Steam Turbine Generator Research Articles

Research on the versatility of Arctic marine nuclear power plant

Research on the versatility of nuclear power plants can increase the utilization rate of nuclear power plants and reduce the development cycle and cost. By comparing the power requirements of Russian nuclear power icebreakers, polar transport ships, and floating nuclear power plants, and combining the development status of Russian marine reactor devices and steam turbine generator sets, the analysis shows that marine nuclear power plants can be based on low (38tMW), The three-level benchmark reactor devices of medium (175tMW) and high (350tMW) and the two-level benchmark steam turbine power plants of low (6∼8 eMW) and medium (35-40 eMW) are designed for multi-scheme combination.

Flow mapping using 3D full-scale CFD simulation and hydrodynamic experiments of an ultra-supercritical turbine’s combined valve for nuclear power plant

In a typical steam turbine generator system, electrical power output is related to the steam flow regulated by a control valve. Hence, to ensure adequate electrical load as well as the proper stability of the turbine, a linear operation of the control valve is desired. However, in reality, the control valve exhibits different flow characteristics (FCs), both linear and nonlinear, which stem from its complex shape of plug and stem lift. Therefore, precise estimation of FCs is of utmost importance for better controllability, reliability, and safety of the turbine system. In this study, experiments and CFD simulations were carried out to evaluate the hydrodynamic FCs of a combined emergency stop and control valve to be employed in an ultra-supercritical (USC) turbine system for power plant. A full-scale prototype valve was designed, fabricated, and tested for a vendor company. Experiments were performed in the so-called VELO (Valve Engineering Layout Operation) test bench, and CFD simulations were conducted using a commercial code STAR CCM+. Air was used for experiments and simulations for simple economic and safe operation. Hydrodynamic characteristics were analyzed, and the theoretical mass flow rate of the valve was estimated. Finally, the valve coefficient of the turbine system was determined from the obtained FC curves. The simulation and test data showed a scale deviation of 15–16% for the original model valve and the simplified test valve. The test valve required such scaled modification to match with the test bench and fabrication. The prospective future research and improvement were recommended. This study's findings would support improving the turbine system performance to ensure safer, reliable, and modular power conversion systems for nuclear and conventional fossil fuel-based power plants.

Analysis of Muara Tawar CCPP Block 1 Steam Turbine Vibration

Condition monitoring of steam turbine enables early detection of faults and avoid unexpected breakdowns. Vibration analysis has gained much attention in the field of condition monitoring because of its accuracy in detecting faults and its ability for proper diagnosis of the faults. Muara Tawar CCPP block 1 has a steam turbine generator with a capacity of 215 MW. Steam turbine roll after inspection shows high vibration occurs on bearing 1. This study aims to find the cause of this high vibration and provide recommendations to avoids such symptoms. The vibration data used in the analysis are obtained from vibration analyzer tools associated with vibration monitoring systems. It is found that the amplitude of vibration at rotational speed frequency (1X) increased and phase angle changes at a constant speed. The vibration level at the coast down is higher than the observed vibration level at run-up. There is a shift in the position of critical speed which indicates a change of rotor stiffness. It is concluded that the high vibration is likely by a thermal bow on the rotor. The thermal rotor bow is caused by a light partial rubbing between rotor and labyrinth seal on the stator.

Re-design and Upgrade Bearing Materials Traveling Drum Screen in Muara Karang Combined Cycle Power Plant Block 1

The cooling system in the Steam Turbine Generator (STG # 1.0) is adjusted to the cleanliness conditions of seawater, using Traveling Drum Screen (TDS) as a filter. In January 2019, Traveling Drum Screen (TDS) suffered bearing and fuse bolt damage until STG # 1.0 was stopped with a potential loss of 28.59 billion rupiahs. The position of the TDS bearing below the surface of the sea makes monitoring difficult. To overcome the problems in TDS bearings, an innovation was made in the form of redesign & upgrading bearing materials. The replacement of TDS bearing material from Pertinax to Pokhout Wood (Lignum vitae) is very appropriate because the material is capable of self-lubrication in seawater and has more strength. In addition to upgrading the material, a redesign of the bearing is also carried out, which is adding a grease groove so that the optimal lubrication process and use finite analysis software to find out safety factors design. By using simulation software, the results show the bearing design with Pokhout material has a safety factor of 1.28 and Pertinax has a safety factor of 0.85. This shows that the re-design and upgrade of materials that have been carried out can increase the safety factor bearing and can reduce the possibility of failure of the bearing.

