New Publications are available for Optimal control
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New Publications are available now online for this publication.
Please follow the links to view the publication.Object-oriented modeling of a power network for model-based voltage control
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0833
This paper deals with the design of dynamic regulators for voltage control in Medium Voltage feeders with Distributed Generators, which can be used as active control elements. A modular object-oriented simulation environment has been developed in Matlab<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">®</sup>/Simulink/Simscape. This tool has been used for the design and validation of a control structure made by control loops acting at different levels. Specifically, two control structures are synthetized: the first one is made by standard PI-PID regulators, while the second one relies on the Model Predictive Control (MPC) approach. (4 pages)Robust stability of solar-power wireless network control system with stochastic time delays based on H2 norm
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0605
In this paper, the robust stability analysis of Solar Wireless Networked Control Systems (SWNCSs) with stochastic time delays and packet dropout is investigated. The Robust Model Predictive Controller (RMPC) technique for the SWNCS is discussed using the linear matrix inequality (LMI) technique. Based on the SWNCS model, the RMPC (a full state feedback controller) can be constructed by using the Lyapunov functional method. Both sensor-to-controller and controller-to-actuator time delays of the SWNCS are considered as stochastic variables controlled by a Markov chain. A discrete-time Markovian Jump Linear System (MJLS) with norm bounded time delay is presented to model the SWNCSs. Sufficient conditions for stochastic stability based on H_2-norm and stabilization of the fundamental systems are derived via LMIs formulation. Finally, an illustrative numerical example is given to demonstrate the effectiveness of the proposed techniques. (6 pages)Wireless sensor networks Zigbee applied on sewage treatment station
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0598
The good efficiency in a sewage treatment plant (WWTP) is a great importance to the environment. The management of electromechanical equipment installed in these stations is a major challenge due to the fact that they are installed on areas of difficult access and maintenance unhealthy and making the time for the correction of any faults is extended. This paper proposes the development of a Wireless Sensor Network (WSN), in order to monitor electromechanical equipment, allowing the Concessionaire a predictive control in real time. The design of a wireless sensors network for monitoring equipment requires not only the development and assembly of the sensor modules, but must also include the development of software for managing the data collected. Thus, this work includes a Zigbee WSN, small, adapted for monitoring of electromechanical equipment and environmental conditions of a WWTP, type stabilization pond, installed in an area of approximately 0.15 km<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup> and the average flow of 320 liters of treatment per second. The experimental results show that this monitoring system can perform with the collection of parameters of performance and quality assessment at the station. (5 pages)Predictive control of a direct AC/AC matrix converter for power supply applications
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0228
The use of Model Predictive Control (MPC) is investigated for a three phase to three phase direct matrix converter with input and output LC filter for power supply applications. It allows generation of sinusoidal output voltages and input currents with low harmonic distortion. The work describes in details the design of the proposed finite states model predictive control in conjunction with a full load observer. The proposed matrix converter power supply produces unity input power factor and a perfect tracking of the sinusoidal output voltage, accurately following the imposed reference in the presence of a linear load. A simulation study is presented to validate the proposed control scheme. (6 pages)Reduction of passive filtering in aerospace starter/generator systems using a multilevel converter with predictive current control
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0250
The application of predictive current control to a multilevel converter is investigated in an aerospace starter-generator system. The use of a multilevel inverter with predictive current control enables the system to reduce the harmonic distortion in the current waveform when compared to a conventional Field Orientated Controller. It is important that the power converter is optimized to control the current harmonics as aerospace starter-generators are typically low inductance machines. Experimental results taken from a prototype inverter show a substantial reduction in THD is achieved using the proposed controller. (5 pages)Predictive control of a photovoltaic DC/DC converter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0330
This paper proposes the use of a predictive controller to regulate a dc/dc converter interacting with a photovoltaic generator and a grid-connected inverter. The proposed solution rejects perturbations generated by environmental conditions and inverter transients. In addition, the predictive controller is able to recover from inverter wrong operation, i.e. drive dc-link voltage under the photovoltaic voltage. The predictive solution is contrasted with a classical PID controller to illustrate its advantages. (6 pages)Comparison of predictive control strategies for direct resonant high voltage DC power supply
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0198
