Distributed data acquisition and control system based on low cost Embedded Web servers

In the present IT age, we are in need of fully automated industrial system. To design of Data Acquisition System (DAS) and its control is a challenging part of any measurement, automation and control system applications. Advancement in technology is very well reflected and supported by changes in measurement and control instrumentation. To move to highspeed serial from Parallel bus architectures has become prevalent and among these Ethernet is the most preferred switched Serial bus, which is forward-looking and backwardcompatible. Great stride have been made in promoting Ethernet use for industrial networks and factory automation. The Web based distributed measurement and control is slowly replacing parallel architectures due to its non-crate architecture which reduces complexities of cooling, maintenance etc. for slow speed field processing. A new kind of expandable, distributed large I/O data acquisition system based on low cost microcontroller based electronic web server[1] boards has been investigated and developed in this paper, whose hardware boards use 8-bit RISC processor with Ethernet controller, and software platform use AVR-GCC for firmware and Python for OS independent man machine interface. This system can measure all kinds of electrical and thermal parameters such as voltage, current, thermocouple, RTD, and so on. The measured data can be displayed on web pages at different geographical locations, and at the same time can be transmitted through RJ-45 Ethernet network to remote DAS or DCS monitoring system by using HTTP protocol. A central embedded single board computer (SBC) can act as a central CPU to communicate between web servers automatically

Corporate Risk-Taking and the Decline of Personal Blame

The ability to maintain state awareness in the face of unexpected and unmodeled errors and threats is a defining feature of a resilient control system. Therefore, in this paper, we study the problem of distributed fault detection and isolation (FDI) in large networked systems with uncertain system models. The linear networked system is composed of interconnected subsystems and may be represented as a graph. The subsystems are represented by nodes, while the edges correspond to the interconnections between subsystems. Considering faults that may occur on the interconnections and subsystems, as our first contribution, we propose a distributed scheme to jointly detect and isolate faults occurring in nodes and edges of the system. As our second contribution, we analyze the behavior of the proposed scheme under model uncertainties caused by the addition or removal of edges. Additionally, we propose a novel distributed FDI scheme based on local models and measurements that is resilient to changes outside of the local subsystem and achieves FDI. Our third contribution addresses the complexity reduction of the distributed FDI method, by characterizing the minimum amount of model information and measurements needed to achieve FDI and by reducing the number of monitoring nodes. The proposed methods can be fused to design a scalable and resilient distributed FDI architecture that achieves local FDI despite unknown changes outside the local subsystem. The proposed approach is illustrated by numerical experiments on the IEEE 118-bus power network benchmark.QC 20141114</p

Multi-agent based protection scheme using current-only directional overcurrent relays for looped/meshed distribution systems

The complexity of the design of the protection system using directional over current relays, for modern power distribution systems has been increased due to the looped/meshed operation and the penetration of distributed generations. Finding a reliable and efficient protection scheme that can be easily implemented in these distribution systems is a major challenge. An efficient solution could be the use of artificial intelligent-based multi-agent systems. This paper proposes a novel distributed intelligent based multi-agent protection scheme, which makes use of current-only directional over current relays as agents for detecting and locating faults and isolating faulty areas (lines/busbars) in the distribution systems. All agents can make on-board decisions by exchanging binary data, and do not need a control centre, so the safety of the protection system against one-point failures and cyber-attacks is increased. The proposed scheme does not need to exchange analogue data, and, therefore, it prevents the high bandwidth communication links. Moreover, it is free from the traditional coordination between relays. This scheme is implemented on the IEEE-14 bus and IEEE-30 bus test systems with the distributed generations and several scenarios have been simulated to evaluate its performance

Modeling, Simulation, and Hardware-in-the-Loop Implementation of Distributed Voltage Control in Power Systems with Renewable Energy Sources

This dissertation develops and analyzes distributed controllers for power systems with renewable energy sources. A comprehensive state space modeling of voltage source inverters (VSIs) is developed specifically to address the secondary voltage control. This model can be used for simulation and control design. Unlike frequency, voltage is a local phenomenon, meaning that it cannot be controlled from a far distance. Therefore, a voltage zoning matrix that relates the sensitivity of the loads to the sources is proposed. The secondary voltage control is designed by applying the eigenvalue decomposition of the voltage zoning matrix to obtain the reference generators voltages. The developed algorithm in this study has been tested on multiple IEEE case studies, and the results show its effectiveness, yet it is a centralized control algorithm. To reduce the risk of a single point of failure in the centralized controllers, distributed secondary voltage controllers have been proposed in the recent literature. However, the communication messages are still exchanged among all controllers in the system. Therefore, a fully distributed algorithm is proposed in this dissertation study through the design of a communication layer by clustering the sources based on a developed sensitivity methodology. A modified IEEE 13 bus feeder with integrating renewable energy sources shows a significant improvement in time of convergence. A real communication protocol is then applied to the system to analyze the communication effect of packet loss and latency on the given distributed control system. Furthermore, to demonstrate the voltage control problem on the hardware-in-the-loop system, the detailed steps to implement the simulation model in the OPAL-RT real-time simulator (RTS) are discussed. The results of RTS coordinate with the software modeling outcomes