Electromechanical speed control system for steam turbine generator

The paper considers the application of a turbine speed electromechanical control system. The range of questions includes a description of the principle of operation and mathematical description of the turbine unit with electromechanical control system, as well as the close motoring for electromechanical control system. The mathematical description is presented in the form of transfer functions based on the linearization of the motion equation of turbine in the relative deviations of the parameters of the turbine unit and the electric drive of the electromechanical control system. The linearized description will allow us to apply classical methods of synthesis of controllers of an electromechanical control system. The use of an electric drive instead of a hydraulic actuator, which are used for centrifugal and hydroelectric controllers, will lead to an improvement in the quality of regulation in terms of precision and speed. This will increase the reliability of synchronization of generators. This will allow you to adjust the rotation speeds of all generators in a coordinated manner, rather than individually.

Dynamic Modelling and Simulation of Coal Pulverizer

The mathematical model and simulation of coal pulverizer has been presented in the paper using first principle mass and heat balance equations based on physical insight. The coal mass flow is modelled based on the mass balance model. The pulverized coal temperature is modelled by considering the coal and the pulverized coal as a lumped thermal mass. The multi variable non-linear model is simulated in Python environment and the parameters are obtained by using the moving horizon estimation. The archived data from an operating 660 MW coal fired boiler database are used to identify the parameters and to be compared with the model outputs. As the megawatt power output of thermal power generating plant is directly influenced by the coal being fired into the boiler, it is necessary to study the dynamic behaviour of the model as their poor dynamic performance causes a slow megawatt ramp up or ramp down rate and also causes shutdown of plant in some cases. In view of more and more penetration of renewable energy in the power grid, rapid and automatic flexible operation of coal fired boiler is necessary to accommodate injection of renewable power or withdrawal of renewable power as both remain connected directly or indirectly to the same power grid. Hence, fast response of the steam generating boiler is desired in a coal fired thermal power generating unit to generate the megawatt load as per the demand placed on the grid to maintain the power system frequency which calls for support of boiler steam flow, pressure and temperature to the steam turbine generator equipment. In order to achieve that, performance of combustion control of the boiler is one of the important factors which can be improved by modelling and implementing the predictive dynamic behaviour of coal pulverizer under varying coal feed rate in the boiler control system. The main focus of the work is to determine the pulverizer response under varying coal flow and coal characteristic condition with an objective of keeping minimum differential pressure across it based on a realistic mathematical model of pulverizer so that the boiler response can be improved under transient condition of megawatt load demand variation. The simulated model responses for various scenarios are also presented in this paper.

Research on Vibration Fault Diagnosis Technology of Steam Turbine Unit in Power Plant Based on Wavelet Theory

Aiming at the frequency spectrum characteristics of the vibration of steam turbine generator sets, a fault diagnosis method of steam turbine rotor vibration based on wavelet packet transform is proposed, which can better reflect the spectral components and energy contained in vibration signals than general wavelet transform. Experimental analysis shows that the fault feature extraction method based on wavelet packet analysis and signal energy decomposition can obtain the fault status of steam turbine rotor vibration; according to the frequency spectrum characteristics of different faults, different faults can be identified, so as to perform steam turbine rotor vibration fault diagnosis. This method is more effective than the fault feature extraction method based on Fourier transform and is suitable for mechanical fault diagnosis.

Simulation and economic evaluation of heat and power generation from flare gases in a combined cycle power plant

In recent decades, the release of flare gases from different units of chemical industries into the atmosphere has become a substantial environmental problem all around the world. Therefore, recovery or use of flare gases has become much more critical. Combined heat and power generation from flare gases is one of the most economical methods for recovering flare gases. Two power generator gas cycle power plant or a combined cycle power plant can be used to generate heat and power. In this research, simulation and economic evaluation of heat and power generation from flare gases in a gas cycle power plant and combined cycle power plant using PRO/II v.10 software. Finally, by changing the effective operating parameters such as air to treated flare gas ratio, the outlet pressure of compressors, outlet pressure of steam and gas turbine, outlet pressure of pumps and adiabatic efficiency steam and gas turbine, heat and power generation and total capital and operating cost were investigated and analyzed. The results of simulation and sensitivity analysis showed that the use of flare gas with a mass flow rate of 9700 kg/h (mole fraction of CH4: 0. 84) could be used to construct a combined cycle power plant with a capacity of 115 MW with an investment cost of 100 M$. This value of energy surpasses the need for an average community with 85000 families, and the excess can be sold to the national grid.

