Multi Controller Research Articles

Tidal Energy Integrated Robust Frequency Control of an Islanded AC Microgrid with Improved-MFO Tuned Tilt Controller

In recent electrical energy scenario different renewable energy based distribution generation (DG) systems have been developed to provide electrical power to distant and remote consumers. In view of this current research article presents a Tidal Power Plant (TPP) and its integration with an Islanded AC Microgrid system. The tidal energy based TPP is modelled to generate required electrical power. However the inherent dynamic behaviour of TPP largely affects the microgrid system frequency especially in islanded mode of operation. In regard to this to obtain necessary control mechanism in an islanded AC microgrid system , present research article proposes a tilt multistage TDF/(1+TI) controller and to show effectiveness of proposed tilt controller for microgrid control it has been compared with multistage PDF/1+PI and PID controllers. To obtain optimal gain parameters of above implemented controllers an Improved- Moth Flame Optimization (I-MFO) technique has been proposed for this study. To justify viability of proposed I-MFO algorithm its performances have been compared with original MFO algorithm. Finally it has been noticed that to obtain robust frequency control in an islanded AC microgrid system, proposed I-MFO optimized tilt multistage controller exhibits outstanding performance under wind, solar and tidal energy uncertainties.

Latency-Based Dynamic Controller Assignment in Hybrid SDNs: Considering the Impact of Legacy Routers

Software-defined networking (SDN) is a modern network architecture, which separates the network control plane from the data plane. Considering the gradual migration from traditional networks to SDNs, the hybrid SDN, which consists of SDN-enabled devices and legacy devices, is an intermediate state. For wide-area hybrid SDNs, to guarantee the control performance, such as low latency, multi SDN controllers are usually needed to be deployed at different places. How to assign them to switches and partition the network into several control domains is a critical problem. For this problem, the control latency and the packet loss rate of control messages are important metrics, which have been considered in a lot of previous works. However, hybrid SDNs have their unique characters, which can affect the assignment scheme and have been ignored by previous studies. For example, control messages pass through Legacy Forwarding Devices (LFDs) in hybrid SDNs and cause more latency and packet loss rate for queuing compared with SDN-enabled Forwarding Devices (SFDs). In this paper, we propose a dynamic controller assignment scheme in hybrid SDNs, which is called the Legacy Based Assignment (LBA). This scheme can dynamically delegate each controller with a subset of SFDs in the hybrid SDNs, whose objective is to minimize average SFD-to-control latency. We performed some experiments compared with other schemes, which show that our scheme has a better performance in terms of the latency and the packet loss rate.

A gray wolf optimized FPD plus (1+PI) multistage controller for AGC of multisource non-linear power system

Purpose The paper has proposed to implement gray wolf optimization (GWO)-based filter-type proportional derivative with (FPD) plus (1+ proportional integral) multistage controller in a three-area integrated source-type interlinked power network for achieving automatic generation control. Design/methodology/approach For analysis, a three area interconnected power system of which each area comprises three different generating units where thermal and hydro system as common. Micro sources like wind generator, diesel generator and gas unit are integrated with area1, area2 and area3 respectively. For realization of system nonlinearity some physical constraints like generation rate constraint, governor dead band and boiler dynamics are effected in the system. Findings The supremacy of multistage controller structure over simple proportional integral (PI), proportional integral, derivative (PID) and GWO technique over genetic algorithm, differential evolution techniques has been demonstrated. A comparison is made on performances of different controllers and sensitivity analysis on settling times, overshoots and undershoots of different dynamic responses of system as well as integral based error criteria subsequent a step load perturbation (SLP). Finally, sensitive analysis has been analyzed by varying size of SLP and network parameters in range ±50 per cent from its nominal value. Originality/value Design and implementation of a robust FPD plus (1 + PI) controller for AGC of nonlinear power system. The gains of the proposed controller are optimized by the application of GWO algorithm. An investigation has been done on the dynamic performances of the suggested system by conducting a comparative analysis with conventional PID controller tuned by various optimization techniques to verify its supremacy. Establishment of the robustness and sensitiveness of the controller by varying the size and position of the SLP, varying the loading of the system randomly and varying the time constants of the system.

