Possibilities of Load Shedding in Distribution Automation

Tänä päivänä sähkön laadulla, keskeytyksillä ja sitä kautta asiakkaiden tyytyväisyydellä on yhä suurempi merkitys. Sähkökatkoista voi seurata asiakkaille nopeastikin rahallista menetystä. Yksi tapa turvata sähkönsyöttö tärkeille kuormille, on panostaa kuormanpudotukseen, joka irrottaa vähemmän tärkeitä kuormia tuotanto-ongelmien aikana. Markkinoilla on monia kuormanpudotukseen soveltuvia järjestelmiä ja laitteita. Kaikista näistä laitteistoista ei täysin tiedetä, mihin toteutuksiin ne sopivat parhaiten ja minkälaisissa toteutuksissa niitä ei sovi käyttää. Osa ratkaisuista sopii nopeaan kuormanpudotukseen, jossa vaatimuksena on erittäin nopea reagointi järjestelmän tuotanto-ongelmiin. Osaa kuormanpudotuksen ratkaisuista ei taas pystytä käyttämään nopeassa kuormanpudotuksessa, koska niiden reagointinopeus ei riitä. Työssä tutkitaan ABB Oy:n käyttämiä kuormanpudotuksen ratkaisuja. Tutkittavia ratkaisuja ovat kaukokäyttöjärjestelmä MicroSCADA, ohjelmoitavat PLC-logiikat RTU ja AC800 sekä uusi kuormanpudotusohjain PML630. Jokaista näistä tuotteista on käytetty kuormanpudotuksessa aikaisemmin. Työn tavoitteena on selvittää, minkälaisissa tilanteissa ratkaisuja kannattaa käyttää ja minkälaisissa ei. Tuotteista ja niiden sopivuudesta eri kuormanpudotuksen toteutuksiin ei ole aikaisemmin tehty yhtä laajaa vastaavaa tutkimusta. Koska aikaisempaa yhtä laajaa tutkimusta ei ole, voi tätä työtä käyttää myyntivaiheessa selvittämään, mikä ratkaisu kyseiseen projektiin on paras. Tutkimus toteutettiin vertailemalla laitteistoilla jo tehtyjä projekteja ja omilla simuloinneilla. Tutkimuksissa saatiin tehtyä hyvä vertailu laitteiden ominaisuuksista, joiden avulla niiden käytön rajoitukset on helppo tunnistaa. Tutkimuksissa havaittiin, että suurin rajoittava tekijä nopeassa kuormanpudotuksessa on erilaisten väyläkommunikointiyhteyksien hitaus. Positiivisena yllätyksenä väyläkommunikointiyhteyksien nopeudesta on kuitenkin IEC 61850 GOOSE -kommunikointi, joka mahdollistaa laitteiden välisen horisontaalisen, erittäin nopean, liikennöinnin. Tutkimuksissa saatiin tulos, jossa PML630 pystyi reagoimaan verkon tuotanto-ongelmaan keskimäärin enintään noin 48 ms:n kuluessa. Toinen tärkeä huomio oli kuormanpudotustoiminnallisuuden suuri ohjelmointityön määrä. Jos ratkaisuissa on valmis pohja kuormanpudotusta varten, asettaa se yleensä rajoituksia myös sähköaseman koolle, joka tulee ottaa huomioon projektia suunniteltaessa.Nowadays, power quality, interruptions and customer satisfaction have an increasingly important role. Power interruptions can quickly cause monetary losses to customers. One way to secure power supply for important loads is to invest in load shedding which will disconnect less important loads during power production failures. On the market, there are many systems and devices suitable for load shedding. It is not exactly clear which device is always the most suitable for a situation at hand and in which kind of situation it should not be used. Some of the solutions are best suited for fast load shedding in which quick reaction time in power production failures is crucial. Some of the solutions cannot be used in fast load shedding because of their slow reaction time. In this thesis, load shedding products used by ABB Oy are examined. The solutions studied are control system MicroSCADA, programmable logic controllers RTU and AC800 and a new load shedding controller PML630. All of the products have been used in load shedding before. The goal of this thesis is to figure out in which kind of situations each of the solutions could be used. No research regarding products and their suitability for load shedding as extensive as this thesis has been made before. Therefore, during tender phase, this thesis can be used to find out which solution is best for the project in question. The research was carried out by comparing projects made with the devices and through simulations. A thorough comparison was made regarding the properties of the devices which made it easy to recognise their limitations. It was discovered that the most limiting factor in fast load shedding is the slowness of the communication protocols. It came as a surprise that IEC 61580 GOOSE communication protocol, which makes horizontal, very fast, communication possible, was as fast as it was. It was discovered that PML630 has the ability to react to power production failures in maximum averige of 48 ms. Another important observation was the programming work needed for load shedding. If the solution has a template set up for load shedding, it usually sets restrictions for the size of the substation which should be noted when planning a project

