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In parallel with the technological advances, the electrical power demand is constantly increasing and this makes the voltage stability difficult for the electrical power systems. At this point, FACTS (Flexible AC Transmission System) devices come into prominence in order to provide the voltage stability and increase the power transfer capacity. In this study, the most critical buses are determined...
In this paper a 27-Level Asymmetric Multilevel STATic COMpensator is presented aimed to compensate reactive power. The STATCOM is controlled with a master-slave approach, where the master loop is responsible to regulate the DC voltage using a Proportional-Integral controller, while the inner loop is in charge to track the reference currents through a Proportional-Resonant control block. The presented...
This paper presents an analytical model to provide a rapid estimation of the steady-state averaged power loss of a T-type STATCOM with Virtual Zero level Modulation (VZM) to balance the neutral point voltage. A case study is then conducted on a 54kVA rated T-type STATCOM system to investigate the power loss distribution over power devices and variations over switching frequency. A comparison is made...
Electrical resonance with the grid is an increasingly common problem for wind turbines and PV inverters, especially those connected to a weak grid. Such resonance problems can usually be solved by modifying turbine or PV inverter control to reshape its output impedance. There are, however, situations where this may not be effective or not feasible at all due to e.g. limitations in turbine design or...
Static Synchronous Compensators (STATCOMs) are being applied for offshore wind power plants to satisfy the grid codes under both normal operation and grid fault conditions. This paper investigates the performances of Modular Multilevel Cascade Converters (MMCC) for the STATCOM application, with special focus is on asymmetrical Low-Voltage-Ride-Through (LVRT) operation under grid faults. The design...
Small-signal models of impedances for grid-tied converters have recently attracting researchers' attention and shown of great importance in stability analysis. This paper proposes the impedance model in d-q frame for STATCOMs, including dynamics from synchronization, current and voltage loops and reveals the significant features compared to other types of grid-tied converters that the 1) grid impedance...
In small-signal stability studies, various stability criteria have been proposed based on impedance or admittance norms to assess the stability of power systems. Controlling these norms can drag a system from a stable to an unstable operating condition. Therefore, finding a control variable that has a direct linear relation with these norms will facilitate the utilisation of data-driven control principles...
In this paper reactive power compensation using an infinite level inverter based STATCOM is proposed. Nowadays, the society is becoming increasingly dependent on the electrical supply. New equipment's are more sensitive to power quality variations. This causes the transmission line to transfer equal or sometimes more than its capacity, which leads to overloading, voltage fluctuations etc. in the system...
Impedance-based stability criterion has been proven to be a powerful tool for small-signal stability analysis and design, derived from Nyquist stability criterion and first developed in dc-dc power electronics converter systems. Recently it has been extended to ac systems to address the issues and challenges coming with more and more power electronics based converters connected to the existing ac...
Electric Arc Furnaces have very fast changing current, rich in harmonic components, especially in the early stages of the melting process. This is why power factor correction of arc furnaces is a demanding task, involving complex power electronic devices with active control like STATCOMs, etc. In this paper, a mixed approach is described, where power factor correction of arc furnace is accomplished...
In order to obtain an effective control range analysis method of different capacitor voltage balancing control strategies, this paper proposes a control range analysis method based on virtual loss difference resistance model. In this paper, the virtual loss difference resistance model is established on the submodules of cascaded converters. The control ranges of several conventional capacitor voltage...
Because of the wind speed change, the weak magnetic of turbine and the hysteresis of the converter, wind turbines may cause voltage fluctuation, voltage drop and other instabilities on PCC(point of common coupling). An eliminating technology is urgently to be developed. Feed forward decoupling method will be used in this paper to design the controlling system with a current inner-loop and a voltage...
In this paper, a new DC ice-melting scheme based on hybrid modular multilevel converter (MMC) is proposed considering the problems of existing DC ice-melting device, such as high harmonic content, complicated mode switching operation, large size and so on. In the scheme, a novel structure of MMC is composed of the upper bridge arm all using full bridge sub-module (FBSM) and the lower bridge arm all...
The three-phase short circuit fault in power system is a common problem, and the fault in the power grid will cause huge economic losses. Aiming at the three-phase short-circuit fault which in the power grid, a complete indirect control strategy of current is designed. Firstly, the principle and characteristics of (STATCOM) Static Synchronous Compensator of voltage bridge circuit are analyzed, and...
Quality and quantity of the power being transmitted is an important datum to utilize the full potential of the existing transmission line networks. This paper presents a STATCOM having transformerless Cascaded Multilevel Inverter(CMI) with level shifted modified Space Vector Pulse Width Modulation(SVPWM) technique that provides both reactive power compensation and harmonic reduction. Synchronous Reference...
Performance analysis of STATCOM is presented for 400kV Indian grid level application. The paper contains the investigation based on simulation carried out in PSS/E software. The principles of STATCOM operation along with basic concepts of power system voltage stability are addressed. PV/QV analysis shows the impact of STATCOM on steady state or small disturbance voltage stability. Large disturbance...
A Modular multilevel converter (MMC) based new generation (NG) STATCOM for the improved power transfer capability and enhancement of power system stability have been presented. The MMC comes with a scalable technology which increases the voltage and power capacity. We calculate the mathematical equation for MMC, power flow result for an uncompensated system and NG-STATCOM based on MMC with a different...
A new fuzzy control approach of STATCOM has been designed according to micro-genetic algorithm in this paper. Initial membership functions and control rules of FLC were fast obtained by fuzzy toolbox of MATLAB and selecting input and output observed signals, membership functions and control rules are optimized simultaneously by micro-GA. Simulation experiments for four machines power system with STATCOM...
A nonlinear controller is presented in this paper. Replacing STATCOM controller in wind farm which is equipped with DFIG using input-output feedback linearization controller, the needed reactive power is considered when error is occurred. The results show that with the proposed controller, STATCOM has done its duty well and the network bus voltage and reactive power to sustain the wind farm equipped...
In this paper the fundamental and advanced developments in shunt FACTS devices for modeling and control are reviewed. The voltage along a transmission can be controlled using shunt-connected FACTS controllers. More than sixty research publications have been classified and appended for a quick reference.
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