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Over the last two decades, variable renewable energy technologies (i.e., variable-speed wind turbines (VSWTs) and photovoltaic (PV) power plants) have gradually replaced conventional generation units. However, these renewable generators are connected to the grid through power converters decoupled from the grid and do not provide any rotational inertia, subsequently decreasing the overall power system’s inertia. Moreover, the variable and stochastic nature of wind speed and solar irradiation may lead to large frequency deviations, especially in isolated power systems. This paper proposes a hybrid wind–PV frequency control strategy for isolated power systems with high renewable energy source integration under variable weather conditions. A new PV controller monitoring the VSWTs’ rotational speed deviation is presented in order to modify the PV-generated power accordingly and improve the rotational speed deviations of VSWTs. The power systems modeled include thermal, hydro-power, VSWT, and PV power plants, with generation mixes in line with future European scenarios. The hybrid wind–PV strategy is compared to three other frequency strategies already presented in the specific literature, and gets better results in terms of frequency deviation (reducing the mean squared error between 20% and 95%). Additionally, the rotational speed deviation of VSWTs is also reduced with the proposed approach, providing the same mean squared error as the case in which VSWTs do not participate in frequency control. However, this hybrid strategy requires up to a 30% reduction in the PV-generated energy. Extensive detailing of results and discussion can be also found in the paper.
Ana Fernández-Guillamón; Guillermo Martínez-Lucas; Ángel Molina-García; Jose-Ignacio Sarasua. Hybrid Wind–PV Frequency Control Strategy under Variable Weather Conditions in Isolated Power Systems. Sustainability 2020, 12, 7750 .
AMA StyleAna Fernández-Guillamón, Guillermo Martínez-Lucas, Ángel Molina-García, Jose-Ignacio Sarasua. Hybrid Wind–PV Frequency Control Strategy under Variable Weather Conditions in Isolated Power Systems. Sustainability. 2020; 12 (18):7750.
Chicago/Turabian StyleAna Fernández-Guillamón; Guillermo Martínez-Lucas; Ángel Molina-García; Jose-Ignacio Sarasua. 2020. "Hybrid Wind–PV Frequency Control Strategy under Variable Weather Conditions in Isolated Power Systems." Sustainability 12, no. 18: 7750.
The lack of synchronous inertia, associated with the relevant penetration of variable speed wind turbines (VSWTs) into isolated power systems, has increased their vulnerability to strong frequency deviations. In fact, the activation of load shedding schemes is a common practice when an incident occurs, i.e., the outage of a conventional unit. Under this framework, wind power plants should actively contribute to frequency stability and grid reliability. However, the contribution of VSWTs to frequency regulation involves several drawbacks related to their efficiency and equipment wear due to electrical power requirements, rotational speed changes, and subsequently, shaft torque oscillations. As a result, wind energy producers are not usually willing to offer such frequency regulation. In this paper, a new control technique is proposed to optimize the frequency response of wind power plants after a power imbalanced situation. The proposed frequency controller depends on different power system parameters through a linear regression to determine the contribution of wind power plants for each imbalance condition. As a consequence, VSWTs frequency contribution is estimated to minimize their mechanical and electrical efforts, thus reducing their equipment wear. A group of sixty supply-side and imbalance scenarios are simulated and analyzed. Results of the case study are compared to previous proposals. The proposed adaptive control reduces the maximum torque and rotational speed variations while at the same time maintaining similar values of the load shedding program. Extensive results and discussion are included in the paper.
Ana Fernández-Guillamón; Guillermo Martínez-Lucas; Ángel Molina-García; Jose Ignacio Sarasua. An Adaptive Control Scheme for Variable Speed Wind Turbines Providing Frequency Regulation in Isolated Power Systems with Thermal Generation. Energies 2020, 13, 3369 .
AMA StyleAna Fernández-Guillamón, Guillermo Martínez-Lucas, Ángel Molina-García, Jose Ignacio Sarasua. An Adaptive Control Scheme for Variable Speed Wind Turbines Providing Frequency Regulation in Isolated Power Systems with Thermal Generation. Energies. 2020; 13 (13):3369.
Chicago/Turabian StyleAna Fernández-Guillamón; Guillermo Martínez-Lucas; Ángel Molina-García; Jose Ignacio Sarasua. 2020. "An Adaptive Control Scheme for Variable Speed Wind Turbines Providing Frequency Regulation in Isolated Power Systems with Thermal Generation." Energies 13, no. 13: 3369.
