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This article presents a new collaborative control method based on expert decision, proposed for the combined system of an ac grid with a low THD thyristorized static var compensator (SVC), interconnected to a dc microgrid through a distribution static compensator (D-STATCOM) that also works as a bidirectional power converter. The combination of large rating SVC and a low rating D-STATCOM functions as a hybrid compensator for the ac distribution grid. In the combined mode of operation, the D-STATCOM mitigates voltage fluctuations and compensates initial var demands, while the SVC caters to the base var requirements. The D-STATCOM has also been used for integration of a dc microgrid to the utility grid, permitting exchange of power between the grids and thereby reducing voltage fluctuations of both the systems. The proposed collaborative control method based on expert decision can extract the full advantages of the respective subsystems as per demand of the operating condition. This combined system complies with the relevant harmonic standards and can effectively correct system power factor, stabilize bus voltage, and mitigate voltage flicker under fluctuating load conditions. Theoretical analyses with simulation results as well as experimental results show that the proposed system can meet the requirement of continuous dynamic reactive power compensation and voltage stabilization with low cost, high reliability, and large capacity. [ABSTRACT FROM AUTHOR]

Addressing power quality issues in shipboard microgrids (SMs), which are mainly attributable to the increased installation of power converters, has received much attention recently. To this end, static VAR compensators, such as thyristor-switched capacitors and fixed capacitors-thyristor controlled reactors (FCs-TCRs), can be effective solutions. Controlling these compensators, however, is not a trivial task as it involves sophisticated operations, especially estimating the firing angle, which should be carried out based on some nonlinear equations. This article aims to propose the application of some simple yet numerically efficient algorithms based on bisection, Newton–Raphson, false position, and secant methods for estimating the firing angle of the FC-TCR. The effectiveness and robustness of these algorithms are demonstrated via modeling of the FC-TCR with the electrical power system of a practical hybrid ferry under MATLAB/Simulink environment, where the results proved that the enhanced power quality issues respect the IEC standards 61000-4-7/30. Furthermore, an experimental setup consists of a digital signal processor and a programmable source is used to demonstrate that these techniques can be effectively applied in real-time applications. [ABSTRACT FROM AUTHOR]

A line-commutated converter-based (LCC) high-voltage direct current (HVdc) transmission system without ac harmonic filters for series-connected wind power plants has been proposed. This type of wind power plant is expected as a next-generation offshore wind power plant due to offshore substation free. In the LCC-HVdc system, power compensators are connected to each receiving-end circuit instead of the conventional ac harmonic filters and static var compensators (SVC). In this article, steady-state characteristics of the system are investigated through theoretical and experimental investigations. A set of steady-state equations for the system is derived first. The steady-state characteristics of the system for changes in wind speed are discussed using experimental setup built in our laboratory, and the validity of the derived equations is confirmed. Also, it is shown that the output active power and reactive power of the system can be controlled independently. Finally, the steady-state characteristics of a practical-scale system are investigated using the steady-state equations. [ABSTRACT FROM AUTHOR]

This article proposes a probabilistic optimal reactive power planning keeping in view the uncertainties in renewable generations (wind and photovoltaic systems), loads, and electric vehicle charging. High voltage direct current based on voltage-sourced converters is an important part in the connection between offshore wind farms and grid. In this article, a probabilistic ac–dc load flow method is used, which includes the connection between the offshore wind farms and grid. For the reactive power planning, capacitor and static Var compensator (SVC) banks have been used. A strategy has been adopted to find the rating of SVCs and capacitor banks. The extensive simulation studies have been performed on a modified IEEE-118 bus system and the results obviates the aptitude of proposed method. [ABSTRACT FROM AUTHOR]

