Computer simulation for a solar heating system

In this paper a simulation model for a basic solar heating system which is suitable for control and optimization studies is developed. A model for flat plate solar collectors using fluids for the heat transfer which allows the analysis of operation in great detail is presented. The simulation model for the solar collectors has also the characteristic that its inputs and outputs are quantities which are easily measurable in the real world. The effect of temperature stratification in the heat storage device model is considered by simulating two storage chambers of variable volume. The heat storage model requires relatively small time increments, a requirement which is not as stringent as that for the solar collectors. The tank's model primary variables are the easily measurable quantities of temperature and flow rates with the addition of volume as an internal variable. Weather, load and control modeling is also presented. The gradient search method is then applied to study optimal sizing of solar heating components of The University of Toledo solar house.     

Adaptative state-space model predictive control of a parabolic-trough field

Model Predictive control algorithms for trough solar plants make use of solar radiation measurements and the overall efficiency knowledge which are very useful in order to reject disturbances. However, direct solar radiation, mirror reflectivity and metal absorptance which affect overall efficiency, can only be measured locally. In this paper, an adaptative model predictive control using an unscented Kalman filter (UKF) to estimate both the effective solar radiation and the metal–fluid temperature profiles is proposed. The control algorithm is validated by tests with real data taken from the ACUREX field of the PSA in Almería (Spain).     

一种太阳能在汽车上应用的设计

电动汽车是未来汽车的发展方向,作为环保型能源,太阳能电池得到了迅猛的发展且逐步应用在汽车上。本文提出了一种控制方法,其既可以满足目前燃油汽车加装太阳能电池板的要求,也充分考虑了混合动力汽车与纯电动汽车将来使用太阳能电池进行供电、充电的可行性。     

Analysis of a rule-based control strategy for on-board energy management of series hybrid vehicles

In the paper, the performances of a rule-based (RB) control strategy for series hybrid vehicles are assessed via comparison with a batch Genetic Algorithm-based (GA) optimization. The suitability of GA optimization as reference benchmark for series architecture is demonstrated through comparison with Dynamic Programming technique. Specifically in this paper, a hybrid solar vehicle (HSV) was considered, thus requiring to define the heuristic rules as function of both average traction power and current solar irradiation. The comparison with the reference GA benchmark confirms the suitability of the proposed RB strategy for HSV on-board energy management. Extensive simulations were performed to test the influence of driving cycle features, power-prediction time-horizon and solar irradiation on HSV fuel economy. Such simulation analysis, beyond providing useful indications about correct implementation of the RB strategy on both hybrid and solar hybrid cars, also demonstrates the potentialities offered by HSV powertrains in both urban and highway driving conditions.     

Temperature control of a solar furnace for material testing

A solar furnace is a thermodynamic device that concentrates sun radiation in order to achieve high-temperatures at a focus, where a sample of the material to be tested is located. This article address the problem of designing a control architecture for solar furnaces. It is motivated by the use of a solar furnace as an instrument in material science research to perform two types of experimental tests. In the first type, samples are tested in high-temperature stress cycles. In these experiments it is important to control the temperature profile. The second test type is characterised by imposing a solar radiation flux profile. On both experiment types there are strong nonlinear effects, a significant degree of parametric uncertainty and disturbances, such as solar radiation fluctuation due to clouds and to sun's apparent movement. Although the actuator (shutter) is much faster than the thermic system, it may destabilise the overall controlled system. The contribution of this article consists in the design of a control architecture for solar furnaces and the application of singular perturbation methods in order to derive conditions in the form of bounds for the speed of actuator dynamics so that the closed-loop system is stable.     