No effects of Epichloë endophyte infection on nitrogen cycling in meadow fescue (Schedonorus pratensis) grassland

Peer reviewe

Temperature effects on the temporal dynamics of a subarctic invertebrate community

Climate warming is predicted to have major impacts on the structure of terrestrial communities, particularly in high latitude ecosystems where growing seasons are short. Higher temperatures may dampen seasonal dynamics in community composition as a consequence of earlier snowmelt, with potentially cascading effects across all levels of biological organisation. Here, we examined changes in community assembly and structure along a natural soil temperature gradient in the Hengill geothermal valley, Iceland, during the summer of 2015. Sample collection over several time points within a season allowed us to assess whether temperature alters temporal variance in terrestrial communities and compositional turnover. We found that seasonal fluctuations in species richness, diversity and evenness were dampened as soil temperature increased, whereas invertebrate biomass varied more. Body mass was found to be a good predictor of species occurrence, with smaller species found at higher soil temperatures and emerging earlier in the season. Our results provide more in-depth understanding of the temporal nature of community and population-level responses to temperature, and indicate that climate warming will likely dampen the seasonal turnover of community structure that is characteristic of high latitude invertebrate communities.Peer reviewe

Lead (Pb) contamination alters richness and diversity of the fungal, but not the bacterial community in pine forest soil

Peer reviewe

Soil organic matter, rather than temperature, determines the structure and functioning of subarctic decomposer communities

The impacts of climate change on ecosystem structure and functioning are likely to be strongest at high latitudes due to the adaptation of biota to relatively low temperatures and nutrient levels. Soil warming is widely predicted to alter microbial, invertebrate, and plant communities, with cascading effects on ecosystem functioning, but this has largely been demonstrated over short-term (Peer reviewe

Biostimulation proved to be the most efficient method in the comparison of in situ soil remediation treatments after a simulated oil spill accident

The use of in situ techniques in soil remediation is still rare in Finland and most other European countries due to the uncertainty of the effectiveness of the techniques especially in cold regions and also due to their potential side effects on the environment. In this study, we compared the biostimulation, chemical oxidation, and natural attenuation treatments in natural conditions and pilot scale during a 16-month experiment. A real fuel spill accident was used as a model for experiment setup and soil contamination. We found that biostimulation significantly decreased the contaminant leachate into the water, including also the non-aqueous phase liquid (NAPL). The total NAPL leachate was 19 % lower in the biostimulation treatment that in the untreated soil and 34 % lower in the biostimulation than oxidation treatment. Soil bacterial growth and community changes were first observed due to the increased carbon content via oil amendment and later due to the enhanced nutrient content via biostimulation. Overall, the most effective treatment for fresh contaminated soil was biostimulation, which enhanced the biodegradation of easily available oil in the mobile phase and consequently reduced contaminant leakage through the soil. The chemical oxidation did not enhance soil cleanup and resulted in the mobilization of contaminants. Our results suggest that biostimulation can decrease or even prevent oil migration in recently contaminated areas and can thus be considered as a potentially safe in situ treatment also in groundwater areas.Peer reviewe

Defoliation and patchy nutrient return drive grazing effects on plant and soil properties in a dairy cow pasture

