Zone model predictive control for pressure management of water distribution network

In the water distribution network (WDN), although the water demand of the node is changing constantly, the water quantity and water pressure of the node need to be met at each moment. To realize energy saving and consumption reduction, it is proposed to control the nodal water head of WDN in an appropriate narrow range. The frequent large fluctuation of the water demand, which may lead the water pressure exceed the expected range, increases the difficulty of the zone control. To realize optimized WND control, a novel zone predictive control is proposed, where two switching cases are considered. The switching condition is whether there are feasible solutions to keep the pressure within the expected region over the prediction horizon. When the condition is satisfied, the controller minimizes the variation of inputs with constraints of pressure range for ensuring the tank level staying within the expected zone and obtaining optimal economic cost. When the current pressure is out of the expected region or the condition is not satisfied due to the large variation of water demand, a reference trajectory of outputs is introduced, which is combined with the inputs as an optimization variable, and the constraints of expected zone are moved from the output to the introduced reference trajectory. Through minimizing the distance between reference trajectory and output, the controller will keep the tank level from deviating too far from the expected zone and will drive the tank level rapidly into the expected zone once the tank level exceeds the expected range. An application of the proposed zone MPC to WDN in Shinan District of Shanghai is given to illustrate its effectiveness.     

Polymer brush coatings for combating marine biofouling

A variety of functional polymer brushes and coatings have been developed for combating marine biofouling and biocorrosion with much less environmental impact than traditional biocides. This review summarizes recent developments in marine antifouling polymer brushes and coatings that are tethered to material surfaces and do not actively release biocides. Polymer brush coatings have been designed to inhibit molecular fouling, microfouling and macrofouling through incorporation or inclusion of multiple functionalities. Hydrophilic polymers, such as poly(ethylene glycol), hydrogels, zwitterionic polymers and polysaccharides, resist attachment of marine organisms effectively due to extensive hydration. Fouling release polymer coatings, based on fluoropolymers and poly(dimethylsiloxane) elastomers, minimize adhesion between marine organisms and material surfaces, leading to easy removal of biofoulants. Polycationic coatings are effective in reducing marine biofouling partly because of their good bactericidal properties. Recent advances in controlled radical polymerization and click chemistry have also allowed better molecular design and engineering of multifunctional brush coatings for improved antifouling efficacies.     

基于NMPC-PID的大型风力机独立变桨控制

大型风力机的不平衡载荷会使叶片断裂,造成事故从而减短其使用寿命。针对大型风力发电系统在高风速区的不平衡载荷问题,提出一种NMPC-PID的独立变桨载荷控制方法。非线性模型预测控制(NMPC)用于及时调整风机桨叶的桨距角,PID控制则用于消除塔架振动的影响。运用机制方法在仿真平台搭建风力发电系统模型,运用所提控制策略进行仿真实验,并在两种情况下与模型预测控制方法(MPC)进行对比,验证了所提控制策略的可行性与有效性。     

氨合成塔支撑结构比较与挂式支座有限元分析简

氨合成塔设备庞大,重量大。对于承受重量、风载荷、地震载荷作用下挂式支座,现有标准没有成熟的计算方法;本文通过对焊接裙座和挂式支座对比,利用ANSYS对这种结构支座建立了有限元模型,使用MPC法加载后对结构支座进行了整体应力分析和焊缝应力分析,给出了相应部位的应力分布图,为做类似产品的设计者提供参考借鉴。     

一种应用于异步电机的基于Laguerre函数的模型预测控制电流调节器

电动汽车用异步电机复杂的运行工况,造成电机参数改变,传统同步PI控制性能不甚理想。基于复矢量比例积分(PI)控制和模型预测控制(MPC)的电流调节器,使得其控制效果得到一定改善,但仍然存在响应时间长和超调大的问题。针对电动汽车用异步电机控制器,设计一种基于Laguerre函数的模型预测控制(LMPC)电流调节器,该电流控制器根据过去和现在的信息,对系统的状态量进行多步预测,并综合考虑控制对象的预期值和控制量的变化等评价指标,得到最优的控制律。仿真和实验结果表明,该调节器相比于复矢量PI控制和模型预测控制,具有更快的动态响应和更好的参数鲁棒性。     