This paper studies the application of distributed and centralized solutions for voltage control in low voltage (LV) grids with high photovoltaic (PV) penetration. In traditional LV grids, the coordination of distributed PV converters and a centralized device would require massive investments in new communication and control infrastructures. The alternative of exploiting distributed PV converters for voltage control is discussed, showing that it can help to stabilize the voltage in the grid connection points also without coordination between them and/or with a centralized unit. The goal of this paper is to investigate how the setup of the voltage controllers inside PV inverters affects the operation of these controllers taking into account the limits for reactive power injection. In addition, the interaction of distributed PV converters with centralized devices (static var compensators and on load tap changers) is analyzed to assess whether additional benefits may come in these cases. [ABSTRACT FROM AUTHOR]

In the same feeder, it will decline the power quality of power supply when the quality is poor at load side, which can cause other equipment malfunction and even damage devices. Therefore, a reactive power compensation method is suggested to improve the power quality of the electric arc furnace in a distribution power system. Both the static var compensator (SVC) and an active filter can modify power factor and balance three phase currents simultaneously. The active filter can solve the problem of instantaneous state of an SVC. Then, an SVC can reduce power quantity of the active filter. Finally, field measurement data in a metal factory were analyzed. Simulation results confirmed the feasibility of correcting the power factor and balancing load currents simultaneously using the proposed method. [ABSTRACT FROM AUTHOR]

This steel maker upgraded the electric arc furnace (EAF) melt shop to increase production and improve the metallurgical quality of their product. The increased electrical load and harmonic generation for the new 50 MVA furnace operation necessitated the installation of an 80 MVAR static VAR compensator (SVC) to meet utility interconnect requirements. This paper is a follow-up and companion to the author's previous paper that documented comprehensive analysis to specify the SVC. This paper describes the sequence of events during the installation, commissioning, and operation of the SVC. It will assess the performance of the SVC compared with the electrical requirements of the utility for voltage regulation, flicker, harmonics, and power factor. Power quality measurements during EAF operation without the SVC established a baseline to compare improvements provided by the SVC as well as compliance with the utility limits. Additionally, events encountered during the commissioning are shared as lessons learned. [ABSTRACT FROM PUBLISHER]

This steel maker is upgrading the electric arc furnace (EAF) melt shop to increase production and improve metallurgical quality of their product. The increased electrical load and harmonic generation for the new furnace operation necessitated the installation of a static var compensator (SVC) to meet utility interconnect requirements. This paper describes a sequence of comprehensive analysis performed to specify the SVC including load flow analysis, flicker analysis, and harmonic analysis studies. The analysis presented in this paper sized and evaluated the proposed SVC reactive compensation to mitigate flicker, harmonics, and power factor for the new EAF and ladle melt furnace installations to comply with the utility interconnect requirements. [ABSTRACT FROM PUBLISHER]

Voltage sag is the most important power quality problem. The classical solution to protect industrial processes against voltage sags is based on the use of a large series voltage compensator (SVC), such as the dynamic voltage restorer. Although the SVCs are a general solution, in most cases alternative measures should be checked before purchasing such an expensive piece of hardware. For instance, some adjustable speed drives (ASDs) have embedded protection functions to mitigate voltage sags. In addition, contactors and power line carriers could be protected by low-power single-phase square-wave SVCs, which have been shown to be cost effective. This paper shows that, using the “ride-through” function of ASDs combined with cost-effective square-wave SVCs, a significant improvement in the ride-through capability of the protected process is achieved. Extensive testing of a low-power ASD panel supports the proposed voltage sag mitigation alternative. [ABSTRACT FROM PUBLISHER]

With a step-out distance of 161 km and a design power of 55 MW, Martin Linge offshore gas field will be the longest ac submarine cable power supplying an entire offshore oil and gas platform from the shore. This field development comprises a platform with a jack-up rig and a floating storage offloading unit. This paper discusses the criteria that have been considered to select a power-from-shore concept instead of an offshore gas turbine power plant, which is the current practice in the offshore oil and gas industry. Since in a first approach, for such a long step-out distance, the choice of power from shore would be to select a dc transmission line, this paper discusses the design and the main technical challenges of this long step-out ac transmission development. Finally, the system approach that is required for the development of the onshore and offshore parts of the project is described. [ABSTRACT FROM PUBLISHER]