Large herbivores can influence plant and soil properties in grassland ecosystems, but especially for belowground biota and processes, the mechanisms that explain these effects are not fully understood. Here, we examine the capability of three grazing mechanisms-plant defoliation, dung and urine return, and physical presence of animals (causing trampling and excreta return in patches)-to explain grazing effects in Phleum pratense-Festuca pratensis dairy cow pasture in Finland. Comparison of control plots and plots grazed by cows showed that grazing maintained original plant-community structure, decreased shoot mass and root N and P concentrations, increased shoot N and P concentrations, and had an inconsistent effect on root mass. Among soil fauna, grazing increased the abundance of fungivorous nematodes and Aporrectodea earthworms and decreased the abundance of detritivorous enchytraeids and Lumbricus earthworms. Grazing also increased soil density and pH but did not affect average soil inorganic-N concentration. To reveal the mechanisms behind these effects, we analyzed results from mowed plots and plots that were both mowed and treated with a dung and urine mixture. This comparison revealed that grazing effects on plant attributes were almost entirely explained by defoliation, with only one partly explained by excreta return. Among belowground attributes, however, the mechanisms were more mixed, with effects explained by defoliation, patchy excreta return, and cow trampling. Average soil inorganic-N concentration was not affected by grazing because it was simultaneously decreased by defoliation and increased by cow presence. Presence of cows created great spatial heterogeneity in soil N availability and abundance of fungivorous nematodes. A greenhouse trial revealed a grazing-induced soil feedback on plant growth, which was explained by patchiness in N availability rather than changes in soil biota. Our results show that grazing effects on plant attributes can be satisfactorily predicted using the effects of defoliation, whereas those on soil fauna and soil N availability need understanding of other mechanisms as well. The results indicate that defoliation-induced changes in plant ecophysiology and the great spatial variation in N availability created by grazers are the two key mechanisms through which large herbivores can control grassland ecosystems.Large herbivores can influence plant and soil properties in grassland ecosystems, but especially for belowground biota and processes, the mechanisms that explain these effects are not fully understood. Here, we examine the capability of three grazing mechanisms-plant defoliation, dung and urine return, and physical presence of animals (causing trampling and excreta return in patches)-to explain grazing effects in Phleum pratense-Festuca pratensis dairy cow pasture in Finland. Comparison of control plots and plots grazed by cows showed that grazing maintained original plant-community structure, decreased shoot mass and root N and P concentrations, increased shoot N and P concentrations, and had an inconsistent effect on root mass. Among soil fauna, grazing increased the abundance of fungivorous nematodes and Aporrectodea earthworms and decreased the abundance of detritivorous enchytraeids and Lumbricus earthworms. Grazing also increased soil density and pH but did not affect average soil inorganic-N concentration. To reveal the mechanisms behind these effects, we analyzed results from mowed plots and plots that were both mowed and treated with a dung and urine mixture. This comparison revealed that grazing effects on plant attributes were almost entirely explained by defoliation, with only one partly explained by excreta return. Among belowground attributes, however, the mechanisms were more mixed, with effects explained by defoliation, patchy excreta return, and cow trampling. Average soil inorganic-N concentration was not affected by grazing because it was simultaneously decreased by defoliation and increased by cow presence. Presence of cows created great spatial heterogeneity in soil N availability and abundance of fungivorous nematodes. A greenhouse trial revealed a grazing-induced soil feedback on plant growth, which was explained by patchiness in N availability rather than changes in soil biota. Our results show that grazing effects on plant attributes can be satisfactorily predicted using the effects of defoliation, whereas those on soil fauna and soil N availability need understanding of other mechanisms as well. The results indicate that defoliation-induced changes in plant ecophysiology and the great spatial variation in N availability created by grazers are the two key mechanisms through which large herbivores can control grassland ecosystems.Large herbivores can influence plant and soil properties in grassland ecosystems, but especially for belowground biota and processes, the mechanisms that explain these effects are not fully understood. Here, we examine the capability of three grazing mechanisms-plant defoliation, dung and urine return, and physical presence of animals (causing trampling and excreta return in patches)-to explain grazing effects in Phleum pratense-Festuca pratensis dairy cow pasture in Finland. Comparison of control plots and plots grazed by cows showed that grazing maintained original plant-community structure, decreased shoot mass and root N and P concentrations, increased shoot N and P concentrations, and had an inconsistent effect on root mass. Among soil fauna, grazing increased the abundance of fungivorous nematodes and Aporrectodea earthworms and decreased the abundance of detritivorous enchytraeids and Lumbricus earthworms. Grazing also increased soil density and pH but did not affect average soil inorganic-N concentration. To reveal the mechanisms behind these effects, we analyzed results from mowed plots and plots that were both mowed and treated with a dung and urine mixture. This comparison revealed that grazing effects on plant attributes were almost entirely explained by defoliation, with only one partly explained by excreta return. Among belowground attributes, however, the mechanisms were more mixed, with effects explained by defoliation, patchy excreta return, and cow trampling. Average soil inorganic-N concentration was not affected by grazing because it was simultaneously decreased by defoliation and increased by cow presence. Presence of cows created great spatial heterogeneity in soil N availability and abundance of fungivorous nematodes. A greenhouse trial revealed a grazing-induced soil feedback on plant growth, which was explained by patchiness in N availability rather than changes in soil biota. Our results show that grazing effects on plant attributes can be satisfactorily predicted using the effects of defoliation, whereas those on soil fauna and soil N availability need understanding of other mechanisms as well. The results indicate that defoliation-induced changes in plant ecophysiology and the great spatial variation in N availability created by grazers are the two key mechanisms through which large herbivores can control grassland ecosystems.Peer reviewe

