Corneliu Marinescu

Bio: Corneliu Marinescu is an academic researcher from Transilvania University of Brașov. The author has contributed to research in topics: Energy storage & Wind power. The author has an hindex of 19, co-authored 92 publications receiving 1435 citations.

Control Strategy of Three-Phase Battery Energy Storage Systems for Frequency Support in Microgrids and with Uninterrupted Supply of Local Loads

Abstract: Frequency control in autonomous microgrids (MG) with high penetration of renewable energy sources represents a great concern to ensure the system stability. In this regard, this paper presents an enhanced control method for battery energy storage systems (BESS) to support the frequency of MG and with the ability of disconnecting from the MG to supplying in the island mode a local consumer. A frequency controller, combining a conventional droop control with an inertia emulation function, governs the BESS active power transfer during the primary frequency control level. The BESS may also provide voltage support in the point of common coupling with the MG. Moreover, the proposed BESS may compensate, partially or totally, the power absorbed by the local loads in order to improve the MG frequency response. When the MG power quality worsens below a certain level, in terms of voltage and frequency, the BESS detaches from the MG and continues to operate islanded. The reconnection is accomplished following a smoothly resynchronization of the local voltage with the MG, without disturbing the local loads supply. Additionally, this paper also discusses about the aspects related to the BESS management and its integration within the proposed system. The simulation and experimental results assess the feasibility of the proposed control solutions.

Control Structure for Single-Phase Stand-Alone Wind-Based Energy Sources

Abstract: This paper is analyzing the operation of a stand-alone wind turbine system with variable-speed permanent-magnet synchronous generator (PMSG) and a system for storing energy during wind speed and load variations. Energy storage devices are required for power balance and power quality in stand-alone wind energy systems. Initially, the holistic model of the entire system is achieved, including the PMSG, the boost converter, and the storage system. The power absorbed by the connected loads can be effectively delivered and supplied by the proposed wind turbine and energy storage systems, subject to an appropriate control method. The main purpose is to supply 230-V/50-Hz domestic appliances through a single-phase inverter. The simulation results, validated by experimental testing, show a good prediction of the electrical parameter waveforms. The control system is implemented on a dSPACE DS1103 real-time board. Furthermore, the results confirm the stability of the supply.

Battery energy storage system for frequency support in microgrids and with enhanced control features for uninterruptible supply of local loads

Abstract: This paper proposes a battery energy storage system (BESS) to support the frequency control process within microgrids (MG) with high penetration of renewable energy sources (RES). The solution includes features that enhance the system’s stability and security of supply. The BESS can operate connected to MG or islanded and the transition between the two states is seamlessly coordinated by an original method. The BESS active power response is governed by an improved frequency controller on two layers, namely primary and secondary. It responds to frequency deviations by combining a conventional droop control method with a virtual inertia function to improve the system’s stability. The proposed BESS may also compensate the power of the local loads, so that the MG frequency transients can be reduced and, depending on the remaining inverter capacity, voltage support in the point of common coupling with the MG may be provided. If the MG power quality degrades in terms of the voltage and frequency, the BESS and the local load are disconnected from the MG and continue operating islanded. The BESS is reconnected to the MG after a smoothly resynchronization of the local voltage with the MG, without disturbing the local loads supply. Simulation and experimental results assesses the proposed control solutions.

Stand-alone wind system with Vanadium Redox Battery energy storage

Abstract: Energy storage devices are required for power balance and power quality in stand alone wind energy systems. A Vanadium Redox Flow Battery (VRB) system has many features which make its integration with a stand alone wind energy system attractive. This paper proposes the integration of a VRB system with a typical stand-alone wind energy system during wind speed variation as well as transient performance under variable load. The investigated system consists of a variable speed wind turbine with permanent magnet synchronous generator (PMSG), diode rectifier bridge, buck-boost converter, bidirectional charge controller, transformer, inverter, ac loads and VRB (to store a surplus of wind energy and to supply power during a wind power shortage). The main purpose is to supply domestic appliances through a single phase 230 V, 50 Hz inverter. Simulations are accomplished in order to validate the stability of the supply.

VRB modeling for storage in stand-alone wind energy systems

Abstract: This paper proposes into determining an appropriate electrical Vanadium Redox Flow Battery (VRB) model and its integration with a typical stand-alone wind energy system during wind speed variation as well as transient performance under variable load. The investigated system consists of a 3kW variable speed wind turbine with permanent magnet synchronous generator (PMSG), diode rectifier bridge, buck-boost converter, bidirectional charge controller, transformer, inverter, ac loads and VRB. Vanadium Redox batteries are well suited for this type of application because of their high efficiency, high scalability, fast response, long life and low maintenance requirements.

Electrical Energy Storage for the Grid: A Battery of Choices

Abstract: The increasing interest in energy storage for the grid can be attributed to multiple factors, including the capital costs of managing peak demands, the investments needed for grid reliability, and the integration of renewable energy sources. Although existing energy storage is dominated by pumped hydroelectric, there is the recognition that battery systems can offer a number of high-value opportunities, provided that lower costs can be obtained. The battery systems reviewed here include sodium-sulfur batteries that are commercially available for grid applications, redox-flow batteries that offer low cost, and lithium-ion batteries whose development for commercial electronics and electric vehicles is being applied to grid storage.

Overview of current development in electrical energy storage technologies and the application potential in power system operation

Abstract: Electrical power generation is changing dramatically across the world because of the need to reduce greenhouse gas emissions and to introduce mixed energy sources. The power network faces great challenges in transmission and distribution to meet demand with unpredictable daily and seasonal variations. Electrical Energy Storage (EES) is recognized as underpinning technologies to have great potential in meeting these challenges, whereby energy is stored in a certain state, according to the technology used, and is converted to electrical energy when needed. However, the wide variety of options and complex characteristic matrices make it difficult to appraise a specific EES technology for a particular application. This paper intends to mitigate this problem by providing a comprehensive and clear picture of the state-of-the-art technologies available, and where they would be suited for integration into a power generation and distribution system. The paper starts with an overview of the operation principles, technical and economic performance features and the current research and development of important EES technologies, sorted into six main categories based on the types of energy stored. Following this, a comprehensive comparison and an application potential analysis of the reviewed technologies are presented.

A review of energy storage technologies for wind power applications

Abstract: Due to the stochastic nature of wind, electric power generated by wind turbines is highly erratic and may affect both the power quality and the planning of power systems. Energy Storage Systems (ESSs) may play an important role in wind power applications by controlling wind power plant output and providing ancillary services to the power system and therefore, enabling an increased penetration of wind power in the system. This article deals with the review of several energy storage technologies for wind power applications. The main objectives of the article are the introduction of the operating principles, as well as the presentation of the main characteristics of energy storage technologies suitable for stationary applications, and the definition and discussion of potential ESS applications in wind power, according to an extensive literature review.