太阳能路灯控制器的智能化设计

介绍的智能型控制器用于太阳能路灯系统,其主要功能是白天将太阳能电池发的电存储到蓄电池中,晚上将蓄电池中的电提供给光源进行照明。该控制器在太阳能电池、蓄电池及光源间加入一个有 A/D 转换寄存器和 PWM 输出的8位单片机,通过一定的算法控制,实现了对光源实施时控、光控、分辨季节时差的控制,以及在对蓄电池充电过程中通过PWM调制实现最大功率跟踪技术。在控制器设计中,给出了蓄电池的过充及过放、蓄电池及太阳能电池的防反接、负载的防短路、太阳能路灯系统防雷电、抗干扰等保护措施。     

Fuzzy tuning control approach to perform cooperative object manipulation by a rigid–flexible multibody robot

We study cooperative object manipulation control of rigid–flexible multibody systems in space. During such tasks, flexible members like solar panels may get vibrated. Which in turn may lead to some oscillatory disturbing forces on other subsystems and consequently produce errors in the motion of the end-effectors of the cooperative manipulating arms. Therefore, to design and develop capable model-based controllers for such complicated systems, deriving a dynamics model is required. However, due to practical limitations and real-time implementation, the system dynamics model should require low computations. So, first, to obtain a precise compact dynamics model, the rigid–flexible interactive dynamics modeling (RFIM) approach is briefly introduced. Using this approach, the system is virtually partitioned into two rigid and flexible portions, and a convenient model for control purposes is developed. Next, a fuzzy tuning manipulation control (FTMC) algorithm is developed for a simple conceptual model for cooperative object manipulation. In fact, a suitable setup is designed for practical implementation of this controller. After that, a wheeled mobile robot (WMR) system with flexible appendages is considered as a practical case that necessitates delicate force exertion by several end-effectors to move an object along a desired path. The WMR system contains two cooperative manipulators, appended with two flexible solar panels. To reveal the merits of the developed model-based controller, the maneuver is deliberately planned such that flexible modes of solar panels get stimulated due to arms motion. The obtained results show an effective performance of the proposed approach as will be discussed.     

太阳能无人机控制律设计

在地面太阳辐射计算模型基础上引入大气透明率,建立了用于太阳能无人机的随高度变化的辐射模型,并对赤纬角的计算做了修正,使之更为简洁;结合太阳能无人机能源约束等特点,从能量转化角度设计控制器:由剩余能量控制高度变化率,由电机功率差值控制螺旋桨差动实现平面内转弯;避免了传统的控制方法带来的控制指令超出能量所能提供的范围或超出机体结构强度的负荷等不合理现象,得到了更为直观的控制效果。     

Fractional robust PID control of a solar furnace

This paper deals with the fractional control of the temperature in solar furnace plants. As for all the concentrated solar plants, the solar furnace can be modeled as a nonlinear system, where the dynamics strongly depends on the operating temperature. However, to improve the effectiveness of this technology, the control system should guarantee an acceptable performance independently from the operating point. In order to overcome this problem, we propose to use the generalized isodamping technique, where we aim at achieving the invariance of the control loop phase margin with respect to the plant operating point through a properly designed fractional-order proportional-integral-derivative controller. A gain-scheduling algorithm is also introduced to cope with wide plant variations. Simulation and experimental results show the effectiveness of the proposed methodology.     

Sliding mode predictive control of a solar air conditioning plant

In this work, sliding mode predictive control (SMPC) was applied to an air conditioning solar plant. The process has a variable time delay with non-minimum phase behavior, whose inverse response changes with the operating point. Disturbances are produced by changes in solar irradiation and solar collectors’ inlet temperature. The algorithm combines the design technique of sliding mode control (SMC) with model-based predictive control (MPC). The SMPC showed a considerable robustness improvement with respect to MPC under experimental validation on a real plant and also showed an enhanced ability to handle set point changes and disturbance rejection.     

