A Comparison of Small-Scale Gas Turbine Control Schemes

2017 ◽  
Author(s):  
Ahti Jaatinen-Värri ◽  
Jari Backman ◽  
Juha Honkatukia ◽  
Matti Malkamäki
Keyword(s):  
Gas Turbine ◽  
Power Output ◽  
Gas Turbines ◽  
Energy Generation ◽  
Developed Countries ◽  
Small Scale ◽  
Variable Speed ◽  
Part Load ◽  
Control Schemes ◽  
Distributed Energy Generation

Throughout the world there is pressure to increase distributed energy generation. Driving factors include for example political and environmental concerns in developed countries and reliability in places where centralized grid does not either exist or is too unreliable. The energy generation based on renewable fuels such as biogas is also usually decentralized. To answer this demand, the number of small-scale gas turbine combined heat and power (CHP) installations have increased. Due to its nature, the required power output of distributed generation is highly variable. The power output of decentralized power plant needs to follow the local consumption power need and thus it needs to be efficiently controlled. Therefore, the requirement for variable output necessitates that small-scale gas turbines are often run at part-loads. Previously, most of the installed small-scale gas turbines have been single-spool units with either fixed or variable speed shafts. Control schemes and part-load performance are somewhat different for the two setups. Recently, a two-spool gas turbine where the spools can be controlled independently has been proposed as a feasible alternative. The possibility to produce the desired power output with two spools, both having their own generator, which can be controlled independently of each other, offers significantly more possibilities for the control. Therefore, it might also offer better part-load performance. In this paper, the control schemes of three different small-scale gas turbines are compared. Especially, the part-load electrical efficiency is studied. The studied gas turbines are: a single-spool fixed speed, a single-spool variable speed driven, and a two-spool variable speed driven gas turbine. The part-load performance of different machines is studied and then compared against each other. Furthermore, some estimations are given on how the part-load performance of each machine fares against certain load profiles.

Analysis of Part Electric Gas Turbine: A Novel Hybrid Propulsion Concept

2019 ◽  
Author(s):  
M. S. N. Murthy ◽  
Subhash Kumar ◽  
Sheshadri Sreedhara
Keyword(s):  
Gas Turbine ◽  
Electric Motor ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Variable Speed ◽  
Hybrid Propulsion ◽  
Design Point ◽  
Part Load ◽  
Wide Range ◽  
Efficient Option

Abstract A gas turbine engine (GT) is very complex to design and manufacture considering the power density it offers. Development of a GT is also iterative, expensive and involves a long lead time. The components of a GT, viz compressor, combustor and turbine are strongly dependent on each other for the overall performance characteristics of the GT. The range of compressor operation is dependent on the functional and safe limits of surging and choking. The turbine operating speeds are required to be matched with that of compressor for wide range of operating conditions. Due to this constrain, design for optimum possible performance is often sacrificed. Further, once catered for a design point, gas turbines offer low part load efficiencies at conditions away from design point. As a more efficient option, a GT is practically achievable in a split configuration, where the compressor and turbine rotate on different shafts independently. The compressor is driven by a variable speed electric motor. The power developed in the combustor using the compressed air from the compressor and fuel, drives the turbine. The turbine provides mechanical shaft power through a gear box if required. A drive taken from the shaft rotates an electricity generator, which provides power for the compressor’s variable speed electric motor through a power bank. Despite introducing, two additional power conversions compared to a conventional GT, this split configuration named as ‘Part Electric Gas Turbine’, has a potential for new applications and to achieve overall better efficiencies from a GT considering the poor part load characteristics of a conventional GT.