A PSO Based Modified Multistage Controller for Automatic Generation Control with integrating Renewable Sources and FACT Device

This study focuses on modelling of two area hydro-thermal interconnected system integrated with wind, Small Hydro Plant (SHP) and Solar Thermal Plant (STP). Flexible AC Transmission (FACT) device named as Static Synchronous Series Compensator (SSSC) and an energy storing element called Super Magnetic Energy Storage (SMES) unit is incorporated in the model. To control and monitor the system, an effective Particle Swarm Optimization (PSO) optimized multistage controller is proposed. The effectiveness of the suggested controller is verified under diverse step and time varying load perturbation. The superiority of controlling action of the proposed controller is also proved to be efficient than other prominent controllers. System stability is analyzed and found to be stable through the establishment of Eigen value analysis and bode plot. Furthermore, the system behavior is studied with various combination of SSSC and SMES in different area simultaneously. To make the analysis more realistic, appropriate time delay is included in the proposed study. Finally, sensitivity analysis of the network by varying the different system parameters, governed through a multistage controller is carried out.

Multi-robot Cooperation Strategy Based on Wireless Sensor Network

To realize the design of multi-robot cooperative control based on wireless sensor networks, a large number of local control research experiments are carried out on a specific model of mobile robots. Combined with the kinematic model of mobile robot, the motion characteristics of this kind of mobile robot are grasped. On the basis of realizing the multi-target tracking and positioning of wireless sensor network, a multi mobile robot cooperative control system based on the feedback of wireless sensor network is developed, and the synchronous motion between the master and the robot is maintained through the feedback control of the network. Finally, a cooperative trajectory tracking control algorithm for mobile robot is introduced, and the principle of the controller design is mastered. A multi mobile robot cooperative trajectory tracking LQG controller is designed for mobile robot in wireless sensor network. The simulation results show that the algorithm can reach the cooperative control target.

Optimal placement method of multi UPFCs to damp power system oscillations

Summary This paper proposed the placement of multi unified power flow controllers (UPFCs) using the system critical modes and residue factor to increase damping of the electromechanical oscillations in power system. For this purpose, the critical modes are used to determine the number of UPFCs and their optimal locations are determined using residue factor. Also, the dynamic model of UPFC, which is consists of a voltage source and a current source is used for small signal stability analysis. To control the parameters of this model, supplementary controller is designed and applied. Detection of the input signal for this controller is based on the participation factor, which is a simple and effective method. Finally, the proposed method is investigated on IEEE 39-bus system and the results are presented.

Robust flatness-based switching reconfiguration control using state flow machines of electronic throttle valve

In this paper, a robust Fault Tolerant Control reconfiguration approach using State Flow Machines is proposed. Indeed, this reconfiguration strategy is based on robust flatness-based switching control using state machines and flow charts. This approach is developed in discrete time framework in order to track a reference trajectory starting from a flat output variable. For each model, a corresponding flatness-based controller is designed and consequently, a multi controller structure is obtained. The switching flatness-based control is based on switching between identified Operating Modes (OM) using state flow machines. The Luenberger observer’s gains are determined using LMIs tools in order to identify the corresponding OM. The localization of the current OM is carried out by minimization of a performance test characterizing the distance between the system and the given OM. Study of the stability as well as the use of anti-windup devices related to switching between controllers have been considered in the proposed approach. The proposed approach is applied to the nonlinear system which is in our case of study an Electronic Throttle Valve (ETV) using state flow machines modeling.