Adaptive UKF-based model predictive control of a Fresnel collector field

One of the ways to improve the efficiency of solar energy plants is by using advanced control and optimization algorithms. In particular, model predictive control strategies have been applied successfully in their control.The control objective of this kind of plant is to regulate the solar field outlet temperature around a desired set-point. Due to the highly nonlinear dynamics of these plants, a simple linear controller with fixed parameters is not able to cope with the changing dynamics and the multiple disturbance sources affecting the field.In this paper, an adaptative model predictive control strategy is designed for a Fresnel collector field belonging to the solar cooling plant installed at the Escuela Superior de Ingenieros in Sevilla. The controller changes the linear model used to predict the future evolution of the system with respect to the operating point.Since only the inlet and outlet temperatures of the heat transfer fluid are measurable, the intermediate temperatures have to be estimated. An unscented Kalman filter is used as a state estimator. It estimates metal-fluid temperature profiles and effective solar radiation.Simulation results are provided comparing the proposed strategy with a PID + feedforward series controller showing better performance. The controller is also compared to a gain scheduling generalized predictive controller (GS-GPC) which has previously been tested at the actual plant with a very good performance. The proposed strategy outperforms these two strategies.Furthermore, two real tests are presented. These tests show that the proposed controller achieves adequate set-point tracking in spite of strong disturbances.     

Application of solar and wave energies for long-range autonomous underwater vehicles

The solar-powered autonomous underwater vehicle (AUV) may have unlimited autonomous capability in time and be an efficient tool to explore the ocean. The performances of solar powered AUV, evidently, depend on available solar energy. The low efficiency of industrially produced solar panels (10-16%) affords sufficient amounts of energy at low latitudes, but does not at high latitudes of about 60° and more. On the contrary, available wave energy distribution increases with latitude. A similar relation of solar and wave energies occurs regarding their seasonal variations. Hence, the combination of solar and wave energies promises more efficient use of the vehicle at all latitudes over the whole year. Converters of wave energy to electrical energy are usually cumbersome mechanical structures unsuitable for installation on an AUV.In this sense, it is more reasonable to use wave energy to aid the vehicle's motion. In this case a very fortunate situation occurs. It was shown that the best shape for a solar vehicle is a wing. At the same time it is possible to transform wave oscillations to forward movement using three wings, fixed on the hull of the vehicle. In this way, the demands of efficient solar-powered and wave-driven vehicles fully coincide. These relationships are considered in the paper and some resulting data are given.     

Deployment and control of flexible solar array system considering joint friction

It is well known that the traditional modeling theories adopt the Cartesian coordinates to establish the dynamic equation of solar array system. The order of this equation is often very high, which is inconvenient for controller design. The Cartesian coordinates are difficult to be measured in practice. In this paper, the joint coordinates are used as generalized variables to establish the dynamic equation of the solar array system. The single direction recursive construction method and the Jourdain’s velocity variation principle are used in modeling the system. The order of the established equation is lower, and the joint coordinates are easily measured in practice. Besides the dynamics modeling, joint friction and control design are extensively studied in this paper too. A three-dimensional revolute joint model is introduced, and the contribution of joint friction to the dynamic equation of the system is deduced. A fuzzy PD controller is designed to eliminate the drift of spacecraft caused by the deployment of solar array. In the end of this paper, numerical simulations are carried out to analyze the deployment dynamics and control effect of the solar array system with friction.     

Data mining and statistical techniques for characterizing the performance of thin-film photovoltaic modules

A method for characterizing the performance ratio of thin-film photovoltaic modules based on the use of data mining and statistical techniques is developed. In general, this parameter changes when modules are working in outdoor conditions depending on irradiance, temperature, air mass and solar spectral irradiance distribution. The problem is that it is usually difficult to know how to include solar spectral irradiance information when estimating the performance of photovoltaic modules. We propose five different solar spectral irradiance distributions that summarize all the different distributions observed in Malaga. Using the probability distribution functions of these curves and a statistical test, we first checked when two spectral distributions measured can be considered to have the same contribution of energy per wavelength. Hence, using this test and the k-means data mining technique, all the measured spectra, more than two hundred and fifty thousand, are clustered in only five different groups. All the spectra in each cluster can be considered as equal and the k-means technique estimates one centroid for each cluster that corresponds to the cumulative probability distribution function that is the most similar to the rest of the samples in the cluster. The results obtained proves that 99.98% of the functions can be considered equal to the centroid of its cluster. With these five types of functions, we have explained the changes in the performance ratio measured for thin-film photovoltaic modules of different technologies.     

