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This paper further describes our work presented in Industry Application Society 2016 Conference, with more details related to the control and operation of the microgrid. The DC microgrid facility was custom designed and implemented at CCNY with minimal off-the-shelf components to enable flexibility and reconfiguration capability. The design steps, requirements, and experimental results of the developed...
By intensifying renewable energy sources integration to the power grid and forming the microgrids (MGs) concept, many studies have been done to investigate MGs operation, control, protection, and etc. The performance of loads can play a major role in the MG behavior. Different load models can be implemented in MGs. The voltage and frequency (VF) dependent load is a substantial load model which few...
Electricity in rural area of Indonesia is mostly in small-scale with diesel generator as the main power source. These diesel generators are mostly in the latter stage of operational age, thus have limited capability and poor performance. Microgrid has been introduced lately, as a system to integrate more renewable energy sources to the existing power system. Photovoltaic (PV) source is one of the...
The voltage source inverters operating in islanded microgrid are used as sources of power similar to synchronous generators (SG) in conventional power system. Unlike synchronous generators, these inverters neither have a natural droop (P-f and Q-V) characteristics nor rotational inertia. The electrical time constant is much lesser than mechanical time constant and hence the load changes will show...
A hybrid impedance model of Islanded MicroGrid with Paralleled Inverters Controlled by Droop and PQ Strategies (IMG-PICDPS) is derived, in which the PQ-controlled Inverters (PQ-Invs) are equivalent to Norton's circuits, while the DRoop-controlled Inverters (DR-Inv) to Thevenin's circuits in this paper. An impedance-based stability analysis method is further proposed according to the Nyquist criterion...
This paper highlights the power limited nature of the Distributed Generation inverter and demonstrates the practical way to integrate them into the microgrid. Since the energy source of Distributed Generation inverters is power limited in nature, they constrain the operation of inverters to which they are coupled. If the power demanded from these inverters is beyond their capability, their DC-link...
This paper proposes a new control method for two stage converters to realize the virtual synchronous generator (VSG) operation, which also can help eliminate circulating power between energy storage (ES) converters. It is proven in this paper that the proposed method shares stronger resemblances with synchronous generators (SGs) than traditional VSG in aspects of power conversion process and mathematical...
Power quality of ac bus voltage is a key issue for microgrids. A model-predictive-control (MPC)-based distributed bus voltage compensation methods using inverter-interfaced distributed generators (DGs) connected to the concerned bus is proposed. The presented method can compensate bus voltage unbalance and harmonics and share the compensated current between inverters autonomously, with neither communication...
To address the DC link voltage regeneration issue in parallel Uninterruptible Power Supply (UPS) system, a DC link voltage protection (DCVP) method through online virtual resistance regulation is proposed. The proposed control strategy is able to protect the DC link from overvoltage that may trigger the protection mechanism of the UPS system. Moreover, a current sharing control strategy by regulating...
In order to address the economical dispatch problem in cascaded microgrids, this digest proposes an optimal economical-sharing scheme via decentralized approach only with the local information. This overcomes the limitations of centralized control, where the central controller and external information exchange are needed. The frequency and current are used as carriers driven the distributed generators...
Chaotic nature of renewable energy sources connected with nonlinear loads may cause serious problems to the utility grid, e.g. voltage and frequency disturbances, harmonic pollution. Due to that, many European governments have set strict regulations to the grid energy injection. As a result, the power quality has become one of the major obstacles for nearly zero energy buildings to be connected with...
Fault current limiters (FCLs) are one class of solutions to cope with the upcoming challenges in microgrid protection. Considering high penetration of distributed generations (DGs) in microgrids, the necessity of designing cheap and effective FCL is getting higher. This paper attempts to fill this gap by proposing an embedded FCL operating based on modifying the secondary control of DGs. As this method...
This paper presents a comprehensive overview of power converters and their control techniques for AC microgrids. The aim is to give an insight and direction for researchers and applications on promising topologies, control, and application within future smart grid. The paper first focuses on presenting various power converter topologies used in AC microgrids. Then, suitable control techniques for...
In this paper, the relationship between real and reactive power sharing in islanded microgrid considering the complex impedance effect is analyzed. It is determined that traditional droop control has drawbacks in achieving accurate power sharing caused by the mismatched feeder line effect. In order to enhance the power sharing accuracy, an adaptive droop control using virtual impedance for islanded...
The paper presents an overview about operation and control of the inverter-interface generation units (IGUs) when connected to a microgrid either alone or together with other generation units. The following key connection paradigms are considered: i) one IGU and a grid, ii) one IGU and one machine-interface generation unit, iii) a single IGU, and iv) two IGUs. After illustrating how the IGUs operate...
Microgrids with a high share of renewables may become the keystone of the new energy transition. With the present inverters interfacing the various DERs (Distributed Energy Resources) to microgrids, the stability of such power systems is threatened if the share of renewables increases. In this paper a robust solution to solve this problem is presented. The proposed solution is based on the concept...
The microgrid with distributed PV and air source heat pump is studied, aim at the problem of controller saturation caused by the lag of the static switch and the mismatch between the operation mode and the control method, droop control is used in island mode and grid-connected mode, an improved pre-synchronization control algorithm is proposed to ensure the smooth transition of the microgrid transient...
In this work is present the comparison of two methods of controllers design and the model of a single phase inverter for island mode operation in a microgrid. These methods are: direct current conventional method based on frequency analysis that allows the design of a proportional-integral controller and a second method based on dc-ac coordinate transformation, that allows the design of a proportional...
Cascaded H-bridge converters based islanded microgrids are applied to integrate the distributed generators (DGs). The accurate load sharing is an important task for the research of microgrids. Due to the characteristics of series connection, all DGs share a single common current. In this paper, the power factor of each DG is assigned to be consistent via regulating both the frequency and voltage....
Nonlinear loads connected to the microgrid distort the voltage of the Point of Common Coupling (PCC) and the grid current. Therefore, A droop control based harmonic voltage compensation strategy of voltage controlled inverter in islanded/grid-connected mode is proposed in this paper. To compensate the PCC voltage distortion, fundamental and harmonic voltage components are controlled separately in...
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