Hydraulic Turbine Generator Research Articles

Controls of Hydraulic Wind Turbine

In this paper a hydraulic wind turbine generator system was proposed based on analysis the current wind turbines technologies. The construction and principles were introduced. The mathematical model was verified using MATLAB and AMsim. A displacement closed loop of swash plate of motor and a speed closed loop of generator were setup, a PID control is introduced to maintain a constant speed and fixed frequency at wind turbine generator. Simulation and experiment demonstrated that the system can connect grid to generate electric and enhance reliability. The control system demonstrates a high performance speed regulation and effectiveness. The results are great significant to design a new type hydraulic wind turbine system.

Multi-unit hydroelectric generator based on contact electrification and its service behavior

Water is one of the most abundant energy sources in our environment and hydroelectric power has been one of the main forms of macro-energy supply. However, for harvesting green micro-energy from water presented in our residential zone, industry or agricultural irrigation, traditional electromagnetic hydraulic turbine generator has limited applications due to its large size, complexity and high cost. Here we report a novel design of the multi-unit hydroelectric generator (HEG) for harvesting water-related energy based on contact electrification. The instantaneous output power density of the multi-unit HEG array is 0.07W/m2, which is 9 times of that from the individual HEG with the same dimension. Moreover, the rational design of the multi-unit HEG can increase the safety for its future service. By integrating with the multi-unit HEG, the household faucet can be a power source to supply clean energy continuously. Given the compelling features, such as, highly efficient, easily implemented, lightweight and extremely cost-effective, the multi-unit HEG renders a promising approach toward clean energy harvesting from ambient environment.

Study on the stability of waterpower-speed control system for hydropower station with air cushion surge chamber

According to the fact that the effects of penstock, unit and governor on stability of water level fluctuation for hydropower station with air cushion surge chamber are neglected in previous researches, in this paper, Thoma assumption is broken through, the complete mathematical model of waterpower-speed control system for hydropower station with air cushion surge chamber is established, and the comprehensive transfer function and linear homogeneous differential equation that characterize the dynamic characteristics of system are derived. The stability domain that characterizes the good or bad of stability quantitatively is drawn by using the stability conditions. The effects of the fluid inertia in water diversion system, the air cushion surge chamber parameters, hydraulic turbine characteristics, generator characteristics, and regulation modes of governor on the stability of waterpower-speed control system are analyzed through stability domain. The main conclusions are as follows: The fluid inertia in water diversion system and hydraulic turbine characteristics have unfavorable effects on the system while generator characteristics have favorable effect. The stability keeps getting better with the increase of chamber height and basal area and the decrease of air pressure and air polytropic exponent. The stability of power regulation mode is obviously better than that of frequency regulation mode.

Hybrid reliability model of hydraulic turbine-generator unit based on nonlinear vibration

In order to study the vibration reliability of hydraulic turbine-generator unit, the nonlinear dynamic equation of the main shaft system of hydraulic turbine-generator unit is established by the finite element method. Then the nonlinear vibration characteristics of the system are analyzed and the excitation frequencies of the system are obtained by the method of multiple scales. Based on the criterion that the absolute values of difference between the natural frequencies and excitation frequencies of the system should be less than specific values, the hybrid probabilistic, nonprobabilistic, and fuzzy reliability model of the system based on nonlinear vibration is constructed. By the hybrid reliability model, the reliability of system can be calculated. Finally, an example is presented.

PID controller design for hydraulic turbine based on sensitivity margin specifications

The paper presents a proportional-integral-derivative (PID) controller design procedure for a hydraulic turbine generator governor meeting sensitivity margin specifications. The closed-loop performance is guaranteed over wide range of operating conditions of the interconnected system. The main advantage of the proposed method consists in the simple design using only one tuning parameter. The control performance of the presented method is compared on simulations with the procedure guaranteing gain and phase margins using non-convex optimization.

Study on method of electricity and heat storage planning based on energy demand and tidal flow velocity forecasts for a tidal microgrid

The rapid tidal current near a lake inlet is transformed into electrical energy with Darius-type hydraulic turbine generators. When the tidal power generation is insufficient, the stored excess electric power generated from midnight to early morning of a representative day is used. The balance of energy supply and demand for all sampling events in a representative day must be predicted very accurately in a system with energy storage. In this study, electric power and heat demand are forecasted on the basis of weather data obtained from the Internet, and the corresponding values are used to plan the storage of electricity and heat from midnight to early morning. The results of the case analysis show the influence of the economic efficiency of the heating system, the capacity of the tidal power generator, the prediction error of the tidal power generator, and the insulation efficiency (Q-value) on the energy cost. Optimization of the introduced simulation model was considered. The objective functions of optimization were minimization of operation cost and facilities cost of the simulation model.

