In this brief, a new stabilizing controller for the power system of an industrial plant operating in a co-generation scheme is proposed. The main source of perturbations considered in the operating conditions are random abrupt fluctuations in the local load, corresponding to the industrial processes being turned on and/or off. These fluctuations are described as Markovian jumps in the parameters of the power system. The proposed controller follows a standard structure which combines an automatic voltage regulator with a supplementary stabilizing term. This term is obtained with a fuzzy-model-based control technique formulated in the context of linear matrix inequalities under damping and control input constraints. Simulations performed on both a single-machine infinite-bus model and on a multimachine model show the effectiveness of the proposed fuzzy control strategy in reducing the oscillations as well as in maintaining a desired operating condition

The paradigm that distribution networks are free from problems related to electromechanical oscillations (due to their mainly passive nature and relatively large resistances) is about to change with the increase in the number of small generators connected to them. This paper shows a real situation in which the connection of a few small generators in the distribution network can significantly deteriorate the damping in the system response to small perturbations. The effects of the system response on the power quality across the network are also discussed. The analyzed system is located within the state of Sao Paulo, Brazil, having 3 feeders (comprising 57 kilometers of cables) and 32 buses distributed along these feeders. The need for an adequate assessment of the oscillations and their impacts over power quality is pointed out. It is shown that conventional PSSs can be a simple, cheap, and effective solution to keep the power quality standards as the number of generators entering the grid increases.

The design of supplementary damping controllers to mitigate the effects of electromechanical oscillations in power systems is a highly complex and time-consuming process, which requires a significant amount of knowledge from the part of the designer. In this study, the authors propose an automatic technique that takes the burden of tuning the controller parameters away from the power engineer and places it on the computer. Unlike other approaches that do the same based on robust control theories or evolutionary computing techniques, our proposed procedure uses an optimisation algorithm that works over a formulation of the classical tuning problem in terms of bilinear matrix inequalities. Using this formulation, it is possible to apply linear matrix inequality solvers to find a solution to the tuning problem via an iterative process, with the advantage that these solvers are widely available and have well-known convergence properties. The proposed algorithm is applied to tune the parameters of supplementary controllers for thyristor controlled series capacitors placed in the New England/New York benchmark test system, aiming at the improvement of the damping factor of inter-area modes, under several different operating conditions. The results of the linear analysis are validated by non-linear simulation and demonstrate the effectiveness of the proposed procedure.

The de‐loaded operation of wind turbine generators (WTGs) with inertial and frequency control considerably affects the dynamics and stability of variable speed wind turbines. In this context, this work proposes a comprehensive assessment of the simultaneous impact of virtual synchronous generator and frequency controllers on the electromechanical dynamics of type 4 WTGs. The proposed power balance formulation and the performed analysis, which are the main contributions of this work, provide insight into the simultaneous impact of the inertial and frequency control on the dynamics of the wind generation unit and system frequency. The assessment has been performed by means of an analytical formulation for the power balance in the WTG, characteristic curves of the wind turbine, and non‐linear time‐domain simulations of two test systems. The analyses have shown that the speed and torque deviation magnitudes of the wind turbine, as well as the amount of kinetic energy released by the wind turbine, depend on the wind turbine operating point. The study has also shown that the de‐loaded operation considerably increases the inertial response capability of WTGs. The integrated inertial and frequency control approach has resulted in well‐behaved electromechanical dynamics for the WTG.