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MTDC systems need to provide a high level of reliability as well as efficient support to the interconnected AC grids. This can be achieved by equipping each converter with a dual controller combining both the voltage-droop and the frequency-droop control techniques. In this article, the theory behind the coupling between the two droops is investigated and an electromagnetic transient study of a 5-terminal...
In this paper, a high gain single-stage buck-boost grid-connected system is proposed. The proposed system consists of a high voltage gain - high efficiency - switched inductor buck-boost converter (SIBBC) and a folded cascade H-bridge inverter. The proposed converter switch is derived with a sinusoidal modulation, so that the converter output voltage is a rectified sine wave which requires only a...
In this paper, some of the aspects related to the design and implementation of grid connected DC microgrids are investigated. A prototype system has been designed and implemented to address these aspects. The described system is dependent mainly on sustainable energy sources. Hence, a special care has been given to dealing with these kinds of sources while designing different components of the system...
The micro grid is an integrated form of distributed energy resources. The interconnection of small modular generation technologies at the medium voltage (MV) and low voltage (LV) distribution levels may affect the power system performance. This type of the networks will use the best combination of control and modeling technologies to meet the specific capacity, quality and reliability. For the MG...
This paper presents a grid-connected PV system where the PV source is replaced by a real time emulator. The PV emulator is based on a DC/DC converter controlled by the pole placement technique according to PV current-voltage characteristics. These characteristics are obtained by an analytical model whose parameters are identified on the basis of an actual PV installation. In the proposed plant the...
Stand-alone photovoltaic (SAPV) system is more favourable than grid connected photovoltaic (PV) system in areas where extension of power grid is impracticable. However, the high set up cost of a SAPV system requires cost efficient solar energy harvesting methods. To improve the energy harvesting efficiency of a PV system, a large, centrally controlled PV array can be rearranged into smaller PV modules...
This paper proposes three phase grid connected anti-islanding controller based on distributed generation interconnection. This method is a combination of two detection methods namely active and passive. Firstly, Active islanding detection generates disturbances at the output of the distributed generation by use of Positive feedback and Continuous feedback signal injection which is based on DQ implementation...
In order to ensure that UHV AC Pilot Project can go into operation successfully and operate safely, the voltage and reactive power characteristic of UHV AC pilot project has been analyzed in this paper. Then it has been studied, that the cooperation of voltage and reactive power together with concrete scheme and the principle of operation and control in interconnected power grid with UHV AC project...
Based on the synthetic control of microgrid, a flexible power electronics interface is developed in this paper. Considering distributed generation types and storage devices, different control strategies are adopted in controller design for different distributed generation units. The interface comprises a couple of back-to-back VSC converters, and exports variable active power and reactive power in...
After the synchronous interconnection of Turkish Power System to ENTSO-E CESA (former UCTE) System, inter-area oscillations in the range of 0.15 Hz are prone to occur, according to simulation studies. Therefore, some preventive measures should be considered in order to ensure stable operation of the network after the interconnection. This study summarizes the effects of following measures based on...
Grid-connected photovoltaic (PV) generation attracts increasing attention in countries around the world and it has been extensively studied during last ten years. In the literature, the control system for PV systems has been designed to respond extremely fast to changed weather condition, and the whole regulating duration is generally within tens of milliseconds. As PV installation is moving towards...
This paper discusses the dynamic voltage restorer (DVR) supported wind power generator connected to the grid to improve the low voltage ride through (LVRT) capability of the grid. The wind power generators are connected to the grid through a feeder to the distribution system and the DVR is connected to the point of common coupling (PCC), where loads are connected. The main aim of the DVR is to regulate...
This paper presents design and implementation of a 5 kW 1 φ bi-directional inverter with wide inductance variation. The bi-directional inverter can fulfill grid connection and power factor correction, in which inductor current can vary from 0 to 32A in one line cycle. This will result in wide inductance variation, around 7 times for an inductor constructed with an MPP core, and thus high current ripple...
Distributed power generation systems (DPGS) such as wind and solar become more and more widely spread. As a consequence grid operating companies demand system services. As part of the general fault ride through (FRT) requirements this paper deals with low voltage ride through (LVRT) capability of a three-phase-four-wire grid-tied solar inverter. The standard system will be described and necessary...
In the future, distributed generation (DG) needs to be enabled to actively participate in control of grid voltage and frequency. An efficient grid integration strategy is required to interconnect the DG to conventional power systems and to improve the power quality and reliability (PQR) as well. The main task of the interconnected system is to control and maintain frequency and voltage of the power...
A comparative review is presented for integrated PEM Fuel Cell and Photovoltaic generating system to single phase utility grid. Different techniques of common coupling for integration have been investigated for this system. For both common AC bus and Common DC bus integration schemes, two different current control techniques have been investigated. The simulation result shows that common DC bus integration...
In recent years there have been many strategies have been proposed for use of proportional plus resonant P-R controllers both in the stationary and in the synchronous reference frame that demonstrate grid-connected converter performance can be improved under non-ideal supply conditions such as supply asymmetry and supply voltage distortion. However, when employed in systems with high frequency variability...
Accurate and fast detection for phase angle of the generated voltage is important in parallel grid- connected wind energy conversion systems (WECSs) utilizing converter-inverter unites. Software Phase Locked Loop (SPLL) technique is presented here for precisely detecting the phase angle during presence of the 5th and 7th harmonics. A second-order loop filter design is proposed here as a good trade-off...
This paper presents an intelligent fuzzy method for maximum power point tracking (MPPT) of a single grid-connected photovoltaic system. The fuzzy inference system can easily synthesize the algorithm to perform MPPT. The MPPT fuzzy method is improved by weighting the control action by the short-circuit current. Hence, it is proposed an estimator of the short-circuit current based on a Takagi-Sugeno...
In this paper, a new type of controller is proposed for series connected PV inverter for grid voltage compensation. The inverter operates during the day time as an active power compensator as well as load voltage regulator under grid voltage sag, swell or even under normal condition. The compensating voltage provided by the inverter is added vectorially in series with the grid voltage in such a way...
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