Object oriented modelling and simulation of hydropower plants with run-of-river scheme: A new simulation tool

This paper presents the design of a component library for modelling hydropower plants, and describes the development of a new simulation tool for small hydropower plants with a run-of-river scheme. After reviewing the desirable features of simulation, an approach based on an object oriented modelling language, like EcosimPro, is presented. A general model of hydropower plant with run-of-river scheme is created with this component library. It provides the possibility of choosing a specific number of turbines and spillway gates. In this way, several hydropower stations of similar operating characteristics can be simulated using this same general model. It is expected to obtain interesting information in simulation like the reservoir level, water flows, turbine efficiencies, and so on. In addition, a graphical user interface has been designed in order to operate this general model more easily, to configure plant parameters and to simulate the plant behaviour under different conditions. Three real stations have been used as real examples for validating the model and testing the simulator: hydropower stations of Villafranca and El Carpio (Córdoba, Spain) and Marmolejo (Jaén, Spain)

Load Frequency Control of Multiple-Area Power Systems

In an interconnected power system, as a power load demand varies randomly, both area frequency and tie-line power interchange also vary. The objectives of load frequency control (LFC) are to minimize the transient deviations in theses variables (area frequency and tie-line power interchange) and to ensure their steady state errors to be zeros. When dealing with the LFC problem of power systems, unexpected external disturbances, parameter uncertainties and the model uncertainties of the power system pose big challenges for controller design. Active disturbance rejection control (ADRC), as an increasingly popular practical control technique, has the advantages of requiring little information from the plant model and being robust against disturbances and uncertainties. This thesis presents a solution to the LFC problem based on ADRC. The controller is constructed for a three-area power system with different turbine units including non-reheat, reheat and hydraulic units in different areas. The dynamic model of the power system and the controller design based on the model are elaborated in the thesis. Simulation results and frequency-domain analyses proved that ADRC controller is attractive to the LFC problem in its stability and robustnes

Load Frequency Control of Multiple-Area Power Systems

In an interconnected power system, as a power load demand varies randomly, both area frequency and tie-line power interchange also vary. The objectives of load frequency control (LFC) are to minimize the transient deviations in theses variables (area frequency and tie-line power interchange) and to ensure their steady state errors to be zeros. When dealing with the LFC problem of power systems, unexpected external disturbances, parameter uncertainties and the model uncertainties of the power system pose big challenges for controller design. Active disturbance rejection control (ADRC), as an increasingly popular practical control technique, has the advantages of requiring little information from the plant model and being robust against disturbances and uncertainties. This thesis presents a solution to the LFC problem based on ADRC. The controller is constructed for a three-area power system with different turbine units including non-reheat, reheat and hydraulic units in different areas. The dynamic model of the power system and the controller design based on the model are elaborated in the thesis. Simulation results and frequency-domain analyses proved that ADRC controller is attractive to the LFC problem in its stability and robustnes

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

Optimal Control Strategy of Turbine Governor Parameters Based on Improved Beetle Antennae Search Algorithm

Aiming at the occurrence of long-term and ultra-low frequency oscillations in the hydropower network system, this paper derives the generalized turbine transfer function speed control system model including the flow factor Tpq based on the generalized turbine model, and analyzes the influence of Tpq and PID parameters on the ultra-low frequency damping of the hydraulic turbine governing system. In order to better suppress the ultra-low frequency oscillation caused by improper PID parameter settings, a comprehensive optimization objective function reflecting damping and turbine speed deviation index (ITAE) in ultra-low frequency band is established. Based on the fast and efficient optimization strategy of Beetle Antennae Search, an improved beetle antennae particle swarm optimization is constructed. In single-machine and multi-machine systems, the improved algorithm is compared with different optimization algorithms. The simulation results show that the improved algorithm can overcome the slow convergence speed and easily fall into local optimization problem, effectively improve the damping level of hydraulic turbine governing system in ultra-low frequency, and is more effective and superior than other optimization algorithms. It provides a new way of thinking and technical means to suppress the ultra-low frequency oscillation by optimizing the parameters of the speed control system

