Unit Trip Research Articles

Innovative Approaches to Hydraulic Turbine Advanced Condition Monitoring

Abstract This research paper introduces advancements in hydraulic turbine condition monitoring through the implementation of vibration-based condition indicators. Conventional methods rely on vibration monitoring systems, triggering alarms or unit trips based on overall measured values at specific points. However, these methods may generate false alarms under changing operating conditions, such as variations in head or flow rate. In response, our study focuses on the development and validation of condition indicators derived from vibration data, considering the turbine’s operating conditions. Our methodology defines and validates these condition indicators, providing a detailed understanding of the hydraulic turbine’s condition. By employing an enhanced condition monitoring framework, our approach not only improves fault detection accuracy but also offers a comprehensive perspective on the overall health of the turbine. Experimental results from a prototype Kaplan turbine showcase the effectiveness of our methodology in detecting and characterizing faults, enabling proactive maintenance strategies. The Kaplan turbine studied is one of the demonstrators of the XFLEX HYDRO project. In conclusion, this research delivers a valuable tool for industry professionals and researchers involved in hydraulic turbine maintenance and optimization.

Calculation of greenhouse gas emissions of urban rail transit systems in China

In China, the total energy consumption and greenhouse gas (GHG) emissions will reach considerable levels based on the current speed of urban rail transit system development. Based on the life-cycle assessment theory, this research constructs an urban rail transit system GHG emission assessment method, calculates emission outputs based on resource inputs from actual investigated data and makes a quantitative analysis of GHG emissions. The results show that in recent years, the GHG emission of urban rail transit construction and operation in China is between 2000 × 104 and 4200 × 104 tonnes of carbon dioxide equivalent (tCO2e) per year. The proportions of the construction and operational phases in this emission are 57 and 43%, respectively. In the construction phase, the GHG emission intensity per unit mileage of shield tunnels and per unit area of stations is about 1.3 × 104 tCO2e/km and 3.71 × 104 tCO2e/ha, respectively. In the operational phase, the GHG emission intensity per unit trip is 0.084 kg carbon dioxide equivalent/passenger-km. The entire life-cycle GHG emission per kilometre of urban rail transit systems is 11.69 × 104 tCO2e (with a service life of 50 years) in China. The construction phase and operation phase generated about 18.73 and 81.27% of this emission, respectively. The preliminary conclusions of this study may help shed light on the emission reduction potential of urban rail transit systems and the emission reduction targets in China.

Analisis Tarif Ideal Angkutan Barang Lintas Banjarmasin – Amuntai

Tariff is the level of price or fee paid by users of goods transport services per unit trip, weight or per unit volume per kilometer. Because the tariff is intended to encourage the creation of optimum use of transportation infrastructure and facilities by considering the traffic concerned. In calculating the cost (transportation rate) of goods using an approach to vehicle production costs, it means that the ideal freight rate is determined based on vehicle operating costs plus a number of percentages of management and profits that are allowed. This case study reviews the special freight rates for the Banjarmasin – Amuntai route along 200 km. by land transportation. Where in this case, due to low tariffs, the tendency of owners of transportation services to increase the number of transport loads, one of the impacts on road network infrastructure is not achieving the planned age of the road construction. The calculation of transportation rates refers to the technical guidelines for determining tariffs for goods and passengers from the Director General of Land Transportation of the Ministry of Transportation with three basic components, namely ownership costs, fixed costs and vehicle operating costs. From the combination of the three components, the basic tariff value for goods transportation from Banjarmasin - Amuntai per kilogram is Rp.681.39 so that the expedition company can determine the ideal tariff according to the level of service to service users

