This article proposes a novel method for estimating multiharmonic sources in the underdetermined measurement system. In proposed methodology, supposing that number of harmonic measurements (HMs) is less than unknown state variables, HM system can be mathematically described as matrix equations, which has infinitely many solutions corresponding to all possibilities locations and current emissions actual sources. Because from nonharmonic source buses are approximately zero, by fitting emission...

The existing noninvasive methods estimating utility harmonic impedance are usually based on the assumption that is constant during a time interval of concern. In fact, variable due to various reasons such as possible short-circuit faults, grid operation changes, and capacitor switching. Thus, this paper proposes novel method estimate by minimizing sum weighted variations variance background voltage variations. proposed can track continuous abrupt changes impedance. effectiveness has been...

The existing methods for estimating harmonic impedance usually assume that is constant in a measurement period. However, variety of practical reasons, such as the load change power grid, utility may be changed. So reasonable hypothesis time-varying, but variation not large at adjacent sampling time. Thus, this paper proposes novel method to estimate by taking criterion minimum norm differences times with According proposed criterion, an objective function built and voltage moments. And then,...

Modular Multilevel Converter (MMC) has been applied in the demonstration project of flexible dc distribution network, whose output voltage spectrums is very wide. Field test cases show that when MMC connected to city network through long cable, distributed capacitance cable may cause amplification high frequency harmonics and even supraharmonics resonance detected , especially islanded power supply mode. This article establishes mathematical model for converter-long cable-load system...

With the large increase of wide-frequency and high-order harmonic in power electronic based systems as well wide use cables with distributed capacitance modern grids especially renewable energy generations, amplification becomes a serious problem. Some researchers have paid attention to this problem, but quantitative relationship between cable length has not been determined, which is studied paper cover shortage. First, influence factors are converted into two rotation phasors. These...

In order to deal with the increasingly serious power quality problem of distribution network, this paper focuses on APF compensation scheme and a variety parallel combination schemes are studied for limited capacity applications. Then improved modular independent controller that can be flexibly configured coefficient is proposed. The hierarchical control strategy designed. first layer coordination between modules based bus communication current-sharing control. second fine inside module...

The verifications of the calculated harmonic impedances are necessary for impedance estimation. Among existing methods verifications, method, by matching background voltage with measured when customer is out operation, widely used. harmonics can be based on IEC61000-3-6 (named as IEC method) or superposition index. However, some researchers ignore fact that these two cannot chosen arbitrarily, otherwise, misjudgments may occur. In our study, nonlinear customers classified into categories...

The recent increase in renewable energy adoption has enhanced the penetration rate of electronic equipment, leading to an increased risk wideband oscillations. Existing wide-area measurement systems mainly focus on fundamental phasors, which cannot effectively monitor This study presents accurate oscillation monitoring method based radial basis function (RBF) neural networks and Taylor–Fourier transform (TFT). First, discrete Fourier is used obtain a preliminary estimation signal, then, TFT...

Due to the influence of complex distribution parameters, there is a large error in harmonic measurement by capacitor voltage transformer (CVT). According typical circuit structure CVT, this paper firstly establishes an equivalent transfer model with all distributed parameters considered. And cascade analysis method based on Y-Δ transformation proposed simplify and calculation function when considering parameters. Then four key CVT characteristics are analyzed details, which can provide...

In order to further optimize the compensation effect of active power filter, a harmonic method based on improved generalized integral controll is proposed. By introducing first-order differential link into traditional controller, phase margin system greatly improved. Meanwhile, multi-channel control structure in synchronous rotating coordinate constructed reduce design complexity and effectively avoid crossover problem filtering frequency bands. On this basis, influence characteristics...