3.通過比較“內(nèi)部”的IntCalcSPLo和IntCalcSPHi值與(HMI)用戶指定的SPLo和SPHi值，確定SP限是否被送到SMOCPro內(nèi)核。被送往內(nèi)核的實際SPs是處于最保守的用戶輸入設(shè)定點限和內(nèi)部計算限之間。
值得一提的是，通常情況下不會超出用戶輸入的SP限。但如果當(dāng)前SP值碰巧位于用戶設(shè)定限外，通常提供的計算SP限將以最大允許變化率（Max Move Size最大動作幅度）將MV驅(qū)動回允許區(qū)域。
從圖1可以看出，如果dSPdVLo和dSPdVHi值選擇過小，內(nèi)部計算的IntCalcSPLo和IntCalcSPHi限近似值可能會大大偏離真實限。在圖中的計算我們高亮了相關(guān)參數(shù)，其中用戶必須輸入的需要值用紅色塊表示，而對某一給定OP值由SMOCPro計算出的值則用藍(lán)色塊表示。下列指南給出了如何設(shè)置dSPdVLo/Hi參數(shù)的內(nèi)容。
| 用戶指定輸入| |
| ------------- |:-------------:| :-----:|
| OPLo| 閥門操作低限（開度）。|
| OPHi| 閥門操作高限（開度）。|
| SPLo| 最小SP值。|
| SPHi | 最大SP值。|
| dSPdVLo | 在閥門操作低限時，閥位(OP)與操作設(shè)定點（SP）間的增益關(guān)系。|
| dSPdVHi | 在閥門操作高限時，閥位(OP)與操作設(shè)定點（SP）間的增益關(guān)系。|
|SMOCPro 計算值||
| ------------- |:-------------:| :-----:|
|dSPdV |在當(dāng)前操作點閥位值(OP)時閥位(OP)與操作設(shè)定點(SP)之間的增益關(guān)系。|
|IntCalcSPLo |內(nèi)部計算的當(dāng)給定OPLo時最小可達(dá)到SP值。|
|IntCalcSPHi |內(nèi)部計算的當(dāng)給定OPHi時最大可達(dá)到SP值。|
|CalcSPLo |對于給定傳遞到內(nèi)核的OPLo，計算最小可到達(dá)的SP值。|
|CalcSPHi |對于給定傳遞到內(nèi)核的OPLo，計算最大可到達(dá)的SP值。|
SMOCPro dSPdV的數(shù)學(xué)解釋
我們現(xiàn)在提供dSPdV計算的基本步驟。算法的第一步是根據(jù)當(dāng)前的OP, dSPdV計算OP對SP的增益。該值通過用戶指定dSPdVLo/Hi和OPLo/Hi值的內(nèi)插法確定。
一旦dSPdV已經(jīng)確定，下一步就是計算“內(nèi)部”SP限。計算按照下列關(guān)系式進(jìn)行：
原文：
- Determine the SP limits to be sent to the SMOCPro kernel by comparing the “internal” IntCalcSPLo and IntCalcSPHi values to the (HMI) user-specified SPLo and SPHi values. The actual SPs sent to the kernel are the most conservative between the user-entered set point limits and the limits calculated internally.
It is worth mentioning that the SP limits entered by the user are never exceeded by the routine. Also, if the current SP value happens to be outside the user-set limits, the routine provides calculated SP limits to drive the MV back towards the allowed region, at the maximum allowable rate-of-change (Max Move Size).
In Figure 1, it can be seen that the internally calculated IntCalcSPLo and IntCalcSPHi limits are approximations that can be quite far off the real limits if the dSPdVLo and dSPdVHi values are chosen too small. We highlight the parameters involved in the calculation in the figure, where the required values that the user must specify are shown in red blocks and the values that are calculated by SMOCPro for a given OP value are encased in blue blocks. Guidelines are given below on how to set the dSPdVLo/Hi parameters.
| User-specified Inputs| |
| ------------- |:-------------:| :-----:|
| OPLo | The valve’s low (opening) operating limit.|
| OPHi | The valve’s high (opening) operating limit.|
| SPLo | Minimum SP value.|
| SPHi | Maximum SP value.|
| dSPdVLo | The valve position (OP) to manipulated set point (SP) gain relationship at the valve’s low operating limit.|
| dSPdVHi | The valve position (OP) to manipulated set point (SP) gain relationship at the valve’s high operating limit.|
| SMOCPro calculated Values| |
| ------------- |:-------------:| :-----:|
| dSPdV | The valve position (OP) to manipulated set point (SP) gain relationship at the current valve (OP) operating point.|
| IntCalcSPLo | Internally calculated minimum achievable SP value for the given OPLo.|
| IntCalcSPHi | Internally calculated maximum achievable SP value for the given OPHi.|
| CalcSPLo | Calculated minimum achievable SP value for the given OPLo passed to the kernel.|
| CalcSPHi | Calculated maximum achievable SP value for the given OPHi passed to the kernel.|
**SMOCPro dSPdV Mathematical Explanation **
We now provide the basic steps of the dSPdV calculation. The first step in the algorithm is to calculate the OP to SP gain to be used for the current OP, dSPdV. This value is determined using an interpolation of the user-specified values dSPdVLo/Hi and OPLo/Hi.
Once dSPdV has been determined, the next step is to calculate the “internal” SP limits. The following relationships show the calculation:
2016.7.3