Analisa Pemasangan UPS VFD LFO Feeder Untuk Mengantisipasi Gangguan Eksternal

On July 1 and July 26 2017 there was a simultaneous trip of PLTDG Units 1,2,5,5,6,7,8 and PLTDG Units 1,3,4,5,6,7,8,9 due to a momentary drop voltage due to disturbance kites on the 150 KV line network sanur – gianyar. From the trip conditions, it shows that there is a problem with the generator unit equipment which causes PLTDG units 1,2,3,4,5,6,7,8,9 to trip due to a momentary drop voltage. From the results of the analysis, it is known that the unit trip was caused by a trip on the Pht Line 150 KV to the ship - Padang sambian on the Padang sambian side which resulted in a drop voltage on the low voltage side of 280.4 V or 29.9%. from Unominal. The trip limit of 200MW low-voltage PLTDG according to technical data is 351V or 12.3% of Unominal. The best option to solve the drop voltage fault solution is to install a 10KVA UPS on the LFO feeder pump power supply. The difference before and after the installation of the UPS feeder LFO is that before the installation of the low voltage UPS it drops to 280.4 V or 29.9% of Unominal, and the machine load drops to 11.6 MW. For the results after UPS installation there is no drop voltage value on the low voltage side which means that the UPS installation is successful as a voltage drop solution. So that the difference is obtained on the low voltage side of 119.6 V and on the engine load of 5 MW. Thus, the implementation of a UPS installation on a 200MW PLTDG is very important, in addition to supporting the reliability of the generator system and speeding up recovery in the event of a drop voltage, it can also be economically profitable, so that the company does not lose when the generating unit trips.

Handling Water Leaking on The Turbine Pit ULPLTA Bakaru due to Damage of the Guide Vane Part using Automatic Method with Motorized Valve

The Bakaru PLTA is the largest hydroelectric power plant in South Sulawesi with a capacity of 126 MW. To generate that much power, a lot of water is required, therefore, the Bakaru hydropower dam is designed to be able to accommodate a lot of water. In operation, the Bakaru hydropower plant consists of 2 units. However, not all units operate normally, such as unit 2. In unit 2, there is a leak that occurs in the Turbine Pit. This leak is caused by abrasion of the u-packing guide vane. With a leak in the turbine pit, more approaches are needed to dispose of the water in the turbine pit to the pit drainage. Which later developed into an infusion system that utilizes gravity to discharge water from the turbine pit in basement 2 to the drainage pit in basement 3. However, in its development, it turns out that the volume of water discharged cannot be controlled so that, it can cause a condition where one day the infusion hose does not flow and causes an increase in the water level in the turbine pit. This rise in the level of the turbine pit is dangerous for the unit. This is because water can enter the breathing hole of the bearing turbine tank and contaminate the oil so the bearing temperature is high and causes a trip or in the worst case, causing equipment damage. However, in reality, using an infusion system using human labor is still often constrained in terms of time efficiency, consistency and cost. Because every time this activity is carried out, the workers who do it are not always the same person and scheduled. Therefore the efficiency is still low. The purpose of this study was to determine the optimal method of handling the increase in water level in the turbine pit so that unit trips do not occur caused by the increase in the water level in the turbine pit. Finally, it is interesting to discuss and find a solution by relocating the handling of leaks by "using an automatic method with a motorized valve by installing a Motorized Valve on the Turbine Pit, so there are financial and non-financial benefits to be obtained. From the results of using the automatic method with a motorized valve, the results obtained are faster cycle times for handling leaks in the turbine pit so there is no stop unit due to leakage disturbances in the turbine pit.

Application of Battery Energy Storage Systems for Relief of Generation Curtailment in Terms of Transient Stability

Maintaining transient stability is crucial in power system operation. Transient stability is mainly affected by the generation amount of the study region, as well as the transmission topology. Several countermeasures can be taken for transient stability, but the usually used control means are generating unit tripping and generation curtailment. In terms of economic operation, one can say that the solution of generating unit tripping is more beneficial. To maintain the transient stability of the east coast region in the Korean power system, applying generation curtailment in the normal state is further needed, because the required tripping amount is too large for the case of only taking generator tripping, and this might cause a critical decrease in system frequency, possibly resulting in operation of the first stage of under frequency relay (UFR). This paper presents the application of battery energy storage systems (BESSs) to relieve the generation curtailment, using the characteristic of fast response of BESS. Assuming that BESSs are installed in the candidate location in the study region, the adequate BESS action of absorbing the kinetic energy from those critical generators after disturbances can improve transient stability, and it can decrease the amount of generation curtailment. This paper includes the results of simulation studies to show the effectiveness of the BESS control for the relief of generation curtailment.