This paper presents a comparison between two predictive control strategies for a HVDC power supply based on a direct resonant power converter: Input Predictive Control (IPC) and Output Predictive Control (OPC). IPC regulates the input filter capacitor voltage and OPC, the tank capacitor voltage. The resonant converter corresponds to a three phase to single phase matrix converter which feeds a resonant tank (SRPL). Both predictive strategies allow soft commutations, thus, minimizing the switching losses. Previous work has analysed the effects of the control choice on an AC voltage power supply only. The main contribution of this paper is the consideration of the effect of the control choice on the input current as well HVDC quality produced by the power supply. (6 pages)Optimum power control for arrays of direct drive wave energy converters
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0160
This paper proposes control strategies for arrays of direct drive wave energy converters. Two control strategies taken from the theoretical study of the hydrodynamic properties of oscillating bodies are applied to a wave energy converter (WEC) system including a linear generator (LG) and voltage source converter system. The purpose of this study is to investigate the feasibility of the control strategies on WECs working in arrays. Simulations of an array of direct-drive WECs connected together by DC link were developed in Matlab/Simulink. The study concludes with a discussion on their feasibility in terms of electrical power generated and the deployment suitability in real seas. (6 pages)Predictive PID controller for DC-DC converters using an adaptive prediction error filter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0213
This paper presents a predictive PID controller for DC-DC converters using an adaptive prediction error filter (PEF) in the controller feedback loop. The concept of using an adaptive PEF is clearly described, and mathematical analysis of central concepts, such as the Auto-Regressive (AR) process generator and Moving Average (MA) identifier are explained in detail. The direct relationship between an adaptive PEF and a digital Proportional-Derivative (PD) controller is also presented. This leads to the development of an adaptive Proportional-Derivative + Integral (PD+I) control structure which is an effective substitute to a conventional PID controller. Experimental validation shows that the approach results in a fast adaptive controller with self-loop compensation. (6 pages)Decentralized coordinated robust controller design for multimachine power system based on multi-agent system
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0084
A decentralized coordinated control is researched based on multi-agent structure for transient stability improvement of large-scale power system in this paper. First, a multi-agent system (MAS) model is structured based on the wide-area measurement system (WAMS), which consists of both upper and lower level agents. The upper level coordinated agents are mainly responsible for coordinating and controlling the lower level agents via sending coordinated control signals into local decentralized control loops in order to damp lower frequency oscillations between regions. And the main function of lower level agents is to continuously regulate generator unit through excitation controller to overcome small disturbances. Then, the focal task of this paper is to design a decentralized coordinated controller based on the MAS model. To eliminate the nonlinearities and interconnections of multimachine models, a direct feedback linearization (DFL) compensator is designed through the decentralized excitation control loop. Besides, taking consideration of the effects of uncertainty introduced by transient process, the H<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">∞</sub> robust control method integrating with linear matrix inequality (LMI) technology is used to seek the solutions of the decentralized coordinated controller. Finally, simulation demonstrates that the MAS based decentralized coordinated robust controller has better transient stabilization performance than the conventional PSS. (6 pages)Contingency constraint corrective rescheduling with the presence of wind farm
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0349
This paper describes the impact of wind generation to enhance the power system security level following a line contingency. In this formulation, fixed speed wind turbine generating unit (FSWTGU) is used. A contingency analysis (CA) and ranking process is used to determine the most severe contingency considering line overloads and bus voltage limit violations. The optimal power flow (OFF) model and contingency constraint optimal power flow (CCOPF) model with FSWTGU are developed. The FSWTGU is modelled as PQ bus in investigating its impact on power system security analysis. An artificial bee colony (ABC) based optimization algorithm is used for solving the OFF model. The proposed algorithm was tested on IEEE-30 bus system. In order to validate the results obtained, the same CCOPF has been solved without the presence of wind farm. The obtained results show the effectiveness of wind farm to enhance the security margin of power system.Predictive control strategies used to solve challenges related to modern railway vehicles
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0615
This paper is an attempt to collate and critically appraise the recent advances in control strategies used to solve challenges related to railway vehicles which present nonlinearities and uncertainties. These strategies concentrate on stability of solid axle-wheelsets, guidance for wheelsets to provide the function of track following and curving to reduce all unnecessary creep forces and associated wear/noise. The focus is on active primary and secondary suspensions, braking and traction sub systems. This paper examines potential new and efficient applications of modern predictive control methods, analysis tools and techniques which could be used in effective and reliable condition monitoring systems allowing informed decision making on maintenance and renewals activities. (5 pages)Design of robust power system stabilizer using mixed sensitivity based H<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">∞</sub> output-feedback control in LMI framework