With high levels of wind energy penetration, the frequency response of isolated power systems is more likely to be affected in the event of a sudden frequency disturbance or fluctuating wind conditions. In order to minimize excessive frequency deviations, several techniques and control strategies involving Variable Speed Wind Turbines (VSWTs) have been investigated in isolated power systems. In this paper, the main benefits and disadvantages of introducing VSWTs—both their inertial contribution and primary frequency regulation—in an exclusively renewable isolated power system have been analyzed. Special attention has been paid to the influence of the delays of control signals in the wind farm when VSWTs provide primary regulation as well as to the wind power reserve value which is needed. To achieve this objective, a methodology has been proposed and applied to a case study: El Hierro power system. A mathematical dynamic model of the isolated power system, including exclusively renewable technologies, has been described. Representative generation schedules and wind speed signals have been fixed according to the observed system. Finally, in order to obtain conclusions, realistic system events such as fluctuations in wind speed and the outage of the generation unit with the higher assigned power in the power system have been simulated.
Guillermo Martínez-Lucas; José Ignacio Sarasúa; Juan Ignacio Pérez-Díaz; Sergio Martínez; Danny Ochoa. Analysis of the Implementation of the Primary and/or Inertial Frequency Control in Variable Speed Wind Turbines in an Isolated Power System with High Renewable Penetration. Case Study: El Hierro Power System. Electronics 2020, 9, 901 .
AMA StyleGuillermo Martínez-Lucas, José Ignacio Sarasúa, Juan Ignacio Pérez-Díaz, Sergio Martínez, Danny Ochoa. Analysis of the Implementation of the Primary and/or Inertial Frequency Control in Variable Speed Wind Turbines in an Isolated Power System with High Renewable Penetration. Case Study: El Hierro Power System. Electronics. 2020; 9 (6):901.
Chicago/Turabian StyleGuillermo Martínez-Lucas; José Ignacio Sarasúa; Juan Ignacio Pérez-Díaz; Sergio Martínez; Danny Ochoa. 2020. "Analysis of the Implementation of the Primary and/or Inertial Frequency Control in Variable Speed Wind Turbines in an Isolated Power System with High Renewable Penetration. Case Study: El Hierro Power System." Electronics 9, no. 6: 901.
The relevant integration of wind power into the grid has involved a remarkable impact on power system operation, mainly in terms of security and reliability due to the inherent loss of the rotational inertia as a consequence of such new generation units decoupled from the grid. In these weak scenarios, the contribution of wind turbines to frequency control is considered as a suitable solution to improve system stability. With regard to frequency response analysis and grid stability, most contributions introduce wind control discuss generation tripping for isolated power systems under arbitrary power imbalance conditions. Frequency response is then analyzed for hypothetical imbalances usually ranged between 5% and 20%, and assuming averaged energy schedule scenarios. In this paper, a more realistic framework is proposed to evaluate frequency deviations by including high wind power integration. With this aim, unit commitment schemes and frequency load shedding are considered in this work for frequency response analysis under high wind power penetration. The Gran Canaria Island’s isolated power system (Spain) is used for evaluation purposes. Results provide a variety of influences from wind frequency control depending not only on the wind power integration, but also the generation units under operation, the rotational inertia reductions as well as the available reserves from each resource, aspects that have not been addressed previously in the specific literature to evaluate frequency excursions under high wind power integration.
Ana Fernández-Guillamón; José Ignacio Sarasúa; Manuel Chazarra; Antonio Vigueras-Rodríguez; Daniel Fernández Muñoz; Ángel Molina-García. Frequency control analysis based on unit commitment schemes with high wind power integration: A Spanish isolated power system case study. International Journal of Electrical Power & Energy Systems 2020, 121, 106044 .
AMA StyleAna Fernández-Guillamón, José Ignacio Sarasúa, Manuel Chazarra, Antonio Vigueras-Rodríguez, Daniel Fernández Muñoz, Ángel Molina-García. Frequency control analysis based on unit commitment schemes with high wind power integration: A Spanish isolated power system case study. International Journal of Electrical Power & Energy Systems. 2020; 121 ():106044.
Chicago/Turabian StyleAna Fernández-Guillamón; José Ignacio Sarasúa; Manuel Chazarra; Antonio Vigueras-Rodríguez; Daniel Fernández Muñoz; Ángel Molina-García. 2020. "Frequency control analysis based on unit commitment schemes with high wind power integration: A Spanish isolated power system case study." International Journal of Electrical Power & Energy Systems 121, no. : 106044.