Flexible operation control strategy for thermos-exchanger water level of two-by-one combined cycle gas turbine based on heat network storage utilization

The high penetration of renewable energy sources makes the two-by-one combined cycle gas-turbine (2 × 1 CCGT) with high operational flexibility (OPFL) become the mainstream of deep peak-load units. However, the thermos-exchanger water level (TEWL) often exceeds the limit and causes unit trip during flexible operations. For this reason, this paper proposes a flexible operational TEWL control strategy. First, by modeling and analyzing the thermodynamics of the thermal-supply system of 2 × 1 CCGT unit, the exhaust steam pressure of intermediate pressure cylinder (IPEP) is chosen as an upstream controlled variable with mathematical-model derived setpoint to stabilize the TEWL; Secondly, considering the heat storage utilization of heating network, the heating-network circulating water flow is selected as the manipulated variable of IPEP control, then forming a pilot IPEP control loop cooperating with the existing TEWL control loop to stabilize the TEWL. Several control algorithms are designed and compared to determine the most effective one for the IPEP pilot-TEWL control. The results show that the maximal deviation of TEWL can be reduced to 7 mm and the OPFL indexes can be significantly improved, i.e. the average power ramp rate is 6.74 MW/min, and the power capacity is 69.55 MW from 158 MW steam turbine.

IDENTIFICATION OF INDUCED DRAFT FAN (IDF) DAMAGE IN BOILER WASTE GAS SYSTEM

Induced Draft Fan (IDF) is a fan that sucks air from inside the boiler out to the chimney, producing negative pressure on the boiler, keeping the circulation of combustion air in the boiler normal. IDF is one of the main components in the exhaust gas system which serves to maintain the temperature and vacuum of the furnace in the boiler. This report will identify IDF damage using vibration indication control instruments by looking at vibration indication trending data through the Distributed Control System (DCS) in the Central Control Room (CCR). The results of the trending data will then be identified whether the vibration in Induced Draft Fan has increased, if the vibration ≥ 5.6 mm/s is declared an alarm and if the vibration ≥ 7.1 mm/s then the unit trip or must be stopped. Based on the results of research during industrial practice in Banten 2 PLTU Labuan there were 2 conditions in the IDF, namely when there was a disturbance with a height of X and Y side vibrations of 22.5 mm/s, and conditions after improvement with the height of X vibration side that is, an average of 4.2 mm/s and Y side averaging 4.1 mm/s. The high vibration is affected by the damage of several IDF components, caused by the amount of ash remaining combustion that enters the IDF which causes abrasion of the impeller blade.

Penilaian Impak Trafik ke atas Sebuah Pembangunan Baharu di Kawasan Kejiranan Bandar Ampang di Selangor

Traffic impact assessment (TIA) on a proposed commercial development in the neighbourhoods of Ampang Town in Selangor was conducted. In this study, trip rate analysis and regression analysis were carried out to assess future traffic expected to be generated by the proposed new commercial development. Calculations of trips were based on the Malaysian Highway Planning Unit (HPU) Trip Generation Manual (TGM) Malaysia 2010 related to a category of proposed new commercial development. Before and after construction study on the proposed new commercial development at neighbouring critical intersections and roads was carried out to determine existing and projected traffic volumes. A Statistical Package for the Social Sciences (SPSS) software was used to analyse traffic growth rate. This procedure uses a growth factor in the traffic data to show an increase in demand for transport journeys in the future. Then, intersections and roads traffic performances were analysed using the Signalised and Un-signalised Intersection Design and Research Aid (SIDRA) software. Result of SIDRA analysis with traffic projection horizon of year 2026 shows deterioration in Level of Service (LOS) D at one of the existing main junctions leading to the proposed new commercial development. Finally, traffic improvements were proposed to address future impact of generated traffic caused by the proposed new commercial development. Consequently, this study has provided a framework for TIA preparation and would assist developers and local authorities in their decision making to meet all the requirements needed in the design and improvement of traffic flow.

