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This paper presents a new power control strategy of grid-connected converter under grid fault conditions. Positive-and negative-sequence reactive power are controlled separately in order to effectively support unbalanced grid voltage. Both maximum phase current limit and maximum active power oscillation limit are taken into consideration which makes the converter operate safely under grid faults....
Traditional state estimation methods are not well suited for power systems with FACTS devices. A novel approach to state estimation of systems with interphase power controllers (IPC) is proposed. The extension of the conventional model of the system necessitates the use of constraints accounting for limits associated with the IPC operation and ratings. Results of tests on the IEEE 14 bus system using...
Regional reliability organizations require power plants to validate the dynamic models that represent them to ensure that power systems studies are performed to the best representation of the components installed. In the process of validating a wind power plant (WPP), one must be cognizant of the parameter settings of the wind turbine generators (WTGs) and the operational settings of the WPP. Validating...
This paper proposes a novel control method for harmonic power sharing in an islanded microgrid, without employing any control interconnections between the distributed generation (DG) units. The fundamental real and reactive power is shared by implementing conventional P-f and Q-V droop control. A virtual negative output impedance at harmonic frequency is introduced to control the distribution of harmonic...
Increased load demand and penetration levels of renewable energies are imposing great challenges in maintaining the voltage profile of the distribution feeders at high quality. Various solutions such as volt/VAR control and tap changers are employed in the system to regulate the secondary voltage within a typical band of ± 5%. This paper presents a novel device for distribution grid control. The proposed...
This paper presents a novel model predictive sliding mode control (MPSMC) strategy for a three-phase grid connected AC/DC converter. The grid current is predicted for controlling the active and reactive power flows for the next sampling time instead of predicting them directly. This MPSMC scheme employs a sliding mode control (SMC) algorithm to calculate the reference values of active and reactive...
The matrix converter solid state transformer (MC-SST), formed from the back-to-back connection of two three-to-single-phase matrix converters, is studied for use in the interconnection of two ac grids. The matrix converter topology provides a light weight and low volume single-stage bidirectional ac-ac power conversion without the need for a dc link. Thus, the lifetime limitations of dc-bus storage...
This paper proposes a low voltage ride through (LVRT) control strategy for energy storage systems (ESSs). The LVRT control strategies for wind turbine systems and photovoltaic systems have been researched until now. Regardless of the energy source, the main aim of the LVRT control strategies for a grid side converter is to inject the reactive power according to the gird code regulations. The main...
In this paper, a novel reverse zero-sequence current (RZSC) compensation strategy for three-phase four-wire back-to-back active power conditioner (APC) is proposed. The objective of the APC is to achieve the active and reactive power compensation between two micro-grids. However, for the unbalanced voltage sag micro-grid system, the double-line frequency oscillation exists in the output active/reactive...
Controlled Power Converters are extensively used in industrial applications as they can adapt the electrical energy as required by the application. However, these devices must be properly commutated in order to control voltages and currents. Indeed, power converters are known to be multivariable, coupled, and nonlinear systems; therefore, the control technique needs to be chosen carefully. There are...
This paper investigates energy storage configuration strategy for virtual synchronous machine (VSM). The proposed VSM provides virtual inertia and damping to maintain stability of grid. Virtual inertia and damping need to be established by energy storage system (ESS). So that a strategy of energy storage configuration has been investigated through theoretical analysis and simulations in this paper...
This paper presents a novel active synchronization control strategy of multi-bus microgrid based on distributed cooperation technology. The method can reconnect microgrid back to utility grid (UG) seamlessly with sparse communication channels. Through the cross product of voltage vectors in the synchronizer, the frequency and phase of microgrid can track the main grid simultaneously. The voltage differences...
This paper introduces a new method to stabilize synchronous reluctance motors (SynRMs) driven by efficiency optimized V/f control utilizing optimized flux. Efficiency optimized V/f driven SynRMs are prone to instabilities. Specifically, it becomes unstable for either fast ramp acceleration or large load disturbances. For example, in an efficiency optimized V/f control scheme, flux is reduced under...
In conventional droop control, accurate proportional load sharing could not be achieved among parallel operated inverters due to the mismatch of output impedance and system disturbances. In this paper, an uncertainty and disturbance estimator (UDE)-based robust droop control strategy is proposed for accurate proportional load sharing, particularly reactive power sharing, among parallel operated L-inverters...
In this paper, two different Reactive Power Injection (RPI) methods for a fully distributed PV inverter architecture are investigated. RPI methods are parts of ancillary service requirements for modern PV systems to play a more active role in grid regulation and control in future high penetrated PV generation networks. The main objective of this paper is to demonstrate and test RPI methods on a panel-level...
Nowadays, latest advancements in power electronics have devised new ways to optimise power systems by reducing power losses. These developments provide convenience for private power producers to harness renewable energy and allow injection of optimised reactive currents to compensate for the reactive power drawn from the grid. This paper presents the development of an efficient laboratory based system...
Cascaded H-Bridge (CHB) inverter is the most widely used topology for Medium Voltage (MV) drive system due to the high degree of modularity, easier implementation of medium output voltage, and ability to continuous operation under the cell fault condition. Because each power cell of CHB should have isolated DC source, multi-winding input transformer and three phase Active Front-End (AFE) are generally...
This paper proposes a control scheme for the wide operation range of an induction generator (IG) with a Vienna rectifier. A Vienna rectifier has the limited operation range because the sign of the current should be the same as that of the voltage in the normal operation. For this reason, the power factor of a Vienna rectifier is also limited. In the IG, the d-axis stator current is necessary for the...
The microgrid inverter experiences the power oscillations and current harmonics in case of the unbalanced grid voltage faults. However, there is a trade-off between power oscillations and current harmonics should be considered in three phase three wire inverter systems during the conventional fault ride through control. In order to solve this problem, a novel control strategy is proposed to enhance...
This paper proposes a single-phase SEPIC rectifier that works in discontinuous conduction mode (DCM). The proposed rectifier employs a three-stage switch and a voltage-doubler structure. Hence, it works as two half-wave rectifiers with the output voltages series-connected and thus it provides a higher voltage gain. The paper presents the theoretical analysis of the proposed structure and it also discusses...
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