Decentralized fault-tolerant control of inland navigation networks: a challenge

Inland waterways are large-scale networks used principally for navigation. Even if the transport planning is an important issue, the water resource management is a crucial point. Indeed, navigation is not possible when there is too little or too much water inside the waterways. Hence, the water resource management of waterways has to be particularly efficient in a context of climate change and increase of water demand. This management has to be done by considering different time and space scales and still requires the development of new methodologies and tools in the topics of the Control and Informatics communities. This work addresses the problem of waterways management in terms of modeling, control, diagnosis and fault-tolerant control by focusing in the inland waterways of the north of France. A review of proposed tools and the ongoing research topics are provided in this paper.Peer ReviewedPostprint (published version

Optimal Control Design for Multiterminal HVDC

This thesis proposes an optimal-control based design for distributed frequency control in multi-terminal high voltage direct current (MTDC) systems. The current power grid has become overstressed by rapid growth in the demand for electric power and penetration of renewable energy. To address these challenges, MTDC technology has been developed, which has the potential to increase the flexibility and reliability of power transmission in the grid. Several control strategies have been proposed to regulate the MTDC system and its interaction with connected AC systems. However, all the existing control strategies are based on proportional and integral (PI) control with predetermined controller structures. The objective of the thesis is to first determine if existing control structures are optimal, and if improved controller structures can be developed.The thesis proposes a general framework to determine the optimal structure for the control system in MTDC transmission through optimal feedback control. The proposed method is validated and demonstrated using an example of frequency control in a MTDC system connecting five AC areas

Load frequency controllers considering renewable energy integration in power system

Abstract: Load frequency control or automatic generation control is one of the main operations that take place daily in a modern power system. The objectives of load frequency control are to maintain power balance between interconnected areas and to control the power flow in the tie-lines. Electric power cannot be stored in large quantity that is why its production must be equal to the consumption in each time. This equation constitutes the key for a good management of any power system and introduces the need of more controllers when taking into account the integration of renewable energy sources into the traditional power system. There are many controllers presented in the literature and this work reviews the traditional load frequency controllers and those, which combined the traditional controller and artificial intelligence algorithms for controlling the load frequency

Decentralized disturbance observer-based sliding mode load frequency control in multiarea interconnected power systems

The load frequency control (LFC) problem in interconnected multiarea power systems is facing more challenges due to increasing uncertainties caused by the penetration of intermittent renewable energy resources, random changes in load patterns, uncertainties in system parameters and unmodeled system dynamics, leading to a compromised reliability of power systems and increasing the risk of power outages. In responding to this problem, this paper proposes a decentralized disturbance observer-based sliding mode LFC scheme for multiarea interlinked power systems with external disturbances. First, a reduced power system order is constructed by lumping disturbances from tie-line power deviations, load variations and the output power from renewable energy resources. The disturbance observer is then designed to estimate the lumped disturbance, which is further utilized to construct a novel integral-based sliding surface. The necessary and sufficient conditions to determine the tuning parameters of the sliding surface are then formulated in terms of linear matrix inequalities (LMIs), thus guaranteeing that the resultant sliding mode dynamics meet the ${H_\infty }$ performance requirements. The sliding mode controller is then synthesized to drive the system trajectories onto the predesigned sliding surface in finite time in the presence of a lumped disturbance. From a practical perspective, the merit of the proposed control method is to minimize the impact of the lumped disturbance on the system frequency, which has not been considered to date in sliding mode LFC design. Numerical simulations are illustrated to validate the effectiveness of the proposed LFC strategy and verify its advantages over other approaches

Novel control design and strategy for load frequency control in restructured power systems

In restructured electric power systems, a number of generation companies and independent power producers compete in the energy market to make a profit. Furthermore, a new marketplace for ancillary services is established, providing an additional profit opportunity for those power suppliers. These services are essential since they help support the transmission of power from energy sources to loads, and maintain reliable operation of the overall system. This dissertation addresses regulation , a major ancillary service also known as the load frequency control (LFC) problem, and presents novel control designs and strategies for the LFC in restructured power systems.;A power system is an interconnection of control areas, which are operated according to control performance standards established by the North American Electric Reliability Council (NERC). LFC is a necessary mechanism in each control area because it maintains a balance between power demand and power generation while assuring compliance with NERC standards.;This dissertation first develops three new control designs that yield effective and robust load frequency control actions. All controllers developed here require only local measurements. The first control design is based on decoupling each area thru modeling of the interconnection effects of other control areas. The second control design relies on the robust H infinity theory in terms of linear matrix inequalities (LMIs). The third control design is achieved by the collaboration between genetic algorithms (GAs) and LMIs. The first two control designs result in high-order dynamic controllers. The third design requires only a simple proportional-integral (PI) controller while yielding control performance as good as those resulting from the previous two designs. Consequently, the third control design is the most preferable due to its simplicity and suitability for industry practice. Furthermore, a stability analysis method based on perturbation theory of eigenvalues is developed to assess the stability of the entire power system being equipped by the proposed controllers.;Second, to comply with NERC standards, two LFC strategies are developed to direct LFC\u27s actions. One strategy employs fuzzy logic to mimic a skillful operator\u27s actions so that all decisions are made efficiently. The other strategy treats the compliance with NERC standards as constraints while minimizing the operational and maintenance costs associated with LFC actions. Three new indices are introduced to assess economic benefits from the strategy compared to the conventional methods. Simulation is performed to demonstrate performances of all proposed methods and strategies