Modeling method of steam turbine generator set based on cascade feedforward PID coordinated control system

Objective In order to quickly and accurately evaluate the reliability of a steam turbine generator set under actual working conditions, it is necessary to construct a visual model of the set. Method Based on an analysis of a mathematical model of a traditional steam turbine generator set, a cascade PID method is proposed and a feedforward link added. Then, based on a Matlab Simulink environment, a visual model of the optimized control of a steam turbine generator set is built, and the steady state and fault state of the set are simulated and analyzed with the help of the simulated fault module. Results The simulation results show that the output speed of the steam turbine generator set based on cascade feedforward PID coordinated control is higher than the given speed for a short time when starting under load, but the stable value is quickly restored under the action of the control feedback. In the case of failure, the rotation speed can also fluctuate within a given range. Conclusion This modeling method of a steam turbine generator set based on a cascade feedforward PID coordinated control system can be popularized in the modeling of nuclear turbine propulsion systems, providing an analytical means of achieving the visual analysis of the unit's operation state, and saving both cost and time.

Damping of Subsynchronous Resonance in a Hybrid System With a Steam-Turbine Generator and an Offshore Wind Farm Using a Unified Power-Flow Controller

This article proposes a unified power-flow controller (UPFC) to suppress subsynchronous resonance occurred in a hybrid power-generation system connected to an infinite bus through a series-capacitor compensated line. The hybrid power-generation system contains a steam-turbine generator (STG) and an offshore wind farm (OWF) based on doubly-fed induction generator (DFIG). The d – q axis equivalent-circuit model under three-phase balanced loading conditions is derived to establish the complete system model including the STG set, the DFIG-based OWF, the series-capacitor compensated line, the UPFC, etc. A damping controller of the proposed UPFC is designed by using pole-assignment approach based on modal control theory to effectively damp out unstable STG modes of the studied system. Both small-signal stability and transient simulation results of the studied system are systematically performed. The simulation results show that the proposed UPFC joined with the designed damping controller can effectively suppress unstable STG modes of the studied power system.

Research And Practice Of Dry Wet Combined Cooling For 600 MW Steam Turbine Generator Unit

Taking 600MW steam turbine generator set as an example, this paper analyzes the dry wet combined cooling scheme of auxiliary cooling water system, so as to make rational use of local limited water resources.

Performance Analysis of Combined Cycle with Air Breathing Derivative Gas Turbine, Heat Recovery Steam Generator, and Steam Turbine as LNG Tanker Main Engine Propulsion System

This study explains the performance analysis of a propulsion system engine of an LNG tanker using a combined cycle whose components are gas turbine, steam turbine, and heat recovery steam generator. The researches are to determine the total resistance of an LNG tanker with a capacity of 125,000 m3 by using the Maxsurf Resistance 20 software, as well as to design the propulsion system to meet the required power from the resistance by using the Cycle-Tempo 5.0 software. The simulation results indicate a maximum power of the system of about 28,122.23 kW with a fuel consumption of about 1.173 kg/s and a system efficiency of about 48.49% in fully loaded conditions. The ship speed can reach up to 20.67 knots.

Inertia and Droop Controller for a Modern Variable Speed Wind Turbine to Provide Frequency Control in a Microgrid

The increasing penetration of modern Variable Speed Wind Turbines (VSWTs) in microgrids creates the problem of frequency stabilization due to reduced inertia of the power system. To emulate the Inertia Response of the conventional synchronous machines, wind turbines can be provided with an inertia emulation controller. The modelling presented in this paper aims at equipping the modern Type D wind turbine with inertia response and primary frequency control (PFC) capabilities. Two controllers — inertial and droop, are implemented and their frequency control capabilities are compared in an isolated power system which consists of a conventional steam turbine generator and a wind farm. The results suggest that proposed controllers help in better frequency control performance in the microgrid

Understanding a Type of Forced Oscillation Caused by Steam-Turbine Governors

This letter studies the mechanism of a type of forced power system oscillation induced by imperfect nonlinearity compensation with a steam-turbine governing system. The nonlinear valve control characteristic of a steam turbine is usually compensated by its inverse characteristic performed by its governor for an overall linear characteristic of the governing system. In reality, a governing system may remain nonlinear due to imperfect compensation, which can result in a limit cycle forcing the generator and even an extensive neighboring area of the power grid to oscillate at a low frequency. A compensation imperfection index is proposed to evaluate the residual nonlinearity and discover how a limit cycle can occur and cause forced oscillation of a steam-turbine generator. Time-domain simulation on a real forced oscillation event caused by a steam-turbine governor validates the finding of the paper and supports the fact that opening the governor control loop of the oscillation-source generator can effectively eliminate this type of forced oscillation.

Investigation of the Cooling of Water-Cooled and -Moderated Reactors Based on Electricity Generation Via Residual Heat in Emergency Situations with De-Energization

Safety enhancement of NPP power units with water-moderated and -cooled reactors on the basis of installation of additional multifunctional low-power steam-turbine generators is studied. It is shown that the parameters of the primary and secondary loops change as the VVER-1000 reactor is cooled via the use of the residual heat in the core to generate steam that serves as the working body for a low-power steam-turbine plant. Uninterrupted power supply for the NPP’s own needs is achieved on account of the fact that in normal and emergency regimes the low-power turbine unit supplies electricity to power consumers during cooldown of a reactor in an emergency situation with a blackout. It is shown for the example of 6 and 12 MW turbine units that the residual heat from one VVER-1000 reactor is sufficient to cool two such reactors for 72 h with de-energization of the NPP and depressurization of the primary loop in one of them.