El Hierro, island declared as a biosphere reserve by the UNESCO in 2000, aims to become self-sufficient in energy and 100% free of greenhouse gas emissions. This isolated power system consists of diesel units and a hybrid Wind- Pump Storage Hydropower Plant (W-PSHP), equipped with Variable Speed Wind Turbines (VSWTs), Pelton turbines and a pump station with both fixed- and variable-speed pumps. During last years the annual average renewable energy participation is increasing, especially due to the improvements in the frequency control strategies in PSHP including the operation in short circuit mode. This performance involves an important reduction of the system efficiency but allows PSHP to regulate frequency deviations when available wind power is higher than power demand and the Diesel units are disabled. In this paper different alternative frequency control schemes are proposed so that Pelton units support to the frequency control can be substituted, avoiding energy losses owing to short-circuit operation. This way renewable energy participation would be increased. The control schemes are developed using pumping station regulation capacity, the proper kinetic energy of the VSWTs rotors and a new Flywheel Energy Storage System connected to the grid by means of power electronics. Nine different control cases have been presented, including hydraulic short circuit operating mode. Different simulations have been carried out and they confirm that proposed control schemes fulfil the initial research objectives and enable to improve the global energy efficiency of the system.
José Ignacio Sarasúa; Guillermo Martínez-Lucas; Marcos Lafoz. Analysis of alternative frequency control schemes for increasing renewable energy penetration in El Hierro Island power system. International Journal of Electrical Power & Energy Systems 2019, 113, 807 -823.
AMA StyleJosé Ignacio Sarasúa, Guillermo Martínez-Lucas, Marcos Lafoz. Analysis of alternative frequency control schemes for increasing renewable energy penetration in El Hierro Island power system. International Journal of Electrical Power & Energy Systems. 2019; 113 ():807-823.
Chicago/Turabian StyleJosé Ignacio Sarasúa; Guillermo Martínez-Lucas; Marcos Lafoz. 2019. "Analysis of alternative frequency control schemes for increasing renewable energy penetration in El Hierro Island power system." International Journal of Electrical Power & Energy Systems 113, no. : 807-823.
The wind energy penetration rate is being increased in majority of European countries. However, a high penetration rate could endanger the stability of power systems, particularly in small islands. Hydropower plays an important role in the regulation and control of isolated power systems with renewable sources, but it may not be able to maintain the frequency within grid requirements. This is the case of El Hierro power system (Canary archipelago), where a hybrid wind–pumped storage hydropower plant (PSHP) was committed to reduce the use of fossil fuels. Currently, frequency regulation is only provided by the PSHP and diesel generators. Therefore, it is proposed that variable-speed wind turbines (VSWTs) contribute to frequency regulation, thereby minimizing the need for fossil fuels. This study aims to conduct an analysis on the effect of the VSWT contribution to frequency regulation in the power system of El Hierro. It is based on classical control tools from a linearized mathematical model considering different VSWT regulation strategies. The eigenvalues, damping ratio, and participation factors of the state variables have been obtained. The more significant oscillation modes in the dynamic response of the system have been identified. According to this modal analysis, a methodology for the adjustment of the PSHP and VSWT controller gains is proposed. An improvement in the quality of frequency regulation while maintaining the El Hierro system frequency within grid requirements has been proved based on simulating different events related to wind speed or variations in the power demand, using a nonlinear model of the combined wind–hydro power plant.
Guillermo Martínez-Lucas; José Ignacio Sarasúa; José Ángel Sánchez-Fernández. Eigen analysis of wind–hydro joint frequency regulation in an isolated power system. International Journal of Electrical Power & Energy Systems 2018, 103, 511 -524.
AMA StyleGuillermo Martínez-Lucas, José Ignacio Sarasúa, José Ángel Sánchez-Fernández. Eigen analysis of wind–hydro joint frequency regulation in an isolated power system. International Journal of Electrical Power & Energy Systems. 2018; 103 ():511-524.
Chicago/Turabian StyleGuillermo Martínez-Lucas; José Ignacio Sarasúa; José Ángel Sánchez-Fernández. 2018. "Eigen analysis of wind–hydro joint frequency regulation in an isolated power system." International Journal of Electrical Power & Energy Systems 103, no. : 511-524.
Frequency control is one of the most critical tasks in isolated power systems, especially in high renewable penetration scenarios. This paper presents a new hydropower pumped-storage dual control strategy that combines variable-speed-driven pumps and fixed-speed-driven pumps. A possible case for implementation of such a control scheme is described based on El Hierro Island’s power system. This isolated power system consists of a hybrid wind pumped-storage hydropower plant and diesel generators. The pumped-storage power plant is divided into a hydropower plant equipped with four Pelton turbines and a pump station equipped with both fixed- and variable-speed pumps. According to the proposed control scheme, frequency regulation will be provided by a dual controller: a continuous controller for the variable-speed pumps and a discrete controller for the fixed-speed pumps. The Pelton units, which operate as synchronous condensers, also supply the power system inertia. Therefore, diesel units may be disconnected, decreasing generation costs and greenhouse gas emissions. Owing to the combination of both controllers and the inertia of the Pelton units, an acceptable frequency regulation can be achieved. This technique has been validated through computer simulations.
