Application Of Power Flow Controller Research Articles

Design and Analysis of CPAT for Unified Power Flow Controller Application

Design and Analysis of CPAT for Unified Power Flow Controller Application

Comparison of matrix converter stabilisation techniques based on the damping resistor and digital filter approaches for bidirectional power flow control

The matrix converter is becoming a mature technology with its specific advantages and limitations and can be effectively used as interface link in the future smart grids. In this context, the stability of the converter under different power flow conditions is highly important and needs more clarification. The input inductor-capacitor filter can significantly impact the stability of the converter when the output is tightly regulated, especially in bidirectional power flow control applications where a low-impedance source is connected to the converter output. This study investigates the matrix converter stability for bidirectional power flow control, considering the input filter and other parameters of the system. A detailed analysis of two commonly used active and passive stabilisation techniques known as digital filter and damping resistor approaches is presented, and a combination of these two methods is suggested as a better choice. The converter stability region for the proposed technique is determined by using the small-signal model of the converter. The converter performance for the methods is compared in terms of the efficiency, stability, transients, and quality of the input and output currents. Numerical simulations and experimental tests are conducted on a prototype direct matrix converter to validate the proposed method.

Studies on dynamic responses and impedance of the vanadium redox flow battery

This paper studies the feasibility of using the vanadium redox flow battery (VRB) for power quality control applications. This work investigates the dynamic voltage and current responses of the VRB to load changes over a range of frequencies (up to 5 kHz), through experimental studies on a laboratory scale testing system. Experiments were carried out under different operating conditions to examine the effects of system SOC, discharging current and temperature. The analysis shows that the magnitude of battery impedance is higher at low frequencies but lower at high frequencies. These results suggest that the VRB has the ability to handle charging-discharging power fluctuations in a frequency range up to a kHz level. By using the concept of fractional order systems, the transient behaviour of the VRB cell was modelled as an equivalent circuit that utilises a constant phase element to represent the electrochemical double layer and a Warburg element to describe the effect of concentration polarisation. This equivalent circuit model is useful for electrical interface design and power flow control applications.

Towards composition principles and fractal architectures in the context of smart grids

Abstract The operation of smart grids is based on different energy management and control systems. Despite their variety, all of them offer similar functionalities to achieve a stable, reliable, sustainable and economic supply of energy. Similarity offers advantages for the construction of systems that are not well reflected in current system architectures. This work introduces foundations for specifications and development of fractal architectures that are based on self-similarity. We aim to apply those principles on two smart grid use cases: virtual power plants and optimal power flow control applications.

Magnetic Amplifier-Based Power-Flow Controller

The concept of the magnetic amplifier, a common electromagnetic device in electronic applications in the past, has seldom been used in power systems. The magnetic amplifier-based power-flow controller (MAPFC), an innovative low-cost device that adopts the idea of the magnetic amplifier for power-flow control applications, is introduced in this paper. The uniqueness of MAPFC is in the use of the magnetization of the ferromagnetic core, shared by an ac and a dc winding, as the medium to control the ac winding reactance inserted in series with the transmission line to be controlled. Large power flow in the line can be regulated by the small dc input to the dc winding. A project on the R&D of an MAPFC has been funded by the U.S. Department of Energy (DOE) and conducted by the Oak Ridge National Laboratory (ORNL), the University of Tennessee-Knoxville, and Waukesha Electric Systems, Inc. since early 2012. Findings from the project are presented along with some results obtained in a laboratory environment.

Optimal unified power flow controller application to enhance total transfer capability

For a power transfer path, total transfer capability (TTC) represents maximum power that can be transferred over the transmission system. Unified power flow controller (UPFC) is a device that can be used to increase in TTC. This study presents a new method for optimal UPFC application to minimise power loss while enhancing TTC. Based on UPFC injection model, the solution region of UPFC parameters is first found using the proposed method to maximise TTC. It then searches the solution region to find optimal UPFC control mode and setting to minimise system power loss. The proposed method is applied to the IEEE-Reliability Test System and the UPFC application impact are evaluated. Comparative studies are conducted between the TTC results obtained by the proposed method with those obtained using the existing approaches.

Multiphase Zero-Current Switching Bidirectional Converters and Battery Energy Storage Application

A multiphase quasi-resonant (QR) zero-current switching (ZCS) switched capacitor (SC) bidirectional dc-dc converter structure is proposed to reduce current ripple and switching loss, and significantly increase converter efficiency and power density. This approach provides a more precise output voltage to obtain voltage conversion ratios from the double-mode versus half-mode to <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> -mode versus 1/ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> mode. This is accomplished by adding a different number of switched capacitors and power MOSFET switches with a small series connected resonant inductor for forward and reverse schemes. The size and cost can be reduced when the proposed converter is designed with coupled inductors. Simulation and experimental results demonstrate four-phase with and without coupled inductor interleaved QR ZCS SC converter performance for bidirectional power flow control applications. A battery energy storage system for a bidirectional power flow control application is demonstrated.

Thyristor and Gate-Controlled Series Capacitors: A Comparison of Components Rating

The thyristor-controlled series capacitor (TCSC) is a commercially available flexible AC transmission system (FACTS) device developed for controlled compensation of transmission-line impedance, which consequently leads to the control of transmission-line power flow. The gate-controlled series capacitor (GCSC), a FACTS device based on a pair of gate-commutated switches in parallel with a capacitor, can also control impedance and power flow of transmission lines. Here, it is shown that in many situations where a controllable series compensator must be installed, the GCSC may be used instead of the TCSC, possibly with some advantages. A comparison of the sizing of the TCSC and the GCSC components is presented. It is shown that the capacitor in the GCSC can have lower megavolt-amperes than in the TCSC, especially for power-flow control applications. Also, it is shown that the thyristor valve in the TCSC needs to have a higher current rating than the gate-commutated switch valve in the GCSC.

Modeling and Analysis of Under-Load Tap-Changing Transformer Control Systems

This paper considers the problem of modeling and analysis of under-load tap-changing (ULTC) transformer control systems. A nonlinear system model is derived, suitable for analysis of voltage and reactive power flow control applications of ULTC transformers in the consideration of mid-term and long-term dynamics and steady-state behavior of power systems. The model is verified with the example of a distribution ULTC transformer, used for the voltage control. As an illustration of the feasibility of the model in various voltage and reactive flow control applications, some digital simulation results of such a distribution voltage control are also presented.