基于极值搜索的光伏电池最大功率点跟踪仿真

针对光伏发电系统中最大功率点跟踪问题,在太阳能电池的数学模型的基础上建立了PV模块的Matlab仿真模型;考虑到了太阳能的波动性和随机性对太阳电池阵列的影响,利用一种基于极值搜索方法的实时MPPT控制原理,控制Buck DC/DC变换电路,结合S函数在Matlab/Simulink环境下建立其动态仿真模型,实现了光伏电池输出的最大功率跟踪;仿真结果表明,该算法具有较好的动态特性和稳态特性,具有一定的实用价值。     

太阳能与市电互补LED照明控制系统研究

提出一种基于PIC16F877A为控制核心的太阳能与市电互补LED照明系统。介绍系统的组成和工作原理、系统控制器和直流LED负载,分析了系统的工作状态和程序控制流程。结合现有小区草坪灯、路灯的实际供电情况,提出了太阳能和市电互补照明的设计思想,在实际中具有良好开发和应用前景。     

基于PID的轿车空调系统设计

轿车空调系统由鼓风机、循环风门、混合风门、蒸发器、加热器、太阳辐射、室外空气对室内空气影响、乘客热负荷、车速等部分构成,由热平衡原理及能量守恒定律建立完整的轿车空调系统数学模型。针对空调模型,设计相应的PID控制器,来调节混合风门的开度以实现轿车车室温度调节。在Matlab 2009仿真软件中,利用Simulink工具箱建立空调控制系统的仿真模型。在仿真试验中,车室温度的调节过程大约需要1 min,温度控制准确度高。由于将一些热负荷考虑到模型中,能够较好地实现对干扰信号如太阳辐射强度、系统参数如蒸发器温度等变化量进行抑制。仿真试验表明所建立的数学模型和控制器设计是正确、可行的。     

太阳能跟踪控制器硬件设计

为了实现对太阳能全面而且有效率的使用,常用的方法是跟踪太阳的方位角,从而增加太阳能吸收的输出功率。这篇文章描述了太阳能跟踪控制器的控制思想,以及系统硬件组成控制算法。通过这种简易跟踪控制器的设计以及双轴太阳能跟踪控制器的可靠控制,可以实现太阳能利用率的提高。而且,通过手电筒模拟太阳光源,可以证明的是这个系统可以可靠的工作。整个系统主要由硬件和软件组成,硬件部分包括：单片机89C54RD＋外围电路,8位模数转换电路,光电检测电路,EEPROM电路,LED信号显示电路,供电电路,串行通讯电路等。此外,软件中单片机的控制和主监控程序是基于KeiluVision2．0平台编写的。最后,两个电动的舵机拖动双轴机械装置对太阳光源进行方位角和高度角两个方向的跟踪。     

Satellite attitude stabilization using solar radiation pressure and magnetotorquer

The paper presents three-dimensional (3-D) attitude stabilization of a geosynchronous satellite. The solar radiation pressure is considered for the satellite pitch and roll stabilization while the yaw attitude is stabilized by a magnetotorquer. The general formulation of the system comprised of a satellite body, two solar flaps, and a magnetotorquer is obtained through Euler's equations. The linearized system model is derived and then the control laws are developed for suitable rotations of solar flaps and variations in magnetic moment. The numerical simulation of the governing nonlinear system equations of motion establishes the feasibility of achieving the desired 3-D satellite attitude. The controllers are successful in stabilizing the satellite attitude even in the presence of orbital eccentricity and variations in system parameters.