José Ignacio Sarasúa; Guillermo Martínez-Lucas; Carlos A. Platero; José Ángel Sánchez-Fernández. Dual Frequency Regulation in Pumping Mode in a Wind–Hydro Isolated System. Energies 2018, 11, 2865 .
AMA StyleJosé Ignacio Sarasúa, Guillermo Martínez-Lucas, Carlos A. Platero, José Ángel Sánchez-Fernández. Dual Frequency Regulation in Pumping Mode in a Wind–Hydro Isolated System. Energies. 2018; 11 (11):2865.
Chicago/Turabian StyleJosé Ignacio Sarasúa; Guillermo Martínez-Lucas; Carlos A. Platero; José Ángel Sánchez-Fernández. 2018. "Dual Frequency Regulation in Pumping Mode in a Wind–Hydro Isolated System." Energies 11, no. 11: 2865.
The upgrade of a pumped-storage power plant (PSPP) to allow variable speed operation offer several advantages in pumping and generating modes. However, in pumping mode at part load, both pressure and torque pulsations develop in the pump turbine runner. This paper evaluates the risk of fatigue damage in the penstock of a variable-speed PSPP due to the propagation of the pressure pulsations developing in the pump turbine runner at partial load in pumping mode. For that purpose, a simulation model of a variable-speed PSPP has been developed. The pressure and torque pulsations are generated each from a different set of sinusoidal functions calibrated from the results of a Computational Fluid Dynamic model, which was in turn validated from experimental data. A Monte Carlo simulation has been performed considering different temporal gaps between the sinusoidal functions reproducing the pressure pulsations in one and another pump turbine. The number of stress cycles that may cause fatigue damage in the penstock has been obtained from the results of the simulations and the fatigue curves defined in the Eurocode, and then transformed into the maximum number of hours per year the PSPP can operate at partial load in pumping mode to avoid fatigue damages.
Guillermo Martínez-Lucas; Juan I. Pérez-Díaz; Manuel Chazarra; José I. Sarasúa; Giovanna Cavazzini; Giorgio Pavesi; Guido Ardizzon. Risk of penstock fatigue in pumped-storage power plants operating with variable speed in pumping mode. Renewable Energy 2018, 133, 636 -646.
AMA StyleGuillermo Martínez-Lucas, Juan I. Pérez-Díaz, Manuel Chazarra, José I. Sarasúa, Giovanna Cavazzini, Giorgio Pavesi, Guido Ardizzon. Risk of penstock fatigue in pumped-storage power plants operating with variable speed in pumping mode. Renewable Energy. 2018; 133 ():636-646.
Chicago/Turabian StyleGuillermo Martínez-Lucas; Juan I. Pérez-Díaz; Manuel Chazarra; José I. Sarasúa; Giovanna Cavazzini; Giorgio Pavesi; Guido Ardizzon. 2018. "Risk of penstock fatigue in pumped-storage power plants operating with variable speed in pumping mode." Renewable Energy 133, no. : 636-646.
Currently, some small islands with high wind potential are trying to reduce the environmental and economic impact of fossil fuels by using renewable resources. Nevertheless, the characteristics of these renewable resources negatively affect the quality of the electrical energy, causing frequency disturbances, especially in isolated systems. In this study, the combined contribution to frequency regulation of variable speed wind turbines (VSWT) and a pump storage hydropower plant (PSHP) is analyzed. Different control strategies, using the kinetic energy stored in the VSWT, are studied: inertial, proportional, and their combination. In general, the gains of the VSWT controller for interconnected systems proposed in the literature are not adequate for isolated systems. Therefore, a methodology to adjust the controllers, based on exhaustive searches, is proposed for each of the control strategies. The control strategies and methodology have been applied to a hybrid wind–hydro power plant on El Hierro Island in the Canary archipelago. At present, in this isolated power system, frequency regulation is only provided by the PSHP and diesel generators. The improvements in the quality of frequency regulation, including the VSWT contribution, have been proven based on simulating different events related to wind speed, or variations in the power demand.
Guillermo Martínez-Lucas; José Ignacio Sarasúa; José Ángel Sánchez-Fernández. Frequency Regulation of a Hybrid Wind–Hydro Power Plant in an Isolated Power System. Energies 2018, 11, 239 .
AMA StyleGuillermo Martínez-Lucas, José Ignacio Sarasúa, José Ángel Sánchez-Fernández. Frequency Regulation of a Hybrid Wind–Hydro Power Plant in an Isolated Power System. Energies. 2018; 11 (1):239.