Passivity - Based Control and Stability Analysis for Hydro-Solar Power Systems

Los sistemas de energía modernos se están transformando debido a la inclusión de renovables no convencionales fuentes de energía como la generación eólica y fotovoltaica. A pesar de que estas fuentes de energía son buenas alternativas para el aprovechamiento sostenible de la energía, afectan el funcionamiento y la estabilidad del sistema de energía, debido a su naturaleza inherentemente estocástica y dependencia de las condiciones climáticas. Además, los parques solares y eólicos tienen una capacidad de inercia reducida que debe ser compensada por grandes generadores síncronos en sistemas hidro térmicos convencionales, o por almacenamiento de energía dispositivos. En este contexto, la interacción dinámica entre fuentes convencionales y renovables debe ser estudiado en detalle. Para 2030, el Gobierno de Colombia proyecta que el poder colombiano El sistema integrará en su matriz energética al menos 1,2 GW de generación solar fotovoltaica. Por esta razón, es necesario diseñar controladores robustos que mejoren la estabilidad en los sistemas de energía. Con alta penetración de generación fotovoltaica e hidroeléctrica. Esta disertación estudia nuevas alternativas para mejorar el sistema de potencia de respuesta dinámica durante y después de grandes perturbaciones usando pasividad control basado. Esto se debe a que los componentes del sistema de alimentación son inherentemente pasivos y permiten formulaciones hamiltonianas, explotando así las propiedades de pasividad de sistemas eléctricos. Las principales contribuciones de esta disertación son: una pasividad descentralizada basada control de los sistemas de control de turbinas hidráulicas para sistemas de energía de múltiples máquinas para estabilizar el rotor acelerar y regular el voltaje terminal de cada sistema de control de turbinas hidráulicas en el sistema como, así como un control basado en PI pasividad para las plantas solares fotovoltaicas

On the inertia of power electronics converters

Electrical power systems are going through a transition in its energy matrix. Renewable energy sources based generation and distributed generation grow in number. There is a concern among academics and system operators that the lack of spinning mass’ inertia in these new generating units will negatively contribute to frequency stability in electrical power systems. However, there is not an adequate established method for quantifying the contribution a power electronics based generating unit provides to grid frequency stability. This work seeks to define such a method and to analyze control techniques from the point of view of contribution to electrical power systems frequency stability.Os sistemas elétricos de potência passam por um momento de transição da matriz energética. Crescem em número as unidades de geração baseadas em fontes renováveis de energia e as unidades de geração distribuída. Há uma preocupação entre acadêmicos e operadores do sistema elétrico de que a falta da inércia de uma massa girante nessas novas unidades geradoras contribua negativamente para a estabilidade de frequência de sistemas elétricos de potência. Entretanto, não há um meio adequado estabelecido de quantificar a contribuição de uma unidade geradora baseada em eletrônica de potência à estabilidade de frequência da rede. Este trabalho busca a definição de tal meio e a análise de técnicas de controle sob a perspectiva da contribuição à estabilidade de frequência de sistemas elétricos de potência

A Robust Decentralized Load Frequency Controller for Interconnected Power Systems

A novel design of a robust decentralized load frequency control (LFC) algorithm is proposed for an inter-connected three-area power system, for the purpose of regulating area control error (ACE) in the presence of system uncertainties and external disturbances. The design is based on the concept of active disturbance rejection control (ADRC). Estimating and mitigating the total effect of various uncertainties in real time, ADRC is particularly effective against a wide range of parameter variations, model uncertainties, and large disturbances. Furthermore, with only two tuning parameters, the controller provides a simple and easy-to-use solution to complex engineering problems in practice. Here, an ADRC-based LFC solution is developed for systems with turbines of various types, such as non-reheat, reheat, and hydraulic. The simulation results verified the effectiveness of the ADRC, in comparison with an existing PI-type controller tuned via genetic algorithm linear matrix inequalities (GALMIs). The comparison results show the superiority of the proposed solution. Moreover, the stability and robustness of the closed-loop system is studied using frequency-domain analysis

Modeling and Optimal Operation of Hydraulic, Wind and Photovoltaic Power Generation Systems

The transition to 100% renewable energy in the future is one of the most important ways of achieving "carbon peaking and carbon neutrality" and of reducing the adverse effects of climate change. In this process, the safe, stable and economical operation of renewable energy generation systems, represented by hydro-, wind and solar power, is particularly important, and has naturally become a key concern for researchers and engineers. Therefore, this book focuses on the fundamental and applied research on the modeling, control, monitoring and diagnosis of renewable energy generation systems, especially hydropower energy systems, and aims to provide some theoretical reference for researchers, power generation departments or government agencies