Results and comparision between different control algorithms for a quadrotor using ArduPilot framework

Determining the most suitable control algorithm for a system is not an easy task. In theory, each controller has its own advantages and disadvantages comparing to the others. However, in the real world, the behavior of the controller also depends on many other factors such as the calculating ability of the control board, the accuracy of the sensors, the way the hardware communicate with the others, etc. In order to find the pros and cons of each control algorithm in the real world, each of them has to be tested and then comparing their results. This article presents a simple way to test the behavior of various control algorithms, with the quadrotor as the control target and ArduPilot is the framework to create the firmware carrying multi controllers. At the end of this article, the results of 3 control algorithms: Original PID of ArduPilot, new developed PID and Integral Backstepping will be presented and compared. These data is created by using Software In The Loop simulation (SITL), a tool provided by ArduPilot to test the new developed firmware.

Griffin: Programmable Optical DataCenter With SDN Enabled Function Planning and Virtualisation

Optical networking technologies are very attractive for intra-DataCenter (DC) interconnectivity due to their intrinsic high-bandwidth and low-latency characteristics. As the bandwidth demand grows, quantity and size of IT and network infrastructure grows, which puts pressure on power, cost, and space consumption. Therefore, programmable optical networking solutions, which are highly controllable and provide granularity and scalability in services, can greatly enhance operations and resource efficiency for DC interconnects. This paper proposes and reports on a novel function-programmable and application-aware intra-DC technology. The hardware platform uses FPGA implementation of top-of-rack (ToR) switch which supports two main software-defined network functions of a) Ethernet over WDM and b) Ethernet over TDM sub-WDM. Each switch can be programmed to virtually operate as an optical Ethernet or subwavelength transport system. The TDM function further supports a range of additional programmable features in time-slice and frames. The system can be controlled to switch between the functions on-demand and on a hitless manner. This platform with unique flexibility in functions and features is configured to operate with various processing times, throughput, and delays, enables on-demand quality of service (QoS) definition to match diverse cloud application requirements. Optical fast switches enable all-optical transport between the ToRs, further supporting low-latency and resource efficiency. A multistage software-defined controller is built which at the first stage uses application requirements to virtually create function programmable subnetworks by repurposing the data plane functions as well as control plane (algorithms) features. In the second stage, it allows dynamic allocation of resources of the subnetwork for the duration of the application. This platform is characterised to operate with different QoS metrics and evaluated for DC use cases.

A Novel Power Grid Restoration Scheme Using Active PFC

Abstract The Distributed Generator (DG) based intentional islanding is very useful and improves the stability of power system. But the inverter based connection of DG leads to power quality related issues like harmonics injunction, voltage flicker and non-sine wave output. As a remedy, modeling and control of fuel cell based distribution generation system is studied and implemented for Thermal Power Station (TPS) for improving power system reliability. The TPS auxiliaries which are receiving power from station transformer during healthy system conditions, stop functioning during faulty grid conditions as it is difficult to fulfill their power demand. The paper proposes a novel method for running TPS auxiliaries during system disturbance using fuel cell as an alternative source of power. The voltage profile in the proposed method is maintained using power flow controller (PFC). The multi converter power flow controller is used for easy power and voltage profile control. It is observed that separate use of fuel cell as a DG and Generalized Unified Power Flow Controller (GUPFC) as a PFC fail to show desired results. The proposed method is studied and simulated with standard IEEE and real time test systems. It is observed that using proposed method uninterrupted working of TPS auxiliaries is possible during condition of system disturbance. This unaffected TPS system is identified as a source of power during system restoration which is followed by grid disturbance.

Multiparameter controller usage for gas pumping unit control

Based on the experiment on a centrifugal supercharger Ц-6,3, which is included in anti-surge regulation of gas pumping units it is defined the productivity change of centrifugal supercharger and changes in the degree of increase in gas pressure, from which is derived the transfer function of a centrifugal supercharger of gas compressor unit.The method of parameter determining of regulator setting through such component of Matlab software as Check Step Response Characteristics block is given. The technological process simulation is conducted with PID, PIDD2-, PIDD2D3-, PDD2-, and PDPD controllers based on the determined values in Matlab software and their optimal settings are determined.During research of system using multi controllers it is found that operation speed of system increases in comparing with PID-controller at: PIDD2 controllers to 4,44 %, PIDD2D3 controllers to 22,67 %, PDD2 controllers to 89,33 %, and PDPD controllers to 98,22 %.