Chicago/Turabian StyleGuillermo Martínez-Lucas; José Ignacio Sarasúa; José Ángel Sánchez-Fernández. 2018. "Frequency Regulation of a Hybrid Wind–Hydro Power Plant in an Isolated Power System." Energies 11, no. 1: 239.
This paper presents a dynamic simulation model of a laboratory-scale pumped-storage power plant (PSPP) operating in pumping mode with variable speed. The model considers the dynamic behavior of the conduits by means of an elastic water column approach, and synthetically generates both pressure and torque pulsations that reproduce the operation of the hydraulic machine in its instability region. The pressure and torque pulsations are generated each from a different set of sinusoidal functions. These functions were calibrated from the results of a CFD model, which was in turn validated from experimental data. Simulation model results match the numerical results of the CFD model with reasonable accuracy. The pump-turbine model (the functions used to generate pressure and torque pulsations inclusive) was up-scaled by hydraulic similarity according to the design parameters of a real PSPP and included in a dynamic simulation model of the said PSPP. Preliminary conclusions on the impact of unstable operation conditions on the penstock fatigue were obtained by means of a Monte Carlo simulation-based fatigue analysis.
G Martínez-Lucas; Juan Ignacio Pérez-Díaz; J I Sarasúa; G Cavazzini; Giorgio Pavesi; G Ardizzon. Simulation model of a variable-speed pumped-storage power plant in unstable operating conditions in pumping mode. Journal of Physics: Conference Series 2017, 813, 12028 .
AMA StyleG Martínez-Lucas, Juan Ignacio Pérez-Díaz, J I Sarasúa, G Cavazzini, Giorgio Pavesi, G Ardizzon. Simulation model of a variable-speed pumped-storage power plant in unstable operating conditions in pumping mode. Journal of Physics: Conference Series. 2017; 813 ():12028.
Chicago/Turabian StyleG Martínez-Lucas; Juan Ignacio Pérez-Díaz; J I Sarasúa; G Cavazzini; Giorgio Pavesi; G Ardizzon. 2017. "Simulation model of a variable-speed pumped-storage power plant in unstable operating conditions in pumping mode." Journal of Physics: Conference Series 813, no. : 12028.
Pumped storage hydro plants (PSHP) can provide adequate energy storage and frequency regulation capacities in isolated power systems having significant renewable energy resources. Due to its high wind and solar potential, several plans have been developed for La Palma Island in the Canary archipelago, aimed at increasing the penetration of these energy sources. In this paper, the performance of the frequency control of La Palma power system is assessed, when the demand is supplied by the available wind and solar generation with the support of a PSHP which has been predesigned for this purpose. The frequency regulation is provided exclusively by the PSHP. Due to topographic and environmental constraints, this plant has a long tail-race tunnel without a surge tank. In this configuration, the effects of pressure waves cannot be neglected and, therefore, usual recommendations for PID governor tuning provide poor performance. A PI governor tuning criterion is proposed for the hydro plant and compared with other criteria according to several performance indices. Several scenarios considering solar and wind energy penetration have been simulated to check the plant response using the proposed criterion. This tuning of the PI governor maintains La Palma system frequency within grid code requirements.
Guillermo Martínez-Lucas; José Ignacio Sarasúa; José Ángel Sánchez-Fernández; José Román Wilhelmi. Frequency control support of a wind-solar isolated system by a hydropower plant with long tail-race tunnel. Renewable Energy 2016, 90, 362 -376.
AMA StyleGuillermo Martínez-Lucas, José Ignacio Sarasúa, José Ángel Sánchez-Fernández, José Román Wilhelmi. Frequency control support of a wind-solar isolated system by a hydropower plant with long tail-race tunnel. Renewable Energy. 2016; 90 ():362-376.
Chicago/Turabian StyleGuillermo Martínez-Lucas; José Ignacio Sarasúa; José Ángel Sánchez-Fernández; José Román Wilhelmi. 2016. "Frequency control support of a wind-solar isolated system by a hydropower plant with long tail-race tunnel." Renewable Energy 90, no. : 362-376.
In this paper, the dynamic response of a long penstock pumped-storage hydropower plant which is equipped with a single pump-turbine and a doubly-fed induction machine, is analyzed in detail in generating mode. The pumped-storage hydropower plant is connected to a small island power system with thermal generation, and provides load–frequency control under the orders of an automatic generation control system. The output power of the pumped-storage hydropower plant is assumed to be controlled by the rotor-side frequency converter. The unit running speed is controlled by an isochronous PI governor. The dynamic response of the pumped-storage hydropower plant is analyzed by using a linearized reduced order dynamic model, which considers the elastic water column effects in the penstock. Two governor tuning criteria are proposed in the paper: one is devised from the root locus analysis of the plant dynamic model, and the other one is based on a Pareto approach. The proposed tuning criteria are compared with each other and with a recently published tuning criterion through a set of commonly used performance indexes and by means of simulations with a nonlinear dynamic model.
