The integration of converter-interfaced distributed generation in microgrids has raised several technical issues, including the successful operation protective devices during faults. protection issue is associated with lack large current injection a fault, due to limits imposed by semiconductor switches. This paper proposes fault-detection and clearing control strategy method for symmetrical asymmetrical line faults looped microgrid. are simple overcurrent same settings, microgrid topology....

The high proliferation of converter-dominated Distributed Renewable Energy Sources (DRESs) at the distribution grid level has gradually replaced conventional synchronous generators (SGs) transmission system, resulting in emerging stability and security challenges. inherent characteristics SGs are currently used for providing ancillary services (ASs), following instructions Transmission System Operator, while DRESs obliged to offer specific system support functions, without being remunerated...

In this letter, a new methodology is proposed to extend the applicability of conventional power flow methods islanded microgrids (MGs), operating with droop control method. A slack bus considered be connected at random MG node. The operational conditions as well rest nodes are determined through an iterative procedure. objective procedure force active and reactive flowing zero, representing operation. approach has similar accuracy time-domain simulations, while it reduces significantly...

This paper proposes a precise power flow algorithm for islanded hybrid AC/DC microgrids (HMGs). In our analysis, we have considered multi-grounded unbalanced bipolar DC microgrid and four-wire AC connected through one or more interlinking converters (ICs). The proposed method is based on the implicit ZBUS method, presenting fast convergence robustness regardless of R/X ratio lines. It can be applied in all network configurations including highly meshed distribution systems. Numerical...

The operation of photovoltaic (PV) units connected to the grid is characterized by several uncertainties due number currently operating units, points where these are sited, exported power, and injection harmonic currents. objective this paper investigate impact penetration PV in low-voltage (LV) network. Thus, a model has been developed for computation load flows, harmonics, voltages feeders. A panel modeled as an irradiance-driven current generator, with embodied maximum power point (MPP)...

When a microgrid is mainly supplied by renewable energy sources (RESs), the frequency deviations may deteriorate significantly power quality delivered to loads. This paper proposes frequency-based control strategy, ensuring among strict limits imposed Standard EN 50160. The of common AC bus determined storage converter, implementing proposed droop curve state charge (SoC) battery and frequency. Therefore, information SoC becomes known every distributed resource (DER) determines active...

In this paper, a centralized control strategy for low-voltage networks is proposed, aiming to coordinate the droop characteristics of distributed renewable energy sources. The main objectives are overvoltage mitigation and optimal network operation in terms maximum power injection uniform curtailment. distinct features proposed method incorporation droop-based techniques into conventional flow formulation use sensitivity theory as means significantly decrease computational burden. validity...

Since the penetration of photovoltaic (PV) systems in low voltage (LV) distribution network is increasing, need to register and model contribution these harmonic distortion current waveforms becoming an up-to-date issue. As PV incorporate power conditioning units, which are generating devices, they will have influence on quality supply, reliable operation system equipment as well component life expectancy. This paper investigates impact a 20 kWp connected LV Greece. The behavior plant...

The gradual displacement of synchronous generators driven by conventional power plants, due to the increasing penetration distributed renewable energy sources (DRES) in distribution grids, is creating a shortage crucial ancillary services (AS) which are vital for frequency and voltage stability grid. These AS, some new ones, could now be offered DRES, particularly those that converter interfaced, coordinated way order preserve grid resilience. Although recent standards codes specify DRES...

This paper deals with the provision of primary frequency response (PFR) as ancillary service (AS) from active distribution networks (ADNs) to transmission system (TS). In particular, two methodologies are developed. The first one aims quantify PFR capability range ADN. is defined by determining aggregated, i.e., equivalent, power - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P(f)$...

This paper investigates the ac resistance in presence of harmonics and proposes ampacity derating factors for cables made according to CENELEC Standard HD603. These are widely used low-voltage industrial building installations. Four-conductor small, medium, large conductor cross sections considered. The fourth is as neutral conductor. modeled using finite-element analysis software. ac/dc ratio shown increase with frequency current section conductor, being much larger when zero-sequence...

In this paper, a nearly decentralized voltage regulation algorithm is proposed that effectively coordinates the operation of distributed generation (DG) units in order to minimize active power losses and total reactive consumption medium-voltage (MV) networks with radial topology. This control requires minimum communication infrastructure, whereas decisions are individually taken by each DG unit based on local remote measurements. Furthermore, new cooperative on-load tap changer employed...

The growing penetration of converter-interfaced distributed renewable energy sources (CI-DRES) has posed several challenges into the electric power systems, e.g., instability caused by intermittent nature primary sources, quality issues, etc. Several algorithms have been proposed to mitigate CI-DRES fluctuations and reduce high active ramp-rates (RRs) at point common coupling (PCC) with grid using storage systems (ESS). However, these present some drawbacks. In this article, a new ramp-rate...

With the advent of bulk volumes renewable energy, RES aggregators have evolved into key market players energy industry. This paper presents a holistic approach to derive optimal offering strategy price-taker aggregator in day-ahead and ancillary services markets. The day-ahead, real-time balancing functions are modeled detail. Fundamental imbalance settlement mechanisms examined, namely Single Pricing, Two Price Dual Pricing. Several sources uncertainty considered affecting prices, prices...

This article proposes a new control strategy for the voltage regulation of unbalanced low-voltage (LV) distribution grids with high penetration distributed renewable energy sources (DRESs). The proposed method uses available reactive power DRESs as primary means regulation. Furthermore, its distinct feature is use architecture prioritizing response to maintain network voltages within permissible limits and minimize losses. prioritization process locally implemented by each DRES combining two...

In this paper, a two-stage approach is introduced to efficiently solve the optimal voltage regulation problem in radial medium-voltage (MV) distribution networks. The proposed method uses available reactive power of distributed generation units and on-load tap changer (OLTC) high-voltage/MV transformer regulate network voltages, while also minimizing two conflicting objectives, namely energy losses frequency changes. This bi-objective addressed distinct stages. first stage, linearized...