Hua Xue

Adaptive passivity-based control strategies of doubly fed induction wind power generator systems

Nonlinear control strategies of variable speed constant frequency(VSCF) wind power generator systems, especially passivity-based control(PBC) methods, have been a focus in the literature. The main purpose of this paper is to develop a control algorithm that forces the wind driven doubly fed induction generator(DFIG) to track reference flux and speed trajectories with time-varying load torque. To achieve this, an adaptive PBC method based on Euler-Lagrange(EL) system is developed. PBC combined with adaptive control scheme not only reserves the advantages of PBC such as nonexistence of singularity, but also repressed the harmonic current tracking error caused by resistance and inductance variation. This leads to a simple control structure and enhances the robustness of the control system. The reasonability and validity is testified by the experimental results based on dSPACE.

Study on improved PR control of direct-drive permanent magnet wind power generation system

This paper analyzed the principle and performance characteristics of PR controller, and proposed a control strategy based on improved PR controller of direct-driven permanent magnet synchronous wind power generation system. Instead of the traditional PI controller, improved PR controller is used to saving a coordinate transformation, eliminating the cross-decoupling terms and feed-forward compensation items, and simplifying the control algorithm. The introduction of improved PR controllers has superior performance in permanent magnet synchronous motor control system, it can realize no static difference to the AC input signal. For validation, simulation model is built to experiments and analysis.

Research on the fluctuation mechanism of electric arc furnace voltage using chaos theory

The wide application of electric arc furnace (EAF) loads usually cause negative effects in the grid, especially drastic voltage fluctuation. Chaos theory is used to study ac EAF voltage fluctuation mechanism in this paper. Firstly, C-C method is adopted to reconstruct phase space of voltage time series. According to BDS(named after Brock, Dechert, and Scheinkman) statistics, the optimal delay time and embedding dimension are determined. Then, trajectory divergence rates in the phase space are calculated by improved Wolf algorithm as nearest points evolve along the trajectory. By fitting these divergence rates through least square method, the maximum Lyapunov exponent (MLE) is obtained. Results show that the voltage fluctuation of ac EAF has chaotic property, which lays the foundation for analysis and prediction of voltage fluctuation using chaotic method.

Study on Fuzzy PI Control Strategies of Networked Control System

When using a remote networked control system, a network-induced time-delay is generated, which causes advert effects on the closed-loop networked control system such as performance degradation and system destabilization. For solving the time-delay in remote control system, intelligent fuzzy logic compensator is introduced in this paper to improve the traditional networked PI control system. In the full adaptive fuzzy parameter adjustment, off-line optimization and on-line adaptation are applied to the design of the controller, So that the consequent parameters can be tuned adaptively, As well as the membership functions in the antecedent part Simulation results of a networked controlled Brushless DC motor is used to illustrate the effectiveness and feasibility of the proposed fuzzy PI control scheme.

Research of the Power Control for a MCFC/GT Hybrid System

Molten carbonate fuel cell/ gas turbine hybrid power system (MCFC/GT) output power should real-time response the demand of load. The auto-tuning ZieglerNichols tuned PI controller (AZNPIC) as a feedback controller for power corrective action is added to the hybrid power system. The optimal setpoints and feed forward control inputs of the controller are given by Multi-output Support Vector Machine Regression (MSVR) predictor for the hybrid system. Simulation results show that the power of hybrid system can be effectively close to the desired setpoints based on the control method.

Hardware Design for Simulating the Chaos in Electric Arc Furnace

A chaotic circuit was designed to simulate the chaotic phenomenon observed in power supply system of electric arc furnace (EAF). Based on volt-ampere characteristic of the negative resistance converter (NRC) composed of the integrated operational amplifier (IOA), two NRCs with different parameters are connected in parallel in this circuit. The positive and negative power supply sources of the IOA are unequal in voltage amplitude. Experimental results show that the circuit has characteristics of general Chuas circuits and can generate an asymmetric double-scroll chaotic attractor, which helps establish the foundation for chaotic model of AC arc furnace used to study power quality.

Research of the Temperature Decoupling Control for a MCFC/GT Hybrid System

To a molten carbonate fuel cell/ gas turbine hybrid system, operating temperature which has significant influence on the performance and lifespan of system is researched. The decoupling control of multivariable system is proposed in the temperature control of a hybrid system. In the designing of decoupling controller, the intelligent decoupling method is used based on Quasi-Diagonal Recurrent Neural Network-PID. Simulation results show that the operating temperature of hybrid system can be effectively close to the desired setpoints based on the decoupling controller.

Research on Control Strategy of Supercapacitors Energy Storage System

Supercapacitors have characteristics of high power density, long life, and quick charging and discharging. DC-DC converter can be used for changing, processing and regulating the power. Supercapacitors energy storage system consisted of supercapacitors and DC-DC converter can be widely used in distributed power generation system to the stability of dc bus voltage and the improvement of the power quality. For simulation, the mathematical models of DC-DC converters and supercapacitors are developed using MATLAB/SIMULINK. The sliding mode controller of the supercapacitors energy storage is presented, and the simulation results verify the control method is feasible．

Simulation Study of Harmonics and Reactive Power in Three-Phase Full-Bridge Controlled Rectifier Circuit with Resistance-Inductance Load

In order to evaluate the harm and impact of power electronic devices on the grid and provide numerical basis for specific design of the corresponding compensated devices, the harmonics and reactive power of three-phase full-bridge controlled rectifier circuit with resistance-inductance load are studied in this paper. Firstly, the harmonics and power factor of the ac side current are analyzed theoretically; the harmonics contents and power factor are calculated. Secondly, the model of three-phase full-bridge controlled rectifier circuit is built in Matlab/Simulink, and the simulation analysis of the ac side power factor and harmonics is achieved, the simulated values are similar to the theoretical values. The results show that the complex calculations of harmonics and power factor can be completed simply and intuitively using simulation study, the simulation study is efficient and accurate.

Adaptive optimal fuzzy control of asymmetric nonlinear Chua's circuit chaos systems

This paper deals with the chaos phenomenon of asymmetric nonlinear Chuas circuit for wind power generation systems. The Takagi-Sugeno (T-S) fuzzy model of asymmetric nonlinear Chuas circuit chaos system is built. Based on the optimal theory, the extreme sensitivity in the state trajectory with respect to the initial conditions is exhibited and an adaptive optimal fuzzy controller is designed in the form of linear matrix inequality (LMI). Thus the chaos of asymmetric nonlinear Chuas circuit with parametric uncertainties is eliminated. The simulation results show that the adaptive optimal fuzzy control system adopting the designed method has good performance and robust capability.