A SC/battery Hybrid Energy Storage System in the Microgrid

The major challenges in power systems are driven by the energy shortage and environmental concerns, namely facilitating the penetration of renewable energy and improving the efficiency of the renewable powers. Due to the variable nature of renewables, the generated power profile may not be able to match the load requirement. Accordingly, much attention has been focused on the development of energy storage technologies to guarantee renewable power penetrations. Recently, advances in the supercapacitor (SC) have made the SC and battery hybrid energy storage systems (HESS) technically attractive. Compared with other energy storage technologies the principal advantages of SC are: the high power density, high cycling life, and high peak current handling capacities. However, SC is also deficient in low energy density. The battery is characterised by large energy density but low in power capacity. In the microgrid systems, high-frequency power fluctuations will cause a significant degree of battery power cycling. This, in turn, has been shown to lead to a significant reduction in battery service life. Therefore, the concept of the SC and battery hybrid scheme is proposed. A case study of the HESS based on a microgrid is introduced in this paper. A simplified microgrid system is established to test the performance of the proposed design

Hierarchical power flow control of a grid-tied photovoltaic plant using a battery-supercapacitor energy storage system

A two-layer power flow control for a grid-tied photovoltaic plant equipped with battery-supercapacitor energy storage system is presented in this paper. The proposed strategy aims at simultaneously handling the intermittent nature of the solar radiation received by the photovoltaic collectors and the need to consistently supply the specified power taking advantage of the complementary characteristics of the energy storage technologies. It relieves the batteries from stress through the use of the photovoltaic and the supercapacitor to supply the high frequency power demands by means of hierarchical control. Extensive simulation results confirm the effectiveness of the proposed power flow control strategy.http://www.elsevier.com/locate/procediaam2019Electrical, Electronic and Computer Engineerin

Power dispatching techniques as a finite state machine for a standalone photovoltaic system with a hybrid energy storage

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Hybrid switched-capacitor/switched-quasi-Z-source bidirectional DC-DC converter with wide-voltage-gain range for hybrid energy sources EVs

In this paper, a hybrid switched-capacitor/ switched-quasi-Z-source bidirectional dc-dc converter is proposed for electric vehicles (EVs) with hybrid energy sources, which has a wide voltage gain range in the bidirectional energy flows. Compared with the traditional quasi-Z-source bidirectional dc-dc converter, the proposed converter only changes the position of the main power switch, and employs a switched-capacitor cell at the output of the high voltage side. Therefore, the advantages of the wide voltage gain range and the lower voltage stresses across the power switches can be achieved. The operating principle, the voltage and current stresses across the power switches and the comparisons with other converters are analyzed in detail. Furthermore, the parameter design of the main components, the dynamic modelling analysis and the voltage control scheme are also presented. Finally, the experimental results obtained from a 400W prototype validate the characteristics and the theoretical analysis of the proposed converter

A common ground switched-quasi-Z-source bidirectional DC-DC converter with wide-voltage-gain range for EVs with hybrid energy sources

A common ground switched-quasi-Z-source bidirectional DC-DC converter is proposed for electric vehicles (EVs) with hybrid energy sources. The proposed converter is based on the traditional two-level quasi-Z-source bidirectional DC-DC converter, changing the position of the main power switch. It has the advantages of a wide voltage gain range, a lower voltage stress across the power switches, and an absolute common ground. The operating principle, the voltage and current stresses on the power switches, the comparisons with the other converters, the small signal analysis and the controller design are presented in this paper. Finally, a 300W prototype with Uhigh=240V and Ulow=40~120V is developed, and the experimental results validate the performance and the feasibility of the proposed converter

BASSILO - Battery storage sizing and location in distribution systems

This thesis addresses the problem of sizing and optimal location of non-domestic energy storage, batteries, in distribution networks that integrate distributed photovoltaic generation, with the objective of analysing its exploration potential in the energy business. For this purpose, a formulation based on line programming and the EPSO metaheuristic (Evolutionary Particle Swarm Operation) has been proposed for the minimization of the costs of including a storage system in the energy grid.Given the size and location of the battery, a formulation based on linear programming will allow to determine the optimal operation of the battery for the following cases: in the first study, the operation of the battery in the base of one day. In the second, the operation of the battery in the base of multiple consecutive days. The optimal size and location of the battery is determined using the EPSO metaheuristics, which will evaluate the costs involved in the two perspectives of operation of the battery, previously proposed.The results presented are for a realistic power network, CIGRE - European MV distribution network benchmark, modified to be operated as a radial network, comprising distributed loads (commercial and residential) and photovoltaic generation for several operating scenarios in which the variation of energy prices, are considered to validate the proposed business exploration model