Significant reliability improvements in reciprocating gas compressor packages at Arrow Energy

Arrow Energy operates a fleet of four-stage reciprocating compressors in the Surat Basin, boosting low-pressure coal-seam gas (at 60 kPag) to transmission pipeline pressure (in excess of 9000 kPag). Historically, the compressors and the gas engine drivers exhibited persistent problems associated with high vibrations, inadequate engine and process gas cooling, poor compressor valve reliability and premature engine component failures. Hot Queensland summer conditions further exacerbated these problems, which resulted in frequent unit trips during hot periods when gas and electricity prices demanded consistent gas production at nameplate capacity. Since 2014, Arrow Energy has carried out systematic analytical studies to establish the compressor package component limitations and develop technical solutions to address these. Stub shaft-driven air coolers, compressor valves, gas engine heads and valves, compressor frame and crosshead mounting arrangements were some of the key components studied in detail. Utilising systematically designed field tests with laboratory calibrated test instruments, scale model laboratory tests, advanced computer simulations, data analytics and new technology trials, several key design modifications were implemented. The outcome of these design changes has enabled Arrow Energy to achieve a step-change in reliability for the better, with each reciprocating compression package (including gas engine driver) operating in excess of 98% reliability. The implemented changes were executed at minimal cost and resulted in significant reduction in maintenance costs. The increased reliability and consistent production during the peak summer hours easily justified the modifications made to the packages. This paper describes the technical work undertaken, changes implemented and their outcomes.

TRIP RATES FOR CONDOMINIUM CONSTRUCTION PROJECT

The number of large scale condominium construction projects had dramatically increased in Bangkok. Many projects had occurred in either densely populated areas or in central business districts, where traffic conditions were usually highly congested. To prevent traffic problems, a traffic impact study must be prepared and submitted for review by concerned public authorities. Unit trip generation rates were important data in traffic impact analysis. Without accurate unit trip generation rates, public agencies could not obtain accurate information on the traffic that will be generated. This study aimed to study trip rates and the factors affecting them for condominium construction project in Bangkok. The data were collected from 30 condominium construction sites located in 15 districts of Bangkok. The analysis used the linear regression method and was divided into three cases: 1) trip rates for all vehicles, 2) trip rates for classified vehicles, and 3) trip rates for all types of condominium. All case analyses considered weekdays, Saturday, and Sunday. The results found that trip rates related to the number of dwellings in the condominium. The trip rates for all vehicle types on weekdays, Saturday, and Sunday were 10.636, 4.647, and 9.294 vehicles per 100 dwelling units per day respectively. The trip rates for six-wheeled and ten-wheeled trucks on weekdays, Saturday, and Sunday were 2.046, 0.975, and 0.575 vehicles per 100 dwelling units per day respectively. The trip rate for four-wheeled trucks and passenger cars on weekdays was 1.960. Regarding condominium types, the trip rate for low rise condominiums for all vehicle types on weekdays was 5.315 while the trip rates for high rise condominiums for weekdays, Saturday, and Sunday were 3.965, 2.667, and 1.261 respectively.

TRIP RATES FOR CONDOMINIUM CONSTRUCTION PROJECT

The number of large scale condominium construction projects had dramatically increased in Bangkok. Many projects had occurred in either densely populated areas or in central business districts, where traffic conditions were usually highly congested. To prevent traffic problems, a traffic impact study must be prepared and submitted for review by concerned public authorities. Unit trip generation rates were important data in traffic impact analysis. Without accurate unit trip generation rates, public agencies could not obtain accurate information on the traffic that will be generated. This study aimed to study trip rates and the factors affecting them for condominium construction project in Bangkok. The data were collected from 30 condominium construction sites located in 15 districts of Bangkok. The analysis used the linear regression method and was divided into three cases: 1) trip rates for all vehicles, 2) trip rates for classified vehicles, and 3) trip rates for all types of condominium. All case analyses considered weekdays, Saturday, and Sunday. The results found that trip rates related to the number of dwellings in the condominium. The trip rates for all vehicle types on weekdays, Saturday, and Sunday were 10.636, 4.647, and 9.294 vehicles per 100 dwelling units per day respectively. The trip rates for six-wheeled and ten-wheeled trucks on weekdays, Saturday, and Sunday were 2.046, 0.975, and 0.575 vehicles per 100 dwelling units per day respectively. The trip rate for four-wheeled trucks and passenger cars on weekdays was 1.960. Regarding condominium types, the trip rate for low rise condominiums for all vehicle types on weekdays was 5.315 while the trip rates for high rise condominiums for weekdays, Saturday, and Sunday were 3.965, 2.667, and 1.261 respectively.

