Distributed FACTS—A New Concept for Realizing Grid Power Flow Control

Abstract—
Flexible ac Transmission Systems (FACTS) devices are used to control power flow in the transmission grid to relieve congestion and limit loop flows. High cost and reliability concerns have limited the widespread deployment of FACTS solutions. This paper introduces the concept of Distributed FACTS (D-FACTS) as an alternative approach to realizing cost-effective power flow control. By way of example, a distributed series impedance (DSI) and a distributed static series compensator (DSSC) are shown that can be clipped on to an existing power line and can, dynamically and statically, change the impedance of the line so as to control power flow. Details of implementation and system impact are presented in the paper, along with experimental results.

Performances of Fuzzy-Logic-Based Indirect Vector Control for Induction Motor Drive

Abstract—

This paper presents a novel speed control scheme of an induction motor (IM) using fuzzy-logic control. The fuzzy-logic controller (FLC) is based on the indirect vector control. The fuzzy-logic speed controller is employed in the outer loop. The complete vector control scheme of the IM drive incorporating the FLC is experimentally implemented using a digital signal processor board DS-1102 for the laboratory 1-hp squirrel-cage IM. The performances of the proposed FLC-based IM drive are investigated and compared to those obtained from the conventional proportional-integral (PI) controller-based drive both theoretically and experimentally at different dynamic operating conditions such as sudden change in command speed, step change in load, etc. The comparative experimental results show that the FLC is more robust and, hence, found to be a suitable replacement of the conventional PI controller for the high-performance industrial drive applications.

COMPARISON OF TRANSIENT BEHAVIORS OF DFIG WIND TURBINE

 Abstract--

DFIG is the emerging technology for wind turbine and still it is needed to improve the
performance of it during the fault situations. So, in this project my objective is to determine
the transient behaviors of the DFIG wind turbine under different operating conditions and
compare it.
Control circuitry of DFIG consists of two converters. Rotor-side and Grid-side
converters. Here I have designed both the converters and performed the simulation of the
transmission line having faults during different operating conditions like under sub- and
super-synchronous.
The waveforms shown includes the Generated active power, Generated reactive
power, speed of the turbine, pitch angle etc. the waveforms are vary during the different
faults. At the same grid voltage drop, if the initiation generator speed is higher, the active and
reactive power has a larger oscillation. However, in the low speed, the variation time of the
generator speed is larger and the pitch angle of the shaft system is constant. Under fixed
voltage operation strategy, the wind power generation system could help increase the voltage
level of stator terminals by regulating its reactive power output. Therefore, the ability of fault
ride-through and transient stability of the wind farm are improved.
During serious disturbances of the grid, such as a three-phase ground fault, the
power balance between two sides of the DC-Link are destroyed, causing the voltage to
increase rapidly and reach the over-voltage limit in short time, protection schemes are
triggered to protect damage on the wind turbine system. Therefore, taking measures to
limit rotor power output and reduce the power imbalance of the converters under large
disturbances so that the grid-connection is preserved are of importance to increase the
ability of fault ride-through and the global transient stability and dynamic voltage
stability of wind power generation system.

 

Five-Level Inverter for Renewable Power Generation System

Abstract—

In this paper, a five-level inverter is developed and applied for injecting the real power of the renewable power into the grid to reduce the switching power loss, harmonic distortion, and electromagnetic interference caused by the switching operation of power electronic devices. Two dc capacitors, a dual-buck converter, a full-bridge inverter, and a filter configure the five-level inverter. The input of the dual-buck converter is two dc capacitor voltage sources. The dual-buck converter converts two dc capacitor voltage sources to a dc output voltage with three levels and balances these two dc capacitor voltages. The output voltage of the dual-buck converter supplies to the full-bridge inverter. The power electronic switches of the full-bridge inverter are switched in low frequency synchronous with the utility voltage to convert the output voltage of the dual-buck converter to a five-level ac voltage. The output current of the five-level inverter is controlled to generate a sinusoidal current in phase with the utility voltage to inject into the grid. A hardware prototype is developed to verify the performance of the developed renewable power generation system. The experimental results show that the developed renewable power generation system reaches the expected performance.

Design, Analysis and Simulation of Linear Controller of a STATCOM for Reactive Power Compensation on Variation of DC link Voltage

Abstract--

 The STATCOM (STATic synchronous COMpensator) is a shunt connected voltage source converter using self-commutating
device and can be effectively used for reactive power control. Its principle of operation is similar to that of a synchronous condenser. This paper describes the modeling of STATCOM along with the design of linear current and voltage controllers. The design of controllers for the converters can be realized in two ways. The first method is a non-linear realization, which results in simple control rules with faster dynamics. The second method is a linear method, which requires system modeling. The second approach is adopted and simulated waveforms are presented in the paper. The designed controllers with variation of DC link voltage have been applied to the STATCOM and suitable DC link voltage has been selected on basis of spike and over shoot of the responses. All responses are obtained through MATLAB SIMULINK tool box and presented here for clarity of the control strategy.

Analysis and Enhancement of Low-Voltage Ride-Through Capability of Brushless Doubly Fed Induction Generator

Abstract—

This paper discusses the dynamic behavior of the brushless doubly fed induction generator during the grid faults which lead to a decrease in the generator’s terminal voltage. The variation of the fluxes, back EMFs, and currents are analyzed during and after the voltage dip. Furthermore, two alternative approaches are proposed to improve the generator ride-through capability using crowbar and series dynamic resistor circuits. Appropriate values for their resistances are calculated analytically. Finally, the coupled circuit model and the generator’s speed and reactive power controllers are simulated to validate the theoretical results and the effectiveness of the proposed solutions. Moreover, experiments are performed to validate the coupled circuit model used.

A Novel Converter Topology for Stand-Alone Hybrid PV/Wind/Battery Power System using Matlab/Simulink

 Abstract—

The objective of this paper is to propose a multi-input power converter for the hybrid system that interfaces two unidirectional ports for input power sources, a bidirectional port for a storage element, and a port for output load in a unified structure.  The two input ports for simultaneously converting two different input power sources with low voltages to a stable output power with a high voltage.  According to various situations, the operational states of the proposed converter can be divided into three states based on battery utilization .In order to ensure that the system operates with high efficiency, this paper  proposes a power management control scheme, which controls the bidirectional converter operating under boost  mode according to the operation condition of the PV/Wind , so that the battery can be charged or discharged. The integration of the hybrid renewable power system is implemented and simulated using MATLAB/SIMULINK.