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Dynamic voltage restorer (DVR) is a custom power device suitable for solving voltage related power quality (PQ) problems including voltage sags and voltage swells. This paper compares four topologies for three-phase DVRs. Also, a three-phase DVR using push-pull inverters is proposed. The inverter of each phase in the proposed DVR operates and is controlled independently so that the unbalanced voltage...
The objective of this paper is to propose an improvement of transient response for islanding control of microgrid. The proposed bidirectional inverter is able to offer active and reactive power from battery during the microgrid voltage sag. After the microgrid voltage returns to its normal condition, the inverter can quickly provide the reactive power to microgrid system. Also, the reactive power...
This paper brings the PV model of a real PV farm installation with a total power of 917 kW. All the elements of the PV farm (panels and inverter) are described. Simulation on PSCAD and experimental results at the installation are reported. The PV model is submitted to voltage sags originated in the grid as well as their impact on the photovoltaic power plant.
Aiming a cost reduction, this paper presents an eight-switch power conditioner for current harmonic compensation and voltage sag mitigation derived from the nine-switch converter. The nine-switch converter has some restrictions in the total attainable amplitude at its outputs, depending on the phase shift between its two terminal sets. However, with an appropriately designed control scheme, the nine-switch...
This paper presents Dynamic Voltage Restorer (DVR) based on bidirectiona l full-bridge dc-dc converter to compensate severe voltage sag/swell problems in medium voltage system. Voltage swell causes the continuous rise at dc-link voltage of DVR which may damage the dc-link capacitors and solid-state devices, and increase the power losses. Unidirectional dc-dc converters based DVRs do not allow power...
This work presents a nonlinear control of a wind generator equipped with a Permanent Magnet Synchronous Generator (PMSG). Three SISO controllers are developed, a Passivity based controller for the PMSG and its converter, and two Lyapunov controllers for the DC link and for the grid side converter, respectively. A general Control Strategy is presented in order to pass severe faults as symmetrical grid...
This paper proposes a simplified PWM strategy for fault tolerant control of an open winding permanent magnet synchronous motor (OW-PMSM) fed by hybrid inverter (HI). The HI usually consists of two six-switch three-phase inverters (SSTPIs), the inverter powered by a DC source is named as main inverter (MI) and the inverter powered by a capacitor is named as compensation inverter (CI). When a power...
This paper describes the situation of a modern electric drive (induction machine supplied from indirect frequency converter with voltage source inverter) in industry (paper mills, etc.), where a voltage sag can bring significant problems with long-time interruption of the production process. One method of operation is a direct increase of voltage in the DC-link of a frequency converter with a step-up...
Fully converter wind turbines and solar power utilise an inverter to connect to grid. The inverters are vulnerable to voltage sag in their terminal due to its damaging effect on semiconductor self-turnoff switches. In this paper, a bridge-type fault current limiter (B-FCL) is proposed for low voltage ride-through (LVRT) of the inverters during different types of fault with simple control system. The...
In this paper, application of a cascaded H-bridge (CHB) converter to connect strings of solar panels to a single-phase medium voltage AC grid is discussed. With solar insolation levels differing from one string to another, it is challenging to control a CHB converter in order to minimize the variations in the dc link voltages of each of the converter modules and hence the device voltage stress levels...
This paper investigates the impact of grid disturbances on the electric vehicle (EV) batteries in the grid-to-vehicle (G2V)/vehicle-to-grid (V2G) mode and the vehicle-to-home (V2H) mode. An 8 kW bi-directional EV charger system is designed and simulated. Based on the developed EV charger system, the different practical cases of voltage sag, voltage unbalance and local load variation are tested and...
Sags are the foremost power quality problem encountered by industrial consumers since they frequently causes the interruption of manufacturing processes that can result in significant economic loss. To resolve such problems, a voltage sag compensator is often installed by industrial consumers within critical industrial applications. However, the operation of the compensator takes a few milliseconds...
The future custom power park will realize the hierarchical power supply of different voltage quality grade, meanwhile and present the grid-friendly characteristics including low pollution for grid, organic combination with distributed generation (DG) and energy storage (ES). In order to gradually achieve the goals, the function reuse and integration in the equipment level should be solved firstly...
In general, residential solar inverters can operate in either island or grid-tied mode. In grid-tied mode, the inverter can be operated based on either voltage control or current control. In this paper, a grid-connected current controlled inverter is presented. A stationary frame nonideal proportional resonant (PR) controller, in lieu of a conventional PI based controller, is applied to the outer...
Increased penetration levels of Distributed Generation (DG) can cause steady state and transient voltage issues and possible overloading conditions. This paper aims to verify the overvoltage and overloading issues caused by DG at high penetration levels. A typical utility distribution feeder was selected using cluster analysis for simulations. DG at various penetration levels was interconnected at...
Dc microgrids including grid-tied inverter, energy storage system, and distributed generations have the advantage of high efficiency as compared to the ac system. Droop control has been realized to suppress the current mismatching among distributed sources. However, the conventional droop control involves distribution loss due to the line impedance. In this paper, a novel droop control is proposed...
A DC-link voltage compensation method for a photovoltaic (PV) generation system with energy storage system(ESS) is presented. When PV power is oscillated, the DC-link voltage is also influenced. And this fluctuation of DC-link critically affects the load voltage when the ESS is operated in stand alone mode. In conventional method, huge capacitor bank is necessary to reduce the fluctuation. In this...
In this paper, a smart distribution transformer which addresses power quality issues in the electrical power distribution system is presented. The proposed system is comprised of a line frequency transformer connected to a power electronic converter that is ‘auto-connected’ on the secondary side. The auto-connection is facilitated by the use of a high-frequency (HF) / medium frequency (MF) transformer...
Increasing penetration of PV sources in LV grids is introducing new challenges to the quality of voltage. Variability of solar radiation can cause power ramps of up to the nominal power of the plant in one second, which directly induces voltage fluctuations on distribution feeders. To mitigate this impact on power quality, we investigate the introduction of dc micro-grids interfaced to the ac grid...
In recent years the grid connected photovoltaic (PV) micro-generation facilities in individual homes has increased due to the adopted governmental policies and the industry attention. The power feed-in of PV generation in rural low-voltage grid can influence the power quality and the facility operation and reliability. This paper presents the results of a power quality analysis of a real PV generation...
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