Load Control Algorithm Research Articles

Adaptive Exercise Stress System SAKR-VELO for Load Tests

The design and principle of operation of the SAKR-VELO stress system for examination of the functional state of a subject’s cardiovascular system under strictly dosed physical load with noninvasive measurement of blood pressure (at each heart beat), heart rate, and respiratory flows is described. A load control algorithm based on continuous monitoring of force applied to the pedal and the cycling speed is used. The protocol for stress testing is substantiated.

Coexistence of ZigBee-Based WBAN and WiFi for Health Telemonitoring Systems.

The development of telemonitoring via wireless body area networks (WBANs) is an evolving direction in personalized medicine and home-based mobile health. A WBAN consists of small, intelligent medical sensors which collect physiological parameters such as electrocardiogram, electroencephalography, and blood pressure. The recorded physiological signals are sent to a coordinator via wireless technologies, and are then transmitted to a healthcare monitoring center. One of the most widely used wireless technologies in WBANs is ZigBee because it is targeted at applications that require a low data rate and long battery life. However, ZigBee-based WBANs face severe interference problems in the presence of WiFi networks. This problem is caused by the fact that most ZigBee channels overlap with WiFi channels, severely affecting the ability of healthcare monitoring systems to guarantee reliable delivery of physiological signals. To solve this problem, we have developed an algorithm that controls the load in WiFi networks to guarantee the delay requirement for physiological signals, especially for emergency messages, in environments with coexistence of ZigBee-based WBAN and WiFi. Since WiFi applications generate traffic with different delay requirements, we focus only on WiFi traffic that does not have stringent timing requirements. In this paper, therefore, we propose an adaptive load control algorithm for ZigBee-based WBAN/WiFi coexistence environments, with the aim of guaranteeing that the delay experienced by ZigBee sensors does not exceed a maximally tolerable period of time. Simulation results show that our proposed algorithm guarantees the delay performance of ZigBee-based WBANs by mitigating the effects of WiFi interference in various scenarios.

Design of a Controller for Active Power Sharing in a Highly-Resistive Microgrid

This paper presents a new control algorithm for active load sharing in a highly-resistive inverter-connected microgrid under different loading conditions. A systematic procedure for modifying the conventional droop control approach, regarded as reverse droop control, is presented in this paper. The gains of the proposed controller are selected based on the eigenvalues obtained from linear modal analysis. The linearized microgrid model is further analyzed to develop a mathematical expression for sharing active power. The proposed accurate successive approximation among line parameters, load and control gains gives equal power sharing among distributed generators without any communication. The performance of the proposed control methodology is verified on a low voltage (LV) test microgrid by applying severe faults, including load change scenario and disconnection of one DG unit. It is clearly observed from case studies that the proposed control scheme is effective to stabilize this kind of microgrids and provides excellent power sharing performance in islanded mode.

Longer battery lifetime provided by a priority load control algorithm on stand-alone photovoltaic system

Access to electricity has a positive impact on the socio-economic activity in rural livelihoods. Stand-alone photovoltaic (SAPV) systems are the most popular PV application for rural electrification in areas nonconnected to the grid, but it is still relatively expensive. Batteries are considered as a weak component of the system, comprising an important part of the total cost and are usually replaced multiple times during PV system lifetime. A priority load control algorithm has been developed in order to gain a better energy management over system loads and the battery storage, and therefore guarantee the energy supply for critical loads and extends the battery service lifetime. This will increase the reliability of the system and the end-user satisfaction. This article describes a stand-alone PV system model used for the development of a priority load control algorithm and explains and implements the algorithm. The results of several test scenario simulations are shown and discussed.

실시간요금제하에서 산업용 수용가의 부하제어알고리즘 개발

실시간요금제하에서 산업용 수용가의 부하제어알고리즘 개발

A Novel Adaptive Load Balancing Algorithm in Heterogeneous Wireless Networks

Based on WLAN and UMTS coexistence scenario, a novel adaptive load balancing algorithm is proposed, in order to achieve efficient network resources utilization under unbalanced network conditions. Firstly, we propose a Markov model-based adaptive load control algorithm to adaptively allocate new arriving calls. Secondly, considering the difference of the network load, we adaptively calculate the amount of vertical handoff. Finally, considering extra signaling for vertical handoffs, a cost function-based terminal selection algorithm is proposed to perform vertical handoffs. Simulation results show that, the proposed adaptive load balancing algorithm can effectively improve fairness in network load, reduce network congestion and signaling overhead, and thereby improving system performance.

Priority load control algorithm for optimal energy management in stand-alone photovoltaic systems

In stand-alone PV System facilities no grid connection exists, therefore the solar generator and battery bank have to be carefully sized in order to supply the energy demand for a given period of time. Batteries are considered as a weak component of the system, comprising an important part of the total cost and are usually replaced one or two times during PV system lifetime. A priority load control algorithm has been developed in order to gain an optimal energy management over system loads and the battery storage, and therefore provides a better energy management efficiency and guarantee the energy supply for critical loads. This will increase the reliability of the system and the end-user satisfaction. This article describes a stand-alone PV system model used for the development of a priority load control algorithm and explains and implements the algorithm. The results of several test scenario simulations are shown and discussed.