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0397
This paper presents the design of robust power system stabilizer (PSS)for damping low frequency oscillations. The proposed damping controller design is formulated as mixed sensitivity based H<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">∞</sub> output-feedback control with pole placement constraints. The synthesis problem can be formulated into a standard linear matrix in equalities (LMIs) framework which can be tractable numerically. A single generator, 3-bus system is used to demonstrate the effective ness and robustness of the designed controller at different system operating conditions. The MATLAB simulation result shows good damping and robustness.Effect of fractional-order controller on automatic generation control of a multi-area thermal system
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0365
A concept of fractional order (FO) control has received an increasing interest recently in the control areas. This paper investigates the effect of a fractional-order Proportional plus Integral plus Derivative (FOPID) controller in automatic generation control (AGC) of interconnected two unequal and three unequal area thermal systems considering appropriate generation rate constraint (GRC). Integral square error (ISE) criteria have been used as performance index to design the optimal controller keeping frequency bias setting fixed at frequency response characteristics. The performance of FOPID controller is investigated and compared with several integer-order (10) classical controllers such as integral (I), Proportional plus Integral (PI), Proportional plus Integral plus Derivative (PID). The optimum value for several parameters is obtained using classical approach minimising cost function J. Studies reveal that FOPID controller having five tuning knobs are quite robust and provide superior dynamic performances in terms of settling time and reduction in oscillation of frequency and tie line power deviation dynamic response as compared to all the conventional 10 controllers. System performances are examined with 1% step load perturbation in ureal.Optimal power flow controlling with TCSC using expert system
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0393
This paper presents the solution of Optimal Power Flow (OPF) with different objective functions i. e. fuel cost minimization and active power loss minimization using Genetic Algorithm (GA). The basic OPF solution is obtained with fuel cost minimization as the objective function and the optimal settings of the power system are determined. For reactive power optimization, active power loss has been taken as the objective function. OPF solution with Thyristor Controlled Series Compensator (TCSC) device is carried out considering fuel cost minimization and active power loss minimization as objective. TCSC is used to relieve the overloading of the lines under heavy loading conditions. The results obtained using IEEE 75-bus Indian system is presented.Practical aspects of storage modeling in the framework of microgrid real-time optimal control
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0136
One of the important aspects of microgrids in the long-term is the optimization of power generation. A real-time optimization-based controller can determine the optimal contribution of multiple generation assets or storage devices within the microgrid to meet the demand at minimum operation or emission costs. Since storage devices are indispensable components of microgrids, especially when intermittent power generation sources are employed, their appropriate modeling in this optimization framework is of crucial importance. This paper discusses in detail the technical complexities associated with the practical consideration of storage devices within the framework of microgrid power generation optimization problems, as well as presenting feasible solutions to address these problems. (6 pages)Optimal corrective control for the stability enhancement of power systems considering wind penetration
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0180
This paper proposes an optimal corrective control method to enhance the small signal stability of power systems considering grid-connected wind penetration. The proposed method can optimally compute the amount of generator decreasing and load shedding at selected buses to damp the oscillation. The optimal corrective control procedure for small signal stability enhancement has been present. An eigenvalue sensitivity based optimal corrective control problem with linearized small signal stability constraint is introduced and solved in an iteration manner. Effectiveness of the proposed method is demonstrated by numerical simulation on a modified example of 16-machine power system with 3 grid-connected wind farms. (6 pages)Transient stability analysis and optimal coordinated control of multi-terminal VSC-HVDC based offshore wind farms
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0216
This paper presents control strategies with specific control targets designed for generator- and grid-side voltage-sourced converters (VSCs) of wind turbines with permanent magnetic synchronous generator (WT-PMSGs) as well as those for rectifier- and inverter-side VSCs of multi-terminal VSC HVDC (MTDC) transmission system. With the proposed coordination control of VSCs in the WT-PMSGs and VSC HVDC system, the dynamic stability of the whole offshore wind energy system can be maintained under large disturbances. Then the particle swarm optimisation (PSO) method is proposed for tuning controller parameters of VSCs to improve the dynamic performances of the whole energy system. Finally, case studies for transient stability analysis are carried out to validate the proposed coordinated control strategy and parameters tuning by PSO method. In the testing system, two offshore wind farms and one AC power grid are interconnected as the meshed structure via the 3-terminal VSC-HVDC transmission system. The digital simulations are carried out with Matlab/Simulink. (6 pages)Voltage control system and transient analysis of DG interfaced DC distribution system
