ScandiNova Systems AB är ett företag som utvecklar och producerar pulsmodulatorer. Till deras senastutvecklade modulator vill ScandiNova ha en elektrisk konstlast för att testa den, innan den levereras. Just denna modulator kommer att ingå i en cancerbehandlingsmaskin hos kunden. I detta arbete tas det tillsammans med ScandiNova fram en kravspecifikation på hur konstlasten ska vara. Därefter tas en konstruktion i CAD-programvaran Autodesk Inventor fram. Arbetet resulterade i en konstruktion som uppfyller de flesta kraven förutom att den blev för dyr. Konstlasten kommer trots det att tillverkas och ScandiNova har precis påbörjat en utveckling på en ny konstruktion. / ScandiNova Systems AB is a company that develops and produces pulse modulators. For their latest developed modulator, ScandiNova wants an electric load to test it before it is delivered. The customer will use this particular modulator as a part of a cancer treatment machine. While working with this project, together with ScandiNova, a requirement specification on how the art load should be is taken. Next, a design is embodied with the CAD software Autodesk Inventor. The work resulted in a construction that meets most of the requirements except that it became too expensive. The load will nevertheless be manufactured and ScandiNova has just started a development on a new design.

This paper describes the design of control, measurement and power electronics department for dynamic loading of electronically commutated motors with electric brakes. After comparing the advantages and disadvantages of possible conceptions the proposal focuses on electric brake operating in generator mode and the value of load is controlled by the current dissipated in a dummy load.

This master thesis examines technical requirements for small hydro power plants (HPP) to operate proximate parts of the power grid in island mode. The work examines how small hydropower can be modified and complemented with additional technologies to achieve sufficient frequency control capabilities. A case study was performed within the concession area of power grid operator Ålem Energy. One of the HPPs, located in Skälleryd, is owned by Ålem Energy and became the focal point of the study. Relevant parts of the concession area were surveyed for properties such as system inertia, electric load and available power. Furthermore, a model of Kaplan turbine 1 in Skälleryd HPP was created with the purpose of studying the benefits of bypassing regulation control from the wicket gates directly to the runner. The method was tested in an off-grid islanding test. Frequency control of the turbine was tested powering electric heaters and, using a new method, controlling a virtual power grid. Finally, a theory was developed to estimate the transient disturbance resilience (TDR) of a power grid. The theory was applied to the HPP in Skälleryd to suggest modifications for the plant to achieve sufficient islanding capabilities. The survey of the power system revealed a promising potential for the HPPs to operate in island mode, especially at later stages when the grid spans several HPPs for more system inertia. The available power from the HPPs was however strongly seasonal which imposes flexibility on a future plan of action for engaging the grid in island mode. The method of controlling the turbine power from the runner proved to have several difficulties. Firstly, the current hydraulics system was not able to freely control the runner as the hydrodynamic forces on the runner blades were too large. Secondly, the method was found to be unstable due to inherent amplification of speed deviations. Furthermore, the low inertia at Skälleryd is likely detrimental to the lone frequency control of the turbine. Therefore other methods for improving frequency control were suggested. The developed theory for TDR was used to create charts describing the TDR for various combinations of system inertia and regulation speed. By studying the proprieties of Skälleryd HPP in the charts the necessary modifications could be rationally chosen. A frequency regulating dummy load was found to be the simplest option. A control scheme was suggested with the dummy load performing primary frequency control and the turbines at Skälleryd performing secondary control, restoring the dummy load to its nominal state.