José Ignacio Sarasúa; Juan Ignacio Pérez-Díaz; José Román Wilhelmi; José Ángel Sánchez-Fernández. Dynamic response and governor tuning of a long penstock pumped-storage hydropower plant equipped with a pump-turbine and a doubly fed induction generator. Energy Conversion and Management 2015, 106, 151 -164.
AMA StyleJosé Ignacio Sarasúa, Juan Ignacio Pérez-Díaz, José Román Wilhelmi, José Ángel Sánchez-Fernández. Dynamic response and governor tuning of a long penstock pumped-storage hydropower plant equipped with a pump-turbine and a doubly fed induction generator. Energy Conversion and Management. 2015; 106 ():151-164.
Chicago/Turabian StyleJosé Ignacio Sarasúa; Juan Ignacio Pérez-Díaz; José Román Wilhelmi; José Ángel Sánchez-Fernández. 2015. "Dynamic response and governor tuning of a long penstock pumped-storage hydropower plant equipped with a pump-turbine and a doubly fed induction generator." Energy Conversion and Management 106, no. : 151-164.
This paper analyses different control strategies for the speed control loop of a variable-speed pump-turbine unit equipped with a doubly fed induction generator, operating in generating mode in an isolated power system with high penetration of intermittent renewable energy. The control strategies are evaluated and compared to each other in terms of the amount of water discharged through the pump-turbine and of the wicket gates fatigue while providing primary and secondary load-frequency control. The influence of the penstock length and the initial operating point on the performance of each control strategy is studied in detail. For these purposes, several simulations have been performed with a suitable dynamic model of the pumped-storage hydropower plant and the power system. The results of the paper indicate that a proper control strategy would consist in updating the reference speed according to the power generation schedule and keeping it constant within each scheduling period (typically 1 h).
José Ignacio Sarasúa; Juan Ignacio Pérez-Díaz; Blanca Torres Vara. On the Implementation of Variable Speed in Pump-Turbine Units Providing Primary and Secondary Load-Frequency Control in Generating Mode. Energies 2015, 8, 13559 -13575.
AMA StyleJosé Ignacio Sarasúa, Juan Ignacio Pérez-Díaz, Blanca Torres Vara. On the Implementation of Variable Speed in Pump-Turbine Units Providing Primary and Secondary Load-Frequency Control in Generating Mode. Energies. 2015; 8 (12):13559-13575.
Chicago/Turabian StyleJosé Ignacio Sarasúa; Juan Ignacio Pérez-Díaz; Blanca Torres Vara. 2015. "On the Implementation of Variable Speed in Pump-Turbine Units Providing Primary and Secondary Load-Frequency Control in Generating Mode." Energies 8, no. 12: 13559-13575.
In this paper the power-frequency control of hydropower plants with long penstocks is addressed. In such configuration the effects of pressure waves cannot be neglected and therefore commonly used criteria for adjustment of PID governors would not be appropriate. A second-order Π model of the turbine-penstock based on a lumped parameter approach is considered. A correction factor is introduced in order to approximate the model frequency response to the continuous case in the frequency interval of interest. Using this model, several criteria are analysed for adjusting the PI governor of a hydropower plant operating in an isolated system. Practical criteria for adjusting the PI governor are given. The results are applied to a real case of a small island where the objective is to achieve a generation 100% renewable (wind and hydro). Frequency control is supposed to be provided exclusively by the hydropower plant. It is verified that the usual criterion for tuning the PI controller of isolated hydro plants gives poor results. However, with the new proposed adjustment, the time response is considerably improve
Guillermo Martínez De Lucas; José Ignacio Sarasúa; José Ángel Sánchez-Fernández; José Román Wilhelmi. Power-frequency control of hydropower plants with long penstocks in isolated systems with wind generation. Renewable Energy 2015, 83, 245 -255.
AMA StyleGuillermo Martínez De Lucas, José Ignacio Sarasúa, José Ángel Sánchez-Fernández, José Román Wilhelmi. Power-frequency control of hydropower plants with long penstocks in isolated systems with wind generation. Renewable Energy. 2015; 83 ():245-255.
Chicago/Turabian StyleGuillermo Martínez De Lucas; José Ignacio Sarasúa; José Ángel Sánchez-Fernández; José Román Wilhelmi. 2015. "Power-frequency control of hydropower plants with long penstocks in isolated systems with wind generation." Renewable Energy 83, no. : 245-255.
