As the load on the power system grows and new transmission facilities become increasingly difficult to build, the utilities must look to ways to make the most of the current transmission system. Adaptive relaying is one way to enhance the ability of the power system. On the Florida - Georgia interface an adaptive out-of-step relay is being installed. This relay determines if swings on the power system will remain stable by performing a better then real-time transient stability study. Because of the computing capacity required for a transient stability study, the study cannot be performed on the full power system. A reduced model must be used. In this thesis, various methods of obtaining reduced models for use in the relay will be explored. The models will be verified with a full system model using Electric Power Research Institute's (EPRI) Extended Transient-Midterm Stability Package (ETMSP). / Master of Science

På det kommunalägda energiföretaget Sala Heby Energi AB pågår arbetet med att konvertera styrningen av en värmepanna från relästyrning och analog övervakning till digital styrning med PLC. Inom ramarna för detta examensarbete studeras tre specifika delar av denna konvertering: en teoretisk studie med syfte att kartlägga fördelar och nackdelar med konverteringen, en undersökning huruvida det finns möjlighet att förbättra en-skilda styrfunktioner i samband med konverteringen och upprättande av ett principschema eller översiktsbild över värmepannan som ska fungera som underlag till dess implementering i kraftvärmeverkets SCADA-system. En fördel med relästyrningen är att den kan vara kostnadseffektiv för att klara enskilda enkla styruppgifter. Dock, överlag och i synnerhet för styrning av större mer komplexa processer talar det mesta till den digitala styrningens fördel. Detta i form av kostnadseffektivitet för större system, möjligheter till mer effektiv larmhantering och möjligheten till loggning av driftdata. Två enskilda funktioner studeras: reglering av värmepannans siktskärm i förhållande till ångdomstrycket och styrning för bränslehanteringen. För reglering av siktskärmens höjd jämförs två alter-nativ med hjälp av simuleringar i Simulink. Konventionell PID-reglering jämförs mot en egenkonstruerad fuzzy-regulator. Mycket på grund av en bristfälligt underbyggd modellering av processen går inte fuzzy-regulatorns eventuella fördelar mot PID-regulatorn att fastställa. Framtida studier av fuzzy-regulatorn skulle potentiellt kunna ändra på detta förhållande. Vidare diskuteras styrningen av funktioner i bränslehantering och då främst autentisering av chaufförer som ska bränslefylla. För att de ska få tillgång till bränslehanteringens funktioner när kraftvärmeverket är obemannat föreslås det en lösning med nyckelbrytare för att aktivera aktuella styrfunktioner. Slutligen tas en ny digital översiktsbild fram över systemet för värmepannan. Denna innehåller mindre uppdateringar och anpassningar jämfört med två översiktsbilder som finns uppritade på de gamla styrskåpen. / At the municipality-owned energy company Sala Heby Energi AB work is underway to convert the control of a heating-pan from relay control and analog monitoring to digital control with PLC. Within the framework of this degree project, three specific parts of this conversion are studied: a theoretical study aimed at mapping the pros and cons of the conversion, an examination of the possibility of improving individual control functions in conjunction with the conversion and the establishment of a schematic diagram or overview of the heat boiler that will serve as a basis for its implementation in the SCADA-system of the combined power and heating plant. An advantage of relay control is that it can be cost-effective to handle individual simple control tasks. However, overall and in particular for controlling major more complex processes the benefits of digital control is large. This in terms of cost-effectiveness for larger systems, possibilities for more efficient alarm management and the ability to log operational data. Two individual functions are studied: control of the heating pans damper in relation to the steam pressure and fuel management control. To adjust the height of the damper, two control options are compared using Simulink simulations. Conventional PID control is com-pared to a self-configured fuzzy controller. Much due to a poorly substantiated modelling of the process, the fuzzy regulator's possible benefits to the PID regulator can not be determined. Future studies of the fuzzy regulator could potentially change this circumstance. Furthermore, the control of functions for the fuel management are discussed, mainly authorship of drivers who will fill fuel to the fuel storage. In order for them to have access to the fuel management functions when the combined power and heating plant is unmanned, a key switch solution is proposed to activate the control functions. Finally, a new digital overview picture is produced for the system of the heating pan. This contains minor up-dates and adjustments compared to two overview images depicted on the old control cabinets.

In this thesis, we investigate cooperation by applying OFDM signals to cooperative relay networks. We consider the single path relay network and the multiple path relay network. Using the amplify-and-forward relay algorithm, we derive the input-output relations and mutual informations of both networks. Using a power constraint at each relay, we consider two relay power allocation schemes. The first is constant gain allocation, where the amplifying gain used in the amplify-and-forward algorithm is constant for all subcarriers. The second is equal power allocation, where each subcarrier transmits the same power. The former scheme does not require CSI (channel state information), while the latter one does. We simulate the mutual informations using the two relay power allocation schemes. Results indicate that equal power allocation gives a slightly higher mutual information for the single path relay network. For the multiple path network, the mutual information is practically the same for both schemes. Using the decode-and-forward relay algorithm, we derive the input-output relations for both networks. The transmitter and each relay are assumed to have uniform power distributions in this case. We simulate the BER (bit error rate) and WER (word error rate) performance for the two networks using both the amplify-and-forward and decode-and-forward relay algorithms. For the single path relay network, amplify-and-forward gives very poor performance, because as we increase the distance between the transmitter and receiver (and thus, add more relays), more noise and channel distortion enter the system. Decode-and-forward gives significantly better performance because noise and channel distortion are eliminated at each relay. For the multiple path relay network, decode-and-forward again gives better performance than amplify-and-forward. However, the performance gains are small compared to the single path relay network case. Therefore, amplify-and-forward may be a more attractive choice due to its lower complexity.

This master thesis deals with the mechanical and electrical design of the drive of the inclined construction lift. Individual components are selected in the design. Furthermore, a theoretical research is carried out regarding wireless modules and logic controllers. The selection of sensors is made and the method of retrieving signals from sensors and converting them into iputs the control circuits is also outlined. A program is written in Arduino IDE that wirelessly controls the motion of a motor via variable frequency drive.