Aero-Thermodynamic Simulation of a Double-Shaft Industrial Evaporative Gas Turbine

2000 ◽  
Author(s):  
S. M. Camporeale ◽  
B. Fortunato
Keyword(s):  
Ambient Temperature ◽  
Gas Turbine ◽  
Power Output ◽  
Gas Turbines ◽  
Thermodynamic Simulation ◽  
Inlet Temperature ◽  
Part Load ◽  
Design Performance ◽  
Water Rate ◽  
Advanced Cycles

A modeling study has been carried out in order to determine the behavior of evaporative industrial gas turbines power plants at part-load and for varying ambient temperature. On-design and off-design performance have been analyzed by means of a computational program developed for the analysis of advanced cycles. In order to verify the mathematical model and to evaluate the characteristics of up-to-date gas turbine technology, an industrial engine, presently available on the market, has been simulated. A double-shaft gas turbine for power generation has been considered. On-design performance and ratings vs. ambient temperature have been evaluated, with good accordance. It is assumed that, in order to realize a Recuperated Water Injected (RWI) cycle, the industrial gas turbine could be modified, maintaining substantially unchanged the compression system and modifying the turbine blades. The thermodynamic analysis of the cycle has been carried out in order to determine efficiency and power output as a function of the amount of water addition. The RWI cycle gas turbine has been designed and the characteristic maps of the two new turbines have been evaluated. The regulation is performed by means of the simultaneous manipulation of fuel flow rate, water rate, and position of the free turbine nozzle guide vanes (NGV). The regulation criteria, the interaction among the input variables, the safety of the operations (max. turbine inlet temperature, surge limits) and the optimization of the part-load efficiency, are examined and discussed. Ratings as a function of the ambient temperature are examined. The possibility to manipulate the water rate and the position of the NGV in order to provide high efficiency and power output, even on hot days, has been examined. The paper shows that maintaining constant the temperature at the power turbine exit, ratings decrease of 17% in power and 5% in efficiency.

The effect of gas turbine coolant modulation on the part load performance of combined cycle plants. Part 1: Gas turbines

1997 ◽  
Vol 211 (6) ◽  
pp. 443-451 ◽  
Author(s):  
T S Kim ◽  
S T Ro
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Combined Cycle ◽  
Part Load ◽  
Turbine Blade Cooling ◽  
Blade Cooling ◽  
Wide Range ◽  
Control Schemes ◽  
Load Characteristics ◽  
Simulation Programme

This paper demonstrates a favourable influence of turbine coolant modulation on the part load performance of gas turbines. A general simulation programme is developed, which is capable of accurately estimating the design and part load performance of modern heavy-duty gas turbines characterized by intensive turbine blade cooling Investigations are made for a typical gas turbine and two distinct load control schemes are considered: the fuel-only control and the variable compressor geometry control. Maintaining blade temperatures as high as possible whose purpose is to minimize coolant consumption is simulated. It is found that the coolant modulation makes the part load characteristics deviate from usual behaviours and creates a considerable enhancement of part load thermal efficiency. For the fuel-only control with coolant modulation, it is predicted that efficiency can be higher than design efficiency over a wide range of part load operation.

A New Concept for Power Grid Stabilization Using a Motor-Assisted Variable Speed Gas Turbine System

2014 ◽  
Author(s):  
Naohiro Kusumi ◽  
Noriaki Hino ◽  
Aung Ko Thet
Keyword(s):  
Gas Turbine ◽  
Power Output ◽  
Gas Turbines ◽  
Power Plants ◽  
Power Grid ◽  
Renewable Energy Sources ◽  
Thermal Power ◽  
Rotational Energy ◽  
Thermal Power Plants ◽  
Variable Speed

As the penetration ratio of renewable energy sources becomes larger, the fluctuations of grid load also become larger and larger because of the intermittent generation of wind power and photovoltaic power. These fluctuations cause instability of voltage and frequency in the power grid. Recently, there has been considerable research into solving these challenges, leading to development such as batteries, flywheels, and improved flexibility of thermal power plants. The batteries and the flywheels are confronted with the challenge of high initial cost for the Mega-Watt class. Improving flexibility for the thermal power plants is effective, but this improvement has several limitations such as load-follow operation capability under mechanical constraints and frequency regulation within governor-free regulating capacity. To overcome these problems, we propose a new gas turbine system named Motor-assisted Gas Turbine (MAGT). MAGT is composed of a two-shaft gas turbine: one free turbine shaft is connected to a synchronous generator rotating at a constant speed, and the other compressor shaft is coupled to an inverter-fed motor controlled at variable speed. The motor and inverter capacity is appropriate: about 5–10 % that of the gas turbine. MAGT improved the reaction rate corresponding to the load fluctuation by changing the speed of the compressor. Since the motor’s shaft, which has a compressor and a high pressure turbine, rotates at high speed and those masses are considerable, it has rotational energy of about several kWh. This energy could be charged and discharged through the converter that controls the motor speed, the same as for flywheels. This response could be much faster than conventional gas turbines, which contain huge amounts of working gas. MAGT controls its rotational energy in seconds and controls gas turbine power in minutes; thereby it improves response totally. Moreover, by assisting the compressor by using motor power, MAGT can increase gas turbine power output. Since the density of air decreases with as temperature increase, the mass of working gas is reduced. Thus, the fuel input must accordingly be reduced to suppress the combustion temperature without damaging turbine blades. As a result, power output is reduced. In such cases, a motor-assisted compressor can increase working gas. That allows more fuel input. The proposed system was evaluated using numerical simulations. The results showed that frequency variations were within ±0.1Hz and the output power was recovered under high ambient temperature.