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0222
In the liberalized power energy market, the delivery of electrical energy with high power quality to the supplied customers can be achieved through low voltage dc distribution systems. The design process of a dc system, where DG and storage system are interconnected, requires the selection of the most suitable devices for responding to the necessities and requirements of the optimal functioning of the power system. The energy management of the proposed dc grid requires the choice of an optimal control strategy for obtaining the best performances of the system through: realization of a bidirectional flow ac-dc; insurance of a high degree of voltage quality and supply continuity; interconnection and efficient use of DG and storage systems. The fast and safe isolation of the dc fault, such that the dc distribution system equipments are not damages, is the most challenging task. The simulations demonstrate the feasibility and correct operation of the system control logic and the dc protection strategy. (6 pages)Direct drive wave energy converter control in irregular waves
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0125
This paper describes causal sub-optimal control of a direct drive linear generator to extract the maximum power from real sea conditions without wave prediction. The reaction force required to control the buoy to move in phase with the ocean waves is provided by the linear generator. After determining the power take-off force based on the model of a machine, the required currents from the generator can be obtained. These currents have varying amplitudes and frequencies thus presenting a challenge to traditional Pulse Width Modulation control. In this paper, a continuously varying average voltage method is presented where the average voltage for each switching cycle is determined by pre-calculated duty ratio to meet the required voltages before coming into the power converter. Using Matlab/Simulink, simulated results of the power converter current control are presented. (6 pages)Coasting boards vs optimal control
http://dl-live.theiet.org/content/conferences/10.1049/ic.2010.0020
Freightmiser is a proven in-cab driver advice system that provides information to train drivers to help them drive efficiently and stay on time. The system has demonstrated fuel savings of up to 22% on a wide variety of railways, including: (1) bulk grain trains (2) long-haul freight trains (3) high-speed intercity passenger trains (4) slow roll-on-roll-off trains . The information provided to the driver can be tailored to each application, and can include (5) depictions of the track showing gradients, curves, speed limits and trackside features, (6) estimated arrival times at key locations, (7) the ideal driving speed and driving mode. The driving strategy minimises the mechanical work done by the train engines to move the train between key locations in the time available, and so will save fuel or energy on any type of traction system, with or without regenerative braking. The optimal driving strategy uses four driving modes: power, speed-hold, coast and brake. The optimal sequence of control modes and precise switching points are continuously updated based on the observed location and speed of the train, which are determined using GPS. The system takes into account train performance, gradients, curves and speed limits. Unlike coasting boards, the system automatically adjusts the strategy to take into account variations in train performance and variations in speed and timekeeping. (5 pages)Dealing with operational constraints in energy efficient driving
http://dl-live.theiet.org/content/conferences/10.1049/ic.2010.0028
The paper presents algorithms for energy-optimal train control which can be applied in Driver Advisory Systems. As the train driver shall be diverted as few as possible by this system, a constructive two-level algorithm based on the theory of optimal control and a gradient method is presented which delivers the energy-optimal regime sequence with the minimal number of regime changes. The integration of operational requirements in this algorithm is discussed in detail, in particular the consideration of the properties of the Dutch train protection system ATB EG and the integration of capacity bottlenecks as minimal speed constraints. The algorithm is applied to some representative line sections of the Dutch railway network in a case study. (7 pages)System structure and control methods of EPC Internet of book's things
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.1088
The application of RFID system is introduced, and the structure characteristics, working principle, components of Electronic Product Code (EPC) system are studied. The control system is analyzed by H<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">∞</sup>, the results of simulation shows that H<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">∞</sup> control is applicable to internet of things system and can improve stability of the system.A filtered tuning method for a GPC controller
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.0509
This paper presents a new tuning method based on model parameters identified in closed-loop. For classical controllers such as PI(D) controllers a large number of simple tuning methods for various application areas exist. However, when it comes to designing a generalised predictive controller (GPC) four parameters have to be specified. To choose those parameters is not a trivial task since they are not directly related to control or regulation performance. The presented tuning method exploits model-parameters to select suitable controller parameters. Additionally, a Rhinehart filter is incorporated in the design to decrease the impact of noise, therefore, a fifth parameter has to be optimised. The proposed method has been tested in simulation and on a real system.A distributed model prediction based method for coordinated voltage control of power system
