8,577 research outputs found
Future work on harmonics : some expert opinions part I : wind and solar power
A workshop on power system harmonics was organized in Stockholm in January 2014. On the agenda was among others a discussion on what are the main issues on harmonics at the moment and in the near future. The results of this discussion are summarized in this paper and some of the issues are discussed in more detail in this paper and in its companion paper. This paper discusses emission from wind and solar power as well as advantages and disadvantages of active and passive filters
A modified sequence domain impedance definition and its equivalence to the dq-domain impedance definition for the stability analysis of AC power electronic systems
Representations of AC power systems by frequency dependent impedance
equivalents is an emerging technique in the dynamic analysis of power systems
including power electronic converters. The technique has been applied for
decades in DC-power systems, and it was recently adopted to map the impedances
in AC systems. Most of the work on AC systems can be categorized in two
approaches. One is the analysis of the system in the \textit{dq}-domain,
whereas the other applies harmonic linearization in the phase domain through
symmetric components. Impedance models based on analytical calculations,
numerical simulation and experimental studies have been previously developed
and verified in both domains independently. The authors of previous studies
discuss the advantages and disadvantages of each domain separately, but neither
a rigorous comparison nor an attempt to bridge them has been conducted. The
present paper attempts to close this gap by deriving the mathematical
formulation that shows the equivalence between the \textit{dq}-domain and the
sequence domain impedances. A modified form of the sequence domain impedance
matrix is proposed, and with this definition the stability estimates obtained
with the Generalized Nyquist Criterion (GNC) become equivalent in both domains.
The second contribution of the paper is the definition of a \textit{Mirror
Frequency Decoupled} (MFD) system. The analysis of MFD systems is less complex
than that of non-MFD systems because the positive and negative sequences are
decoupled. This paper shows that if a system is incorrectly assumed to be MFD,
this will lead to an erroneous or ambiguous estimation of the equivalent
impedance
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Secure High DER Penetration Power Distribution Via Autonomously Coordinated Volt/VAR Control
Traditionally voltage control in distribution power system (DPS) is performed through voltage regulating devices (VRDs) including on load tap changers (OLTCs), step voltage regulators (SVRs), and switched capacitor banks (SCBs). The recent IEEE 1547-2018 from March 2018 requires inverter fed distributed energy resources (DERs) to contribute reactive power to support the grid voltage. To accommodate VAR from DERs, well-organized control algorithm is required to use in this mode to avoid grid oscillations and unintended switching operations of VRDs. This paper presents two voltage control strategies (i) static voltage control considering voltage-reactive power mode (IEEE 1547-2018), (ii) dynamic and extensive voltage control with maximum utilization of DER capacity and system stability. Further, effective time-graded control is implemented between VRDs and DER units to reduce the simultaneous and negative operation. The proposed voltage control strategies are tested in a realistic 140-bus southern California distribution power system through extensive time-domain simulation studies. The results show that voltage quality in a distribution system is effectively achieved through the proposed voltage control strategies with a significantly reduction in the number of switching operations of VRDs. In addition, proposed voltage control strategies increase reliability and security of the DPS during unexpected failures
European White Book on Real-Time Power Hardware in the Loop Testing : DERlab Report No. R- 005.0
The European White Book on Real-Time-Powerhardware-in-the-Loop testing is intended to serve as a reference document on the future of testing of electrical power equipment, with speciïŹ c focus on the emerging hardware-in-the-loop activities and application thereof within testing facilities and procedures. It will provide an outlook of how this powerful tool can be utilised to support the development, testing and validation of speciïŹ cally DER equipment. It aims to report on international experience gained thus far and provides case studies on developments and speciïŹ c technical issues, such as the hardware/software interface. This white book compliments the already existing series of DERlab European white books, covering topics such as grid-inverters and grid-connected storag
Vanadium redox flow batteries: Potentials and challenges of an emerging storage technology
open4noIn this paper an overview of Vanadium Redox Flow Battery technologies, architectures, applications and power electronic interfaces is given. These systems show promising features for energy storage in smart grid applications, where the intermittent power produced by renewable sources must meet strict load requests and economical opportunities. This paper reviews the vanadium-based technology for redox flow batteries and highlights its strengths and weaknesses, outlining the research lines that aim at taking it to full commercial success.openSpagnuolo, Giovanni, Guarnieri, Massimo; Mattavelli, Paolo; Petrone, Giovanni;Guarnieri, Massimo; Mattavelli, Paolo; Petrone, Giovanni; Spagnuolo, Giovann
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