BVOC Emissions From a Subarctic Ecosystem, as Controlled by Insect Herbivore Pressure and Temperature

The biogenic volatile organic compounds, BVOCs have a central role in ecosystem-atmosphere interactions. High-latitude ecosystems are facing increasing temperatures and insect herbivore pressure, which may affect their BVOC emission rates, but evidence and predictions of changes remain scattered. We studied the long-term effects of + 3 degrees C warming and reduced insect herbivory (achieved through insecticide sprayings) on mid- and late summer BVOC emissions from field layer vegetation, supplemented with birch saplings, and the underlying soil in Subarctic mountain birch forest in Finland in 2017-2018. Reduced insect herbivory decreased leaf damage by 58-67% and total ecosystem BVOC emissions by 44-72%. Of the BVOC groups, total sesquiterpenes had 70-80% lower emissions with reduced herbivory, and in 2017 the decrease was greater in warmed plots (89% decrease) than in ambient plots (34% decrease). While non-standardized total BVOC, monoterpene, sesquiterpene and GLV emissions showed instant positive responses to increasing chamber air temperature in midsummer samplings, the long-term warming treatment effects on standardized emissions mainly appeared as changes in the compound structure of BVOC blends and varied with compounds and sampling times. Our results suggest that the effects of climate warming on the total quantity of BVOC emissions will in Subarctic ecosystems be, over and above the instant temperature effects, mediated through changes in insect herbivore pressure rather than plant growth. If insect herbivore numbers will increase as predicted under climate warming, our results forecast herbivory-induced increases in the quantity of Subarctic BVOC emissions.Peer reviewe

Olive oil -based method for the extraction, quantification and identification of microplastics in soil and compost samples

Peer reviewe

Warming and ozone exposure effects on silver birch (Betula pendula Roth) leaf litter quality, microbial growth and decomposition

Background and aims Climate warming is expected to accelerate decomposition in boreal forests, but the concomitant effects of tropospheric ozone (O-3), a phytotoxic greenhouse gas, alone and in combination with warming, are poorly understood. We studied how these two climatic factors affect leaf litter decomposition of two silver birch genotypes. Methods We used field exposure for growing saplings and native and reciprocal transplant experiments for litter incubation to disentangle environmental and litter quality mediated effects of temperature and O-3 on litter mass loss. We analysed litter C% and N% and microbial biomass (using qPCR) in fresh litter and after 217 and 257 days of incubation. Results Warming decreased fresh litter C% and N% and bacterial DNA, whereas elevated O-3 increased N% and bacterial and fungal DNA, equally for both genotypes. In contrast, most effects on microbes during litter incubation varied between the two genotypes. Warming effects on microbes were mainly environmental, but despite having effects on litter quality and microbial growth, warming and O-3 both had only weak or no effects on litter mass loss. Conclusions Litter quality and microbial growth in northern birch stands are likely to change due to warming and O-3 exposures, but effects on litter decomposition rate may remain weak.Peer reviewe