The objective of this paper is to investigate the cause of several unexpected high amplitude oscillations that occurred in the surge tank water level of a real hydropower plant during secondary load-frequency control (LFC) maneuvers, after the replacement of the turbine runner, and to propose solutions that allow the power plant to continue providing secondary LFC in a safe and reliable manner. For this purpose, a simulation model has been developed and calibrated from data gathered during several on-site tests. Two different solutions are proposed in order to cope with the observed problem: using a state-dependent load change rate limiter or modifying the hydro turbine governor gains; the turbine governor remains the same as before the runner replacement. The proposed solutions are tested against a set of realistic secondary LFC signals by means of simulations and compared to each other as a function of the probability that the surge tank water level descends below a minimum safe level and the quality of the secondary LFC response. The results presented in the paper demonstrate the validity of the methodology proposed to determine the state-dependent ramp limit, as well as its effectiveness to prevent the surge tank drawdown and to provide clear insight into the trade-off between response quality and power plant safety.
Juan I. Pérez-Díaz; José I. Sarasúa. Failures during Load-Frequency Control Maneuvers in an Upgraded Hydropower Plant: Causes, Identification of Causes and Solution Proposals. Energies 2015, 8, 10584 -10604.
AMA StyleJuan I. Pérez-Díaz, José I. Sarasúa. Failures during Load-Frequency Control Maneuvers in an Upgraded Hydropower Plant: Causes, Identification of Causes and Solution Proposals. Energies. 2015; 8 (10):10584-10604.
Chicago/Turabian StyleJuan I. Pérez-Díaz; José I. Sarasúa. 2015. "Failures during Load-Frequency Control Maneuvers in an Upgraded Hydropower Plant: Causes, Identification of Causes and Solution Proposals." Energies 8, no. 10: 10584-10604.
In this paper, a hydroelectric power plant with long tail-race tunnel has been modelled for assessing its contribution to secondary regulation reserve. Cavitation problems, caused by the discharge conduit length, are expected downstream the turbine where low pressure appears during regulation manoeuvres. Therefore, governor's gains should be selected taking into account these phenomena. On the other hand, regulation services bidden by the plant operator should fulfil TSO (Transmission System Operator) quality requirements. A methodology for tuning governor PI gains is proposed and applied to a Hydro power plant in pre-design phase in northwest area of Spain. The PI gains adjustment proposed provides a proper plant response, according to some established indexes, while avoiding cavitation phenomena.
Guillermo Martínez-Lucas; José Ignacio Sarasúa; José Román Wilhelmi; Jose Angel Sanchez; Martinez-Lucas G.; Sarasua J.I.; Wilhelmi J.R.; Sanchez J.A.. Contribution to load-frequency regulation of a hydropower plant with long tail-race tunnel. 2015 IEEE 15th International Conference on Environment and Electrical Engineering (EEEIC) 2015, 1886 -1891.
AMA StyleGuillermo Martínez-Lucas, José Ignacio Sarasúa, José Román Wilhelmi, Jose Angel Sanchez, Martinez-Lucas G., Sarasua J.I., Wilhelmi J.R., Sanchez J.A.. Contribution to load-frequency regulation of a hydropower plant with long tail-race tunnel. 2015 IEEE 15th International Conference on Environment and Electrical Engineering (EEEIC). 2015; ():1886-1891.
Chicago/Turabian StyleGuillermo Martínez-Lucas; José Ignacio Sarasúa; José Román Wilhelmi; Jose Angel Sanchez; Martinez-Lucas G.; Sarasua J.I.; Wilhelmi J.R.; Sanchez J.A.. 2015. "Contribution to load-frequency regulation of a hydropower plant with long tail-race tunnel." 2015 IEEE 15th International Conference on Environment and Electrical Engineering (EEEIC) , no. : 1886-1891.
Juan Ignacio Pérez-Díaz; José Ignacio Sarasúa; José R. Wilhelmi. Contribution of a hydraulic short-circuit pumped-storage power plant to the load–frequency regulation of an isolated power system. International Journal of Electrical Power & Energy Systems 2014, 62, 199 -211.
AMA StyleJuan Ignacio Pérez-Díaz, José Ignacio Sarasúa, José R. Wilhelmi. Contribution of a hydraulic short-circuit pumped-storage power plant to the load–frequency regulation of an isolated power system. International Journal of Electrical Power & Energy Systems. 2014; 62 ():199-211.
Chicago/Turabian StyleJuan Ignacio Pérez-Díaz; José Ignacio Sarasúa; José R. Wilhelmi. 2014. "Contribution of a hydraulic short-circuit pumped-storage power plant to the load–frequency regulation of an isolated power system." International Journal of Electrical Power & Energy Systems 62, no. : 199-211.
