Kaur Tuttelberg

Analysis of a slow-speed slotless permanent magnet synchronous generator

Department of Electrical Engineering at Tallinn University of Technology has been involved in the development of novel electrical machines for wind applications. This paper presents the analysis of the electrical parameters of a novel slow-speed slotless permanent magnet synchronous generator. Firstly, some of the design parameters are calculated and a simplified analytical mathematical model of the generator is constructed to calculate the output variables under different operational conditions. Secondly, some FEM calculations are carried out to check the validity of the analytical model. Thirdly, test results are analyzed and compared to the calculated values. Finally, the analytical model is evaluated and final output parameters of the generator are determined.

Optimal placement of branch PMUs for specified redundancy and line observability

This paper presents a solution for the optimal placement of branch PMUs (PMUs that measure a single set of three-phase voltage and current phasors) considering specific measurement redundancy requirements for the observability of buses. The classical bus observability condition in optimal PMU placement assumes the measurement of currents of all lines connected to the PMU bus, making most developed optimisation methods impractical in real-world systems. Compared to existing methods for the optimal placement of branch PMUs (or PMUs with input channel limits), the proposed method inherently enables to consider the outages of all lines or PMUs, distinguishes between the ends of the branches (i.e. for each branch PMU the optimal bus is also chosen), enables to specify conditions for direct observability of transmission lines, and is simple to implement and solve.

Real-time estimation of transmission losses from PMU measurements

This paper discusses the application of PMU measurements in real-time estimation of transmission line power losses. Instead of directly computing the difference between sent and received power, the losses are estimated as separate components, calculated from line equations. On one hand, this provides more information about the operation of the line-active losses are split into Joule and corona losses and the balance of reactive power is separated into inductive losses and capacitive generation. On the other hand, it reveals large measurement errors in active losses on lightly loaded transmission lines, closely related to similar errors in estimated line parameters. This is demonstrated on examples of actual PMU measurements of a transmission line at low loads.

Performance of the Explicit Euler and Predictor-Corrector–Based Coupling Schemes in Monte Carlo Burnup Calculations of Fast Reactors

Abstract We present a stability test of the explicit Euler and predictor-corrector–based coupling schemes in Monte Carlo burnup calculations of the gas fast reactor fuel assembly. Previous studies have identified numerical instabilities of these coupling schemes in Monte Carlo burnup calculations of thermal spectrum reactors due to spatial feedback–induced neutron flux and nuclide density oscillations, where only sufficiently small time steps could guarantee acceptable precision. New results suggest that these instabilities are insignificant in fast-spectrum assembly burnup calculations, and the considered coupling schemes can therefore perform well in fast-spectrum reactor burnup calculations even with relatively large time steps.