We consider the problem of stability analysis for droop–controlled inverter–based microgrids with meshed topologies. The inverter models include variable frequencies as well as voltage amplitudes. Conditions on the tuning gains and setpoints for frequency and voltage stability, together with desired active power sharing, are derived in the paper. First, we prove that for all practical choices o...

electronic copies of this thesis document in whole and in part in any medium now known or hereafter created. ABSTRACT Over the last decade, penetration of microgrids containing distributed generation (DG) sources has increased in grid distribution systems. This requires the stable operation of microgrids when connected to the distribution system as well as during islanding. Islanding that is fa...

The stability is an important topic to plan and manage the energy in the microgrids as the same as the conventional power systems. The voltage and frequency stability is one of the most important issues recently studied in microgrids. The objectives of this paper are the modelling and designing of the components and optimal controllers for the voltage and frequency control of the AC/DC hybrid m...

Microgrids are an increasingly popular class of electrical systems that facilitate the integration of renewable distributed generation units. Their analysis and controller design requires the development of advanced (typically model-based) techniques naturally posing an interesting challenge to the control community. Although there are widely accepted reduced order models to describe the dynami...

The concept of "Microgrid" is one of the most promising architectures expected to support the transition from present to future Electricity Grids by integrating large amounts of Renewable Energy Sources. The numerous benefits of microgrids have attracted attention and during the last decade several projects and researches have focused on this field. Within different European projects the pilot ...

Microgrids are nowadays used to produce electric energy with more efficiency and advantage. However, the use of microgrids presents some challenges. One of the main problems of the microgrids widely used in electrical power systems is the control of voltage, frequency and load sharing balance among inverter- based distributed generators (DGs) in islanded mode. Droop method performance degra...

Microgrids are small scale power systems with local resources for generation; consumption and storage, that can operate connected to the main grid or islanded. For the islanding operation of microgrids, two important tasks are to share the load demand and maintain the voltage and frequency stabilities. In order to achieve this goal, a hierarchical control structure can be employed. This researc...

This paper presents a mathematical model of frequency control in isolated microgrids, which is integrated into the Unit Commitment (UC) problem. In conventional UC formulations, power outputs are considered fixed between two periods, yielding a staircase pattern with respect to the energy balance of the generation and demand for a typical dispatch time horizon (e.g., 24 h). However, in practice...

Microgrids can bring electricity power to rural communities or isolated military forward operation bases. For many rural areas, renewable powers could be the cheapest power sources available. Utilizing renewable power sources and energy storage systems such as batteries requires new power and voltage control strategies. In addition, these microgrids may be reconfigured frequently. Therefore, th...

This paper discusses the control of flexible microgrids, consisting of a Redox Flow Batteries (RFB) and a new power conditioning system (PCS) for the RFB. Considering the importance of energy storage, this study is essential in power systems that are developed cautiously. RFB is connected to power system by a DC/DC or DC/AC converter to produce a DC voltage. It is very important that this conve...