Three Spool High Efficiency Small Scale Gas Turbine Concept

2017 ◽  
Author(s):  
Matti Malkamäki ◽  
Ahti Jaatinen-Värri ◽  
Antti Uusitalo ◽  
Aki Grönman ◽  
Juha Honkatukia ◽  
...  
Keyword(s):  
Power Generation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Small Scale ◽  
Inlet Temperature ◽  
Substantial Impact ◽  
Electrical Efficiency ◽  
Partial Load ◽  
Reciprocating Engines

Decentralized electricity and heat production is a rising trend in small-scale industry. There is a tendency towards more distributed power generation. The decentralized power generation is also pushed forward by the policymakers. Reciprocating engines and gas turbines have an essential role in the global decentralized energy markets and improvements in their electrical efficiency have a substantial impact from the environmental and economic viewpoints. This paper introduces an intercooled and recuperated three stage, three-shaft gas turbine concept in 850 kW electric output range. The gas turbine is optimized for a realistic combination of the turbomachinery efficiencies, the turbine inlet temperature, the compressor specific speeds, the recuperation rate and the pressure ratio. The new gas turbine design is a natural development of the earlier two-spool gas turbine construction and it competes with the efficiencies achieved both with similar size reciprocating engines and large industrial gas turbines used in heat and power generation all over the world and manufactured in large production series. This paper presents a small-scale gas turbine process, which has a simulated electrical efficiency of 48% as well as thermal efficiency of 51% and can compete with reciprocating engines in terms of electrical efficiency at nominal and partial load conditions.

scholarly journals Thermodynamic modelling and efficiency analysis of a class of real indirectly fired gas turbine cycles

2009 ◽  
Vol 13 (4) ◽  
pp. 41-48
Author(s):  
Zheshu Ma ◽  
Zhenhuan Zhu
Keyword(s):  
High Temperature ◽  
Heat Exchanger ◽  
Gas Turbine ◽  
Power Output ◽  
Gas Turbines ◽  
Waste Heat ◽  
Operational Parameters ◽  
Forecast Performance ◽  
Micro Gas Turbine ◽  
Temperature Heat

Indirectly or externally-fired gas-turbines (IFGT or EFGT) are novel technology under development for small and medium scale combined power and heat supplies in combination with micro gas turbine technologies mainly for the utilization of the waste heat from the turbine in a recuperative process and the possibility of burning biomass or 'dirty' fuel by employing a high temperature heat exchanger to avoid the combustion gases passing through the turbine. In this paper, by assuming that all fluid friction losses in the compressor and turbine are quantified by a corresponding isentropic efficiency and all global irreversibilities in the high temperature heat exchanger are taken into account by an effective efficiency, a one dimensional model including power output and cycle efficiency formulation is derived for a class of real IFGT cycles. To illustrate and analyze the effect of operational parameters on IFGT efficiency, detailed numerical analysis and figures are produced. The results summarized by figures show that IFGT cycles are most efficient under low compression ratio ranges (3.0-6.0) and fit for low power output circumstances integrating with micro gas turbine technology. The model derived can be used to analyze and forecast performance of real IFGT configurations.

scholarly journals Inlet Air Fogging of Marine Gas Turbine in Power Output Loss Compensation

