Liu Jianchang

Research on Mill Modulus Control of Strip Rolling AGC Systems

Recently, the accuracy of hot strip gauge is strictly demanded, and the strip thickness becomes the most important quality in hot strip rolling. In order to improve the quality of the hot strip gage and to reduce the strip thickness deviation, the automatic gauge control (AGC) system now is widely used in modern hot strip mills. Mill modulus control (MMC) is one of important methods in AGC system for strip rolling mills. Control theories and models related to MMC were studied deeply in this paper. Its ability to eliminate strip thickness deviation, rolling force noise and roller eccentricity disturbances were simulated respectively based on different virtual mill modulus with MATLAB. As a result, how to get a better control effect was analyzed and confirmed.

A Fault Location Method for Active Distribution Network with Renewable Sources Based on BP Neural Network

This paper presents a neural network method to locate common fault exactly in a distribution power system (DPS) with renewable sources. The back propagation (BP) neural network method is applied to identify patterns of voltage and current measured from distribution branches. The input matrix of BP network consists of the voltage and current values, which can identify the accurate fault position. The fault location of a common short-circuit fault is analyzed thoroughly in an active distribution network (ADN) with the renewable power sources. Simulation results prove the feasibility and usefulness of the fault location method based on the BP neural network, wherein the fault location accuracy can reach 0.09%.

On the simulation application for teaching practice in the course of motion control system

Computer simulation technology, which with application of software platforms likes FLASH, MultiSim and MATLAB/SIMULINK, was introduced into teaching progress, considering the existing teaching situation and features of the motion control system. By combining the theory explaining and simulation results together, it become more easy to reveal and exposit the essence of the lecture, more specific and straightforward to make the teaching process become, moreover, it help students to understand abstract theory and key segments of the motion control system better and stimulate their learning positivity, thereby achieve a outstanding teaching result.

A class of Active Queue Management algorithm based on BP neural network

As an end-to-end congestion control mechanism, Active Queue Management (AQM) technology maintains smaller queue length and higher link utilization through discarding packets in intermediate network nodes. This paper discussed some previous AQM algorithms, RED, BLUE and RLGD, and found out shortcomings in which by comparing with them. On the Basis of Artificial Intelligence (AI) theory and technology, a new AQM algorithm based on BP neural network is proposed. In the end, the implement of the new Active Queue Management algorithm is presented, and the convergence is proved.

Fault Analysis and Fault Diagnosis Method Review on Active Distribution Network

This paper analyses the current situation and researches the fault cause and the common fault type in active distribution network (ADN). The fault diagnosis methods are summarized and the advantage of the common methods are compared. The general problems consist in the current fault diagnosis methods of ADN are researched in this paper. Combining the development trend of ADN and the power supply reliability demand, the further research direction of ADN fault diagnosis method is proposed, which lays the foundation of the AND self healing and protection control.

Performance assessment of cascade control systems based on LQG benchmark

Given that the LQG benchmark is closer to the actual production, performance assessment of cascade control system based on LQG benchmark has been proposed. The joint input and output subspace identification algorithm was used to estimate the process model, noise transfer function, the inner loop controller and the outer loop controller. And three possible cases could be considered to evaluate cascade control systems. First, none of the inner and outer controllers were known and the goal was to design both controllers to get the global optimum. Second, the outer controller was considered to be fixed and one was looking for the best achievable performance by designing the inner controller. Third, the inner controller was considered to be fixed and one was looking for the best achievable performance by designing the outer controller. These three scenarios were used to evaluate the performance of the global, the inner controller performance and the outer controller. According to the simulation results, performance assessment of cascade control systems based on the LQG benchmark not only get the global performance of the system, but also show how much improvement may be achieved by designing inner and outer controllers.

Performance assessment of single loop control systems with LQG benchmark

In the industrial process, not only is the output of the system expected to achieve the minimum variance, but also the variance of process input fluctuates in a certain range. However, minimum variance benchmark can meet the former but not the requirements of latter because of strong control effect. Therefore, subspace identification with combined input and output is utilized in this paper to identify single loop control systems, which obtains the process and the noise model, firstly. Then, the performance of the control system is assessed with LQG benchmark combining the control input and output synthetically, and the specific implementation steps are concluded systematically. Finally, the proposed method is verified effective through simulations.

Research on the gap setting model of short stroke control system in hot edge rolling

According to the phenomenon of width losing in slab end, the spread of slab end including edger pressing, dog bone spread and nature spread, short stroke control was used in 2300 hot strip roughing mill. The parabola model has been proposed in this article, because of the disadvantage of broken line used by 2300 hot strip mill, and the online implementation plan of parabola model has been given. The broken line model and the parabola model have been contrasted by simulation, which indicates that the control effect of parabola model is better than the broken line model.

Optimal controller design based on improved particle swarm optimization for a class of networked control systems

Aiming at a class of networked control systems (NCSs) in the presence of network-induced delay and data packet dropout simultaneously from sensor to controller, a new optimal controller design method is proposed based on particle swarm optimization (PSO) with predatory search strategy. The rough feedback gain and its feasible region are firstly obtained through the state feedback control (SFC) approach, and then, the feed back gain is optimized in the obtained feasible region via improved PSO. The proposed controller can effectively reduce the conservatism of control methodology and improve the performance of whole system. The simulation results demonstrate that the proposed method is valid and effective.

Error Analysis for AGC Model and Research for the New Function of Mill Characteristic Curve

Abstract This paper gives two kind of lock plans of ACC ard advances two control methods of pressure ACC that is one step to the position and several steps to the position. the characteristics of the control methods is discussed, the common formula of the reference value of roll gap is deduced, and the stable error of ACC system is analysed. The paper also studies mill characteristic curve and advances a new optimizing method. so the precision and fitting degree of mill characteristic curve are effectivly improved.