Omid Palizban

Microgrid control principles in island mode operation

Microgrids are small power systems capable of island and grid modes of operation. They are based on multiple renewable energy sources that produce electricity. Managing their power balance and stability is a challenging task since they depend on quite a number of variables. This paper reviews microgrid control principles according to the IEC/ISO 62264 standard along with an example system where electricity is supplied by two renewable energy devices including a PV panel, a Doubly-Fed Induction Generator (DFIG) wind turbine and battery storage. The storage system provides the integral system backup and the storage of surplus energy from renewable sources. System simulation is made with PSCAD/EMTDC software.

Secondary control in AC microgrids challenges and solutions

The hierarchical control structure of a microgrid can be described as consisting of four levels: processing, sensing and adjusting, monitoring and supervising, and maintenance and optimizing. This paper focuses on the secondary control level, which can be classified as centralized or decentralized control. A comprehensive investigation of both centralized and decentralized control is presented in this paper. Decentralized control is proposed in order to deal with some of the disadvantages of central control, such as the high risk of unplanned interruption arising from a Microgrid Central Controller (MGCC) malfunction. However, decentralized control is not yet complete, and some challenges to its implementation remain. This paper also looks at these challenges and proposes some solutions that may help to improve the performance of decentralized control and overcome its disadvantages. Finally, a general methodology of microgrid control is modeled.

Finite control set model predictive control-a powerful control algorithm for grid-connected power converters

This paper presents a detailed description of Finite Control Set Model Predictive Control applied to power converters. Some key features related to this methodology are presented and compared with model predictive control based space vector modulation methods. The basic models, principles, control diagrams, and simulation results are presented to provide a comparison between them. The analysis is performed on a three-phase/ two-level voltage source inverter, which is one of the most common converter topologies used in industry. Among the conclusions are the feasibility and great potential of Finite Control Set Model Predictive Control due to the advanced signal-processing capability, particularly for power systems with a reduced number of switching states and more complicated principles.

Power sharing for distributed energy storage systems in AC microgrid: Based on state-of-charge

The approach to optimal control for distributed energy storage systems has been an issue of interest in recent years. In this regard, the performance of power sharing between Energy Storage Units (ESUs) with different States of Charge (SoC) can be enhanced. In this paper, the SoC of each ESU is balanced using the proposed control method, which is decentralized and based on the adaptive droop control method. The droop coefficient should be adjusted in the system on the basis of the SoC of each ESU. With this control strategy, the storage unit with higher SoC provides more power to support the load, while the unit with lower SoC provides the less power. The method is validated using simulation results from PSCAD/EMTDC software.

Designing and analysis of innovative solutions for harbour area smart grid

Nowadays, different vessel types are mostly operating on diesel generators employing cheap quality fuel, thus causing many types of air pollutions during a stay at the harbour. Thus, electrification by renewable energy based Distributed Generation (DG) and Battery Energy Storage (BES) onboard as well as on shore side are inevitably the best solution to get pollution free energy. In this regard, this paper proposes an innovative design concept of the Harbour Area Smart Grid (HASG) in such a way that it can not only supply the vessels for cold ironing purpose but also supports the hybrid vessels of future technology. The designed HASG is modelled in PSCAD/EMTDC and the simulation case studies have been carried out to validate the performance of the HASG under steady state and transient state.

Evaluation of the hierarchical control of distributed Energy Storage Systems in islanded Microgrids based on Std IEC/ISO 62264

In this paper, a decentralized control methodology based on hierarchical control levels is investigated. In recent years, efforts have been made to develop standards for Microgrids (MGs), and the decentralized control method evaluated here is based on the IEC/ISO 62264 standard. Since the main challenge to decentralized control in Battery Energy Storage Systems (BESSs) is the different levels of stored energy, a modified droop control is used here to share the power between the different storage units, based on the energy level of each unit. The power coefficients of the droop control are set inversely proportionally and directly proportionally, respectively, to the state of charge (SoC) of each battery unit during discharging and charging mode. To evaluate this decentralized method based on the IEC/ISO 62264 standard, PSCAD/EMTDC software is used.