Dynamics Modeling and Control of a Quadrotor with Swing Load

Nowadays, aerial robots or Unmanned Aerial Vehicles (UAV) have many applications in civilian and military fields. For example, of these applications is aerial monitoring, picking loads and moving them by different grippers. In this research, a quadrotor with a cable-suspended load with eight degrees of freedom is considered. The purpose is to control the position and attitude of the quadrotor on a desired trajectory in order to move the considered load with constant length of cable. So, the purpose of this research is proposing and designing an antiswing control algorithm for the suspended load. To this end, control and stabilization of the quadrotor are necessary for designing the antiswing controller. Furthermore, this paper is divided into two parts. In the first part, dynamics model is developed using Newton-Euler formulation, and obtained equations are verified in comparison with Lagrange approach. Consequently, a nonlinear control strategy based on dynamic model is used in order to control the position and attitude of the quadrotor. The performance of this proposed controller is evaluated by nonlinear simulations and, finally, the results demonstrate the effectiveness of the control strategy for the quadrotor with suspended load in various maneuvers.

Mathematical Modelling and Simulation of the Behaviour of the Steam Turbine

Abstract Model simulations are becoming very important in dynamic power system analyses. However, no mathematical system can exactly model a physical process. Based on mathematical models of the processes and design calculations, PC programs allow simulation and the determination of the control system performances. This paper presents the mathematical modelling of the steam turbine unit, developed based on the continuity equation. This model is used to determine the simulation diagram for the steam turbine with high, medium and low pressure sections. Using Matlab/Simulink software facilities, have been simulated the behaviour of the shaft torque, depending of the control valves opening, with uncertain parameters of the process, than the step response of the steam turbine, with load and proportional control algorithm.

Multiple access in DVB‐RCS2 user uplinks

SUMMARYDigital Video Broadcasting, Return Channel via Satellite 2 (DVB‐RCS2) is the second generation of DVB‐RCS communication specification for the return link in broadband interactive geostationary satellite networks. The focus of this paper is the user uplink access mechanism in DVB‐RCS2. The first part of the paper provides a brief description of DVB‐RCS2 user uplink access, with emphasis on improvements with respect to the first generation of the standard. One of these improvements in DVB‐RCS2 is the support for random access (RA) for user traffic. The second part of the paper further delves into the RA load control problem and proposes an analytical model for the DVB‐RCS2 RA load control algorithm followed by performance assessment via numerical computations and simulations. Copyright © 2013 John Wiley & Sons, Ltd.

Modeling and Control of Aggregate Air Conditioning Loads for Robust Renewable Power Management

This paper examines the problem of demand-side energy management in smart power grids through the setpoint control of aggregate thermostatic loads. This paper models these loads using a novel partial differential equation framework that builds on existing diffusion- and transport-based load modeling ideas in the literature. Both this partial differential equation (PDE) model and its finite-difference approximations are bilinear in the state and control variables. This key insight creates a unique opportunity for designing nonlinear load control algorithms with theoretically guaranteed Lyapunov stability properties. This paper's main contribution to the literature is the development of the bilinear PDE model and a sliding mode controller for the real-time management of thermostatic air conditioning loads. The proposed control scheme shows promising performance in adapting aggregate air conditioning loads to intermittent wind power.

Effect of Initial Position of the Counterpunch on T-Shape Hydroforming

The loading path is crucial to the quality of forming parts in the process of tube hydroforming. The counterpunch is usually used to control the protrusion height and also to control the evolution of thickness and avoid over thinning in T-shape hydroforming. In this study, the experiments of T-shape hydroforming are conducted, in which tubular material used is stainless steel and has an outer diameter of 103mm. A fuzzy logic-based load control algorithm is developed for optimizing the loading path, and four different initial positions of the counterpunch are designed to investigate its influence on wall-thinning and the corner radius at protrusion end. The results show that the minimum thinning can be obtained with an initial position of 12.5mm, while a smaller corner radius is obtained with an initial position of 37.5mm.

1114 複数台風力タービンの並列可変速運転による出力変動抑制(負荷制御アルゴリズムの検討)(GS-8 動力エネルギー(2))

1114 複数台風力タービンの並列可変速運転による出力変動抑制(負荷制御アルゴリズムの検討)(GS-8 動力エネルギー(2))

A Unified Library of Nonlinear Solution Schemes

Nonlinear problems are prevalent in structural and continuum mechanics, and there is high demand for computational tools to solve these problems. Despite efforts to develop efficient and effective algorithms, one single algorithm may not be capable of solving any and all nonlinear problems. A brief review of recent nonlinear solution techniques is first presented. Emphasis, however, is placed on the review of load, displacement, arc length, work, generalized displacement, and orthogonal residual control algorithms, which are unified into a single framework. Each of these solution schemes differs in the use of a constraint equation for the incremental-iterative procedure. The governing finite element equations and constraint equation for each solution scheme are combined into a single matrix equation, which characterizes the unified approach. This conceptual model leads naturally to an effective object-oriented implementation. Within the unified framework, the strengths and weaknesses of the various solution schemes are examined through numerical examples.