模型预测控制方法在主动配电网协调控制中的应用

基于主动配电网分层协调控制的特点与储能系统的控制特性,提出应用于主动配电网自治区域的协调控制的模型预测控制方法,并利用动态矩阵控制算法在Matlab 中对主动配电网储能的协调控制进行了场景仿真。仿真结果表明,应用预测控制方法的区域控制器比传统的 PI 控制器有更好的性能。     

Output feedback model predictive control of hydraulic systems with disturbances compensation

Enhancing the robustness of output feedback control has always been an important issue in hydraulic servo systems. In this paper, an output feedback model predictive controller (MPC) with the integration of an extended state observer (ESO) is proposed for hydraulic systems. The ESO was designed to estimate not only the unmeasured system states but also the disturbances, which will be synthesized into the design of the output prediction equation. Based on the mechanism of receding horizon and repeating optimization of MPC, the output prediction equation will be updated in real time and the future behavior of the system will be accurately predicted since the disturbances are compensated effectively. Hence, the ability of the traditional MPC to suppress disturbances will be improved evidently. The experiment results show that the proposed controller has high-performance nature and strong robustness against various model uncertainties, which verifies the effectiveness of the proposed control strategy.     

Anti-disturbance control of oxygen feeding for vehicular fuel cell driven by feedback linearization model predictive control-based cascade scheme

The accurate control of automotive fuel cell oxygen excess ratio (OER) is necessary to improve system efficiency and service life. To this end, an anti-disturbance control driven by a feedback linearization model predictive control (MPC)-based cascade scheme is proposed. It considers strong nonlinear coupling and disturbance injection of fuel cell oxygen supply. A six-order nonlinear fuel cell oxygen feeding model is presented. It is further formulated using an extended state observer to rapidly reconstruct the OER, to overcome the slow response and interference errors of sensor measurements. In the proposed cascade control, the outer loop is the anti-disturbance control which is used to realize the optimized OER tracking and the inner loop via the feedback linearization to linearize the oxygen feeding behaviors conducts MPC to regulate the air compressor output mass flow. The feedback linearization demonstrates a robust tracking performance of nonlinear outputs, and the integral absolute error of anti-disturbance control is 0.3021 lower than that of PI control under a custom test condition. Finally, the numerical validation on a hybrid driving cycle indicates that the proposed cascade control can regulate the fuel cell OER with an average absolute error of 0.02313 in the high air compressor operation efficiency zone.     

A dual Newton strategy for tree‐sparse quadratic programs and its implementation in the open‐source software treeQP

This paper presents a dual Newton scheme for tree‐sparse quadratic programs as they may arise in the field of stochastic programming. Previous work suggests to introduce auxiliary variables to decompose the tree into scenarios and use Newton's method to solve a dual problem formulation. Following a different approach, we apply the same principle directly on the tree‐sparse problem, avoiding the increase in dimensionality. In combination with a tailored algorithm for the calculation of the step direction, which is typically the most expensive operation per iteration, the proposed algorithm achieves a linear complexity in the number of nodes and supports parallel processing of the tree branches in a stage‐wise fashion. An open‐source implementation of the presented dual Newton strategy is publicly available in treeQP , a toolbox of open‐source solvers for tree‐sparse quadratic programs.     

A tracking MPC formulation that is locally equivalent to economic MPC

The stability proof for economic Model Predictive Control (MPC) is in general difficult to establish. In contrast, tracking MPC has well-established and practically applicable stability guarantees, but can yield poor closed-loop performance in terms of the selected economic criterion. In this paper, we derive a formal procedure to design a tracking MPC scheme so as to locally approximate the behaviour of economic MPC. Given an economic stage cost, the desired tracking stage cost can therefore be computed automatically. Because tracking MPC guarantees stability of the closed-loop system, our procedure succeeds if and only if economic MPC is locally stabilising. This fact can be used to certify whether economic MPC is not stabilising. We illustrate the theoretical developments in a simulated example.