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The synchronous generator is one of the most important active components in current electric power systems. New control methods should be designed to guarantee an efficient dynamic performance of the synchronous generator in strongly interconnected nonlinear power systems over a wide range of variable operating conditions. In this context, active suppression capability for different uncertainties and external disturbances represents a current trend in the development of new control design methodologies. In this paper, a new adaptive neural control scheme based on differential flatness with a modified structure including B-spline Neural Networks for transient stabilization and tracking of power-angle reference profiles for synchronous generators in interconnected electric power systems is introduced. These features are attained due to the advantages extracted of these two approaches: (a) a control design stage based on a power system model by differential flatness and (b) an adaptive performance using a correct design of B-spline Neural Networks, minimizing parameter dependency. The effectiveness of the proposed algorithm is demonstrated by simulation results in two test systems: single machine infinite bus and an interconnected power system. Transient stability and robust power-angle reference profile tracking are both verified.

With the deep coupling between the electrical power systems and cyber systems, there is a increasingly detrimental effect of the communication delays and packet losses on the load frequency control (LFC) performance. Traditional methods mainly focus on guaranteeing the asymptotic stability in maximum delay case but ignore improving the system dynamic performance. The resulting designed controller cannot satisfy the actual operational requirements completely. Hence, this paper investigates a novel decentralized LFC strategy based on switching control theory. First, the networked LFC system is modelled as a series of subsystems with transmission delay as the switching decision variable. Compared with the existing modelling methods, our modelling approach can depict the influences of time delay and packet loss on system dynamics more accurately. Second, a memoryless state-feedback control design scheme is proposed. Design constraints are deduced by constructing a Lyapunov function and then presented in a bilinear matrix inequality form. To improve the system dynamic performance in power mismatch and communication change case, an iterative linear matrix inequality (LMI) algorithm is proposed. Finally, simulation results illustrate that our proposed method can restore the frequency deviation to zero quickly.

Modern structures of electrical power systems are expected to have more domination of renewable energy sources. However, renewable energy-based generation systems suffer from their lack of or reduced rotating masses, which is the main source of power system inertia. Therefore, the frequency of modern power systems represents an important indicator of their proper and safe operation. In addition, the uncertainties and randomness of the renewable energy sources and the load variations can result in frequency undulation problems. In this context, this paper presents an improved cascaded fractional order-based frequency regulation controller for a two-area interconnected power system. The proposed controller uses the cascade structure of the tilt integral derivative (TID) with the fractional order proportional integral derivative with a filter (FOPIDN or PIλDμN) controller (namely the cascaded TID-FOPIDN or TID-PIλDμN controller). Moreover, an optimized TID control method is presented for the electric vehicles (EVs) to maximize their benefits and contribution to the frequency regulation of power systems. The recent widely employed marine predators optimization algorithm (MPA) is utilized to design the new proposed controllers. The proposed controller and design method are tested and validated at various load and renewable source variations, as is their robustness against parameter uncertainties of power systems. Performance comparisons of the proposed controller with featured frequency regulation controllers in the literature are provided to verify the superiority of the new proposed controller. The obtained results confirm the stable operation and the frequency regulation performance of the new proposed controller with optimized controller parameters and without the need for complex design methods.

Accurate identification of electromechanical oscillations on power systems and determination of its stability condition is a fundamental process in order to carry out an appropriate control action to prevent the partial loss or complete blackout of the system. However, the non-linear characteristics of measured variables often lead to incorrect information about the development of the electromechanical oscillations, making wide-area monitoring a challenging task. In addition, significant amount of information in extra large power systems is produced, which has to be stored on local servers requiring large amounts of central processing unit (CPU) storage. For these reasons, algorithms for Big Data problems in power systems are required and the methods presented on this chapter introduce some potential solutions. In this context, different data-driving methods based on spectral analysis of linear operator are presented for the analysis of electromechanical oscillations from a spatio-temporal perspective. These algorithms have the ability to process spatio-temporal data simultaneously, making possible to characterize inter-area and global oscillations (from 0.1 Hz to 1.0 Hz). To validate the effectiveness of the proposed approaches, two test systems with different structural and generation capacities are analysed: the Mexican Interconnected (MI) system and the initial dynamic model of Continental Europe from ENTSO-E. First, data collected from a transient stability study on the MI system are used to illustrate the ability of data-driving methods to characterize modal oscillations on longitudinal systems; where several inter-area modes produce interactions of different electrical areas. Then, simulation results from the initial dynamic model of ENTSO-E are analysed to characterize the propagation of its global electromechanical modes across Europe, which have been denominated as the North-South and East-West modes with frequencies of approximately 0.15 Hz and 0.25 Hz, respectively. The second analysis include the interconnection of Turkey (TR) to Continental Europe in December 2010, which derived on the grow of size and complexity of the original system having as result a decrease in the frequency value for the East-West mode and the introduction of a third inter-area mode on the system. The chapter concludes comparing the results of the proposed approaches against conventional methods available in the literature.

