Understanding best practice regarding interruptible connections for wind generation: lessons from national and international experience

The aim of this study is to explore different practices for accelerating the integration of generating facilities to the electricity network using smart solutions. Case studies from Great Britain, Ireland and Northern Ireland and the Unites States were selected. The paper assesses and compares the different Principles of Access (POA) that have been implemented in these countries, such as Last-in First-out (LIFO), Pro Rata and Market-based. The social optimality of these approaches is also discussed. The paper also evaluates how the risk (regarding curtailment and investment) is allocated between parties (distributor network operators, generators and customers). Even though the cases are diverse, important findings and lessons have been identified which may assist UK distribution network operators to address the issue of increasing the connection of distributed generation while managing efficiently and economically energy exports from generators

Distributed Generation: Opportunities for Distribution Network Operators, Wider Society and Generators

This study explores and quantifies the benefits of connecting more distributed generation (with and without the use of smart connections) across different parties (Distribution Network Operators, wider society and generators). Different connection scenarios are proposed (with partial and full interruptible capacity quota, a mix of generation and different technology-specific curtailment levels) for integrating DG units in the constrained area of the March grid (East of England). This constitutes the trial area of the Flexible Plug and Play project, which is being implemented by UK Power Networks. The smart connection option is by far the preferred option across all the scenarios (higher NPV/MW). However, for some generators the results are very sensitive to the discount rate used (i.e. solar PV). The analysis of the distribution of benefits suggests that generators capture most of the benefits while DNOs and wider society capture much less benefit. A smart connection incentive, which recreates the benefits to DNOs from an earlier losses incentive, is proposed. In contrast with other societally desirable metrics which are usually incentivised or penalised, there is currently no direct connection between more DG MWs connected and DNO incentive payments. Our proposed smart connection incentive, by charging DG for smarter connection may help to distribute more efficiently the benefits for connecting more DG

Integrating Distributed Generation: Regulation and Trends in Three Leading Countries

We explore trends in the deployment and integration of distributed generation in Germany, Denmark and Sweden. In particular, we examine the regulation of renewable energy generation with a focus on grid access and connection mechanisms. The high rate of distributed generation penetration in these countries is the result of early support given to the expansion of renewable energy generation – mainly wind and solar - within their respective national policies. Germany and Denmark are the countries with the most sophisticated support schemes, which have shown changes over time. In terms of connections, Germany is the country with the most favourable connection regime. It provides not only priority connection but also priority use of the grid to generation units that produce electricity from renewable energy sources. Sweden guarantees equal treatment among different technologies (i.e. a non-discrimination principle) and is thus the least favourable. High connection costs have been observed, especially in Germany and Denmark. The costs of network upgrades are usually socialised across customers. The use of smart solutions combined with novel business models might allow more efficient use of the current distribution electricity infrastructure. Hence, integration issues should be taken into consideration in order to avoid expansion of distributed generation in a way that unnecessarily raises total system costs, via high connection costs

Suppression of Spin-Orbit Scattering in Strong-Disordered Gold Nanojunctions

We discovered that spin-orbit scattering in strong-disordered gold nanojunctions is strongly suppressed relative to that in weak-disordered gold thin films. This property is unusual because in weak-disordered films, spin-orbit scattering increases with disorder. Granularity and freezing of spin-orbit scattering inside the grains explains the suppression of spin-orbit scattering. We propose a generalized Elliot-Yafet relation that applies to strong-disordered granular regime.Comment: 4 pages 4 figure

Aflatoxines i ocratoxines: agents tòxics que cal controlar

El present article se centra en l'estudi de toxines produïdes per fongs dels gèneres Aspergillus i Penicillium, més concretament en les aflatoxines B1, G1, B2, G2 i ocratoxina A. Es dóna una visió general del tema quant a origen, legislació, toxicitat i control de micotoxines. A més, es presenten tres mètodes per a l'anàlisi d'aquestes toxines en productes vegetals, ja que són els substrats en els quals es presenten més habitualment. Primerament, es desenvolupa un metòde d'anàlisi per a la determinació d'aflatoxines B1, G1, B2 i G2 en una planta medicinal. Posteriorment, s'optimitza l'anàlisi d'ocratoxina A en cafè i finalment es presenta un mètode per a la determinació simultània d'aflatoxines B1, G1, B2, G2 i ocratoxina A en cervesa. En tots els mètodes s'empra extracció en fase sòlida de reblert polimèric i cromatografia líquida de fase inversa. La detecció es realitza per espectrometria de masses de quadrupol simple amb ionització a pressió atmosfèrica.This paper is focused on the study of mycotoxins produced by fungi of the genera Aspergillus and Penicillium, specifically on aflatoxins B1, G1, B2, G2 and ochratoxin A. A general survey of mycotoxin origin, toxicity, legislation and control is presented. Furthermore, three analytical methods for the analysis of mycotoxins in vegetable products is presented, due to these substrates are the most liable to be contaminated. First, a method for the determination of aflatoxins B1, G1, B2 and G2 in a medicinal herb is presented. Afterwards, the analysis of ochratoxin A in coffee was optimized. Finally, a method for the simultaneous analysis of aflatoxins B1, G1, B2, G2 and ochratoxin A in beer is developed. All the methods apply solid-phase clean-up using a polymeric sorbent and liquid chromatography with a reversed phase column. A single quadruple mass spectrometer with an electrospray ionization source was used as a detector

Reactive power control of DFIG wind turbines for power oscillation damping under a wide range of operating conditions

This study analyses the effect of replacing existing synchronous generators (SGs) equipped with power system stabilisers (PSS) by doubly fed induction generator (DFIG) based wind farms on the damping of power system oscillations in a multi-machine power system. A power system stabiliser was designed to enhance the capability of DFIG to damp power systems oscillations. The validity and effectiveness of the proposed controller are demonstrated on the widely used New England 10-machine 39-bus test system that combines conventional SGs and DFIG based wind farms using eigenvalue analysis and non-linear simulation. The non-linear simulation is used to demonstrate how the damping contribution of DFIG based wind farms is affected by different operating conditions within the same wind farm and stochastic wind speed behaviour. The results show that installing conventional fixed parameters PSS within reactive power control loop of DFIG rotor side converter has a positive damping contribution for a wide range of operating conditions. Furthermore, the results clearly show that DFIG based wind farms equipped with the proposed farm level PSS can damp power system oscillations more effectively than SGs PSS

Where next for the electricity distribution system operator? Evidence from a survey of European DSOs and National Regulatory Authorities

This paper seeks to shed light on the nature of optimal regulation of the electricity distribution system operator (DSO) over the period to 2025 and beyond, following the implementation of the EU Clean Energy Package and its constituent parts: Electricity Regulation (EU) 2019/943 and Electricity Directive (EU) 2019/944. We conducted two parallel surveys of DSOs and their national regulatory authorities (NRAs) across 39 European countries. This produced 39 responses from DSOs and 12 responses from NRAs covering, respectively, 40% and 78% of customers in those countries. We asked both DSOs and NRAs three sets of questions related to: (1) the definition and regulation of the future system operator function of the DSO; (2) lessons learned from transmission system operator (TSO) regulation that can be translated to the DSO; and (3) the way in which regulators support the capacity of the DSO to operate and coordinate the system. Our findings are consistent with the observation that the move towards a more active role for the DSO remains work in progress for both DSOs and their NRAs, given the fact that the Clean Energy Package has only passed into European Law relatively recently and some Member States are still implementing its provisions