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摘要: 為提高熱軋換規格首塊鋼頭部卷取溫度命中率,采用數據挖掘技術,從歷史帶鋼冷卻數據中推斷出與實際帶鋼相匹配的卷取溫度模型水冷換熱學習系數,并將其應用于模型預設定計算。首先,對冷卻特征參數進行識別,按照相對型、絕對型、相等型和策略型四種方式進行定義,并對實際帶鋼與歷史帶鋼的各項冷卻特征參數進行相似距離計算。當歷史帶鋼的總相似距離滿足要求時,將其聚類為實際帶鋼的相似卷,并考慮各相似卷的時間影響,計算相似權重值;隨后,基于相似帶鋼的頭部和尾部信息,建立由卷取溫度預報誤差、偏離學習系數回歸值懲罰項和偏離默認值懲罰項等構成的目標函數以及相應的約束條件,采用梯度下降法求解該二次規劃問題,通過三次優化逐步計算出學習系數參考值和表征學習系數與帶鋼速度及目標卷取溫度呈雙線性關系的兩個參數;最后,根據實際帶鋼的穿帶速度、目標卷取溫度等冷卻條件計算冷卻設定所需的學習系數。現場應用表明:基于十萬塊歷史帶鋼冷卻數據驅動的模型參數即時自適應設定算法可增強卷取溫度模型對帶鋼頭部冷卻的預設定能力,學習系數即時自適應設定能力隨著內存中保存的歷史帶鋼冷卻數據的多樣性和檢索出的相似卷數量的增加而提升。Abstract: To improve the coiling temperature control accuracy for change-over strip or the first coil of batch hot-rolling, data mining technology was adopted to infer the water cooling learning coefficient which is used in coiling temperature model preset for actual rolling strip from massive production data. Firstly, cooling feature parameters were recognized and defined respectively as absolute, relative, equal and tactical type. Then, the similar distance of each feature parameter between actual rolling strip and each historical rolled strip was calculated and summed. When the total similar distance of each rolled strip met the requirement, the produced strip was clustered as similar with actual rolling strip. Meanwhile, the weight value of the similar strip was calculated by considering its time effect. Secondly, based on the cooling information of the head and tail ends of each similar rolled strip, three object functions which are respectively composed of temperature predictive error and related penalty items such as a penalty deviated from regression learning coefficient and a penalty departed from the default learning coefficient were created and the corresponding constraints were also given. Gradient descent method was utilized to solve the quadratic programming problem. After three mathematical optimization calculations, a referenced learning coefficient and two parameters reflecting the relationship between the learning coefficient with rolling speed and target coiling temperature were obtained and then used to compute the learning coefficient needed in the cooling schedule calculation according to thread speed and target coiling temperature of the actual rolling strip. Application results show that the presented model’s adaptive parameter setting algorithm, based on the cooling data of 100,000 rolled strips can enhance the pre-setup ability of the coiling temperature model for strip head end. The adaptive setting ability of the learning coefficient will increase with the diversity of the strip cooling data stored in the memory and the number of similar strips retrieved.
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Key words:
- cooling feature parameter /
- clustering /
- self-adaptation /
- parameter estimation /
- coiling temperature
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表 1 三次優化計算采用的初值及計算結果
Table 1. Initial value and results of three optimal computation
Optimization Initial value of iterative computation Optimized calculation results x0(ζ) y0 z0 x*(ζ) y* z* Opt1 1.138 — — 1.1771 — — Opt2 ln(1.1771) 0 0 ln(1.1676) ln(1.405) ln(0.683) Opt3 ln(1.1676) — — ln(1.2117) — — 表 2 卷取溫度控制精度統計結果
Table 2. Statistical result of coiling temperature control accuracy
Coil type Number of coils Rolled-strip length/km Coiling temperature control accuracy/% Control deviation/℃ Sequential coil 10278 7048.875 93.978 ±16 Change-over coil 1684 980.500 92.088 ±18 First coil 183 97.533 90.832 ±18 Total 12145 8126.908 95.134 ±20 259luxu-164 -
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