Steam Turbine Generator Unit Research Articles

Power System Analysis of Steam Power Plant Using ETAP at ULPL Indralaya South Sumatra

PT PLN (Persero) UPDK Keramasan have three group work units in South Sumatra Province which is study has located in Ogan Ilir Regency namely PT. PLN ULPL Indralaya. This study is one steam turbine generator unit often experiences shutdown due to several factors. One of them is out of service for the protection operating system on the 4 MVA to 11.5/6.9 kV transformer unit when there is a disturbance so that there is an inter-trip to the upstream system which results in a blackout system. We analyzed the disturbance using ETAP software. We made three analyzes there are load flow, short circuit and relay coordination. As study results submitted to PT PLN ULPL Indralaya is to scenario 3 for the analysis of the resulting lower flow is a decrease in load of about 63% for short circuit value obtained between 0.011 to 50.776 kA also relay coordination should be adding devices such as IDMT curve Long Time Inverse.

Data analysis and fault-finding case study of a 660 MW steam turbine generator set in a power station,

TG2 is a GE 660 MW steam turbine generator unit at Hartlepool power station in North East of England. The unit consists of an HP turbine, an IP turbine and three LP turbines coupled with an alternator and an exciter. Although the unit was previously operating normally and within the established ISO standards, recent reports indicated excessive loading on the barring gear and instances of the barring gear becoming stuck. EDF Energy's central technical organization conducted a comprehensive analysis of the vibration data, including online, barring, run up, and run down data, to determine the root cause of the overloading. The data analysis revealed that the generator NDE bearing (bearing 12) showed signs of tilting, reducing the clearance between the shaft and the bearing and causing friction. This friction was determined to be the cause of the overloading of the barring gear. The generator operates in a pressurized hydrogen environment and changes in pressure during operation and shutdown had a ratcheting effect on the bearing tilt and clearance reduction. The EDF Energy engineering team responded promptly and professionally, documenting the issue, raising awareness among operations, and implementing a recovery plan.

Diagnosis and Treatment of Burst Vibration Fault of Large Steam Turbine Generator Shaft System

Aiming at the burst vibration fault of a supercritical 600 MW steam turbine generator unit during the on-load operation, the characteristics of sudden vibration faults of the rotor system were compared and analyzed. By analyzing the weight-loss vibration response coefficient and the variation characteristics of the vibration vector, parts falling off fault at the low-low coupling of the rotor system were diagnosed. After inspection, it was confirmed that the burst vibration fault of the rotor system was caused by the falling-off of the blast baffle of the low-low coupling bolt. After the blast baffle was restored by hoisting the installation technique, the vibration of the steam turbine generator unit was stable during start-up and grid connection.

Research on the Torsional Vibration Response Characteristics of Parallel Operation Steam Turbine Generator Unit Shafting

With the continuous increase of unit capacity and the widespread application of series compensation devices in power transmission systems, the risk of coupling oscillation between units and power grids and between units has increased significantly, which seriously endangers the safe operation of units and power grids. In this paper, the torsional vibration response of each unit after grid failure is calculated by establishing a lumped mass model of the shafting torsional vibration of the parallel unit. The effects of fault type, series compensation degree and fault location on the torsional vibration of parallel unit shafting are studied. The results show that the three-phase short-circuit fault in the grid has a greater impact on the unit; the influence of series compensation degree on the torsional vibration of the shaft system decreases first and then increases; when the transmission line fails, it will produce a certain torsional vibration excitation effect on the shafting of all units; when a short-circuit fault occurs at the outlet of a generator, the torsional vibration excitation of the unit is the largest, but it will also produce a certain degree of torsional vibration excitation to other units in the same network.

An Application of the Pythagorean Fuzzy Sets in the Fault Diagnosis

Abstract In this paper, a comprehensive review and critical analyses of methods based on the ordinary fuzzy set, Atanassov’s intuitionistic fuzzy set, and its extensions have been conducted to show their limitations and defects. Then, a novel similarity measure based on the generalized score function has been introduced that incorporates the significance (importance) of information, making it more intuitive to compare them. The proposed method is employed for the fault diagnosis of steam turbine generator unit under Pythagorean fuzzy environment. Ten fault types of rotating machines are established as failure patterns in nine different vibration frequency ranges, expressed in terms of Pythagorean fuzzy numbers. The superiority of the proposed method in dealing with uncertain and vague information is shown by comparing it with some existing measures in numerical examples.