The Research of the Intelligent Given and Control for the Dissolved Oxygen in the Aeration Process of Sewage Treatment

Based on these characteristics of dissolved oxygen control in sewage treatment aeration process, such as nonlinearity, large time delay in a timely manner and difficult to model accurately, this paper puts forward an intelligent control strategy of dissolved oxygen. First, according to feed water quality parameters and environmental factors, we build a rule-based multistage fuzzy controller to make intelligent dynamic dissolved oxygen value setting. Then the feedforward tracking and constant value control are proceed, according to error source and threshold we use fuzzy tracking, fuzzy PID separation control and compound control of the major and minor loop cascade control to stabilize the given value of dissolved oxygen. The system is fast and steady which is proved by simulation and experiment results.

Solving practical power system problems using hierarchical interactive PSO strategy considering SVC controllers

This paper presents a hierarchical interactive particle swarm optimization (HIPSO) for solving the static multi objective optimal power flow (OPF) considering multi SVC controllers and dynamic economic dispatch (DED). This study introduces a variant of PSO using new mechanism search based dynamic adjustment of PSO parameters coordinated with a hierarchical strategy for reactive power planning stage to improve the performances of the original PSO in terms of solution quality and convergence characteristics. The HIPSO algorithm optimizes a combined control variables such as: active power generations, voltage control of generators, tap transformer and the reactive power of multi SVC Controllers installed at a specified buses to minimize fuel cost, total power loss and voltage deviation while satisfying the generators constraints and power system security. The proposed approach examined and applied to many practical test systems: IEEE 57-Bus, IEEE 118-Bus, 40 generating units and 10 generating units to solving; the static multi objective OPF with quadratic fuel cost function, the economic dispatch considering valve point effects and the dynamic economic dispatch considering both valve point effects and ramp rate limits. Simulation results compared to Matpower, to the standard PSO and others recent metaheuristic methods confirm the effectiveness of the proposed combined approach.

Driving/regeneration and stability enhancement of 4WD hybrid vehicles, using multi-stage fuzzy controller

In front wheels driven vehicles, fuel economy can be obtained by summing torques applied on rear wheels. On the other hand, unequal torques applied to rear wheels provides enhanced safety. In this paper, a model with seven degrees of freedom is considered for vehicle body. Thereafter, powertrain subsystems are modelled. Considering an electrical machine on each rear wheel, a fuzzy controller is designed for each driving, braking and stability conditions. Another fuzzy controller recognises the vehicle requirements between the driving/regeneration and stability modes. Simulations performed in MATLAB/Simulink environment show that the proposed structure can enhance the vehicle performance in different modes effectively.

Research of DD2UD with Human Simulating Intelligent Control for a Double Inverted Pendulum

A double pendulum has four equilibrium points (Down-Down, Down-Up, Up-Down, Up-Up). With those equilibrium points, many transfer actions from one equilibrium point to another can be formed. Using the Human Simulated Intelligent Control (HSIC) method based on Sensor-Motor Intelligent Schema, an intelligent control system for the double inverted pendulum which has the structure of multi controller and multi control mode is designed. With this controller, the transfer action of Down-Down to Up-Down (DD2UD) is achieved. The design process of HSIC controller is discussed. The real-time experiment result testified the validation of proposed method.

Adaptive Rollover Prevention for Automotive Vehicles with Differential Braking

Abstract In this paper we present an adaptive controller implementation based on the multiple models, switching, and tuning (MMST) paradigm [Narendra and Balakrishnan, 1994, 1997] for preventing un–tripped rollover in automotive vehicles. Our approach relies on differential-braking to keep the value of the Load Transfer Ratio ( LTR ) below a threshold. We first employ multiple models to infer the unknown center of gravity height and the suspension parameters of the vehicle, which are subsequently used to switch to the corresponding rollover controller. The efficacy of the proposed switched multi–controller scheme is demonstrated via numerical simulations as compared to a robust controller implementation.