Electrical braking of synchronous generators for combined generator and water turbine bearings as well as stray‐load losses determination

This study describes a new method for determining combined synchronous generator and water turbine bearings losses as well as stray-load losses of a generator, based on measurement of the speed change during electrical braking. In the electrical braking regime, the total braking torque of a hydrogenerator is made up of the torques defined by losses in the runner chamber of the hydraulic turbine, ventilation losses in the hydraulic-turbine generator, bearings losses in the generator and the water turbine, as well as electromagnetic and stray-load losses in the short-circuit. In this study, the torque–speed curve is represented by the corresponding equations which describe all the torques occurring during electrical braking. By applying these equations to the measured results and using some numerical calculations, combined generator and water turbine bearings losses as well as stray-load losses can be obtained. The proposed method is applied on a 190 MW generator at the Hydro Power Plant (HPP) Djerdap (in Serbia). The obtained results demonstrated a very high level of accuracy when compared with the values found in the manufacturer's technical documentation (Electrosila). The proposed method has the best and most economical use in large synchronous generators and generators in older power plants.

Nonlinear Vibration Reliability of Hydraulic Turbine-generator Units with Multiple Failure Modes

Taking the main shaft system of hydraulic turbine-generator unit as an object,the nonlinear dynamic equation is established by the finite element method.Based on the equation,the nonlinear vibration characteristics of the system are analyzed and the excitation frequencies of the system are obtained.Considering the randomness of the structure parameters,material parameters,hydraulic parameters and electromagnetic parameters of system,the gradients of natural frequencies to the random parameters are obtained.According to the criterion that the absolute values of difference between the natural frequencies and excitation frequencies of system should be less than specific values,the failure probability with one single failure mode and the combined failure probability with two failure modes are calculated by dividing the variable space into several simple areas.The nonlinear vibration reliability model of the main shaft system of hydraulic turbine-generator units with correlated failure modes is constructed and the method by which the nonlinear vibration reliability of system with multiple failure modes can be analyzed is proposed.An example is presented and the nonlinear vibration reliability model is proved by the Monte Carlo method.

Development of the water-lubricated thrust bearing of the hydraulic turbine generator

In hydropower plant, a large quantities of turbine oil is used as machine control pressure oil and lubricating oil. If the oil leak out from hydropower plant, it flows into a river. And such oil spill has an adverse effect on natural environment because the oil does not degrade easily. Therefore the KANSAI and Hitachi Mitsubishi Hydro developed the water-lubricated thrust bearing for vertical type hydraulic turbine generator. The water-lubricated bearing has advantages in risk avoidance of river pollution because it does not need oil. For proceeding the development of the water-lubricated thrust bearing, we studied following items. The first is the examination of the trial products of water lubricating liquid. The second is the study of bearing structure which can satisfy bearing performance such as temperature characteristic and so on. The third is the mock-up testing for actual application in the future. As a result, it was found that the water-lubricated thrust bearing was technically applicable to actual equipments.

Study on safety operation for large hydroelectric generator unit

Hydroelectric generator unit is a complex mechanical system which is composed of hydraulic turbine and electric generator. Rotary system is supported by the bearing bracket and the reinforced concrete structures, and vibration problem can't be avoided in the process of operating. Many large-scale hydroelectric units have been damaged because of the vibration problem in recent years. As the increase of the hydraulic turbine unit capacity and water head, the safe operation of hydraulic turbine has become a focus research in many countries. The operating characteristics of the hydraulic turbine have obvious differences at different working conditions. Based on the combination of field measurement and theoretical calculation, this paper shows a deep research on the safe operation of a large-scale Francis turbine unit. Firstly, the measurements of vibration, swing, pressure fluctuation and noise were carried out at 4 different heads. And also the relationships between vibrations and pressure fluctuations at different heads and working conditions were analysed deeply. Then the scientific prediction of safe operation for the unit at high head were done based on the CFD numerical calculation. Finally, this paper shows the division of the operating zone for the hydroelectric unit. According to the experimental results (vibrations, swings, pressure fluctuations and noise) as well as the theoretical results, the operating zone of the unit has been divided into three sections: prohibited operating zone, transition operating zone and safe operating zone. After this research was applied in the hydropower station, the security and economic efficiency of unit increased greatly, and enormous economic benefits and social benefits have been obtained.

Modelling of the hydro-generator local network operation and load disturbance rejection

The paper describes models of the local network operation of the hydraulic turbine-generator unit. Two different models are proposed. They describe the dynamic behaviour of a system in which the unit is connected to an equivalent system. A nonlinear model of the interconnection to an equivalent power system is considered. An optimal controller for load disturbance rejection in water turbine speed and power control is designed. The frequency and power deviations are examined in the case of a sudden load change.

Robust PID Controller Design for Hydroturbines

The design and analysis of a robust proportional, integral, derivative (PID) controller for a hydraulic turbine generator governor using a frequency-response technique is presented. The approach uses data from literature on the turbine and on the interconnected system in various modes of operation through a model in the literature to design a single PID controller to guarantee stability and performance over the entire operating range. To ensure stability of the loop for as yet unanticipated operating situations, gain margin, and phase margin, constraints are imposed during the design of the controller. The new PID governor is compared with a high-order controller designed by the H/sub /spl infin// method.

Fault diagnosis system for hydraulic turbine generator

Fault diagnosis system for hydraulic turbine generator

Predictive Maintenance Using the Rotordynamic Model of a Hydraulic Turbine-Generator Rotor

A use of rotordynamic models in predictive maintenance is described in which variables characterizing the state of a deterioration mechanism are determined from online measurements. These variables are trended to determine the rate of deterioration and to perform a simulation to predict either the machine life or the maintenance period. Some useful terms for using models in predictive maintenance are defined and the prediction procedure is described. The procedure is demonstrated with a simple two degree-of-freedom example and the numerical model of an actual hydraulic turbine-generator rotor. Some benefits and problems associated with the implementation of the procedure are then discussed. It is considered that this procedure brings the possibility of a better understanding of deterioration processes and a resulting better life prediction.

Initial breaking speed of hydroelectric units

1. In the majority of hydraulic-turbine generators with r ≤ 0.002, electric braking may be used without apprehension; this braking process is suspended in the zone of the ascending branch of the torque curve, since the total mechanical braking torque provides for braking of the hydroelectric unit to n1/nn=0.14\2-0.16. For machines with a lower stator-winding resistance, it is necessary to perform a detailed calculation. If it is found from the results of the calculation that the braking torque is insufficient within some range of rotational speeds, it is necessary to incorporate a series-resistance stator in the circuit. 2. The magnitude of synchronous inductive impedance exerts an influence primarily only on the minimum rotational speed at which braking of the hydroelectric unit is suspended (n2); this corresponds to the descending branch of the electric-braking curve. As for the second root of Eq. (7a), n1/nn≈100r, i.e., as is apparent from (8), xd has virtually no effect on n1. 3. For any ratio of parameters of the hydraulic-turbine generators, the minimum rotational speed n2 at which the rotational torque and braking torque of the hydroelectric unit are equal is less than 0.05% of the nominal. It therefore follows that the setting for the automatic application of brakes at the end of the electric-braking process may be very low, and selection of the setting may conform only to the condition that the signal for braking was rather stable in terms of speed.

Experience gained by the “Élektrosila” plant in the rebuilding and replacement of hydraulic-turbine generators at operating hydroelectric plants

Experience gained by the “Élektrosila” plant in the rebuilding and replacement of hydraulic-turbine generators at operating hydroelectric plants

Design of an optimal robust governor for hydraulic turbine generating units

Design and analysis of a hydraulic turbine generator governor using optimal robust control methodology are presented. The approach is unique in the sense that the nonlinear characteristics of the turbine are first modelled as multiplicative uncertainties; and an optimal robust governor is designed by taking into account such uncertainties explicitly. The advantage of this approach is that the designed governor will guarantee the stability and the performance of the speed control loop for the entire turbine operating range. The performance of the new governor is shown to be superior to that of the conventional PID controller during large load disturbances. The resulting governor is only a third order. Hence, it has the same level of complexity as any other electrical-hydraulic governor in use today.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Minimum Structured Processes Modelling: A Rule-Based Approach

This paper presents a simple method for minimum structured process modelling via a rule-based technique. Under the assumption that the processes are stable, step input signals are applied and step responses data are collected. Six different types of minimum structured models are then defined. They are Monotone Response (MR), Undershoot Monotone Response (UMR), Oscillatory Response (OR), Undershoot Oscillatory Response (UOR), Odd Undershoot Monotone Response (OUMR), and Odd Undershoot Oscillatory Response (OUOR). A classifier is built which, for a given step response, generates the information about the type of response. A proposed minimum structured model is then obtained. Different minimum structured models are used to achieve the initial fitting for the given response. This leads to the rough tuning of model parameters. Finally, a rule-based fine tuner is constructed and used to find out the accurate parameters of the proposed model. Desirable results are obtained when the method is applied to the modelling of the machine direction weight profile in a paper-making process and the speed control system of a hydraulic turbine generator.

Performance monitoring in expert control systems

A general structure of a real-time expert controller (EC) is proposed in this paper. The controller consists of (i) a knowledge-base, (ii) a real-time inference engine, (iii) a real-time information pre-processor, and (iv) control mechanisms. A real-time information pre-processor is developed. It contains a set of digital signal processing schemes which are used to monitor the overall system performance and diagnose potential control system component failures. Both forward-chaining and backward-chaining inference mechanisms are used in the inference engine. The knowledge-base and the inference engine are constructed using PROLOG, and the C language is used to implement the information pre-processor. The EC is implemented in real-time on a microcomputer. The performance of a prototype EC using the designed information pre-processor is evaluated by simulating in real-time various types of failures in a hydraulic turbine generator governor system.

An optimal turning-off regulation for hydraulic turbine generators

This paper addresses applying nonlinear optimal control theory to the turning-off regulation of hydraulic turbine generators. Using the gradient iterative method in computer-aided design procedures, the authors obtain the optimal turning-off regulation. Simulation and application experiences show that it can greatly reduce the maximal increasing value of hydraulic pressure in water pipes and simultaneously limit rotational speed of the turbine to meet actual requirements when the hydraulic turbine has to throw off its load.