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.0243
This paper mainly study on the model predictive control (MPC) based method in the emergency voltage control. The coordinated voltage control scheme and the MPC model of voltage control are introduced firstly. Next, the Lagrange decomposition and auxiliary problem principle is employed into the MPC model of voltage control and a distributed MPC based voltage control scheme can be obtained, by which an online global centralized optimization problem can be solved in a distributed manner. Some simulations conducted on a typical power networks indicate that this voltage control scheme can prevent the voltage instability effectively. (5 pages)Single agents in smart grids
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.0907
This paper aims to present the development of Single Agents for the energy management of electric energy sources including PVs in buildings from the one hand and acheiving the implementation of Demand Side Management strategies on the other. Actions of electric utilities by TSOs/DSOs could influence the amount or timing of customers' energy demand, in order to utilize scarce electric supply resources more efficiently. Using Smart Metering, consumers receive signals that reflect the actual price of electricity, which fluctuates in response to supply and demand. A Single Agent Thermal Model-Based Predictive controller is developed implementing super cooling/heating strategies, through which a building or a building part is pre-cooled/pre-heated during low peak periods achieving peak shaving in an acceptable way by the users regarding the thermal comfort issue. A pilot application of Single Agents is implemented in a building in Greece, and the results are analysed and presented. (9 pages)Comparative analysis of on-line and off-line explicit solutions, applied in predictive direct current
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.0070
This paper presents a comparative analysis of two Model Direct Predictive Controllers (MDPC), which are applied to the inner loop current control of a field-oriented control scheme for an ac drive. A model of the controlled system which includes the dynamics of the inverter (boolean and discrete) and also of the machine (continuous) is employed to predict the future stator currents for a pre-defined finite horizon. Using such information, a cost function is optimized to determine the value for the actuating variable. Such procedure is realized using an off-line as well as a on-line optimization methods. In this case, the predict control belongs to the group of direct control, therefore the actuating variables are the switching states [S<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">a</sub> S<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">b</sub> S<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">c</sub>] for the inverter. (6 pages)Characterisation and modelling of magnetic couplings and gears for servo control systems
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.0188
This paper investigates control issues for drive trains incorporating non-linear magnetic gears. An analytical model of the magnetic gear is used as the basis for deriving optimum PI controller settings based on minimizing the ITAE metric. It is shown that a linearized two-inertia model of the magnetic gear, and PI controller based on an optimal fourth order ITAE polynomial, provide good control of the highly compliant non-linear magnetic gear characteristics. (6 pages)Analysis of fast-scale instability in dc drives with full-bridge converter using Filippov's method
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.0191
Fast-scale instabilities in full-bridge converter dc drives are analysed in this paper using Filippov's method of differential inclusions. This method is very suitable for stability analysis of systems with switching nonlinearities and has been successfully applied to mechanical switching systems and dc-dc converter circuits. This paper presents the first application of the method in a variable speed drive application. By obtaining the state transition matrix over one complete cycle we were able to determine analytically the parameter values at which the nominal period-1 orbit loses stability. Based on the structure of the state transition matrix across the switching manifold (the saltation matrix) an optimal controller was developed capable of extending the parameter range for safe period-1 operation. (6 pages)Predictive control-based facts devices for power system transient stability improvement
http://dl-live.theiet.org/content/conferences/10.1049/cp.2009.1758
It is generally acknowledged that transient stability of a power system is crucial to secure operation following a large disturbance such as a short-circuit fault. Drawing on the recent availability of, and advances in, high-speed flexible AC transmission systems (FACTS) devices, wide-area measurements (WAMs) and high-performance computer systems, the present paper has the objective of developing a real-time control methodology for enhancing and/or maintaining power system transient stability. The key contribution of the paper is that of deriving the control law based on the detailed dynamic model of the power system in the prevailing operating condition. Identification, in either online or off-line mode, of the model structure/ parameters is not required in the control methodology developed in the paper. Actual power system dynamic model of the form used in time-domain transient stability analysis combined with system dynamic response measurements is adopted for the control law derivation. High accuracy is, therefore achieved with the approach proposed. The effectiveness of the control methodology developed in the paper is illustrated by dynamic simulation using a test power system having a FACTS device of the thyristor-controller series capacitor (TCSC) type. (6 pages)An intelligent integrated navigation and control solution for an unmanned surface craft
