Modeling,Parameter Measurement,and Control of PMSG-based Grid-connected Wind Energy Conversion System

The design of reliable controllers for wind energy conversion systems(WECSs)requires a dynamic model and accurate parameters of the wind generator.In this paper,a dynamic model and the parameter measurement and control of a direct-drive variable-speed WECS with a permanent magnet synchronous generator(PMSG)are presented.An experimental method is developed for measuring the key parameters of the PMSG.The measured parameters are used in the design of the controllers.The generator-side converter is controlled using a vector control scheme that maximizes the power extraction under varying wind speeds.A model predictive controller(MPC)is designed for the grid-side voltage source converter(VSC)to regulate the active and reactive power flows to the power grid by controlling the d-and q-axis currents in the synchronous reference frame.The MPC predicts the future values of the control variables and takes control actions based on the minimum value of the cost functions.To comply with the grid code requirement,a modified design approach for an LCL filter is presented and incorporated into the system.The design process is simple and incorporates significant filter parameters while avoiding iterative calculations.The comparative analysis of the designed filter with conventional L,LC,and iterative LCL filters demonstrates the effectiveness of the modified design approach.The proposed wind energy system with MPC and LCL filter is simulated in MATLAB/Simulink and experimentally implemented in the laboratory using the dSpace digital signal processor(DSP)system.The simulation and experimental results validate the efficacy of the designed controllers using the measured parameters and show dynamic and steady-state performance under varying wind speeds.

A Technology for Online Parameter Identification of Permanent Magnet Synchronous Motor

Accuracy of the motor parameters is important in realizing high performance control of permanent magnet synchronous motor(PMSM).However,the inductance and resistance of motor winding vary with the change of temperature,rotor position and current frequency.In this paper,a technology based on circuit model is introduced for realizing online identification of the parameter of PMSM.In the proposed method,a set of nonlinear equations containing the parameters to be identified is established.Considering that it is very difficult to obtain the analytical solution of a nonlinear system of equations,Newton iterative method is used for solving the equations.Both the simulation and testing results confirm the effectiveness of the method presented.

Quantum Parameter Estimation: From Experimental Design to Constructive Algorithm

In this paper we design the following two-step scheme to estimate the model parameter ω0 of the quantum system: first we utilize the Fisher information with respect to an intermediate variable v = cos(ω0 t) to determine an optimal initial state and to seek optimal parameters of the POVM measurement operators; second we explore how to estimate ω0 from v by choosing t when a priori information knowledge of ω0 is available. Our optimal initial state can achieve the maximum quantum Fisher information. The formulation of the optimal time t is obtained and the complete algorithm for parameter estimation is presented. We further explore how the lower bound of the estimation deviation depends on the a priori information of the model.

Online Pattern Recognition and Data Correction of PMU Data Under GPS Spoofing Attack

Smart grids are increasingly dependent on data with the rapid development of communication and measurement.As one of the important data sources of smart grids,phasor measurement unit(PMU)is facing the high risk from attacks.Compared with cyber attacks,global position system(GPS)spoofing attacks(GSAs)are easier to implement because they can be exploited by portable devices,without the need to access the physical system.Therefore,this paper proposes a novel method for pattern recognition of GSA and an additional function of the proposed method is the data correction to the phase angle difference(PAD)deviation.Specifically,this paper analyzes the effect of GSA on PMU measurement and gives two common patterns of GSA,i.e.,the step attack and the ramp attack.Then,the method of estimating the PAD deviation across a transmission line introduced by GSA is proposed,which does not require the line parameters.After obtaining the estimated PAD deviations,the pattern of GSA can be recognized by hypothesis tests and correlation coefficients according to the statistical characteristics of the estimated PAD deviations.Finally,with the case studies,the effectiveness of the proposed method is demonstrated,and the success rate of the pattern recognition and the online performance of the proposed method are analyzed.