Erinevate energia salvestustehnoloogiate uudsed rakenduspõhimõtted liginullenergiahoonetes

A Thesis for applying for the degree of Doctor of Philosophy in Technical Sciences.In this thesis the renewable energy storage options in residential buildings are under investigation. This is to store cheap electricity due to the temporary overproduction of large wind farms and also on-site solar and wind farms. In an electric system, there should be a balance at all times between energy production and consumption: as much as is produced should also be consumed. Deviating significantly from this balance can damage electrical equipment or cause serious network failures and even blackouts. Unfortunately, both solar and wind energy generation possibilities are associated with (rapid) changes in production. The simplest examples are wind gusts for wind turbines and intermittent cloud cover for solar panels where the electric output power changes in seconds. In order to smooth out the rapid changes in electricity production, the work proposes the possibility to add ultracapacitors to the battery bank for temporary energy storage, which would act as a buffer and are able to temporarily store the produced electricity. So far, the sale of green energy to the electricity grid has been supported at the state level. However, this paper examines the next step in how to support the storage capacity of the produced energy in order to increase self-consumption. To this, a state subsidy measure for battery banks is proposed. Due to short-term overproduction of electricity, there are more and more situations where electricity is sold at zero or even negative prices on the power exchange. The reason is simple - it is more practical for producers to temporarily pay to consumers for electricity consumption than to stop production for a while. This work also proposes a method for storing energy in heat carriers under favorable conditions for the consumer in order to ensure a balance between the production and consumption of the electricity network.Antud doktoritöö käsitleb taastuvenergia salvestusvõimaluste kasutamist elumajades. Seda nii kohapealsete päikeseparkide ja tuulegeneraatorite kui ka suurte tuuleparkide aeg-ajalisest energia ületootmisest tingitud odava elektrienergia salvestamiseks. Energia tootmise ja tarbimise puhul peaks valitsema igas hetkes tasakaal: sama palju kui toodetakse tuleb ka tarbida. Kui sellest tasakaalust väga kõrvale kalduda, võib see elektrilisi seadmed kahjustada või esineb tõsiseid võrgurikkeid ja isegi katkestusi. Paraku on aga nii päikese- kui ka tuuleenergia tootmine seotud (kiirete) muutustega toodangus. Lihtsaimad näited selleks on tuulepuhangud tuulegeneraatorite puhul ning vahelduv pilvisus päikesepaneelide puhul mil elektriline väljundvõimsus muutub sekunditega. Tasandamaks kiireid muutusi elektritootmisel, pakutakse töös välja võimalus lisada akupangale energia ajutiseks salvestamiseks ülikondensaatorid, mis käituks puhvrina ning on võimelised toodetud elektrienergiat ajutiselt salvestama. Senini on riiklikul tasandil toetatud roheenergia müüki elektrivõrku. Antud töös uuritakse aga järgmist etappi, kuidas toetada toodetud energia salvestusvõimalusi eesmärgiga suurendada omatarbimist. Selleks pakutakse välja riiklik akupankade subsideerimise meede. Elektrienergia lühiajalisest ületootmisest tulenevalt esineb üha rohkem olukordi, mil elektribörsil müüakse elektrit null või isegi negatiivse hinnaga. Põhjus on lihtne – tootjatel on otstarbekam ajutiselt elektritarbimisele peale maksta, kui tootmine korraks seisma panna. Antud töös pakutakse samuti välja meetod, kuidas tarbijale soodsatel tingimustel energiat soojuskandjatesse salvestada, tagamaks elektrivõrgu tootmise ja tarbimise tasakaalu.Publication of this theisis is supported by the Estonian University of Life Sciences; and the Doctoral School of Energy and Geotechnology III, (Estonian University of Life Sciences ASTRA project “Valuechain based bio-economy”); and the Estonian Centre of Excellence in Zero Energy and Resource Efficient Smart Buildings and Districts, ZEBE, grant 2014-2020.4.01.15-0016 funded by the European Regional Development Fund