In contrast to the traditional filtering approaches, this paper presents a message passing algorithm for multi-area interconnected power systems. The interconnected power system incorporating the thermal turbines and electrical vehicles is expressed as a state-space framework. The phasor measurement units are used to obtain the system state information. After receiving the sensing information at the energy management systems, the factor graph based message passing algorithm is developed. This algorithm can estimate the system states in a distributed way considering the Bayesian network. Simulation result shows that the developed scheme can be well estimated the system states.

The first contribution of this dissertation is the case studies for capturing the development of different types of dynamic voltage instability, in both the short- and long-term, caused by the dynamics of different power system devices, especially induction machines. In addition, it investigates how the changing nature of systems and their dynamic behaviours cause critical issues that limit the large-scale integration of wind generators and flexible AC transmission system (FACTS) devices. A second and unique contribution of this thesis is the presentation of a method to bound unmodelled nonlinear dynamics and to design excitation control for the enhancement of large-disturbance voltage stability in power systems with significant induction motor loads. A new technique is developed which captures the full nonlinearity of systems in the region of interest. The nonlinear power system model is reformulated with a linear and a nonlinear term. The nonlinear term is the Cauchy remainder in the Taylor series expansion and in this thesis its bound is used in robust control design. This dissertation also presents an algorithm for the design of a decentralised robust controller for static synchronous compensators (STATCOMs) which results in a significant increase in the available dynamic transfer capability of a power system in the presence of fixed-speed induction generators (FSIGs). Another significant contribution of this research is the design of robust controllers which augment the low-voltage ride-through capability of FSIGs during severe disturbances. Control algorithms, using both structured and unstructured uncertainty representations, are developed for the stabilisation of faulted systems under different operating conditions. The performance of the proposed control schemes fulfils the criteria for robust stability and performance, and produces adequate stability margins for a range of test cases. The effectiveness of the suggested control strategies are validated by detailed simulations with complete nonlinear model of the devices. The performances of the designed controllers are also compared with those of conventional controllers. Simulation results show that both the dynamic voltage stability and the transient stability of a power system can be improved by the use of the robust control methods presented in this thesis.

International audience; Multi area power systems work most often with a poor inter-regional coordination about reactive power concerns. Transmission system operators typically do not possess a detailed knowledge about voltage profile across interconnected power systems. In this context, reactive power scheduling may be inefficient and inter-regional reactive power flows become a decisive issue. This inefficiency, associated with economic constraints and increasing stress on interconnection lines, may lead to conflicts, which could be partially avoided with a better scheduling strategy. In addition to inter-utility agreements, part of the solution could be to use appropriate external network modeling. Different modeling are thus presented in this paper and illustrated with an IEEE 118 bus system with 2 separately controlled regions, whose scheduling objective is to minimize active power losses. The regional scheduling process is described and the state of the interconnected power system is compared with a global optimization. Finally, the influence of the external network modeling parameters and the accuracy of their forecast is commented.

This paper describes the control and parallel operation of two Active Power Filters. The filters are coupled in a combined topology in which one filter is connected in a feedback loop and the other is in a feedforward loop for harmonic compensation. Thus, both active power filters bring their own characteristic advantages i.e. the feedback filter improves the steady-state performance of the harmonic mitigation and the feedforward filter improves the stability and the dynamics. Another characteristic of the proposed topology is the cooperation of both filters either as load-sharing or frequency-sharing. The evaluation of the proposed topology concludes that this approach is very practical for achieving both low and high order harmonic compensation and stable grid operation. This is supported by measurement results on a 15 kVA laboratory setup, indicating a reduction in Total Harmonic Current Distortion from existing 30 % to less than 2 % in an adjustable speed drive application.

This article investigates the concept of paralleling power inverters for reactive power and harmonic compensation. The investigation focuses on a topology that shares the dc-bus capacitor between two parallel interleaved inverters. The advantages of the proposed approach are: i) decreased current ripple or use of lower switching frequency due to the interleaving, ii) reduced stress in dc-link capacitor due to the shared connection, iii) efficient implementation for high power applications because of paralleling. Different comparisons between the selected topology and regular power converters are discussed. Practical tests, on a three-phase 5 kVA, 400 V prototype, are presented to validate the analysis.