| Summary: | 碩士 === 中原大學 === 電機工程學系 === 87 === For improving the power quality, mitigating the damage due to harmonics and satisfying the harmonic criterions of utility, most of customers with harmonic currents usually install the harmonic filters to reduce the harmonic currents flowed into the power system and improve the power factors simultaneously. In the broad terms, there are two categories of harmonic filter namely active harmonic filters and passive harmonic filters. These harmonic filters can be installed in low voltage or high voltage sides of customer distribution system. When the large capacity of harmonic filter is required, the passive harmonic filter installed in high voltage side is usually the preferred choice for less construction and maintenance costs and small occupation. However, the system impedance in high voltage side is very small with complex variation. The type, set number and parameters of harmonic filter are critical to the performance of harmonic filtering. In addition to, the high voltage is more risk than low voltage, the specification (rating voltage, rating capacity, etc.), series and parallel numbers and the protections of elements of harmonic filter have crucial affections on the safety of harmonic filter. Thus, the harmonic filters are suitable determined by two stages. The first stage is called planning stage which determines the type, set number and some important parameters of harmonic filter. The second stage is called design stage which determines the specifications, series and parallel numbers and protection of elements of harmonic filter. This thesis aims to the second stage (design stage) where four types of filter namely, single-tune filter and second-order, third-order and C-type damped filters are designed by using the optimization method. In this method, the problem of design of harmonic filter is formulated as an optimization problem with an object (cost) function and several constraints associated with harmonic filtering, power factor, specification, series and parallel numbers and protection of elements of harmonic filter. The capacitors of harmonic filter are commercial specifications, and the specifications of resistors and inductors of harmonic filter are restricted within feasible ranges. Furthermore, the protection performances of capacitor internal fuses are coordinated with requirements of short circuit and unbalance faults protection. The designed harmonic filter will attain minimum cost and satisfy all the constraints. In this thesis, the cost function and constraints of harmonic filter are first constructed based on the cost analysis and the analysis of harmonic filter circuit, respectively. The design algorithm based on the simulated annealing technique is next developed for searching the optimal solution of the design of harmonic filter. Finally, three cases of design of harmonic filter with respect to various harmonic situations are presented to demonstrate the superiority and usefulness of proposed algorithm and the results of design of harmonic filter.
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