Design considerations for an active filter to cancel neutral current harmonics on three-phase, four-wire electric distribution systems /
The increasing power demand of nonlinear electronic aphics.
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| Format: | Thesis eBook |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1998.
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| Summary: | The increasing power demand of nonlinear electronic aphics. loads on the electric distribution system has exacerbated an age-old power system phenomena into a modern trouble spot: excessive zero-sequence harmonic currents that do not cancel in neutral return lines servicing three-phase, four-wire electric distribution systems. This thesis addresses the pressing industry concern over excessive zero-sequence harmonics, particularly third-harmonic currents, with an industrial-grade active filtering solution; namely, an active falter to cancel 100 A of zero- sequence harmonics via the system neutral conductor. The proposed active falter has many advantages: superior cancellation effectiveness, high energy efficiency, location independent of the system impedance, and built-in electronic overload protect- ion. Neutral current harmonics are canceled by continuous feedback measurement and closed-loop control. Harmonic filtering automatically adapts to chant' g load conditions. Unbalanced 60 Hz currents are not measured or canceled, thereby improving falter performance. Upon installation, the active tilter does not form any new system resonances. It is rugged in design, and multiple units can be paralleled for beater cancellation capability. The main focus of the thesis is on the implementation of the 100 A active falter, including detailed analysis and system design. Major emphasis has been placed on the tilter's power electronic active source (inverter plus falter inductor), its electronic design and control, and on the zig-zag connected auto-transformer used to "derive'' the system neutral. Particular attention is also paid to system feedback control strategy, loop stability and closed-loop operation on the distribution system. Test results verifying the successful operation of the active filter are shown. Under laboratory testing, the active filter is applied to a nonlinear test load supplying 100 A of zero- sequence harmonic current. Impact on key system parameters measuring filter performance are discussed. Following the laboratory testing, the filter is evaluated at one building beta site. Key system parameters are once again examined to ascertain and verify expected tilter performance. |
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| Item Description: | "Major subject: Electrical Engineering". Vita. |
| Physical Description: | xi, 110 leaves : illustrations ; 28 cm. Also available online. |
| Bibliography: | Includes bibliographical references: pages 108-109. |