Advanced parameter measurement of energy storage systems for smart grids application

Peer Reviewe

Optimization of Experimental Model Parameter Identification for Energy Storage Systems

The smart grid approach is envisioned to take advantage of all available modern technologies in transforming the current power system to provide benefits to all stakeholders in the fields of efficient energy utilisation and of wide integration of renewable sources. Energy storage systems could help to solve some issues that stem from renewable energy usage in terms of stabilizing the intermittent energy production, power quality and power peak mitigation. With the integration of energy storage systems into the smart grids, their accurate modeling becomes a necessity, in order to gain robust real-time control on the network, in terms of stability and energy supply forecasting. In this framework, this paper proposes a procedure to identify the values of the battery model parameters in order to best fit experimental data and integrate it, along with models of energy sources and electrical loads, in a complete framework which represents a real time smart grid management system. The proposed method is based on a hybrid optimisation technique, which makes combined use of a stochastic and a deterministic algorithm, with low computational burden and can therefore be repeated over time in order to account for parameter variations due to the battery's age and usage

FPGA-based real time compensation method for medium voltage transducers

open5noSince the increase of the distributed power connected to the medium voltage networks, a capillary monitoring of the power quality becomes essential. This entails the spread of transducers with suitable frequency bandwidths, as required by the relevant standards. The paper describes a real time compensation method for the extension of the frequency bandwidth of medium voltage dividers whose performances do not allow to perform measurements over a wide frequency range. This approach will contribute to keep the costs of this innovation lowopenCrotti, Gabriella; Gallo, Daniele; Giordano, Domenico; Landi, Carmine; Inrim, Mario Luiso2 1Crotti, Gabriella; Gallo, Daniele; Giordano, Domenico; Landi, Carmine; Inrim, Mario Luiso2

A real-time compensation method for MV voltage transducer for power quality analysis

Peer Reviewe

Evaluation of Voltage Transformers’ Accuracy in Harmonic and Interharmonic Measurement

The measurement of Power Quality (PQ), generally performed at Low Voltage (LV) level, is gaining more and more importance also at the Medium Voltage (MV) level, due to the increasing presence of switching power converters (both loads or generators) directly connected to MV grids. In this case, the use of Voltage Transformers (VTs) is unavoidable to scale voltage down to amplitudes compatible with the input ranges of PQ instruments. However, the current absence of an international standard dealing with VTs used for PQ measurements leaves the manufacturers and the users in a situation of complete uncertainty, since different products can have performance specifications tested and stated in completely different ways. This paper aims at defining an integrated approach for the evaluation of VTs accuracy used for PQ measurements, focusing on harmonics and interharmonics. The paper provides experimental results of the tests performed on a MV inductive VT according to the proposed procedure. As a result, it is demonstrated that VT accuracy in the measurement of a specific phenomenon should be evaluated with complex waveforms including the contemporary presence of different PQ phenomena

A Web Service Interface for a Distributed Measurement System Based on Decentralized Sharing Network 1

Abstract: The Web Service technology has increased in importance in these years. Accessing to remote resources without knowledge about physical implementation and with a reduced hardware requirement is the main goal of new portable device. The use of Web Service technology allows clients to create a standard interface to access to the measurement service published by the server. In low cost multipoint distributed measurement systems, the measurement services are provided by Smart Web Sensors. A new concept of distributed measurement system arises from the possibility to fuse all services with the same functionality in a single user-transparent service: the response of distributed services network to a user request gives a complete vision of the service by collecting results from any Smart Web Sensor in the network. So, in this paper the development of a multipoint distributed measurement system, based on the peer-to-peer Gnutella network with Web Service interface, is presented. Copyright © 2013 IFSA

A simplified procedure for the Accurate Frequency Response Identification of Voltage Transformers