http://dl-live.theiet.org/content/conferences/10.1049/cp.2009.1686
An adaptive navigation and control algorithm is presented in this paper based on fuzzy logic and optimal control techniques and applied on an unmanned surface vehicle platform. The navigation system consists of an extended Kalman filter with time-varying parameters. Whilst the autopilots include a fuzzy logic based linear quadratic Gaussian controller and a model predictive controller optimized using a genetic algorithm. Both the controllers use the output of the adaptive navigation system as their feedback and therefore creates an integrated system. A multiple waypoint following scenario is considered and tested in real time. Experimental results are shown that demonstrate the efficacy of the proposed system. (6 pages)Particle swarm optimization for use with distributed model predictive control
http://dl-live.theiet.org/content/conferences/10.1049/cp.2009.1697
In Distributed Model Predictive Control (DMPC) the goals of a centralized Model Predictive Control (MPC) system are achieved using communication between agents, in order to coordinate individual agents' responses. This can be achieved using an augmented Lagrangian formulation, which is then distributed between agents using Block Coordinate Descent. Minima in these problems are typically found using deterministic optimization techniques. This paper examines the possible application of Particle Swarm Optimization for this purpose. This stochastic optimization technique is shown to perform similarily to the deterministic techniques in terms of arriving at suitable control inputs but with increased optimization time. (7 pages)Preventive transient stability control using constrained optimal power flow
http://dl-live.theiet.org/content/conferences/10.1049/cp.2009.1801
A new methodology for obtaining the optimal power flow with transient stability constraints is proposed in this paper. The main algorithm decomposes the problem into conventional optimal power flow and optimal control sub-problems, which are solved independently. In the process of optimal control, the transient stability index expressed by semi-infinite dimension constraints is converted into two dimensional inequality constraints by integration of angle and voltage, respectively. The optimal control direction is formed by the gradient of control variables, which is obtained by solving the system trajectory expressed by the differential algebraic equations and trajectory sensitivity expressed by the linear time-dependent dynamic system. Test results on the New England 39-bus power system have verified the effectiveness and reliability of the proposed methodology. (6 pages)Proximal time-optimal control of flexible systems made robust though feedback
http://dl-live.theiet.org/content/conferences/10.1049/cp.2009.1685
The paper presents a new robust acceleration limited time-optimal law for flexible system control by combining the well known open loop time-optimal solution and wave-based control. Using the time optimal solution a new launch wave input to the wave based controller is designed, allowing it to recreate the time optimal solution when the system model is exactly known. If modelling errors are present, or a real actuator is used, the residual vibrations which normally remain when using the time optimal solution alone are quickly suppressed, due to the additional robustness provided by the wave based controller. A proximal time optimal response is still achieved. A robustness study is undertaken and shows significant improvements can be achieved using wave based control in conjunction with the time optimal solution. (6 pages)Real-time voltage control integrated in DMS
http://dl-live.theiet.org/content/conferences/10.1049/cp.2009.0930
The paper deals with the real time optimal voltage control integrated into contemporary Distribution Management Systems. The voltage profile of the entire distribution network is the optimization objective. Tap changer positions of all remotely controlled under load tap changing transformers are control variables. The optimization procedure is based on the results of the real time distribution state estimation running. The quality of the developed voltage control is quantified with the sum of squares of the deviations of voltages on low voltage busbars of the network distribution transformers. The presented results prove that this quality is significantly better than the quality of the network voltage profiles achieved by the application of the classic voltage control. The results are verified in several real-life distribution networks. The paper offers the results of the voltage control verification in the distribution network of the city of Sombor, the branch of the Electric Power Distribution Utility Elektrovojvodina, Novi Sad, Serbia. (4 pages)Linear optimal control of one-machine infinite-bus model & consideration of order increase of machine model
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080536
Network optimization is one of the main ways to reduce the cost of the system and in most cases to improve its stability. LOC is a general stabilizing technique for power electric systems. In fact, this technique is applicable to multi machine, with multimode, high and low-frequency oscillations; although this paper only addresses linear and reduced machine-order equations which are derived from an equivalent system with an infinite-bus and a line. This paper first studies the influence of optimization on a system of one- machine infinite-bus with a line as connector. Then we study the effect of machine order increase in the response of the system.Optimum selection of state feedback variables PWM inverters control