Comparison of Impact on Turbine Shafts Torsional Behavior for Integration of Two Types of Wind Farm into a Series-Compensated Transmission System

Deep decarbonization is the goal of modern power systems, so it is inevitable that large-scale wind farms will be integrated into systems. This also gives rise to many problems, which have been studied in detail in the literature. However, these studies basically have two deficiencies. One is to assume that traditional generator units are fully loaded, and the other is not to compare the differences in the impact of different types of wind farm. This paper discusses these two points in detail. Taking a series-compensated transmission system as the research object, and assuming that the wind farm only replaces part of the power of the traditional generator unit in the transition period of energy conversion, the difference between the torsional vibration behaviors of the traditional unit caused by adopting different types of wind farm is discussed. The results of the study show that the impact of integration of the type 3 wind farm is dominated by the induction generator effect of doubly fed induction generator units. The penetration rate as low as 19% could cause instability. However, the paralleled metal-oxide varistor can effectively improve the stability. For the type 4 wind farm, the dominant factor turns out to be the de-rating operations of the steam turbine generator unit. The allowable penetration rate depends on the turbine damping. When the turbine damping is sufficient, the penetration rate can be as high as 87.5%. In conclusion, in order to integrate wind farms into a series compensated transmission system, one should not only focus on the compensation factor to avoid the sub-synchronous torsional vibrations, but also pay attention to the types of wind farm as well as the penetration rate. The findings can be used as the decision-making basis for the integration of wind farms during the energy transition period.

Dynamic modeling and experimental verification on the rotor-armature structure of a steam turbine-generator unit

The rotor-armature structure of an exciter rotor used in a steam turbine-generator unit is investigated in this work. The objective is to create a base verified linear dynamic model of the exciter rotor for fault diagnosis or nonlinear interactions analysis. Natural frequencies for the rotor-armature structure are obtained from modal testing in free-free conditions. An analytical model for the structure is then constructed using Timoshenko beam theory, in which the linear effect of contact interface between rotor and armature is included. The unknown parameters of the rotor-armature model are identified by comparing analytical and experimental results. The verified dynamic model serves as the base for fault diagnosis and nonlinear response analysis due to the rotor and armature interactions.

Simulation test and parameter optimization of fast cut back of large thermal power plant in the condition of synchronization of large-scale wind power

Fast cut back (FCB) is an important condition in power control of steam turbine generator unit, which is closely related to the flexibility, safety and stability of thermal power unit. In this paper, the traditional single reheat steam turbine model were optimized and improved by adding the key links such as medium pressure control valve and bypass, and further adding the once through boiler, bypass control system, FCB action signal, excitation system and other models. A thermal power unit model suitable for FCB large disturbance condition simulation was established. The simulation results verify the effectiveness of the model, and meet the requirements of power system electromechanical transient simulation and FCB simulation. And then, this paper improved the PSO (Particle Swarm Optimization) algorithm, and combined the advantages of each algorithm in the aspects of calculation difficulty, convergence speed, accuracy, ability to jump out of local optimum, etc., puts forward and verifies the GA-PSO (Genetic Algorithm-PSO) optimization method. Finally, considering the stability and regulation performance of the system, the GA-PSO optimization algorithm was used to obtain the optimal values of the system component parameters. The simulation results indicated that the characteristics of optimized system damping was improved, which enhanced the regulation performance and stability of the system.

Presentation of an integrated cooling system for enhancement of cooling capability in Heller cooling tower with thermodynamic analyses and optimization

Heller dry cooling towers are being handled in combined-cycle power plants to diminish the temperature of the water returned from condenser. Normally, during the hottest or the most intensive wind blowing times, the performance of the Heller cooling towers is attenuated and subsequently the performance of steam turbine Generator unit of the combined-cycle Power Plant decreases. To solve this problem, an integrated system including the additional heat exchanger and a compression refrigeration cycle driven by an Organic Rankine cycle is linked to the Heller cooling tower to enhance the cooling capability of the cooling tower and subsequently the performance of steam unit. Thus, firstly, the additional heat exchanger and the linked compression refrigeration cycle have been designed via the validated ASPEN HTFS and EES code respectively. The proposed system can cool the water from 313K to 303K and returns it to the condenser of the steam unit in the hottest or wind blowing times to create the stability of steam unit. Afterwards, energetic, exergetic, and exergo-economic analyses as well as the multi-objective optimization of the attached system are conducted. According to the results, the proposed system energized by the waste heat of the exhausted gasses, can help the cooling tower during the above-mentioned times. Also, the optimization increases the exergy efficiency from 33.68% up to 37.59% and decreases the total cost rate from 3945 $/h to 3363 $/h.