Run-of-river hydropower plants usually lack significant storage capacity; therefore, the more adequate control strategy would consist of keeping a constant water level at the intake pond in order to harness the maximum amount of energy from the river flow or to reduce the surface flooded in the head pond. In this paper, a standard PI control system of a run-of-river diversion hydropower plant with surge tank and a spillway in the head pond that evacuates part of the river flow plant is studied. A stability analysis based on the Routh-Hurwitz criterion is carried out and a practical criterion for tuning the gains of the PI controller is proposed. Conclusions about the head pond and surge tank areas are drawn from the stability analysis. Finally, this criterion is applied to a real hydropower plant in design state; the importance of considering the spillway dimensions and turbine characteristic curves for adequate tuning of the controller gains is highlighted.
José Ignacio Sarasúa; Paz Elías; Guillermo Martínez-Lucas; Juan Ignacio Perez-Diaz; José Román Wilhelmi; José Angel Sánchez. Stability Analysis of a Run-of-River Diversion Hydropower Plant with Surge Tank and Spillway in the Head Pond. The Scientific World Journal 2014, 2014, 1 -13.
AMA StyleJosé Ignacio Sarasúa, Paz Elías, Guillermo Martínez-Lucas, Juan Ignacio Perez-Diaz, José Román Wilhelmi, José Angel Sánchez. Stability Analysis of a Run-of-River Diversion Hydropower Plant with Surge Tank and Spillway in the Head Pond. The Scientific World Journal. 2014; 2014 (5):1-13.
Chicago/Turabian StyleJosé Ignacio Sarasúa; Paz Elías; Guillermo Martínez-Lucas; Juan Ignacio Perez-Diaz; José Román Wilhelmi; José Angel Sánchez. 2014. "Stability Analysis of a Run-of-River Diversion Hydropower Plant with Surge Tank and Spillway in the Head Pond." The Scientific World Journal 2014, no. 5: 1-13.
The run-of-river hydro power plant usually have low or nil water storage capacity, and therefore an adequate control strategy is required to keep the water level constant in pond. This paper presents a novel technique based on TSK fuzzy controller to maintain the pond head constant. The performance is investigated over a wide range of hill curve of hydro turbine. The results are compared with PI controller as discussed in [1].
Omkar Yadav; Nand Kishor; Jesus Fraile-Ardanuy; Soumya R Mohanty; Juan I. Pérez; José I. Sarasúa. Pond head level control in a run-of-river hydro power plant using fuzzy controller. 2011 16th International Conference on Intelligent System Applications to Power Systems 2011, 1 -5.
AMA StyleOmkar Yadav, Nand Kishor, Jesus Fraile-Ardanuy, Soumya R Mohanty, Juan I. Pérez, José I. Sarasúa. Pond head level control in a run-of-river hydro power plant using fuzzy controller. 2011 16th International Conference on Intelligent System Applications to Power Systems. 2011; ():1-5.
Chicago/Turabian StyleOmkar Yadav; Nand Kishor; Jesus Fraile-Ardanuy; Soumya R Mohanty; Juan I. Pérez; José I. Sarasúa. 2011. "Pond head level control in a run-of-river hydro power plant using fuzzy controller." 2011 16th International Conference on Intelligent System Applications to Power Systems , no. : 1-5.
Nowadays, new small hydro power plants are being built all over the world. In most cases, these power plants lack significant storage capacity; therefore the more adequate control strategy is to keep constant the water level at the intake basin to capture the maximum amount of energy from the river flow. In this paper, the control of a diversion run of river hydro plant is considered. A practical criterion for tuning the gains of the PI controller is proposed. The influence of turbine operating point on controller gains is analyzed. Finally, the results are applied to a model of a typical hydropower plant to verify that the tuning of the PI controller allows a stable and suitable control of the power plant.
Jose I. Sarasua; Jesus Fraile-Ardanuy; Juan I. Perez; Jose R. Wilhelmi; Jose A. Sanchez. Control of a run of river small hydro power plant. 2007 International Conference on Power Engineering, Energy and Electrical Drives 2007, 672 -677.
AMA StyleJose I. Sarasua, Jesus Fraile-Ardanuy, Juan I. Perez, Jose R. Wilhelmi, Jose A. Sanchez. Control of a run of river small hydro power plant. 2007 International Conference on Power Engineering, Energy and Electrical Drives. 2007; ():672-677.
Chicago/Turabian StyleJose I. Sarasua; Jesus Fraile-Ardanuy; Juan I. Perez; Jose R. Wilhelmi; Jose A. Sanchez. 2007. "Control of a run of river small hydro power plant." 2007 International Conference on Power Engineering, Energy and Electrical Drives , no. : 672-677.