The paper proposes a simplified and affordable procedure for instrument transformers frequency characterization for medium voltage applications. It consists of a two steps measurement procedure, where both steps involve the generation of sine waves only, so that the it can be easily performed in instrument transformers calibration laboratories without requiring additional generation features. In the first step, a 50 Hz measurement of the Voltage Instrument Transformer ratio error at rated voltage is performed. The second step consists of a frequency sweep performed at low voltage up to the first resonance. By these two data sets, an approximated but accurate frequency response can be easily obtained using a non-linear fitted model. In the paper, a commercial voltage instrument transformer for medium voltage grids is characterized by the proposed method; results are shown and validated by comparison with a reference frequency characterization performed at INRIM under rated voltage

Lumped Capacitance Thermal Modelling Approaches for Different Cylindrical Batteries

Received: 3 November 2023. Revised: 15 November 2023. Accepted: 8 December 2023. Available online: 29 December 2023.In the pursuit of optimal energy storage solutions, rechargeable batteries have gained significant attention for their applications in electric vehicles, aircraft, and satellites. This research focuses on the thermal management of lithium manganese dioxide and nickelcadmium batteries, utilizing the lumped capacitance thermal modelling technique in the preliminary stage of analysis. The study focuses on the general lumped capacitance thermal equation to estimate battery temperature through analytical and numerical methods. The numerical approach employs the fourth order Runge-Kutta's method, which involved less computational cost, relatively stable and accurate to estimate the temperature with a variable internal resistance, a crucial factor in thermal behaviour analysis. In contrast, the analytical approach assumes a uniform temperature distribution across the battery's surface, simplifying the gradual variance between internal conductive and external convective thermal resistances. A comparative analysis against experimental data using error criterion techniques reveals that the numerical model, considering dynamic changes in internal resistance, aligns more closely with experimental findings and offers a statistically superior fit compared to the analytical model assuming constant internal resistance. This study underscores the effectiveness of the lumped capacitance thermal modelling technique in battery thermal management, emphasizing the importance for dynamic internal resistance for analysis of thermal behaviour

Fast Hybrid MPPT Technique for Photovoltaic Applications: Numerical and Experimental Validation

In PV applications, under mismatching conditions, it is necessary to adopt a maximum power point tracking (MPPT) technique which is able to regulate not only the voltages of the PV modules of the array but also the DC input voltage of the inverter. Such a technique can be considered a hybrid MPPT (HMPPT) technique since it is neither only distributed on the PV modules of the PV array or only centralized at the input of the inverter. In this paper a new HMPPT technique is presented and discussed. Its main advantages are the high MPPT efficiency and the high speed of tracking which are obtained by means of a fast estimate of the optimal values of PV modules voltages and of the input inverter voltage. The new HMPPT technique is compared with simple HMPPT techniques based on the scan of the power versus voltage inverter input characteristic. The theoretical analysis and the results of numerical simulations are widely discussed. Moreover, a laboratory test system, equipped with PV emulators, has been realized and used in order to experimentally validate the proposed technique

ASSESSMENT OF INSTRUMENT TRANSFORMER ACCURACY FOR POWER QUALITY MEASUREMENTS IN DISTRIBUTION GRIDS: RECENT ACTIVITIES AND FIRST RESULTS FROM 19NRM05 IT4PQ PROJECT

Extensive integration of renewables in the electrical energy distribution system is essential for the implementation of green growth strategies. However, it contributes to the degradation of the quality of the electrical power, as such power quality (PQ) monitoring holds greater and greater importance. Currently, there are no standards related to the characterisation of the instrument transformers (ITs) for PQ measurements, even if ITs can introduce significant errors in the PQ measurement chain. Therefore, a project has recently funded to investigate gaps in accuracy assessment and characterisation of ITs when used in PQ measurements and to work out specific performance indices, reference measurement systems and test procedures to evaluate the ITs accuracy and uncertainty contributions in PQ measurements. Guidelines and recommendations for the calibration of ITs used in PQ measurements will be provided to the Technical Committee IEC TC 38