2015 ◽  
Vol 22 (4) ◽  
pp. 53-58 ◽  
Author(s):  
Zygfryd Domachowski ◽  
Marek Dzida
Keyword(s):  
Gas Turbine ◽  
Power Output ◽  
Gas Turbines ◽  
Evaporative Cooling ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Output Loss ◽  
Direct Evaporative Cooling ◽  
Loss Compensation ◽  
The World

Abstract The use of inlet air fogging installation to boost the power for gas turbine engines is widely applied in the power generation sector. The application of fogging to mechanical drive is rarely considered in literature [1]. This paper will cover some considerations relating to its application for gas turbines in ship drive. There is an important evaporative cooling potential throughout the world, when the dynamic data is evaluated, based on an analysis of coincident wet and dry bulb information. This data will allow ships’ gas turbine operators to make an assessment of the economics of evaporative fogging. The paper represents an introduction to the methodology and data analysis to derive the direct evaporative cooling potential to be used in marine gas turbine power output loss compensation.

Gas Turbine and Driven Machinery Management and Diagnostics

2011 ◽  
Author(s):  
Mel Maalouf ◽  
Thomas Eldridge
Keyword(s):  
Gas Turbine ◽  
Power Output ◽  
Gas Turbines

The size and complexity of gas turbines has evolved tremendously over the years and the controls, instrumentation and diagnostics tools have kept pace with the advances. This paper discusses the progress of the tools to keep these complex machines running for continued reliability, efficiency, emissions compliance and power output. The technology to enable the user to manage their machinery on site and remotely will be discussed in this paper along with the benefits added by the technologies.

Grid emulator for small scale distributed energy generation laboratory

2018 ◽  
Vol 43 ◽  
pp. 325-338 ◽  
Author(s):  
Sondes Skander-Mustapha ◽  
Manel Jebali-Ben Ghorbal ◽  
Marwa Ben Said-Romdhane ◽  
Mansour Miladi ◽  
Ilhem Slama-Belkhodja
Keyword(s):  
Energy Generation ◽  
Small Scale ◽  
Distributed Energy ◽  
Distributed Energy Generation

A methodology for identifying the most suitable measurements for engine level and component level gas path diagnostics of a micro gas turbine

2021 ◽  
pp. 095440622110303
Author(s):  
SS Talebi ◽  
AM Tousi ◽  
A Madadi ◽  
M Kiaee
Keyword(s):  
Path Analysis ◽  
Gas Turbine ◽  
Smart Grids ◽  
Gas Turbines ◽  
Complex Dynamics ◽  
Gas Temperature ◽  
Component Level ◽  
Part Load ◽  
Micro Gas Turbine ◽  
Process Gas

Recently, the utilization of micro gas turbines in smart grids are rising that makes the part-load operation principal situation of the engine service. This leads to faster life consumption that increases the importance of the diagnostics process. Gas path analysis is an effective method for gas turbine diagnostics. Complex dynamics of gas turbine induces challenging conditions to perform applicable gas path analysis. This study aims to facilitate MGT gas path diagnostics through reducing the number of monitoring parameters and preparation a pattern for engine level and component level health assessment in both full and part load operation of a recuperated micro gas turbine. To attain this goal a model is proposed to simulate MGT off-design performance which is validated against experimental data in healthy and degraded operation modes. Fouling in compressor, turbine and recuperator and erosion in compressor and turbine as the most common degradations in the gas turbine are considered. The fault simulation is performed by changing the health parameters of gas path components. According to the result investigation, a matrix comprises deviation contours of four parameters, Power, fuel flow, compressor discharge pressure, and exhaust gas temperature is presented and analyzed. The analysis shows that monitoring these parameters makes it possible to perform engine level and component level diagnostics through evaluating a binary code (generated by mentioned parameter variations) against the fault effects pattern in different load fractions and fault severities. The simulation also showed that the most power drop occurred under the compressor fouling by about 8.7% while the most reduction in thermal efficiency is observed under recuperator fouling by about 7.84%. Furthermore, the investigation showed the maximum decrease in the surge margin induced by the compressor fouling during the lower part-load operation by about 45.7% while in the higher loads created by the turbine fouling by about 14%.

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