Argo Rosin

Evaluation of Equivalent Circuit Diagrams and Transfer Functions for Modeling of Lithium-Ion Batteries

Abstract The rapid developments in the field of electrochemistry, enabled lithium-ion batteries to achieve a very good position among all the other types of energy storage devices. Therefore they became an essential component in most of the modern portable and stationary energy storage applications, where the specific energy and the life time play an important role. In order to analyze and optimize lithium-ion batteries an accurate battery model for the dynamic behavior is required. At the beginning of this paper four different categories of electrical models for li-ion cells are presented. In the next step a comparison between equivalent circuit diagrams and fractional rational functions with the complex variable s is shown for lithium-ion battery modeling. It is described how to identify the parameters of the models in the time domain and also in frequency domain. The validation of the different models is made for high and low dynamic current profiles. In the first step the dependency of all model parameters on the temperature and on the battery age is neglected. These effects will be taken into account in the continuation of this work

Residential electricity consumption and loads pattern analysis

This article analyses household electricity consumption in Estonia. Energy consumption of workday and holiday by loads is discussed. The final part describes the evaluation of feasibility of common investments

NordPoolSpot price pattern analysis for households energy management

This paper describes the analysis of price fluctuations in the Nord Pool Spot (NPS) and the possibilities to introduce consumption scheduling and energy storage equipment to reduce price fluctuations in households using the real-time open market electrical energy tariffs.

Control of Ultracapacitors Energy Exchange

Ultracapacitors can store and also give out large energy pulses. That makes them perfectly suitable as short term energy storage devices in electrical vehicles. The usage of ultracapacitors prevents over sizing of the battery pack due to peak power demands. This paper introduces the basic concept of how ultracapacitors could be used in Tramways. The main purpose of the paper is to introduce one possible control-strategy of ultracapacitors energy exchange. With the energy exchange is meant the movement of energy form the ultracapacitors into distribution network and vice versa. Three different regulators, proportional (P), integration (I), and the combination of both (PI) are tested and compared to each other. Practical results are analyzed and compared with the simulation results.

Analysis of Household Electricity Consumption Patterns and Economy of Water Heating Shifting and Saving Bulbs

Analysis of Household Electricity Consumption Patterns and Economy of Water Heating Shifting and Saving Bulbs This article analyses household electricity consumption based on an object in Estonia. Energy consumption of workday and holiday by loads (including high and low tariff energy consumption) is discussed. The final part describes the evaluation of profitability of common investments of consumption shifting and replacing inefficient devices with more efficient ones. Additionally it describes shifting problems and shifting equipment profitability in real-time tariff system.

Large scale electric vehicle integration and its impact on the Estonian power system

This paper presents the main aspects of the study about large scale electric vehicle (EV) integration impacts in Estonia. The complex impact of EV charging and the resulting additional load demand on the Estonian power system is discussed. Two different charging principles are analysed - controlled and unmanaged. Standard and quick charging impacts are assessed together with the preheating strategies due to the climatic conditions. The aim of the paper is to model the impacts of EVs on the Estonian power system at sub regional level and to give an input for the Estonian TSO for its network development plans concerning e-mobility integration.

SOC estimation for Li-Ion batteries based on equivalent circuit diagrams and the application of a Kalman filter

Batteries play an essential role in electric vehicles (EV), and obtain more and more importance also in smart grids due to the non-constant power generation of renewable energy sources. In order to achieve an optimum operation of systems with batteries it is necessary to develop accurate mathematical models for the calculation of the state of charge (SOC), taking into account the individual operation by the user. This paper presents the fundamentals of a method how to determine SOC of lithiumion batteries on the basis of two different equivalent circuit diagrams and an Extended Kalman Filter (EKF). The comparison between measurement and computation results shows a good accordance. The accurate determination of SOC of a battery in an EV is of high importance for the prediction of the distance that can be driven. In the first step the dependency of these parameters on the temperature and on the battery age is neglected.

Electricity consumption analysis and power quality monitoring in commercial buildings

The results of the analysis of the electricity consumption and power quality indicators in two office buildings are presented. It comprises electricity consumption and power quality during work days and weekends. The consumption data analysed is from a one year period and the power quality analysis is based on a one week measuring period. The aim of this analysis is to determine the current situation in these buildings in order to study the possibilities and limitations to implement different energy efficiency measures. In addition to the energy efficiency point of view, the problem is also addressed together with the power quality aspects.

Modelling of electricity spot price and load forecast based new energy management system for households

The aim was to determine probable profit by using electric energy storage (EES) device in a typical household. Focus is on theoretical and practical studies of an energy management system (EMS) based on VRLA battery storage. Use of a battery charge-discharge-schedule (BCDS) enables an optimal operation of EES taking advantage of the low price periods by importing more energy and storing it, while reducing the imported power during high price periods by supporting the load with the stored energy. Forecasted price and load are used to optimize the BCDS of EES, at the same time ensuring load demand supply. In the day-ahead market, the management system uses the mathematical functions to calculate the price of imported energy in each period of time with the day-ahead forecasted price and typical load in the household. The recursion loops in the optimization algorithm search for the best BCDS to reach the highest profit for the end consumer. All the calculations will be tested on the EMS to confirm the theoretical part.

Overview — Pumped-hydro energy storage for balancing wind energy forecast errors

This paper analyses the increasing wind energy integration impacts on the Estonian power system, particularly wind energy production forecast errors. It proposes a solution to integrate wind parks with Estonian power grid, which is mainly based on large thermal power plants utilizing fossil fuels, together with a grid-scale energy storage system, particularly pumped-hydro energy storage, in order to balance the forecast errors in wind energy production utilization. Continuing increase of installed wind power capacity with its impacts on the grid is discussed. The last section describes a technical solution, simulated under real-time situation of the grid, which proves pumped-hydro energy storage as a suitable alternative.