DICE-gas turbine compound reheat combined cycle

Coal-fired Direct Injection Carbon Engine – Gas Turbine (DICE-GT) Compound-Reheat Combined Cycle (CRCC), is a combined cycle power plant comprising a multiplicity of coal-fired reciprocating internal combustion engines (RICE), which is commonly referred to by the acronym DICE (Direct Injection Carbon Engine); a natural gas-fired gas turbine (turbine and combustor); a heat recovery steam generator (HRSG); a steam turbine generator; and an integrally geared and intercooled centrifugal air compressor. The concept uses coal-water slurry/fluid in the DICE and natural gas (or hydrogen) in the gas turbine for unmatched efficiency (well above 50% net LHV) and modularity (block sizes of 120, 240 and 360 MW) with easy adaptability to carbon capture and sequestration with minimal additional cost, complexity and performance hit.

Case study: Paper mill power plant optimization—balancing steam venting with mill demand

Most Power departments are tasked with generating steam to support mill wide operations, gener-ate electricity, and reduce operating costs. To accomplish these tasks, power boilers generate high pressure steam that is reduced to intermediate and low pressures for process utilization in the mill by means of steam turbine generator extraction or pressure reducing valves. The most economical method to reduce steam pressure is the use of steam turbine generators, as electricity is generated from the steam when it is reduced in pressure. Electricity that is produced by these generators provides a substantial financial benefit and helps offset overall operational costs. To achieve tangible financial gains, the mill must evaluate the overall cost of steam production and the price of electricity. The current work provides a case study of power plant optimization that evaluated electricity production and steam production costs balanced with mill steam demand. Process and cost optimization led to a significant reduction in low pressure steam venting, resulting in reduced fuel consumption and reduced operating cost.

Combined Energy Supply for Sixty-Two Heliostats of the Big Solar Furnace

The article discusses the issues of increasing the reliability of regular, systematic, continuous operation during the day of 62 heliostats in the sun tracking mode by connecting to the centralized power network an additional autonomous power supply system with a power of 15 kW, consisting of a standard gasoline engine with an inverter and а solar Fresnel mirror-concentrating system with a steam turbine generator that produces electric power

Quantifying flexibility of industrial steam systems for ancillary services: a case study of an integrated pulp and paper mill

Due to the increasing use of intermittent renewable generation, the power grid requires more flexible resources to balance supply and demand of electricity. Steam systems with turbine-generators, which are widely used in industries, can be operated flexibly to support the power grid. Yet, the available amount of flexibility of industrial steam systems is still not clearly quantified. This study presents the method to quantify electricity generation flexibility of a typical industrial steam system with a steam turbine-generator and process heat demands. The proposed method is introduced based on a real case of an integrated pulp and paper mill in Austria. An integrated mathematical model representing the combined electricity and steam system is developed to simulate the behaviour of the on-site energy system to quantify the potential flexibility provision. Flexibility is represented as the maximum upward and downward changes in the imported electricity from the public power grid. The results demonstrate that it is possible to aggregate the flexibility of the industrial facility as a lookup table. Also, the results reflect key factors that limit the flexibility at different operating points of the turbine-generator.

Modeling of SNCR denitration system based on adaptive weight particle swarm optimization

In view of the improvement of NOX emission control requirements for coal-fired units, traditional PID controllers have been unable to effectively control large delay, large inertia, nonlinear, time-varying SNCR denitration systems, and most advanced control algorithms are often object-based models. Therefore, a model of SNCR denitration system based on adaptive weight particle swarm optimization algorithm is established. A 2×200MW heating steam turbine generator set equipped with a 2×705t/h circulating fluidized bed boiler was used as the test unit, and the selective non-catalytic reduction technology denitration system was analysed. The particle swarm optimization algorithm with adaptive weights was used to model the relationship between the urea flow rate and the NOX concentration at the chimney outlet of the SNCR denitration system under working conditions of 140 MW, 170 MW and 200 MW, respectively, to provide a process for the automatic control of the SNCR denitration systemmodel. Apply the actual data from the field to verify the model. The results show that the error between the output of the model and the actual operational data is within the allowable range, which verifies the validity of the model. This result opens up a new path for the particle swarm optimization algorithm to model the SNCR denitration process, and promotes the application of intelligent algorithms in other industrial processes.