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080496
Different control schemes for voltage source inverter interfacing are presented and compared. Different state feedback control approaches are investigated, therein identifying a generalized optimum control variable selection criterion that is appropriate to the control of inverter systems using an LCL passive filter. A standard synchronous proportional plus integrator (PI) controller is added into the outer loop control to achieve zero steady state error. A (P) proportional inner loop control is used to provide fast dynamic compensation. Finally, system harmonic impedance expressions are derived and used to study the effects of supply voltage distortion on the harmonic performance. The presented optimum variable selection criterion has been verified through the similarities between the different inverter system waveforms and experimental implementation.Optimal control of electromagnetic actuator considering energy loss minimisation in electric circuit
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080217
A finite element - based simulation of the single - phase electromagnetic actuator control including 3D electromagnetic field, circuit and movement model coupling to optimal control is presented. The subject of this paper is to study an optimal control technique that minimises quadratic energy function in the electric circuit. As a new contribution an algorithm based on Linear Quadratic Problem coupled with electromagnetic actuator model in a closed - loop control system is proposed.Experimental characterisation and analysis of wireless network control systems
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080669
This paper presents practical performance results for wireless network control systems (WNCS) using the IEEE 802.11b standard. A practical platform using a reverberation chamber is outlined, which allows for repeatable multipath conditions. Results for a cart-mounted inverted pendulum case study are analysed and the experimentally recorded round trip delay (RTD) is characterised for use in Monte Carlo simulations of a network predictive controller.Control of a highly non-linear multi-variable thermal processing furnace
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080642
Tuning a controller's parameters can sometimes be a very complex and challenging task. Many methods have been used through the years to try and overcome this difficult challenge. In this paper we investigate the linear quadratic regulator (LQR) as a method for giving robust control for the non-linear multiple input multiple output system discussed in this paper. The system is a thermal processing furnace used to anneal 150 mm wafer batches in the 250°C to 450°C range in high vacuum. A plant model was developed which is a hybrid of a physical-law heat-transfer model and measurement data based model of the system. Numerical optimization was used to minimize the difference between measured data and model predicted outputs. Then, multiple linearized models were obtained. LQR was applied to one such model. It achieved the required specifications over the specified temperature range. The important specifications in this application are rise time, steady state accuracy and overshoot which are critical to the process.Wide-area measurement based nonlinear global optimal control for power system stability enhancement
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080070
Centralized control using the wide-area information has been suggested to enhance the dynamic performance of large interconnected power systems. According to the inverse system method and LQR optimal control theory, this paper presents a nonlinear hierarchical global controller based on the wide-area information including the on-line measured center of rotor angle and total unbalanced power. Moreover, it has been verified that the optimal control in the sense of linear quadratic state regulator principle for the linearized system is equivalent to an optimal control in the sense of extended quadratic output regulator performance index for the primitive nonlinear system. So, the designed controller is an optimal controller for the nonlinear system digital simulation demonstrates that the multi-machine power system under the nonlinear global control has less settling time, swing times, oscillatory peak value and more critical clearing time and better voltage stability performance than that under PID control and nonlinear decentralized control.Optimal LQI synthesis for PMSM driving mechanical load with inertia variation and elastic joint
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080596
In industrial world, direct drives are more and more used and rise up new control issues when parameter variations occur. New methods have been created, however, high cost computer and expert is often needed to implement them. In this paper, state feedback controller optimized by linear quadratic principle are shown up. These methods achieve cost requirement cause they provide lighter regulators with constant gain coefficients. Criterions must let the closed loop system stable and keep performances whatever the load inertia is. First method is using an iterative method using linear quadratic criterion with few parameters. The last blends traditional poles placement and linear quadratic principle to achieve a fast synthesis method with interesting results. Experimental results have been obtained taking into account internal current control and inverter limitation too.Advanced methods for control of neural prostheses
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080671