SIP overload control

Overload happens in Session Initiation Protocol (SIP) networks when SIP servers have insufficient resources to handle all messages they receive. Under overload, SIP networks suffer from congestion collapse due to its ineffective overload control mechanism. In this paper we propose a backpressure-based SIP overload control mechanism called Bassoon. It consists of two parts: the first part is a provably optimal load balancing algorithm that ensures full utilization of the available network resources. The second part is an end-to-end load control algorithm that intelligently throttles excessive traffic at the edge of the network. We show that, by combining optimal load balancing and end-to-end load control, Bassoon effectively controls overload in SIP networks and outperforms existing schemes in terms of goodput, fairness and responsiveness.

A Dynamic Downlink Load Control Scheme for WCDMA and HSDPA Systems

Mutual interference among users can abruptly increase othercell interference and cause overload situation in coexisting WCDMA and HSDPA systems. Traffic overloading can degrade the performance of the systems. This letter proposes a new dynamic downlink load control (DDLC) algorithm to reduce performance degradation due to overload in the coexistence of WCDMA and HSDPA systems. With the proposed algorithm, the downlink load is controlled according to load states classified by two load-control thresholds, and traffic overloading is alleviated by dynamically adjusting the CQI values reported by users, based on the downlink load as well as channel variations. The proposed algorithm is simulated and results show that the DDLC scheme improves the performance of both WCDMA and HSDPA systems in terms of outage probability, total system throughput, and radio resource utilization.

Computer controlled system for dieless drawing of tool steel bar

This paper describes the computer controlled processing of AISI-O1 steel rod by a dieless drawing method. Both the operation of a purposely built machine and the results of an experimental programme are described. The machine consisted of elements to provide a drawing force, a PID controlled band heater and an air/water cooling system to carry out the novel bar production process. The untreated material in bar form of initial diameter, 5 mm, was drawn in the temperature range of 600–750 °C at drawing velocities of 2.5–5 mm/min and with air-cooling provided in the pressure range 2–4 × 10 5 Pa. The process ratio, i.e. the ratio of the drawing velocity to the heat/cooling device movement velocity was varied between 0.35 and 1.33. A novel load-control algorithm was executed to ensure a steady-state process and a high tolerance on the final drawn diameter.

Radio resource management in HSDPA and HSUPA

This paper discusses the interaction between high speed downlink packet access (HSDPA) and high speed uplink packet access (HSUPA) scheduling algorithms running in the Node B and other resource management algorithms in the radio network controller (RNC), which are still required to satisfy user-perceived quality. We investigate the effect of load sharing with legacy dedicated channel transmission, and discuss load control algorithms suitable for HSDPA and HSUPA packet transmission. The main concepts of resource allocation are discussed together with results obtained from a dynamic system simulator developed by Alcatel-Lucent. © 2007 Alcatel-Lucent.

우선순위기반 동적 프로그래밍을 이용한 직접부하제어

현재 운용되고 있는 직접부하제어 알고리즘은 직접부하제어 사업에 참여에 따른 수용가의 개별 부하별 우선순위가 고려되지 않고 있고, 또한 제어 시간도 수용가의 불편을 고려되지 않고 획일적으로 일정 시간대에 일률적으로 수용가의 부하를 제어함으로써 참여 수용가의 불편 증대로 참여율이 저조한 실정이다. 따라서 본 연구에서는 참여 수용가의 불편을 최소화시키고 또한 개별 부하에 대한 우선순위 요구를 최대한으로 반영하기 위해 우선순위 기반 동적 프로그래밍을 이용한 직접부하제어 알고리즘을 제시한다. 제시되는 알고리즘은 직접부하제어가 발생되기 1시간 전에 참여수용가가 스스로 해당 부하의 우선순위를 결정하여 직접부하제어 센터로 E-Mail 등으로 보네면 센터에서는 현재 부하의 전력량과 우선순위 그리고 OFF주기 등을 고려하여 동적 프로그래밍을 수행하여 OFF되어야 할 부하들을 선택하게 된다.

Determination of the optimal load path for tube hydroforming processes using a fuzzy load control algorithm and finite element analysis

In the tube hydroforming process, the formability of a metallic tube is directly affected by the forming load path (i.e. axial feed and internal hydroforming pressure). Most tube hydroformed parts are produced by a multistage loading process. The forming limit strains induced during the actual forming operation are therefore path dependent. This paper discusses the optimisation of the forming load path of a typical tube hydroforming process using a fuzzy logic control algorithm, which avoids the failure of the tube due to excessive induced strain during the forming process. This control algorithm is used in conjunction with LS-DYNA FEA code for simulation of the forming process.