Enhanced Detection of Power-Quality Events Using Intra and Interscale Dependencies of Wavelet Coefficients

Mutation point feature of power quality (PQ) disturbance signals are very conducive to the wavelet-based detection and localization of PQ events, but the PQ signals are often disturbed by noise. In order to suppress noise and keep mutation points, an improved threshold function was proposed. According to the fact that the wavelet coefficients of signal and noise distributed on different scale, the threshold σj2lnk amended by to calculate threshold value for each scale adaptively. (k is the number of wavelet coefficients at level j). In simulation, four type of PQ signals and three degrading degrees are testing; meanwhile, four existing algorithm with wavelet shrinkage are performed for comparison. Results reveal that the proposed scheme not only suppresses noise of PQ signal well but also keeps the mutation points nicely.

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Power quality measurements on a 24 m windmill

IEE Proceedings A Physical Science Measurement and Instrumentation Management and Education Reviews ◽

10.1049/ip-a-1.1987.0066 ◽

1987 ◽

Vol 134 (5) ◽

pp. 435

Author(s):

G.J. Taylor

Keyword(s):

Power Quality ◽

Quality Measurements

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Power Quality in Future Electrical Power Systems

10.1049/pbpo092e ◽

2017 ◽

Cited By ~ 6

Keyword(s):

Power Systems ◽

Power Quality ◽

Electrical Power ◽

Electrical Power Systems

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Power Quality Improvement of High Voltage DC Link using Modified Shunt Active Power Filter

Al-Kitab Journal for Pure Sciences ◽

10.32441/kjps.v1i1.91 ◽

2018 ◽

Vol 1 (1) ◽

pp. 54-66

Author(s):

Rakan Khalil Antar ◽

Basil Mohammed Saied ◽

Rafid Ahmed Khalil

Keyword(s):

Power Quality ◽

High Voltage ◽

Pulse Width Modulation ◽

Active Power Filter ◽

Active Power ◽

Voltage Source ◽

Active Power Filters ◽

Power Filter ◽

Power Filters ◽

Power Quality Improvement

A new control strategy for active power filters is proposed, modeled and implemented in order to improve the power quality of a line commutated converter High voltage DC link. The ability of reactive power and harmonics reductions are generally met by using passive and active power filters. In this paper, modified active power filter with a modified harmonics pulse width modulation algorithm is used to minimize the source harmonics and force the AC supply current to be in the same phase with AC voltage source at both sending and receiving sides of a line commutated converter high voltage DC link. Therefore, it is considered as power factor corrector and harmonics eliminator with random variations in the load current. The modified harmonics pulse width modulation algorithm is applicable for active power filter based on a three-phase five-level and seven-level cascaded H-bridge voltage source inverter. Simulation results show that the suggested modified multilevel active power filters improve total harmonics distortion of both voltage and current with almost unity effective power factor at both AC sides of high voltage DC link. Therefore, modified active power filter is an effective tool for power quality improvement and preferable for line commutated converter high voltage DC link at different load conditions.

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