Neural prosthesis based on functional electrical stimulation can restore movement in individuals with paralysis caused by central nervous system injury. Rule based control (RBC) is a promising approach for the control of a neural prosthesis for movement restoration. We present a method for the design of RBC for real time control of walking. For the design of control data from embedded sensors system are used as inputs and muscle activation profiles derived the optimal control simulation as outputs. This is a two step procedure: 1.) The input-output data for machine learning (ML) are generated using biomechanical gait simulations., 2.) The rules are determined by applying ML based on artificial neural network. The controller is trained and evaluated using the data recorded from an able bodied subject walking at two gait speeds. Results showed that the estimation of muscle activations was satisfactory at the gait speed for which the controller was trained. Moreover, the RBC demonstrated the ability to generalize to the gait speed that was higher/lower then the one actually used for the training.Particle swarm optimized induction motor for a textile mill load diagram
http://dl-live.theiet.org/content/conferences/10.1049/ic_20070641
This paper has the main objective of illustrating the importance of controllers in energy saving opportunity of partial loaded three-phase induction motor in textile mill (ring spinning frame) applications. It investigates the economics of a 100 HP induction motor with and without particle swarm optimization (PSO) controller. In this study, the flux level in a machine has been considered to adjust to give maximum efficiency for the textile mill load diagram. The study shows the controller introduces significant difference in the economics in terms of operating cost (energy cost and demand charge cost). The results of a case study show that economic motor will be controlled by PSO controller, because the high price of electricity forces the choice to efficient controllers suitable to variable shaft load. Standard benchmark problem (Rastingen) has been considered for validation of the proposed PSO controller for induction motor loss minimization.Unbiased GM(1,1) model for grey prediction control
http://dl-live.theiet.org/content/conferences/10.1049/cp_20070807
The grey prediction control system whose core is the grey predictor has been widely used in process control. In this paper, the characteristics of the GM(1,1) model which can be used as the prediction model of the grey predictor are analyzed, and the fact that the model is a biased exponential model is testified. Based on the proof, the unbiased GM(1,1) model is proposed. The unbiased GM(1,1) model eliminates the inherent deviation of the GM(1,1) model, which is essentially an unbiased exponential model . Compared with the GM(1,1) model, the unbiased GM(1,1) model is superior in properties and has more extensive application scope. Three examples clearly demonstrate the superiority of the unbiased GM(1,1) model.Adaptive predictive expert control: methodology & application
http://dl-live.theiet.org/content/conferences/10.1049/ic_20060264
This article describes the evolution of control techniques from the beginning of automation until the present, showing how, in spite of these advances, PID control still continues to be the standard in industry today. A new potential standard for advanced control is presented which is not only practical and simple to use, but is also precise and stable in operation. The methodology, on which this new standard is based, is that of adaptive predictive expert control. This article describes the new methodology, based on 30 years of investigation and development, and how it has been integrated via OPC with control systems currently operating within the industrial environment.Design of an unmanned catamaran with pollutant tracking and surveying capabilities
http://dl-live.theiet.org/content/conferences/10.1049/ic_20060267
An unmanned catamaran named Springer is being developed by the Marine and Industrial Dynamic Analysis Research Group at the University of Plymouth to conduct environmental and geographical surveys in shallow waters. An equally important secondary role envisaged for Springer is as a platform for other marine research groups to test their own systems onboard the vehicle. This paper highlights Springer hardware and software architecture including various navigational sensors, speed controller and an environmental monitoring unit. Details regarding the development of a fault tolerant multi-sensor data fusion technique are also outlined. Moreover, control strategy based on a linear quadratic Gaussian with loop transfer recovery theory is presented which would be implemented in Springer for track keeping.Optimal trajectory tracking using an output feedback preview controller
http://dl-live.theiet.org/content/conferences/10.1049/ic_20060560
This paper investigates the use of preview control for optimal trajectory tracking for air-to-surface missiles. An off-line reference trajectory is obtained by solving a trajectory optimisation problem that incorporates the mission constraints. A trajectory following guidance scheme using a preview controller is used to generate the on-line control. An example of a terminal guidance trajectory with a bunt (climb and dive) manoeuvre and a look angle constraint is presented to demonstrate the method.Advanced control and real time optimization for power and industrial energy
http://dl-live.theiet.org/content/conferences/10.1049/ic_20060263
The talk will summarize new development in the area of model predictive control and real time optimization focused on power plant and industrial energy as well as implementation on a new distributed, software component based platform. Successful solution has to bring together process control and optimization functions based on both technical/technological criteria and economic criteria with the application flexibility provided by the latest software technologies.MPC model based predictive control
http://dl-live.theiet.org/content/conferences/10.1049/ic_20060262
The presentation covers the practical implementation of a DeltaV MBPC on furnace control. It describes the importance of step tests and pseudo random binary sequence tests to obtain the process model and how the various tuning parameters affect the performance and robustness of the controller.