Adaptive Input-Output Feedback Linearization Control for Islanded Inverter-Based Microgrids

Due to the growth of renewable energies and the need for sustainable electrical energy, AC microgrids (MGs) have been the subject of intense research. Medium voltage MGs will soon have a special place in the power industry. This paper uses a new and effective control scheme for islanded inverter-based medium voltage MGs using the master-slave (MS) technique. The controllers only need local measurements. The designed controls are based on adaptive input-output feedback linearization control (AIOFLC). These controls have a high-performance response; and are robust against some uncertainties and disturbances. The use of the designed control scheme makes the output voltage of distributed generation (DG) sources have negligible harmonics. Besides, the generated voltage and active/reactive powers track their references effectively. The model of the inverter-based DGs is considered in a stationary reference frame, and there is no need for any coordinate frame transformation. The control method presented in this paper can be used for MGs with any number of inverter-based DGs and parallel inverters. The effectiveness of the proposed control scheme is evaluated by simulation in SIMULINK/MATLAB environment and compared with that of feedback linearization control (FLC) and conventional sliding mode control (CSMC)

Adaptive control design for a synchronous generator

The operating point of a power system changes to an unknown point with an unknown change in the mechanical input power. In this paper, a nonlinear adaptive controller is designed for excitation system of the generator based on the backstepping control technique, in order to achieve transient stability enhancement, in the presence of uncertainties in mechanical power. The designed controller guarantees the convergence of system states to new desired values corresponding to unknown mechanical power. A power system consisting of a synchronous generator connected to an infinite bus through a double circuit transmission line is used in control design and the simulation studies. Computer simulation verifies the effectiveness and the validity of the proposed control, considering faulted system with a clearance and change in network topology. © 2014, Editura Academiei Romane. All rights reserved

Improving the stability of the DFIG power system in the presence of SSSC in a nonlinear manner

In this paper, the problem of improving the stability of the power system with DFIG and in the presence of SSSC using nonlinear method is discussed. The nonlinear controller is designed by the multi-input backstepping method with a sliding mode observer. This controller is applied simultaneously to the excitation system of synchronous generators and the rotor side converter in DFIG and SSSC in a way that improves the stability of the power system compared to the linear and nonlinear methods described in this paper. The control coefficient matrices are adjusted using intelligent algorithms in such a way that the stability of the system is more optimized. Practical constraints on the system are considered in selecting the control inputs. The designed controller is robust to changes in the operating point and the location of the disturbance. The performance of the designed controller in a 39-bus, 10 machines NEW ENGLAND network including DFIG generators and in the presence of SSSC is simulated and investigated using MATLAB software

Transient Stability Improvement of a Power System with Parametric Uncertainties Using a Robust Optimal H2 State Feedback Controller

In recent years, improvement of dynamic behavior of power systems has interested many researchers and to achieve it, various control methods are proposed. In this paper, in order to improve transient stability of power system, a robust optimal H2 state feedback is employed. In order to appropriate formulation of the problem, linear matrix inequality (LMI) theory is used. To achieve the best answer, controller parameters are tuned using particle swarm algorithm. The obtained results of the proposed method are compared to conventional power system stabilizer