ABSTRACT Wiring errors, caused by improper connections between neutral lines and protective earth (PE) due to negligence electrical technicians, are a prevalent type of fault in low‐voltage distribution systems (LVDS). These errors can cause the load current affected users flow back transformer's point via PE line as residual current, leading nuisance tripping devices (RCDs). To maintain normal power supply, may disable RCDs, which compromises safety result severe hazards such electric...

The impedance of inverter and grid is to determine the stability grid-connected systems. Therefore, it great importance obtain accurate impedance. However, previous studies on measurement are easily subject background harmonics frequency deviation, which brings nonunique identification inaccurate extraction current or voltage perturbations. In this article, an improved method investigated for First, a novel selection principle injected perturbation proposed avoid impact measurement....

The wide-bandwidth grid impedance measurement is a vital way in the resonance and stability analysis of grid-tied system. However, inevitably suffers from some nonideal conditions, such as voltage unbalance, frequency deviation, harmonics, interharmonics, which has not been fully considered well handled using pseudorandom binary sequences. To address this challenge, three-stage interpolation-based method for presented letter. proposed adopts cubic spline interpolation to reconstruct sampled...

Phase–locked loop (PLL) is commonly used for the grid-connected voltage-source converter (VSC) to synchronize with grid. Under weak grid conditions, it has been found that frequency-dependent characteristic of network impedance inherently introduces a positive feedback into PLL. Previous studies focused on PLL analysis intuitively believe will deteriorate dynamic performance However, this conclusion not rigorous since only considered and theoretical insufficiency reveal influence system...

The wide bandwidth impedance of grid and inverter are the critical parameters for small-signal stability analysis control optimization grid-tied systems. measurement is an effective way to obtain by injecting a series perturbations into measured system. However, previous studies fail fully consider adverse voltage conditions; including harmonics, unbalance, frequency deviation, sag, phase jump; which may bring errors impedance. In this article, cascaded delayed signal cancellation...

As the crucial interface of renewable energy integration, grid-tied inverter is a complicated system with multi-timescale feature, containing both fast dynamics and slow that determine stability. However, previous researches on stability analysis mainly focus without considering impact dynamics, which may bring to inaccurate prediction. In this paper, investigated for from physical perspective. Considering current control loop network, two degrees-of-freedom oscillator model firstly...

The output impedance of the grid-tied inverter is an important parameter to determine stability its operation. In this paper, influence modulation and dead zone phenomena on measurement analyzed, method based deviate-frequency harmonic current injection proposed. Simulation results are provided demonstrate feasibility performance, show that new can accurately measure amplitude angle in broadband frequency.

Distribution network power quality is closely related to residential electricity, industrial production, problems will seriously affect the normal and safe operation of load, even cause huge economic loss, therefore, management problem very necessary, need reasonable objective evaluation methods provide theoretical guidance. In this paper, firstly, key characteristic parameters harmonic, voltage sag three-phase unbalance are summarized, unified expression node matrix obtained. Then equipment...

In a distribution network system with multiple power quality controllers, the control effect of each controller is to ensure that access node can reach expected goal, but due interaction between controllers adopted in local calculated adjust instruction, unable realize nodes at same time aim. this paper, for IEEE 33-node standard system, contraction method firstly eliminate irrelevant nodes, expression mechanism derived, and relative gain matrix (RGA) introduced quantitatively analyze degree...

In the current distribution network, various types of devices based on DFACTS are used to improve power quality. Due wide variety devices, different functions and flexible applications, coupled with problem electrical coupling between or repeated control objectives, multiple will have certain interaction effects directly affect this paper, in system is studied IEEE33 node taken as research object. An improved genetic algorithm(GA) optimize configuration DFACTS, DAFCTS results optimized...

Impedance measurement unit (IMU) with injection of broadband perturbations is widely used to obtain grid and converter impedance. The accuracy measured impedance the power quality system rely on amplitude control injected perturbations. However, output perturbation IMU lack attention especially around fundamental frequency system. In this brief, a three-phase DC-AC type introduced mechanism solution inaccurate study. First, PR current controllers, DC voltage controller phase locked loop...