Development of a Distributed Multi-MCU Based Flight Control System for Unmanned Aerial Vehicle

[[abstract]]This paper investigates the design and implementation of a distributed multi-microcontroller based control system development environment. A DSPIC microcontroller (MCU) based system architecture is established first. The system contains three major parts, namely, sensing and attitude determination section, control section, and ground section. The sensing and attitude determination section consists of four circuit boards (master control board, slave control board, sensor board, and power supply board) with identical size ( ). The sensor boards contains three axes inertial measurement unit (include gyro, accelerometer, and electronic compass) and a GPS receiver. The sensors and the DSPIC MCUs are connected over an I2C (inter-integrated circuit) data bus with the DSPIC on the master control board as the master MCU. Unscented Kalman filter based attitude estimation is incorporated in this embedded system. With incorporation of modular design, combination of the master control board and the slave control board will form the control section of the system. Communications between sections are achieved through UART interface. Because of modular design, the system can be easily expanded to integrate other avionics functions. A model-based state feedback flight control system with time delay is also presented to deal with the inevitable time delay problem of the network control system. The plant model is used to simulate the plant behavior during the periods when sensor data are not available. When the controller receives the sensor data that were transmitted by the sensor a period of time ago, a propagation unit is employed in the control system to propagate the sensor signals instantaneously to the present time. The estimate is then used to update the model that in turn will generate the control signal for the UAV. Computer simulation confirms the success of the model-based design for the distributed multi-chips flight control system.[[sponsorship]]中華民國航空太空學會; 成功大學[[conferencetype]]國內[[conferencedate]]20141115~20141115[[booktype]]電子版[[iscallforpapers]]Y[[conferencelocation]]台南市, 台

Stability design criteria and volt var control for distribution system with single phase solid state transformers

Due to recent advancements in semiconductor technology, power electronic converters for high voltage, high power, and high frequency applications will soon be commercially available. Conventional single phase distribution transformers are replaced by solid state transformers (SST) in a distribution test system to investigate their interactive dynamics. Under certain circumstances, instabilities due to harmonic resonance are observed. A design criterion for solid state transformer during no load conditions has been proposed in order to avoid instability using an impedance-based analysis. Stability assessment is also extended to include the impact of distribution system voltages and system wide impedance analysis. It is shown that if the SST filters throughout the system are designed with regards to the proposed stability criterion, then system stability is guaranteed regardless of configuration. This leads to two resulting applications: (1) the order in which the SSTs are connected to the system will not generate instability if the criterion is satisfied, and (2) a system configuration change due to a fault will not produce instability. In distribution power systems, feeder voltages can be very sensitive to changes in load and/or distributed generation. A solid-state-transformer-based local voltage control strategy is introduced to reduce variability distribution system bus voltages. An on-line dynamic volt-var control (VVC) algorithm is proposed to regulate bus voltages by injecting or absorbing reactive power through a solid state transformer. The main goal of the algorithm is to enforce strict voltage constraints on the system voltages. The proposed control algorithm is validated in both a radial and meshed distribution system. --Abstract, page iii

Voltage control loss factors for quantifying DG reactive power control impacts on losses and curtailment

Distributed Generators that use reactive power for voltage control in distribution networks reduce renewable curtailment but can significantly increase network losses, undermining the effectiveness of this control. This paper proposes Voltage Control Loss Factors (VCLFs) as a means of understanding the interactions between reactive power flows, losses and curtailment, focusing on commercial-scale generators in radial systems. The metric uses a substitution-based method, whereby a system with voltage control is compared against a counterfactual with no such control. The proposed method studies this metric by coupling numerically precise black-box simulations with analytic results from a Two-Bus network representation. The latter provides a physical explanation for the numerical simulation results in terms of power, voltage and impedance parameters, providing clear explainability which is absent in traditional approaches for determining distribution loss factors. The whole solution space of the Two-Bus system is explored, and VCLFs are calculated for six cases on three unbalanced test networks to illustrate the approach. Relative losses as high as 30% are found in a system with high branch resistance-reactance ratio and large voltage rise. The results have implications for the design of loss allocation algorithms in distribution networks, and the optimal sizing of power-electronic interfaced Distributed Generators