Thermodynamic analyses and optimization of an auxiliary heat exchanger equipped with an absorption refrigeration system to increase the cooling capability of Heller cooling tower

Air-cooled cooling towers are applied to reduce the temperature of water returned from the condenser in the combined cycle power plants. Actually, whenever the ambient temperature increases, the cooling capability of the dry cooling towers decreases and subsequently the performance of the steam turbine Generator (STG) unit of Combined-Cycle Power Plant decreases. To solve this problem, an integrated system including the auxiliary heat exchanger and an absorption refrigeration system is linked to the Heller cooling tower to improve the cooling capability of the cooling tower and subsequently the performance of STG unit. Thus, firstly, the mentioned heat exchanger and the linked absorption refrigeration system have been designed via the validated ASPEN HTFS and Engineering Equation Solver code respectively. Secondly, energetic, exergetic, and exergo-economic analyses of the auxiliary exchanger are conducted. Finally, it is optimized using the Genetic Algorithm. Eventually, the proposed system can help the cooling tower during the hottest times using the wasted heat through the gas stacks. Also, the multi-objective optimization process increases the exergy efficiency from 37.87% up to 39.57% and decreases the total cost rate from 4023.85$/h to 3563$/h.

Diagnosis method of turbine blade loosening

Abnormal vibration of low-pressure rotor occurred after low-pressure cylinder cutting transformation of 330MW steam turbine generator unit in a power plant. Through the analysis of vibration data, the vibration spectrum was mainly manifested as low-frequency component of 18Hz, which fluctuates with time cycle, and it was judged that it might be related to the loosening of low-pressure rotor blades. After 6 months of operation, routine inspection after cylinder cutting showed that there were three loose roots and worn top steam seals on the secondary last stage blades of low pressure rotor. After repairing the blades, the abnormal vibration problem of the low pressure rotor of the turbine generator set was successfully solved.

The Experience in Operation and an Efficiency Analysis for the Use of a Backpressure Steam Turbine Generator Unit in a Boiler House

Turbine generators can be used for utilization of the potential of steam lost in pressure-reducing and cooling units of operating boiler houses. This approach brings about an independent source of power the price of which can be much lower than the established tariff. The features in reconstruction of a boiler house in the city of Bratsk, Irkutsk oblast, carried out in 2012 are examined. Steam generated in a KE-50-14-225 boiler is routed to a 0.3–0.5 MPa common header for use in deaerators and steam-water heaters. Considering an increase in the electricity tariffs, a decision was made to install a 500-kW backpressure turbine generator in the boiler house in parallel with the pressure-reducing unit to generate auxiliary power. The criteria for selecting the number and power of turbine generator units depending on the required steam generation, operating conditions of the consumer, the level of electric loads of the boiler house, and the existing heat supply system are shown. The specifics in operation of the turbine generator unit are examined. To ensure safe and reliable operation of the unit, it is advisable to increase the number of monitored parameters through extension of the normal instrumentation system. The discounted payback period for the reconstruction cost and additional costs for installation of a second turbine generator unit are estimated. The boiler house regimes, a change in the prices for fuel and electricity, and the operator’s labor cost are considered. After installation of the turbine generator, the specific fuel consumption for electricity generation amounts to 180 g.c.e /(kW h). In 2017, the electricity generation cost was 1.23 rubles/(kW h) with the average tariff of 2.13 rubles/(kW h). The discounted payback period for the performed reconstruction does not exceed 6 years, and that for further reconstruction is 8 years.

Coordinated Optimization of Multi Control System for Steam Turbine Generator Unit

A method of the coordinated optimization of multi control system for steam turbine generator unit was proposed in this paper. The primary frequency modulation performance and dynamic stability of the power system were taken into account in the method. The multi-control system to be optimized includes the excitation regulation system, the power system stabilizer (PSS), the speed control system and the boiler-turbine coordinated control system (CCS). And the taboo search (TS) algorithm was introduced as a means to obtain the optimal values of the system control parameters. The simulation result shows that the method can coordinate the primary frequency modulation performance and the dynamic stability of the system, and can effectively prevent the low frequency oscillation caused by the improper multi control system parameters setting.

国投北疆电厂汽轮发电机组安装质量管理方法探讨及实践

国投北疆电厂汽轮发电机组安装质量管理方法探讨及实践

The Trapezoid Counterweight Method in Dynamic Balance of Symmetric Flexible Rotor

Steam turbine generator unit, water pump and other high speed revolution symmetric flexible rotor were regarded as research objects in this paper. According to variation characteristic of rotor shaft in rigid and flexible working mode, nine-reel high pressure water pump rotor was analyzed. The former four-order intrinsic frequency of flexible rotor was obtained by modal analysis and harmonic response analysis. The methods of reaction force response and unbalance response were been studied after first order and second order resonance region eliminating in different modes of simple harmonic exciting force. Based on above theoretical research results, trapezoid counterweight method was proposed for dynamic balance of flexible rotor. This method solved problem that rigid dynamic balance of low speed rotor was destroyed after first order and second order resonance region counter weight in dynamic balance of flexible rotor. The dynamic balancing techniques of flexible rotor could be improved the qualities of rotor and its relative products by this method, eliminating the vibration of unbalance mass of products radically.

