A decentralized multivariable controller for hydrostatic wind turbine drivetrain

Abstract

A hydrostatic drivetrain transmits wind turbine energy to a generator. One hydrostatic transmission system (HTS) configuration utilizes a fixed displacement pump and a variable displacement motor. The system dynamics are captured in a nonlinear multi-input multi-output mathematical model. This paper introduces a decentralized control configuration based on this model to achieve two desired objectives: maximizing the harvested energy without direct measurement of wind and regulating the frequency of the generator without using power electronic converters. To accomplish these objectives, suitable pairing of control actuators and system responses are identified through nonlinear relative gain arrays (RGA) analysis. The pairing also provides a strong decoupling of control loops. So maximum power point tracking (MPPT) is achieved independently while the generator speed is regulated to maintain the frequency of generated power at 60 Hz. Simulation results demonstrate robust performance of MPPT and frequency regulation in the presence of uncertainties in the turbine and HTS model. We also demonstrate that the RGA paired inputout control configuration offers superior performance over other possible input-output paired control configurations. KEYWORDSdecentralized multivariable control, frequency regulation, Hydrostatic pump and motors, maximum power point tracking, nonlinear relative gain array, power transmission

Application of the Feedback Linearization in Maximum Power Point Tracking Control for Hydraulic Wind Turbine

“…Energies 2020, 13,1529 Thus, the zero dynamics is asymptotically stable, and the whole system is asymptotically stable. That is, the selected coordinate transformation can be used to solve the controller, and the system is in a stable state under the controller.…”

“…SP Mulders proposed an implementation, model-free, gradient-based and extremum seeking control optimization strategy to achieve an average maximum power increase in [12]. M, Deldar designed a decentralized control configuration to collect the maximum energy without directly measuring the wind speed in [13]. A digital hydrostatic drive solution was introduced in the HWT to largely utilize the energy captured by the rotor in [14], and the kW 2 control law combined with digital hydrostatic method was proposed to improve HWT energy production.…”

Nonlinear decentralized load frequency control of multi‐machine power systems with exponential stability and low L2 gain against load disturbance

“…In the application aspect, [5] proposed a current sharing control algorithm for parallel DC-DC buck converters based on finite-time control. The decentralized control approach has also been applied to hydrostatic wind turbine drivetrain [6], longitudinal vehicular platoons with non-uniform communication topology [7] and automated highway systems [8]. However, the aforementioned decentralized control schemes are not suitable for an interconnected power system because there exist strong nonlinear interactions among subsystems.…”

Look Ahead Based Control Strategy for Hydro-Static Drive Wind Turbine Using Dynamic Programming

“…Implementation and validation of the control oriented model of the hydro-static drive wind turbine based on published literature [1][2][3][4]. This control oriented model will be the baseline for comparison of benefits with the proposed controller.…”

“…To compare the benefits of the proposed predictive controller the results are analyzed against the traditional optimal controller based on Maximum Power Point Tracking algorithm as proposed in literature [3,4]. Comparing directly to the published results will help understand the benefits of the predictive optimal controller as against the traditional indirect method of trajectory optimization problems (PMP) [5].…”