Multi-stage fuzzy PID power system automatic generation controller in deregulated environments

In this paper, a multi-stage fuzzy proportional integral derivative (PID) type controller is proposed to solve the automatic generation control (AGC) problem in a deregulated power system that operates under deregulation based on the bilateral policy scheme. In each control area, the effects of the possible contracts are treated as a set of new input signals in a modified traditional dynamical model. The multi-stage controller uses the fuzzy switch to blend a proportional derivative (PD) fuzzy logic controller with an integral fuzzy logic input. The proposed controller operates on fuzzy values passing the consequence of a prior stage on to the next stage as fact. The salient advantage of this strategy is its high insensitivity to large load changes and disturbances in the presence of plant parameter variations and system nonlinearities. This newly developed strategy leads to a flexible controller with simple structure that is easy to implement, and therefore, it can be useful for the real world power systems. The proposed method is tested on a three area power system with different contracted scenarios under various operating conditions. The results of the proposed controller are compared with those of the classical fuzzy PID type controller and classical PID controller through some performance indices to illustrate its robust performance.

Decentralised coordination of facts devices for power system stability enhancement using intelligent programming

PurposeThis paper seeks to propose a systematic method to design multi fuzzy FACTS based stabilizers in a multi‐machine power system.Design/methodology/approachConventional FACTS based stabilizers are decentralized controllers that adopt local measurements and operate in closed loop. To improve overall system dynamic performance, a coordinating application of FACTS based stabilizer is essential. Although, numerous researches have indicated the effectiveness and superiority of fuzzy logic controllers in comparison with the conventional linear controllers in power system application but researchers have not adequately investigated coordination of multi fuzzy controllers in multi‐machine power systems to provide optimal performance. Genetic algorithm is used to determine optimum values of controllers' parameters.FindingsThe search space of the optimisation procedure is decreased to a smaller one, design and computation time can be reduced significantly and the design process becomes more systematic.Originality/valueA systematic method is introduced to coordinate multi fuzzy FACTS based stabilizers in multi‐machine power systems.

A novel approach for multistage inference fuzzy control

This paper presents a methodology to the design of a multistage inference fuzzy controller in which the consequence in an inference stage is passed to the next stage as fact, and so forth. A new general method which is based on a performance index of the control system is used to generate fuzzy rule bases for the multistage inference. This proposed method can reduce the design cycle time. In order to reduce the computation time, a method for precomputing the match-degrees of fuzzy values is adopted. Thus, the number of operations that must be carried out at execution time can be significantly reduced. The new method has been applied to two applications, a two-trailer-and-truck system and a three-trailer-and-truck system. The simulation studies showed that the proposed method is feasible.

Comprehensive dynamic modeling and motion/force control of flexible manipulators

This paper presents a comprehensive dynamic modeling of a flexible link manipulator by using Hamilton's principle. The model is formulated by considering the flexible arm as a Timoshenko beam model. Hence, the shear, bending as well as rotational inertia effect of the manipulator are all taken into account in the dynamic formulation. In order to obtain a comprehensive dynamic model, the gravitational effect, which is missing in most of the flexible manipulator dynamic models, is also included in the formulation. Then, an efficient motion and force controller design method utilizing root contour analysis is proposed. With the proposed method the multi controller gains of the position/force controller for the flexible manipulator can be chosen analytically, as opposed to the method of trial and error used conventionally for selecting manipulator controller gains. The tuning process of these controllers' gains proves the simplicity of gains selection. And the motion/force simulation results verify the effectiveness of the controllers. The simulation results also show that the derived control scheme, which is based on a linear control system analysis, can drive the highly non-linear flexible arm to achieve the desired position and force satisfactorily.