Performance of natural draft hybrid cooling system of large scale steam turbine generator unit

To overcome the shortage of dry cooling technology for large scale steam turbine generator unit in summer, the potential feasibility of hybrid cooling was investigated numerically. The physical model was established for the thermo-flow performances of a hybrid cooling system, which combined the air-cooled heat exchangers and water spray facility in a natural draft cooling tower. The mathematical model included the heat and mass transfer between circulating water and cooling air, as well as the condensation of exhaust steam from turbine. The impacts of cooling modes, operating parameters and ambient conditions of the natural draft hybrid cooling system were investigated accordingly. The results showed that both dry and wet cooling sections determined the thermo-flow performances of hybrid cooling system. Due to the blocking effects of upstream air-flows with medium wind speeds, the hybrid cooling mode may have poorer performance than that of dry cooling system. The large droplet diameter and low spray water flow ratio could deteriorate the thermo-flow performances of hybrid cooling mode, which were even worse than that of dry cooling mode and dry cooling system. The operating parameters obtained and the conditions of cooling mode selection may benefit the future application of the hybrid cooling technology.

Economics and greenhouse gas balance of distributed electricity production at sawmills using hermetic turbogenerator

This article focuses on greenhouse gas (GHG) emissions reduction and on the economics in renewable electricity production at sawmills. Electricity production application in this study is a hermetic turbogenerator (HTG). The HTG is a small-scale steam turbine-generator unit of compact size that achieves high efficiency. The paper studies GHG emissions and the economics of HTG use in sawmills using life cycle assessment methodologies. Small- and large-scale HTG processes are studied in three scenarios. Sawmills produce large volumes of biomass by-products which are mainly used to produce heat needed in lumber dryers. However, due to remote location of sawmills there may be no use for excess biomass. HTGs can be used to produce electricity in addition to heat (CHP), which may help to increase renewable electricity production in sparsely populated areas. It is concluded that from the economic perspective HTGs may be an attractive option but financial viability is dependent on energy prices, required investments, and by-product value. From the climate change perspective, electricity production with HTGs may be a good option if there is excess biomass sources available.

Discussion and Realization on Quality Control Methods of Power Steam Turbine-Generator Unit Installation

Based on the practical experience of turbine unit installation, combined with the project quality management theory, analyzed the impact factors of turbine installation quality, explored the quality control content, and formed a more perfect of quality control methods system ultimately. The application of the methods in the SDIC Power Plant team turbine unit installation achieved the good results, and it became the reference for the same or related industry.

Application Study on Low Vacuum Circulating Water Heat Supply of a 50 MW Turbine

This topic mainly research the high back pressure heat supply technology of steam turbine generator unit and the correlation analysis of turbine under high back pressure operating condition. High back pressure heat supply is an energy saving technology developed in order to meet the requirements of energy saving and environmental protection. This technology can not only reduce the cold end losses to improve the thermal efficiency of power plant, but also decrease the energy loss and pollution emissions because it take the place of traditional heating boiler. High back pressure heat supply of steam turbine is to increase the quantity of air inlet and outlet as well as exhaust temperature through improving turbine back pressure. For condensing steam turbine unit of 50 MW studied in this article, back pressure of which rise to 0.032MPa from 0.0046MPa, and the exhaust temperature will increase to 70 °C respectively. Through the calculation of rated condition and variable condition, we can obtain the impact to the unit due to the change of back pressure, and for unit of 50 MW can reduce 30876.9 tons of standard coal consumption in a heating period. It can also decrease the emission of carbon dioxide, sulfur dioxide, smoke and ashes, which effect of energy saving and emission reducing is very obvious.

Optimized Processing Scheme for Abrasive Fault of Steam Turbine Shaft

It is of great significance to adopt the reasonable scheme to repair the abrasive shaft in order to make sure the safety and stable operation of the steam turbine unit. Taking a real 600MW steam turbine generator unit with worn shaft as the target system, we employ finite element software ANSYS to establish the model of the local worn shaft segment in this paper. Two kinds of optimized processing strategies are proposed to repair the worn shaft segment, considering the situation of cutting quantity and shear stress distribution. The two proposed schemes can reduce the stress concentration of the worn shaft parts largely. The study proves that the method is feasible and can be used to processing other similar failures.