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This paper proposes a novel reactive power control strategy based on virtual flux droop method. Firstly, flux droop control method is derived, where comlicated multiple feedback loops and parameter regulation are avoided. Next, the factors influencing reactive power sharing are theoretically analysed in virtual flux control. Then, a novel reactive power droop controller is designed which consists...
The high line impedance and load fluctuations of weak grid can easily lead to grid voltage fluctuations and other issues. In order to make the grid-connected PV inverter have strong robustness and improve the dynamic response speed, the active power control method of PV inverter based on passive theory is proposed. Firstly, the control strategy of the power outer loop is given, and the Euler-Lagrange...
With the development of microgrid technologies, more and more distributed renewable sources have been connected into microgrids to provide power for loads. The coming problem is how to manage the distributed generations (DGs) that are not within the planning of a microgrid, one feasible solution is to realize the plug-and-play function of DGs. Focusing on this problem, this paper proposes a control...
The grid-voltage unbalance can result in a double-frequency component in the output power of a three-phase grid-connected converter, which significantly degrades the system performance. To address this issue, the power decoupling concept, which was previously developed for the single-phase system to handle the double-frequency power oscillation, is applied to the three-phase system in this paper....
In the present work, we introduce a new control approach, called fuzzy direct power control (F-DPC) method for three-phase PWM AC/DC converters. In this study, the control of the dc-bus voltage is performed by self-tuning fuzzy PI regulator and the selection of PWM converter switching-sequences is based on fuzzy logic rules. These rules directly use the instantaneous active and reactive power errors...
As the penetration level of grid-connected PV systems increases, more advanced control functionality is demanded. In order to ensure smooth and friendly grid integration as well as enable more PV installations, the power generated by PV systems needs to be flexible and capable of: 1) limiting the maximum feed-in power, 2) ensuring a smooth change rate, and 3) providing a power reserve. Besides, such...
Conventional table-based direct power control (DPC) achieves quick dynamic response with very simple structure, which has been widely studied for power control of doubly fed induction generator (DFIG) system. However, DPC presents high steady power ripples and rich current harmonics with variable switching frequency. Furthermore, it would produce highly distorted stator current and power oscillations...
A new direct power control (DPC) strategy for open-winding brushless doubly-fed reluctance generators (BDFRGs) with variable speed constant frequency is proposed. The control winding is open-circuited and fed by dual traditional two-level three phase converters using a common DC bus, and the DPC strategy aiming at maximum power point tracking and common mode voltage elimination is designed. Compared...
This paper focuses on the evaluation of a fully decentralized power control aimed to provide an additional source of flexibility to distribution system operators in order to manage low voltage distribution grids. In particular, the proposed approach provides short term power reserve, current and losses reduction, managing residential power demand by regulating the supplying voltages locally, close...
A multiterminal Energy Interconnection System Based on MMC was developed, which connected active sub-modules, DC grids and AC grids. However, the power imbalance of the active sub-modules exists in this system, for example, inconsistent maximum power points of the PV panels will lead to system power loss. In order to solve the problem, this paper first presents a power control scheme between the three-terminals,...
The Cascaded H Bridge (CHB) is a superior topology to integrate PV panels into the grid. However, due to the internal uncertainty power supply of renewable sources, it is difficult to arrange the PV CHB inverter to meet the system scheduling requirement. To overcome this limitation, a CHB inverter topology with both PV arrays and energy storage elements is proposed in this paper. In order to simplify...
Upcoming construction proposals for utility-scale photovoltaic plants and discussion of compensation in Nigeria raise the question of appropriate grid code requirements to support system voltage control objectives. The large geographical extent, long lines, and small number of generators in the Nigerian High Voltage System make voltage control a critical issue. This paper evaluates the effect of different...
Energy efficiency in high performance computing (HPC) will be critical to limit operating costs and carbon footprints in future supercomputing centers. Energy efficiency of a computation can be improved by reducing time to completion without a substantial increase in power drawn or by reducing power with a little increase in time to completion. We present an Adaptive Core-specific Runtime (ACR) that...
In Grid-Connected PV system should not be limited injecting the active power into the grid. However, it must be able to absorb or to generate sufficient reactive power for a certain amount of time according to the grid demand and maintain the grid voltage. This paper proposes sliding mode control that controls powers respectively the active and the reactive power for a Three-Phase Grid-Connected PV...
The voltage control of distributed generators (DGs) is one of the main challenges the distribution networks are facing due to the remarkable increase of DG penetration in the last years. Regarding the photovoltaic (PV) systems, this issue can be accomplished locally through its inverters active and reactive power control capabilities. Thus, in order to investigate the impact of PV systems on the distribution...
The balancing of sub-module capacitor voltages of modular multi-level converters (MMC) is considered to be an essential process for keeping the quality of the output power at considerable limits. This paper presents a new capacitor voltage estimation technique which feeds the capacitor voltage balancing control. This strategy not only eliminates the need for measuring the sub-module capacitor voltages...
Asymmetric body bias control technique is proposed and evaluated. Compared to the conventional symmetric body bias control, the proposed technique provides finer performance control. Real chip measurements proved the feasibility of leakage reduction when asymmetric body bias is employed. In our measurement, 22.3% of leakage reduction is achieved when compared to the conventional body bias control...
Adoption of Battery Energy Storage Systems (BESSs) for provision of grid services is increasing. This paper investigates the applications of BESS for the grid upgrade deferral and voltage support of Medium Voltage (MV) distribution systems. A BESS is modelled in Matlab/Simulink to perform peak load shaving and voltage support service from the perspective of Distribution System Operators (DSOs). An...
For the open-winding brushless doubly-fed generator (BDFG) with the dual two-level voltage source converter fed from a single DC power supply, this paper proposes a common mode voltage (CMV) elimination method, and combines with the direct power control (DPC) to implement the power tracking of the wind power generation system. The proposed control method are proved to be rational and feasible by simulation.
Automatic coupling of 3 phase synchronous alternators to infinite bus AC grid has been discussed and studied, analytically and practically as a case study, to deepen concept of distributed alternators control. The paper introduces an experimental setup for alternator synchronization with active and reactive power control scheme, as a laboratory guide to be followed by engineers in real power stations...
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