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This paper evaluates the effects of voltage fluctuation in a micro grid. The micro grid is modeled and simulated using the DIgSILENT software. The voltage flicker due to the variation of power productions from renewable sources in microgrid during off-grid and grid-connected mode are presented. The results indicate that the main sources of voltage fluctuation in the studied micro grid are PV and wind...
This paper presents the permutation of rate of change of under frequency (ROCOUF) relay to avoid the frequency instability and voltage collapses in microgrid. When some of distributed generators (DGs) in a microgrid are disconnected from the main grid, the system may be imbalance between the power supply and the power demand, resulting in a rapid frequency decline that causes frequency instability...
The dynamic frequency stability issues in microgrids with large penetration of low inertia and intermittent photovoltaic (PV) systems can be improved by using virtual inertia (VI). A VI is the combination of energy storage system, power electronics converter and a proper control algorithm. This paper presents design and experimental verification of the VI in a PV-diesel generator based remote microgrid...
This paper proposes a fault localization, isolation and restoration method for microgrids based on multiagent system (MAS) utilizing a communication network. The agents are located in the middle and the two ends of each section. The fault is detected through phase angle comparison of current signals at both sides of the distribution line and sends the trip signal to circuit breakers. This technique...
The inherent heterogeneity in the uncertainty of variable generations (e.g., wind, solar, tidal and wave-power) in electric grid coupled with the dynamic nature of distributed architecture of sub-systems, and the need for information synchronization has made the problem of resource allocation and monitoring a tremendous challenge for the next-generation smart grid. Unfortunately, the deployment of...
Intermittency of renewable resources represents a major impediment that restricts their integration in microgrids. This paper presents an approach that can contribute to solve this issue by the prediction of near-term future renewable power production, mainly wind power and photovoltaic power, based on weather forecasts. After knowing the future renewable power production, the electric grid manager...
This paper presents the load frequency control in isolated ac microgrid using fuzzy logic table control. The objective of load frequency control is to hold the frequency constant against any load changes. The main task of microgrid is to maintain the voltage level supply to the loads. Any mismatch between the power generations and loads create to the major problem of frequency fluctuation that effected...
The work done in this paper attempts to exploit a Stackelberg game theoretic approach for resilient control of a networked system. A switching control design has been incorporated to modify the system dynamics on occurrence of an attack to enable online recovery. A case of grid forming Voltage Source Inverters (VSI's) is considered and systematic analysis concerning effectiveness of the proposed control...
In this paper, we propose a generation control strategy for islanded lossless microgrids with inverter-interfaced generators. In particular, we address the problem of obtaining a desired active power load sharing while regulating the frequency to some nominal value. The proposed control strategy is based on the slow readjustment of the active power reference of each inverter, i.e., each inverter aims...
This paper studies a practical implementation of a renewable microgrid in a city in the Northwest region of the U.S.A. The microgrid is sourced mainly by the hydro-generation location in midst of the city and future solar installations, which combined could be adequate to run some of the critical loads in the city. This paper will shed light on the possible independent operation of microgrid with...
This paper presents a mathematical formulation for centralized energy management strategy (EMS) of microgrids in both grid connected and isolated modes. The microgrid energy management is formulated as an unit commitment problem with regard to the distribution network and the corresponding constraints leading to a mixed-integer non-linear programming (MINLP) formulation. In order to reduce the computational...
This paper proposes scheduling of induction generators on a DC microgrid system fed by multiple cage-rotor induction generators (CRIGs) to attain regulated voltage with minimal battery support. The capacity of each generator is selected such that next bigger generation unit is double that of previous i.e. the ratio 1∶2∶4∶8‥, which provides easy control of load-generation matching, duly supported by...
This paper studies the market interactions between MicroGrids (MGs) and Aggregators (AGs) from a noncooperative perspective. Specifically, we study a Generalized Nash Equilibrium Problem (GNEP), where players are the MGs and AGs, and aim at maximizing their respective benefits. MGs' actions are the generated energy as well as the traded energy with other MGs, whereas AGs actions are the load scheduling...
This paper investigates cyber-attacks compromising the data integrity of inverter-based islanded microgrids featuring an energy storage system (ESS), a wind turbine generator (WTG), a photovoltaic system (PV) and controllable loads. The ESS operates as the isochronous generator, responsible for forming the microgrid voltage and frequency, whereas the WTG and PV distributed energy resources (DER) operate...
The power flow analysis is one of the important tools of the power management system. The load flow study is essential for proper design and stable operation of power system so as to improve its reliability. The work presents the effect of penetration of a Microgrid into the Main grid. New algorithm is proposed for evaluating optimal penetration ratio of Microgrid. The line losses are minimum at this...
The objective of this paper is to improve the frequency regulation of an islanded microgrid system consisting of non-battery-backed photovoltaic (PV) systems. Operating the PV system in limited power point tracking (LPPT) mode gives provision for the application of droop control on the PV system active power, which in turn enhances the frequency regulation of the microgrid. The LPPT is a control technique...
In this paper, a consensus algorithm based adaptive droop control for DC microgrid is addressed. The optimum energy solution for each convention generator in the microgrid to minimize the system cost is found through a collaborate operation of a droop controller and a consensus algorithm based economic regulator. The proposed control strategy is fully distributed and cooperative such that it eliminate...
This paper presents a new method for operating microgrid. Basic control methodology is to de-couple PQ control for grid-forming distributed generator (DG) whose new extra role is to act as reactive power sensor besides generating real power into the microgrid. Reactive power from the grid-forming DG is transferred to and from the instantaneous var compensator when there is a switch-in or switch-off...
Microgrids are becoming increasingly popular with consumers. In the near future, many microgrids will be installed for consumers with widely varying energy needs. The most challenging of the requirements for these microgrids is finding a suitable protection scheme that is able to protect the microgrid in both grid-connected and islanded modes of operation. The purpose of this paper will be to provide...
This work presents a preliminary analysis considering impact of a grid-connected microgrid on network transmission of the power system. The locational marginal prices of the power system are used to strategically place the microgrid to avoid congestion problems. In addition, a Monte Carlo simulation approach is implemented to confirm that network congestion can be attenuated if appropriate price-based...
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