NASA Tech Briefs, June 1990

Topics: New Product Ideas; NASA TU Services; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences

Design of an Automatic Synchronizing Device for Dual-Electrical Generators Based on CAN Protocol

Automatic synchronizers are widely employed to connect more than one synchronous generator. The main task of a synchronizer is to capture the voltage, frequency and phase differences between the generators accurately and rapidly. This thesis introduces a new automatic synchronizer for dual generators based on CAN “controller area network” protocol. The device consists of three independent microcontroller modules connected with CAN protocol. One of them is called the circuit control breaker, it is responsible for closing the circuit breaker between the generators. The other two modules are assigned to capture the voltage, frequency and phase differences for each generator due to a reference signals, and control the governor of the generators to much the acceptable limits. Due to the fastness and error detection techniques of CAN protocol, the probability of false synchronization decision is minimized which is the main contribution of the thesis, therefore, the reliability of the synchronization is improved. The developed automatic synchronization unit is fast, cost effective, reliable and precise to be used for monitoring, measuring and parallel operations of the synchronous generators

Advanced control system for stand-alone diesel engine driven-permanent magnetic generator sets

The main focus is on the development of an advanced control system for variable speed standalone diesel engine driven generator systems. An extensive literature survey reviews the historical development and previous relevant research work in the fields of diesel engines, electrical machines, power electronic converters, power and electronic systems. Models are developed for each subsystem from mathematical derivations with necessary simplifications made to reduce complexity while retaining the required accuracy. Initially system performance is investigated using simulation models in Matlab/Simulink. The AC/DC/AC power electronic conversion system used employs a voltage controlled dc link. The ac voltage is maintained at constant magnitude and frequency by using a dc-dc converter and a fixed modulation ratio VSI PWM inverter. The DC chopper provides fast control of the output voltage by dealing efficiently with transient conditions. A Variable Speed Fuzzy Logic Core (VSFLC) controller is combined with a classical control method to produce a novel hybrid controller. This provides an innovative variable speed control that responds to both load and speed changes. A new power balance based control strategy is proposed and implemented in the speed controller. Subsequently a novel overall control strategy is proposed to co-ordinate the hybrid variable speed controller and chopper controller to provide overall control for both fast and slow variations of system operating conditions. The control system is developed and implemented in hardware using Xilinx Foundation Express. The VHDL code for the complete control system design is developed and the designs are synthesised and analysed within the Xilinx environment. The controllers are implemented with XC95108-PC84 and XC4010-PC84 to provide a compact and cheap control system. A prototype experimental system is described and test results are obtained that show the combined control strategy to be very effective. The research work makes contributions in the areas of automatic control systems for diesel engine generator sets and CPLD/FPGA application that will benefit manufacturers and consumers.EPSR

Development of Microgrid Test Bed for Testing Energy Management System

Today the world population has reached 7.5 billion, and this number is expected to grow at the rate of 1.13% every year [1]. With this increase in population, the total demand for electricity has also increased. More people means the need for more power: electricity to power homes, schools, industries, hospitals, and so on. In today’s world, where most of the daily activities are dependent on electricity, demand for electricity, therefore, continues to rise. Currently, managing this growing need for electricity is one of the challenges the world is facing. In addition to this, approximately 1.2 billion people live in remote parts of the world where the electricity supply is either limited or non-existent [2]. Providing an affordable and easily available source of electricity to this population is another challenge. In response to these challenges, a significant number of countries are investing in the integration of renewable resources for energy production. Renewable resources such as the sun, wind, and water are free, clean, and readily available. Remote and poor parts of the world can also benefit by utilizing these available energy sources for electricity generation. The use of renewables helps to decrease the overall cost of electricity generation as well. This need for clean and safe energy has contributed to creating and promoting the concept of microgrids around the world. Microgrids are defined as small-scale power distribution networks with distributed energy sources, loads, and storage. They can operate in either grid-connected or islanded mode. Renewable sources are intermittent in nature, and uncertainties are always present in the microgrid operation when using these resources. The Energy Management technique is required for the coordination of these resources in order to mitigate the potential risks. Some studies have been conducted in the area of microgrid operation, stability, and control, and various types of laboratory-based microgrid test beds have been developed. A microgrid test bed allows testing of scaled down systems in order to test and simulate large real-world microgrid projects. The objective of this study is to develop a reconfigurable microgrid test bed. This test bed is created on a laboratory scale and is capable of testing energy management algorithms to validate real-time operation. A novel approach to automatic microgrid operation is proposed with the use of commercial off-the-shelf equipment and the Controller Area Network (CAN) protocol. The OPAL-RT 5600 real-time simulator is used as a central controller for controlling and scheduling microgrid sources to supply the load, charge the battery and, read a state of charge values. The CAN communication protocol is used by the controller to control and coordinate different components. Different cases are studied in order to support the reconfigurability, automatic operation, and energy management in the microgrid test bed using the CAN bus

Digital Control System for Vertical Stability of the TCV Plasma

In advanced mode operation of fusion devices, real time control plays a central role in achieving the desired plasma performance and minimizing the risk of disruptions. With the advances in digital technologies like Digital Signal Processors (DSPs), Field Programmable Gate Arrays (FPGAs) and standard commercial computer processors, the development of digital control systems to use in fusion experiments has spread to all modern tokamaks. Tokamak à Configuration Variable (TCV) had limited control capabilities due to the utilization of an analogue control system. In the first part of the PhD Program an Advanced Plasma Control System (APCS), capable of improving the capacity of control of highly configurable plasma shapes, position, current and density by the introduction of nonlinear digital controllers, was designed, implemented and integrated in TCV. Early tokamaks with circular cross-section plasmas were not prone to the vertical plasma column instability, an inherent problem arising in plasmas with vertically elongated cross sections, with benefits to the energy confinement time, increased plasma current and beta. To overcome this problem, complex closed feedback loop control systems with a vertical position measurement, signal processing, control algorithm, power supplies and active actuating coils are used. In the second part of the PhD Program a predictive vertical stabilization non-linear digital controller was designed and implemented, with the help of a new mathematical simulator based on a rigid plasma model. The layout of a method to define controllable limits for the plasma position and velocity may be used for the design of new control systems. Evidence is presented of the TCV vertical stability enhancement using the implemented controller during experimental tokamak discharges

NASA Tech Briefs, January 1989

Topics include: Electronic Components & and Circuits. Electronic Systems, A Physical Sciences, Materials, Computer Programs, Mechanics, Machinery, Fabrication Technology, Mathematics and Information Sciences, and Life Sciences

Technology 2003: The Fourth National Technology Transfer Conference and Exposition, volume 2

Proceedings from symposia of the Technology 2003 Conference and Exposition, Dec. 7-9, 1993, Anaheim, CA, are presented. Volume 2 features papers on artificial intelligence, CAD&E, computer hardware, computer software, information management, photonics, robotics, test and measurement, video and imaging, and virtual reality/simulation

NASA Tech Briefs, February 1993

Topics include: Communication Technology; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences