Turbine Protection Research Articles

Microplastics Emission from Eroding Wind Turbine Blades: Preliminary Estimations of Volume

The erosion of wind turbine blades is one of the most frequently observed mechanisms of wind turbine blade damage. In recent months and years, concerns about high volumes of eroded plastics and associated pollution risks have surfaced on social networks and in newspapers. In this scientific paper, we estimate the mass of plastic removed from blade surface erosion, using both a phenomenological model of blade erosion and the observed frequency of necessary repairs of blades. Our findings indicate that the mass of eroded plastic ranges from 30 to 540 g per year per blade. The mass loss is higher for wind turbines offshore (80–1000 g/year per blade) compared to onshore (8–50 g/year per blade). The estimations are compared with scientific literature data and other gray literature sources. Using the entire Danish wind farms portfolio, we quantify the yearly mass of plastic from blade erosion to be about 1.6 tons per year, which is an order of magnitude less than that from footwear and road marking and three orders of magnitude less than that from tires. While the contribution of wind blade erosion is small compared to other sources, the results of this work underline the importance of the (A) effective leading-edge protection of wind turbines, (B) regular and efficient maintenance, and (C) the optimal selection of materials used.

PENGEMBANGAN SISTEM PENGEREMAN TURBIN ANGIN SUMBU HORIZONTAL MENGGUNAKAN KONTROL PID

Horizontal axis wind turbines will generate voltage if the turbine rotates due to wind gusts. The bigger the wind blows, the faster the turbine spins and the greater the voltage generated. The braking system is needed for wind turbine protection when it receives very large wind speeds. This system is built using PID control based on microcontroller with reference to the output voltage. There are 2 units resistor designed as voltage sensors to the wind turbine output voltage. In testing, the wind turbine is rotated using artificial wind which is generated through a blower measuring 1.3 x 1.3 x 0.3 m, with a maximum wind speed is 11 m/s. The sistem uses PID kontrol which is used to brake wind turbine rotation and regulate its output voltage. Determination of constant parameters for proportional constant (Kp), integral constant (Ki), and Derivative constant (Kd) were obtained for Kp = 0.139, Ki = 0.715, and Kd = 0.006 respectively. The output voltage of the wind turbine can reach 60 volts and then controlled up to 24 volts according to the battery voltage requirements. In the test results, the control system managed to regulate the wind turbine voltage at 24 volts with a steady state error of 6.62%

Optimization of the Steam Turbine Protection System as Part of an Electrohydraulic Control System

Optimization of the Steam Turbine Protection System as Part of an Electrohydraulic Control System

Study on Condition Monitoring of Pitch Bearings Based on Stress Measurement

Pitch bearings in wind turbines are crucial components that enable safe blade pitching, optimize electrical power output, and ensure turbine protection. Traditional vibration analysis-based methods used for high-speed bearings are not applicable to monitoring pitch bearings, due to its slow non-integer cycle rotation. To address this issue, a stress-based pitch bearing monitoring method is proposed in this paper. First, finite element analysis is conducted to establish the relationship between the maximum surface stress on the outer race of the pitch bearing and the presence of cracks. This relationship allows the identification of cracks on the outer race and an assessment of their severity based on the value of the maximum surface stress. Second, the outer race of the pitch bearing is divided into several segments, and a singularity detection technique is employed to locate the position of cracks on the outer race based on the stresses measured from the segments. To verify the proposed method, a wind turbine pitch bearing test rig was developed in a laboratory. Experimental results have shown that the proposed method can effectively and accurately identify and locate cracks on the outer race of the bearing, thereby demonstrating its great potential as a reliable approach for monitoring the condition of wind turbine pitch bearings.

EMTP-RV Analysis of Lightning Surges on Wind Turbines

This paper is concerned with lightning surge propagation on wind turbines. As wind power generation undergoes rapid growth, lightning incidents involving wind turbines have come to be regarded as a serious problem. Nevertheless, no known studies exist yet in Portugal regarding lightning protection of wind turbines. Hence, we present a case study, based on a wind turbine with an interconnecting transformer, for the analysis of lightning surges. Computer simulations obtained by using the EMTP-RV code are presented. Conclusions are duly drawn.

Optimal design and control of hybrid synchronous generator regulating turbine angular speed for turbine protection

In this paper is presented a methodology of systemic design and control of a synchronous generator with hybrid excitation for the generation of wind energy. The design of the generator is made by the analytical method taking into account the interactions of the global system. Indeed, the regulation of the speed of the turbine is ensured by adjustment of the excitation current to regulate the electromagnetic torque and in this case the excitation current is limited to a fixed value since the increase of excitation current leads to an increase generator’s phase currents magnitude. The increase of the phase’s currents of the generator is linked to the increase of the amplitude of the electromotive forces depending on the excitation current. Therefore, to limit the amplitude of the phase’s currents to the value of the design current fixed by the note book specifications for a given power of the wind turbine, it is necessary to limit the excitation current by limiting the supply voltage of the DC-DC converter used to vary the excitation current for the regulation of the electromagnetic torque. This technique of speed adjustment is simpler and less expensive than techniques using mechanical and hydraulic braking systems.

Effect of degradation of the thermal barrier coating on the cooling performance of vane in gas turbine

Film cooling and thermal barrier coatings are essential for the thermal protection of high temperature gas turbines. Firstly, the degradation of the coating at the vane surface has been scrutinized under condition of 24,000 equivalent operating hours. In the microstructure analysis of coatings, the thickness of the top coating is diminished by 6.6% on average at the equivalent operating hours compared to pristine condition. Noticeably, an average of 15.7 μm of thermally grown oxide has grown at the interface between the top and bond coatings. Although the thermally grown oxide layer has developed over the entire interface between the coating layers, however, no lamination has been detected. Due to the nature of high thermal conductivity of thermally grown oxide, it is significant to investigate its effect on the cooling performance. In this regard, three-dimensional and numerical simulations have been developed to quantitatively evaluate the degraded cooling performance due to the presence of thermally grown oxide. The simulation results show that the degradation of thermal barrier coating decreases the overall cooling effectiveness by 9.4% in comparison to pristine vane. The resulting temperature rise on the substrate is predicted to 52.2 °C in our numerical simulations.

Experimental of the Influence of Blade Pitch Angle Cooler Fan on the Performance of Closed Cooling Water System Gas Turbine

A closed cooling water system is one of the systems contained in gas turbines. The main function of this system is to cool the lubricating oil and winding generator. Decreased performance of closed cooling water system can cause the gas turbine protection system to be active and cause the gas turbine trip. The study began with data collection, both design data for the heat exchanger cooler fan and operating data from the closed cooling water system on the gas turbine. An experiment was carried out by varying the blade pitch angle cooler fan to measure the work parameters in the field and analyzing the results of these measurements against the performance of the heat exchanger cooler fan. Variations of blade pitch angle cooler fan were done by limiting the working parameters of the cooling fan motor. The result of this study was an increase in the blade pitch angle cooler fan results in an increase in the flow rate of the cooler fan, this also affected the heat transfer rate of the heat exchanger cooler fan which grew when the blade pitch angle cooler fan was raised. The increase of blade pitch angle cooler fan also resulted in a decrease in the temperature of closed cooling water on the heat exchanger cooler fan outlet.

A novel reduced column section approach for the seismic protection of wind turbines

The rapid increase in global energy demand over the coming decades must be sustained by a more consistent increment of energy production from renewable sources of which wind energy is currently one of the fast-growing resources. New onshore and offshore wind farms will be rapidly constructed in challenging environments, especially in earthquake-prone areas. As a result, the mitigation of the dynamic vibrations of the wind turbines becomes a fundamental aspect of the seismic design to guarantee their normal operativity and structural safety. Different from past proposals based on traditional passive control devices such as tuned mass dampers or tuned liquid column dampers, this study aims to propose a novel approach, the Reduced Column Section (RCS), to derive an innovative mitigation device which replaces the traditional transition piece of the wind turbine. Analytical formulas to design the proposed RCS will be established. The benefits of the proposed device will be assessed on a real onshore wind turbine located in Italy. Modal properties obtained from the continuous dynamic monitoring of the wind turbine will be used to characterize the numerical finite element model. Therefore, a direct integration analysis with spectrum-compatible real earthquakes and an incremental dynamic analysis will be conducted to evaluate the dynamic mitigation induced by the proposed RCS. Soil-structure interaction effects will be also considered. This study shows that RCS can efficiently mitigate the effective stresses on the wind tower wall by up to 70% compared to the stresses computed on the existing structure.

Effects of hole-inlet velocity on the adiabatic film cooling effectiveness behind crossflow-fed shaped holes

In this contribution, the effect of hole-inlet velocity ratio (VRin) on adiabatic film cooling effectiveness behind crossflow-fed shaped holes is quantified using fast-response pressure-sensitive paint (fast-PSP). The measurement was performed at VRin = 0.38 and VRin = 0.5. For VRin = 0.38, the coolant and channel velocities (VRc &VRch, respectively) were varied as either VRc = 0.8 &VRch=0.3 or VRc = 1.6 &VRch=0.6, while VRin = 0.5 varies as either VRc = 0.8 &VRch=0.4 or VRc = 1.2 &VRch=0.6. The spatial–temporal features of the measured effectiveness were uncovered by the mean and unsteady data. The result affirmed the performance deterioration, which was associated with the asymmetric spreading behind the holes. The channel velocity ratio contributed to the coolant biasing, while the coolant velocity ratio contributed to the coolant spreading. The effectiveness (time-average and statistical) was correlated with identical VRin regardless of VRc &VRch; revealing the similarity and distinction from a qualitative and quantitative point of view, respectively. Based on the analysis, the obtained features indicate the coolant promotion at lower flow conditions (VRc &VRch) for both VRin = 0.38 and VRin = 0.50, although it's higher unsteadiness. Based on SOM, this could enhance the coolant coverage by the fluctuations than the local overheating by the mainstream gases. This research could assist designers to understand the unsteady features, as well as promote new cooling solutions for improved gas turbine protection in the future.

Characterizing Electric Field Distribution Due to Upward Initiated Lightning Around the Blades of a Rotating Wind Turbine

lightning constitutes the greatest threat to wind power industry. The characteristics of the distributed electric field prior to lightning strike plays an important role in determining lightning discharge attachment point as well as the efficiency of wind turbine protection systems. It was assumed that electric field due to upward initiated lightning might be the same as that of downward initiated lightning. However, more lightning damages which are upward initiated are now highly recorded. In this paper, the blades of a modern sized wind turbine (Vestas V100 with 2 MW rated power, 100 m rotor diameter, and 49 m long blade) are rotated from 0 to 360 degrees and used to investigate the characteristics of the distributed electric field around an operational wind turbine. The model of the extended vertical tri-pole cloud charge distribution model developed with finite element analysis is used to study the variations in maximum electric field strength required for the initiation of upward leader. By comparing the electric field strength as the blade is rotated, the field behavior is evaluated. In addition, experimental evaluations are carried out to support the findings. Result showed that the field around the blade surface and the receptor for an upward initiated lightning is more complex than was assumed and different from downward initiated lightning. This will consequently affect the proficiency of the protection device.

Design of Lightning Current Monitoring System on Wind Turbines

In recent years, because climate change is a major issue related to human survival and sustainable development, the global climate is warming and glaciers are melting, so the country has been advocating “green environmental protection, low-carbon life”. To achieve this goal, China is constantly looking for green and sustainable energy. However, in thunderstorm weather, wind turbines are more likely to be attacked by lightning. Even if we have a set of strict technology for lightning protection of wind turbines, we cannot resist direct lightning strikes. The blade of a wind turbine is the first target of lightning strikes. Therefore, this paper designs a lightning current monitoring system for wind turbines based on Rogowski coils, and designs a current measurement system that can be stably used to monitor the whole process of discharge when wind turbines are struck by lightning, so as to improve the safety of wind turbines. To improve the wind power generation technology due to the economic losses caused by lightning strikes to wind power generation enterprises.

Optimizing the Complex Systems Reliability Using Mixed Strategy in Ultra-fast Gas Turbine Protection System

There are four general ways to improve reliability. One of the most popular of these solutions is to add surplus components to the subsystems of a system (known as RRAP) and the reliability-redundancy allocation problem. In a subsystem, how these surplus components are used is of particular importance. How to use surplus components in the subsystem is known as. There are three general strategies for reliability issues known as active, stored, and mixed strategy. The main aim of the study is to create a new formula on the basis of the subsystems that use these two strategies. Model 4 provides a continuous limit of the Markov chain with continuous time. This new formula enables us to perform complex strategy calculations in a very short time and accurately. Finally the exact function obtained for mixed strategy Protective system ultra-fast gas turbine has been tested. Given the results, the new equation decreased the solution time besides the accurate estimation of the system’s reliability.

An LBM-Based Investigation on the Mixing Mechanism of Double Rows Film Cooling with the Combination of Forward and Backward Jets

Film cooling has been widely applied to the highly efficient thermal protection of gas turbines. By using the simplified thermal lattice Boltzmann method (STLBM), a series of large-scale simulations of film cooling are performed to dig up the mixing mechanism of double rows film cooling with the combination of forward and backward jets at the first attempt. The combination of an upstream row with forward jet and a downstream row with backward jet is considered. The Reynolds number is 4000. The blowing ratio of the upstream coolant jet is fixed as BR1=0.5. For the downstream coolant jet (BR2), five values ranging from 0.2–0.8 are considered. The inclination angles of forward jet and backward jet are 35° and 145°, respectively. The numerical results reveal that the performance of film cooling is greatly improved by backward downstream jet due to the suppression of counterrotating vortex pair (CVP). Moreover, the flow structure is changed with the blowing ratio of backward jet. An anti-CVP having the opposite rotational direction to CVP appears as the blowing ratio of backward jet is large. The special flow structure weakens the adverse effect of CVP and transports much coolant jet to the cooled wall. Correspondingly, the time-averaged film cooling effectiveness is increased and the fluctuation of film cooling effectiveness is decreased. All of these indicate that a backward downstream jet with a large blowing ratio improves film cooling performance. The results obtained in this work help to the optimization of film cooling scheme, which also benefit the promotion and application of STLBM in gas turbine engineering.

Unsteady adiabatic film cooling effectiveness behind shaped holes

Gas turbine as a vital component requires higher inlet temperature to improve its thermal efficiency, and thus a thin coolant film spreads over the blade surface to isolate it from hot gases. However, such coolant intensively interacts with the mainstream, leading to highly unsteady coolant coverage, which damages structural integrity, challenging its reliable and sustainable operations. Consequently, fast-response pressure-sensitive paint technique (fast-PSP) was used to measure the coolant unsteadiness behind the shaped holes, considering plenum and crossflow feeds. A steady-RANS simulation was performed to predict the large-scale flow structures and explain the mean results. The measured standard deviation (SD) and fluctuating components were used to uncover the spatial-temporal features associated with the predicted vortical structures. The mean effectiveness was dramatically influenced by the blowing ratios (M), showing attached flow at a low M and lift-off at a high M. The internal crossflow showed asymmetric spreading, resulting in deteriorated performance behind the holes. The unsteadiness was highly influenced by the energetic vortical structures, which originated from the hole entrance, forming in-hole counter-rotating vortex pair (CRVP) and vortex-tube structures. Meanwhile, the vortex-tube formed a swirl-vortex signature downstream of the hole-trailing-edge, leading to asymmetric CRVP. The swirl-vortex interacted with the CRVP windward-leg and reduced the spreading behind the holes, leading to mainstream ingestions. The combined results suggested considering the internal flow effects, which could help the designers understand the characteristics of unsteady effectiveness; promoting advanced cooling strategies for enhanced protection of future gas turbines.

Experimental and Numerical Studies of the Film Cooling Effectiveness Downstream of a Curved Diffusion Film Cooling Hole

Film cooling technology is a commonly used method for thermal protection of gas turbines’ hot sections. A new, shaped, film cooling hole is proposed in this study. The geometry is made of a straight-through cylindrical feed hole at an inclination angle of 30° followed by an expansion section. The expansion section is created by the rotation of the same circular hole on the inclination plane about an axis normal to that plane which passes through the center of the feed hole exit area. This shape was designed to decrease the deteriorating effects of kidney vortices by proper distribution of the coolant flow emerging from the hole exit area. Cases with four rotation angles (7°, 14°, 17.5°, and 21°) were studied both experimentally and numerically and for the blowing ratios of 0.5, 1, and 2.0. For comparisons, the commonly used 7°-7°-7° diffusion hole geometry was also tested under otherwise identical conditions. For data collection, the pressure-sensitive paint (PSP) technique was used to measure the film cooling effectiveness. Streamwise- and spanwise-averaged film effectiveness results were obtained to compare the performance of different geometries. The main conclusions were that the case of 21° rotation angle produced the highest film effectiveness and outperformed the 7°-7°-7° diffusion hole geometry.

Study on reducing the impact to EAST cryogenic system caused by the failure of load devices

EAST tokamak has complicated supercritical helium loops for cooling the superconducting magnets and other thermal loads. When failures occur in these load devices, such as magnet quench or vacuum failure, a large amount of helium evaporated in the cryogenic circuits returns to the cryogenic distribution system, which makes the pressures rise and the helium returning to the refrigerator increases. The refrigerator will run in a supercooling state and the turbine protection shutdown will be triggered with probability, which further affects the operation of the cryogenic system. This paper analyzes the archive data of this undesired phenomenon, the EAST cryogenic system model based on EcosimPro is used to simulate the dynamic process during the failure. A split-range control scheme to stabilize the pressures in the distribution system under failure state is proposed. the control module is developed in EcosimPro, simulation results show that it could achieve a satisfactory control performance and reduce the impact caused by the failure.

Retrofitting of Existing Bar Racks with Electrodes for Fish Protection—An Experimental Study Assessing the Effectiveness for a Pilot Site

Downstream-migrating fish in rivers tend to follow the main current, and are in danger of swimming through the turbines at run-of-river hydropower plants, possibly causing high mortality rates. To avoid these losses, fish must be prevented from entering the turbines. Most existing vertical bar rack systems (used for turbine protection) however usually do not ensure proper fish protection due to large bar spacings. FishProtector technology enables the retrofitting of existing bar racks (i.e., the mechanical barrier) with additional electrodes to create a hybrid barrier. The induced electric field in the water aims to create a behavioral barrier to prevent fish passage through the bar rack. In this study, ethohydraulic experiments to investigate the effect of such a behavioral barrier on fish were performed. In detail, the fish-protection rate at a bar rack with a bar spacing of 30 mm was tested in five different scenarios: (i) a bar rack without electrodes (reference), and four electrified setups with electrode spacings of (ii) 80 mm, (iii) 120 mm, (iv) 160 mm, and (v) 200 mm. A flow velocity of 0.23 m/s was chosen to replicate the situation at a planned pilot site. The study was conducted in an outdoor laboratory flume using small fish of several local riverine species, mostly cyprinids and minnows. The results show that the mean fish-protection rate in the experiments could be increased from 62% in the reference setup up to 96% in the electrified setups.

Surge analysis on wind farm considering lightning strike to multi-blade

The protection of the wind turbines is one of the significant problems, especially as lightning strikes the blades. In this paper, the authors bring forward a model in which nine interconnected wind turbines are connected to the infinitive bus by underground cables. When the blades are struck, for detailed investigation, all the cables inside the wind turbine and underground cables, tower, blades, and other equipment of wind turbine need to be designed in transient mode. Accordingly, the grounding system is also considered by the time-domain model, in which transient grounding resistance behavior is based upon the frequency-dependent model. For this purpose, the EMTP.rv is employed to study the transient behavior of the wind farm when the blades are struck. Eventually, by studying the residual voltage and discharged current in medium voltage surge arrester (MVSA) when lightning strikes WT, the energy absorbed by the MVSA is calculated and employed to evaluate the wind farm resilience against a different type of lightning. As a result, a new approach can be advised for the protection of wind farms against lightning by investigating the energy absorbed by MVSA.

Improvement of Multi-Hole Airflow Impingement on Flow and Heat Transfer Characteristics Inside a Turbine Vane Cavity

The cooling effect of turbine vane is of great importance for ensuring thermal protection and economic operation of gas turbines. This study aims to reveal the influence mechanism and performance of impingement cooling and heat transfer within a turbine guide vane cavity. Then, a turbine guide vane cavity with a complex pin fins structure is numerically investigated at a multi-hole impingement by comparison with experiment verification. The results show that the larger the Reynolds number is, the larger the average Nusselt number is on the upper and lower surfaces of the cavity. The average Nusselt number increased on the upper and lower surfaces as the impingement hole diameter increased. Comparing 1 impingement hole with 16 ones, the average Nusselt number of the lower surface of the latter is 553.9% larger than that of the former. Furthermore, the average Nusselt number of the lower surface for pin fin height of 3 mm is only improved by 11.2% for pin fin height of 24 mm. The heat transfer effect near the impingement holes is better than that far away from the impingement holes. In particular, it is recommended to have 14 impingement holes with a hole diameter of 7.2 mm, as well as circular pin fins with a height of 3 mm and spacing of 25.8 mm. In addition, the entropy generation distribution in impingement cooling is analyzed. This study can provide a reference to enhance the turbine vane cooling performance by optimization design.