BENTLY 3500/05-01-02-00-00-00框架
（0-100%范圍）說(shuō)明了典型的自動(dòng)調(diào)諧練習(xí)。變量1表示閥門(mén)，變量2表示過(guò)程。在這個(gè)例如，該過(guò)程具有標(biāo)準(zhǔn)偏差小于0.5%的噪聲。已設(shè)置%HYS（%滯后帶）
設(shè)置為0.75%，并設(shè)置%DEV（%與設(shè)定點(diǎn)的偏差，該偏差應(yīng)設(shè)置為%HYS值的至少4倍）至3%。
自動(dòng)調(diào)諧器將在第一個(gè)1期間使用初始閥門(mén)步長(zhǎng)（在控制器功能塊中設(shè)置為%步長(zhǎng)）-1/2個(gè)周期來(lái)學(xué)習(xí)過(guò)程的近似增益。然后，它將在以下步驟的剩余時(shí)間內(nèi)調(diào)整閥門(mén)步長(zhǎng)：用于維護(hù)%DEV設(shè)置的自動(dòng)調(diào)整練習(xí)。此測(cè)試結(jié)束時(shí)，建議的設(shè)置為并進(jìn)行20%的設(shè)定點(diǎn)改變，以說(shuō)明控制器的調(diào)整。
當(dāng)為下一次自動(dòng)調(diào)諧練習(xí)啟動(dòng)自動(dòng)調(diào)諧時(shí)，它將使用上一次學(xué)習(xí)的過(guò)程增益確定閥門(mén)步長(zhǎng)的練習(xí)，除非：控制器塊中復(fù)位時(shí)的參數(shù)已存儲(chǔ)為是，在第一次測(cè)試期間出現(xiàn)警告，或電站已通電。過(guò)程噪聲-可能會(huì)導(dǎo)致自動(dòng)調(diào)諧不會(huì)產(chǎn)生周期性閥門(mén)循環(huán)。自動(dòng)調(diào)諧器將完成練習(xí)，但結(jié)果可能不令人滿(mǎn)意。這在圖2中的第一個(gè)自動(dòng)調(diào)整練習(xí)中進(jìn)行了說(shuō)明這是與圖1相同的過(guò)程，但%HYS設(shè)置為0.5%。如果這些結(jié)果發(fā)生在控制器%
HYS已設(shè)置為A（自動(dòng)設(shè)置滯后）
控制器可能難以獲得良好的噪聲系數(shù)，并且應(yīng)考慮手動(dòng)輸入%HYS參數(shù)。%HYS值應(yīng)至少增加到噪聲標(biāo)準(zhǔn)偏差值的兩倍。在噪聲幅度非常大的情況下，濾波器打開(kāi)應(yīng)增加模擬輸入，以最小化控制器看到的噪聲幅度。價(jià)值%DEV參數(shù)應(yīng)設(shè)置為%HYS值的至少四倍，以獲得最佳結(jié)果。
穩(wěn)態(tài)條件-必須在開(kāi)始自動(dòng)調(diào)諧練習(xí)之前為過(guò)程和控制器建立。自動(dòng)調(diào)諧器可以在手動(dòng)或自動(dòng)模式下啟動(dòng)。當(dāng)當(dāng)前閥門(mén)信號(hào)達(dá)到以下?tīng)顟B(tài)時(shí)，達(dá)到穩(wěn)定狀態(tài)：使過(guò)程達(dá)到其當(dāng)前值，并且設(shè)定點(diǎn)等于過(guò)程。當(dāng)不處于穩(wěn)定狀態(tài)時(shí)，閥門(mén)周期將不是對(duì)稱(chēng)的，如圖2中的第二次調(diào)整練習(xí)所示，或者，在更壞的情況下
閥門(mén)可能根本不循環(huán)。如果閥門(mén)確實(shí)循環(huán)，盡管不是對(duì)稱(chēng)的，但仍會(huì)有足夠的調(diào)節(jié)結(jié)果獲得。自動(dòng)調(diào)諧警告-不終止自動(dòng)調(diào)諧練習(xí)，通常通過(guò)增加%來(lái)消除HYS和/或%DEV設(shè)置。在某些情況下，它們可能是由以下過(guò)程中發(fā)生的負(fù)載變化引起的：自動(dòng)調(diào)諧練習(xí)。自動(dòng)調(diào)諧仍將導(dǎo)出推薦的調(diào)諧值，但不會(huì)自動(dòng)導(dǎo)出如果請(qǐng)求該功能，則傳輸?shù)娇刂破?。按下確認(rèn)鍵可清除警告按鈕
Chart 1 (0-100% range) illustrates a typical autotune exercise. Variable 1 is the Valve and 2 the Process. In this
example, the process has noise with a standard deviation of less than 0.5%. The % HYS (% hysteresis band) is set
to 0.75% and the % DEV (% deviation from setpoint which should be set to at least 4 times the % HYS value) is set
to 3%.
The autotuner will use the initial valve step size (set as % STEP in the controller function block) during the first 1-
1/2 cycles to learn the approximate gain of the process. It will then adjust the valve step size during the remainder of
the autotuning exercise to maintain the % DEV setting. When this test concludes, the recommended settings are
transferred to the controller and a 20% setpoint change is made to illustrate the controller tuning.
When the autotuner is started for the next autotune exercise, it will use the process gain learned during the previous
exercise to determine the valve step size unless: the parameter AT RESET in the controller block has been stored as
YES, warnings occurred during the first test, or the station has been power cycled. Process Noise - could have an effect where the autotuner will not produce periodic valve cycles. The autotuner will
complete an exercise but results may not be satisfactory. This is illustrated in the first autotuning exercise in chart 2
which is the same process as chart 1 but the % HYS was set at 0.5%. If these results occur when the controller %
HYS has been set to A (auto set hysteresis) the controller may be having difficulty deriving a good noise figure and
manual entry of the % HYS parameter should be considered. The % HYS value should be increased to at least
twice the standard deviation value of the noise. In cases where the noise amplitude is extremely large, the filter on
the analog input should be increased to minimize the amplitude of the noise seen by the controller. The value of the
% DEV parameter should be set to at least four time the % HYS value for best results.
Steady State Conditions - must be established for the process and controller prior to starting an autotune exercise.
The autotuner can be initiated while in manual or auto. Steady state is reached when the present valve signal has
brought the process to its present value, and the setpoint is equal to the process. When not at steady state, valve
cycles will not be symmetrical as illustrated in the second tuning exercise in chart 2 or, as a worse case situation, the
valve may not cycle at all. If the valve is does cycle, although not symmetrically, adequate tuning results will still
be obtained. Autotuner Warnings - do not terminate the autotune exercise and are normally eliminated by increasing the %
HYS and/or the % DEV settings. In some cases, they may have been caused by load changes that occurred during
the autotune exercise. The autotuner will still derive recommended tuning values but they will not automatically be
transferred to the controller, if that feature was requested. The warnings can be cleared by pressing the ACK
button.
