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  • 作者:Yucai Zhu
        杭州泰极控制技术有限公司于2012年5月注册成立,入驻浙江大学科技园。本公司是由浙江省千人计划引进的大学教授牵头联合国内一流大学教授创办成立。创建人80%具有博士学位或教授、副教授职称。公司拥有世界领先、自主知识产权、基于智能建模的自动控制技术软件,包括模型预测控制软件和PID整定软件。公司从事先进控制技术研发、系统设计,大型流程工业自控项目集成实施、运行维护等技术咨询服务,服务工业包括:石化、化工、发电、冶金、水泥和造纸等。经过20多年的投入,我团队拥有世界领先的建模与控制优化技术,在石化、发电等工业有多个成功案例。



  • 作者:Yucai Zhu, Håkan Hjalmarsson
        An algorithm for identification of single-input single-output Box–Jenkins models is presented. It consists of four steps: firstly a high order ARX model is estimated; secondly, the input–output data is filtered with the inverse of the estimated disturbance model; thirdly, the filtered data is used in the Steiglitz–McBride method to recover the system dynamics; in the final step, the noise model is recovered by estimating an ARMA model from the residuals of the third step...



  • 作者:Yucai Zhu
        In this work we will introduce the asymptotic method (ASYM) of identification and provide two case studies. The ASYM was developed for multivariable process identification for model based control. The method calculates time domain parametric models using frequency domain criterion. Fundamental problems, such as test signal design for control, model order/structure selection, parameter estimation and model error quantification, are solved in a systematic manner...



  • 作者:William P. Snow and Kenneth F. Emigholz,Yucai Zhu
         In industrial model predictive control (MPC), there is a demand for efficient model identification technology. In this work we will study the identification of industrial processes for use in MPC. The advantages of closed-loop identification will be discussed and related issues are outlined. Then, the asymptotic method (ASYM) of identification is introduced. Two case studies are carried out to demonstrate the feasibility of the technology. The first one is a partial closed-loop identification of two distillation columns within a chemical plant. The second case is a total closedloop identification of a simulated distillation column...



  • 作者:Mengyuan Fang, Yucai Zhu
        In this work, firstly, an asymptotic variance expression is derived for the transfer function estimates in the over-sampling based identification scheme. Then the result is used to analyze the over-sampling scheme. The asymptotic variance expression says that the joint covariance matrix of the transfer function estimates is proportional to the ‘‘generalized’’ noise-to-signal ratio. It is an application of the result in Ljung (1985); and it covers both open-loop and closed-loop tests...



  • 作者:Phil Celaya and Bob Tkatch Hovensa LLC,Yucai Zhu
        The Hovensa refinery located in the US Virgin Islands is a joint venture between a subsidiary of Amerada Hess and a subsidiary of Petroleos de Venezuela, S.A. (PDVSA). The facility is one of the most modern refineries in the United States and, with crude oil processing capacity of 495,000 barrels per day (BPD), is one of the largest in the world. The latest round of MPC retesting at the refinery was completed in an automated fashion, stepping multiple independent variables simultaneously while the MPC controller was in service...



  • 作者:Xin Liu,Yucai Zhu
        This work studies the identification of errors-in-variables (EIV) systems. An asymptotic method (ASYM) is developed for the EIV system. Firstly, an auto regressive with exogeneous (ARX) model estimation method is proposed, which is consistent for EIV systems. Then the asymptotic variance expression of the estimated high-order ARX model is derived, which forms the basis of the ASYM method. In parameter estimation, the ASYM starts with a high-order ARX model estimation followed by a frequency domain weighted model reduction...



  • 作者:Yucai Zhu, Rohit Patwardhan, Stephen B. Wagner, Jun Zhao
        The high cost of model predictive control (MPC) technology has hampered its wide application in process industries beyond the refining/petrochemical industry. This work strives to increase the efficiency of MPC deployment. First, a semi-automatic MPC system is introduced. It consists of three modules: an MPC module, an online identification module and a control monitor module. The goal of the MPC technology is twofold: (1) to considerably reduce the cost of MPC commissioning and maintenance and (2) to increase control performance....



  • 作者:Mengyuan Fanga, Yucai Zhu, Håkan Hjalmarsson
        In this work, two fundamental issues in system identification, sampling frequency and anti-aliasing filtering are revisited, questions like, “Can higher sampling frequency help increase model accuracy?”, and, “Can we do better than anti-aliasing filtering?” will be answered. First it is shown that, the traditional anti-aliasing filtering procedure does not give a consistent estimate of the desired model. Then an identification method is proposed based on the over-sampling scheme where a high frequency model is first identified and then converted to the (lower) control sampling frequency...