Output power levelling for DFIG wind turbine system using intelligent pitch angle control

Blade pitch angle control, as an indispensable part of wind turbine, plays a part in getting the desired power. In this regard, several pitch angle control methods have been proposed in order to limit aerodynamic power gained from the wind turbine system (WTS) in the high-windspeed regions. In this paper, intelligent control methods are applied to control the blade pitch angle of doubly-fed induction generator (DFIG) WTS. Conventional fuzzy logic and neuro-fuzzyparticle swarm optimization controllers are used to get the appropriate wind power, where fuzzy inference system is based on fuzzy c-means clustering algorithm. It reduces the extra repetitive rules in fuzzy structure which in turn would reduce the complexity in neuro-fuzzy network with maximizing efficiently. In comparing the controllers at any given wind speed, adaptive neuro-fuzzy inference systems controller involving both mechanical power and rotor speed revealed better performance to maintain the aerodynamic power and rotor speed at the rated value. The effectiveness of the proposed method is verified by simulation results for a 9 MW DFIG WTS

A floating-output interleaved boost DC–DC converter with high step-up gain

A new interleaved boost converter with high step-up gain is presented in this paper. The proposed topology integrates coupled inductors and floating-output capacitors technique into interleaved boost converter to provide high step-up voltage gain without extreme duty cycle. The voltage stress on the power switches and diodes is very low, so low-cost and highperformance semiconductor devices can be employed. Also, the reverse recovery problem of all diodes is mitigated and zero-current-switching (ZCS) turn-on operation of the main switches is established as well. In addition, the passive clamp circuits are employed to suppress the voltage spikes across the main switches during turn-off instants. The operating principles and steady-state analysis of the proposed converter in continuous condition mode are explained. Finally, the simulation and experimental results of prototype 25–400 V circuit with 200 W output power are provided to verify the performance of presented topology

Analysis and optimization of frequency control in isolated microgrid with double-fed induction-generators based wind turbine

In this paper the role of wind energy conversion systems (WECS) was investigated, In particular, variable speed wind turbines (VSWT) based on double-fed induction-generator (DFIG) in control and the optimization frequency with different wind penetration in the isolated system including Traditional Thermal and Non-thermal units have been investigated too. DFIG is capable of providing power at different mechanical speeds and reducing the Instantaneous speed, thus the release of stored mechanical energy; it is able to support traditional units of frequency tuning system. By achieving this through setting the desired speed, controlling DFIG at different levels of wind penetration is possible. This technique utilizes the particle swarm optimization (PSO) algorithm. The simulation results have been compared to the integral of squared error (ISE). The optimal penetration of WECSs by considering changing parameters in the microgrid (MG) frequency is investigated. The presence of wind turbines has been shown to improve the oscillation frequency and In particular the penetration rate of the wind turbine in the MG. The best frequency control will be achieved. To achieve the computing purposes, use of intelligent algorithms is much better than the methods trial and error methods

Analysis and Design of a DSTATCOM Based on Sliding Mode Control Strategy for Improvement of Voltage Sag in Distribution Systems

Voltage sag is considered to be the most serious problem of power quality. It is caused by faults in the power system or by the starting of large induction motors. Voltage sag causes about 80% of the power quality problems in power systems. One of the main reasons for voltage sag is short circuit fault, which can be compensated for by a distribution static compensator (DSTATCOM) as an efficient and economical flexible AC transmission system (FACTS) device. In this paper, compensation of this voltage sag using DSTATCOM is reviewed, in which a sliding mode control (SMC) technique is employed. The results of this control system are compared with a P+Resonant control system. It will be shown that this control system is able to compensate the voltage sag over a broader range compared to other common control systems. Simulation results are obtained using PSCAD/EMTDC software and compared to that of a similar method

A Multi-Slope Sliding-Mode Control Approach for Single-Phase Inverters under Different Loads

In this paper, a new approach to the sliding-mode control of single-phase inverters under linear and non-linear loads is introduced. The main idea behind this approach is to utilize a non-linear, flexible and multi-slope function in controller structure. This non-linear function makes the controller possible to control the inverter by a non-linear multi-slope sliding surface. In general, this sliding surface has two parts with different slopes in each part and the flexibility of the sliding surface makes the multi-slope sliding-mode controller (MSSMC) possible to reduce the total harmonic distortion, to improve the tracking accuracy, and to prevent overshoots leading to undesirable transient-states in output voltage that occur when the load current sharply rises. In order to improve the tracking accuracy and to reduce the steady-state error, an integral term of the multi-slope function is also added to the sliding surface. The improved performance of the proposed controller is confirmed by simulations and finally, the results of the proposed approach are compared with a conventional sliding-mode controller (SMC) and a synchronous reference frame PI (SRFPI) controller

A Novel Resonant LLC Soft-Switching Buck Converter

Abstract-a new LLC resonant DC-DC buck converter is presented. The employed multi-resonant tank provides softswitching conditions for all semiconductor devices independent from the operating voltages and the load current. The proposed converter enjoys useful advantages such as low element count, unconditional soft switching operation, self short-circuit protection, high efficiency and low EMI. Circuit analysis and important relations are presented in this paper. Experimental results from a 60W laboratory prototype confirm the presented theoretical analysis

Designing a Two-Phase BLDC Motor and Finite-Element Analysis of Designing a Controller in Order to Manoeuvre High-Speed Boats in Marine Turbulences

High speed boats are small kind of boats which are piloted with boatman.These boats are usually used in strategic commissions like military which fast speeds and good manoeuvrability are of essential importance.Rough sea path, marine turbulences and multi input multi output nonlinear dynamical model of this boats,make it very difficult to pilot and manoeuvre them.in this paper,.two controller are designed and proposed for pursuing desired path and manoeuvring fast speeds.Fuzzy controller is compared with the result of PID controller. Simulation results also indicate that these proposed controllers have suitable responses and can pilot the boat in the best manner