏在图11.2.11和11.2.12里显示。Figure 11.2.11 Digital Display Process Control Screen图11.2.11数字显示过程控制屏View graphic图Figure 11.2.12 Process Control Screen图11.2.12过程控制屏View graphic图When the control system is in the LOCAL mode, the increase (INC) and decrease (DEC) pushbuttons on the turbine control panel are active for the selected setpoint: NGP, DIS PRS (discharge pressure), SUC PRS (suction pressure), or FLOW. The selected setpoint is highlighted, and blue up and down triangles appear next to the local setpoint value to indicate the setpoint the pushbuttons are controlling.当控制系统在LOCAL（就地）模式，透平控制面板上的增加（INC）和减少（DEC）按钮能调整选择的设定点：NPG，DIS PRS（出口压力），SUC PRS（入口压力），或FLOW。被选择的设定点突出来，蓝色上和下三角形出现在本地设定值显示设定点按钮在控制中。When the control system is in the REM (Remote) mode, the setpoint is controlled by an external source.当控制系统在REM（遥控）模式，设定点由外部源控制。When the load setpoint is in MAN (Manual), the unit NGP setpoint is controlled by a local or remote setpoint. When the load setpoint is in AUT (Auto) mode, the unit setpoint is controlled by process control or load share control setpoints. To select the control mode, press the MAN/AUTO Switch on the turbine control panel, or, on the PROCESS CONTROL screen, use the keyboard up, down, left, right arrows to position the asterisk on the LOAD SET POINT MODE selection and press CNTRL/ENTER to toggle between MAN and AUT. When the LOAD SET POINT MODE selection is in MAN, the OFF/ON asterisk label changes from LOAD SHARE MODE to NGP MSTR (master) MODE.当负载设定点是MAN（手动），NGP设定点受本地或遥控设定点控制。当负载设定点在AUT（自动）模式，设定点受过程控制或负载共享控制设定点控制。按透平控制面板上的MAN/AUTO开关或在压力控制屏上用键盘上，下，左，右箭头让星号位于LOAD SET POINT MODE选择处并按CNTRL/ENTER键选定MAN或AUT。当LOAD SET POINT MODE 选择是MAN，OFF/ON星号标签由LOAD SHARE MODE 改变到NGP MSTR MODE。MULTIPLE PROCESS CONTROL多过程控制With multiple process control, the lower error_gain value is chosen (minimum speed setpoint) by the system (MIN GATE). The selected error_gain parameter goes to the integrator which brings the error to zero by changing the actual gas producer speed setpoint. See Figure 11.2.13.使用多过程控制，低级错误增益值被系统（MIN GATE）选定（最小速度设定点）。被选择的错误增益参数进入积分器，积分器通过改变实际压气机速度设定点来将错误变成零。If the compressor operating point is in or to the left of the antisurge control deadband, the gas producer rate of change is reduced (typically, to 0.1%/second).如果压缩机运行点在反喘振控制死区里面或左边，压气机速度改变减小（一般，到0.1%/秒）。Figure 11.2.13 Multiple Pr