Abstract
Phasor measurement units (PMUs) have become powerful monitoring tools for many applications in smart grids. In order to address the different issues related to harmonics in power systems, the fundamental phasor estimator in a PMU has been extended to the harmonic phasor estimator by several researchers around the world. Yet, the development of harmonic phasor estimators is a challenge because they have to consider time-varying frequencies since the frequency deviation in the harmonic components is proportional to the harmonic order in a dynamic way. In this work, a new algorithm for harmonic phasor estimation using an instantaneous single-sideband (SSB) modulation is presented. Unlike other SSB-based approaches, its implementation in this work is based on concepts of instantaneous phase and instantaneous frequency. In general, the proposed algorithm is divided into two stages. Firstly, the estimation of the fundamental phasor is carried out by means of a complex finite impulse response (FIR) filter which provides the analytic signal used to compute the instantaneous magnitude, phase, and frequency. Secondly, a complex FIR filter bank is proposed for the estimation of the harmonic components, where the instantaneous SSB modulation technique is applied in order to center the harmonic components into specific narrow bands for each complex filter when an off-nominal frequency occurs. The validation of the proposed algorithm is carried out by means of the current standards of phasor measurement units, i.e., Std. C37.118.1-2011 and C37.118.1a-2014, which involve steady-state, dynamic, and time performance tests.
Highlights
Proliferation of non-linear loads along with the growth of distributed generation systems are some of the main causes of power quality problems related to harmonic pollution in modern power systems [1]
The error limits are extended to harmonic components in the most tests except in the modulation tests where the error boundaries depend on the carrier frequency and some adjustments must be carried out
The proposed algorithm is based on complex brick-wall finite impulse response (FIR) filters which are designed at the nominal frequencies for fundamental and harmonic components, while the instantaneous
Summary
Proliferation of non-linear loads along with the growth of distributed generation systems are some of the main causes of power quality problems related to harmonic pollution in modern power systems [1]. This pollution compromises the system reliability, e.g., producing additional losses in transmission or distribution lines, overheating of electrical machines and relays breakdowns [2,3]. Electronics 2019, 8, 135 the fundamental component, phasor measurement units (PMUs) are synchronized remote devices commonly used for wide area monitoring systems with high performance requirements for phasor, frequency and rate of change of frequency (ROCOF) errors defined in the current standard, i.e., the IEEE. A PMU with capabilities for harmonic estimation will allow improving the performance in different applications of power systems such as power quality monitoring, adaptive protections, network reconfiguration under fault conditions, and so on [12]
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