TRIP RATES FOR CONDOMINIUM CONSTRUCTION PROJECT

The number of large scale condominium construction projects had dramatically increased in Bangkok. Many projects had occurred in either densely populated areas or in central business districts, where traffic conditions were usually highly congested. To prevent traffic problems, a traffic impact study must be prepared and submitted for review by concerned public authorities. Unit trip generation rates were important data in traffic impact analysis. Without accurate unit trip generation rates, public agencies could not obtain accurate information on the traffic that will be generated. This study aimed to study trip rates and the factors affecting them for condominium construction project in Bangkok. The data were collected from 30 condominium construction sites located in 15 districts of Bangkok. The analysis used the linear regression method and was divided into three cases: 1) trip rates for all vehicles, 2) trip rates for classified vehicles, and 3) trip rates for all types of condominium. All case analyses considered weekdays, Saturday, and Sunday. The results found that trip rates related to the number of dwellings in the condominium. The trip rates for all vehicle types on weekdays, Saturday, and Sunday were 10.636, 4.647, and 9.294 vehicles per 100 dwelling units per day respectively. The trip rates for six-wheeled and ten-wheeled trucks on weekdays, Saturday, and Sunday were 2.046, 0.975, and 0.575 vehicles per 100 dwelling units per day respectively. The trip rate for four-wheeled trucks and passenger cars on weekdays was 1.960. Regarding condominium types, the trip rate for low rise condominiums for all vehicle types on weekdays was 5.315 while the trip rates for high rise condominiums for weekdays, Saturday, and Sunday were 3.965, 2.667, and 1.261 respectively.

Innovative Control Strategy for Fast Runback Operational Transient Applied to SMRs

The recent interest in the Small Modular Reactor (SMR) for its potential increased economic competitiveness has focused attention in part on reducing operational costs to offset those plant costs that do not benefit from the economies of scale of large traditional units. Plant operation and maintenance economics are significantly driven by plant availability, which can be enhanced by means of innovative control strategies by avoiding unnecessary plant or unit trips. In this context, an effective strategy for achieving fast runback of a sodium-cooled SMR has been developed. In this work, after having defined and modeled a suitable control strategy by adopting the Petri nets formalism, a Model-based Predictive Control regulator has been developed in order to reduce as promptly as possible the power level, without scramming the reactor (fast runback) and possibly limiting the control rod contribution. Such flexibility could lead to significant savings in the operational costs of the reactor while also improving the system availability. The proposed procedure has been characterized by simulating the operational transients on both an oxide-fueled reactor and on a metal-fueled reactor, comparing the responses of the two different configurations and the respectively needed control rod contribution.

Performance viability of a natural gas fired combined cycle power plant integrated with post-combustion CO2 capture at part-load and temporary non-capture operations

Natural gas combined cycle (NGCC) power plants fitted with carbon capture and storage (CCS) technologies are projected to operate as mid-merit plants in the future of the decarbonised energy market. This projection stems from an inherent characteristic of the NGCC plants of being flexible in operation and able to rapidly change their output power. Therefore, it is expected that the NGCC-CCS plants will continue to operate flexibly for a range of operational loads; and therefore compliment the intermittent electricity generation of other low carbon plants to securely maintain the quality of electricity supply. This study aims to evaluate the performance of a triple pressure NGCC power plant fitted with a post combustion CO2 capture plant (PCC) at power plant part loads, and assess the effect of the temporary shutdown of the PCC plant. Steady state simulations of the integrated plant at part loads were performed, as well as the integrated plant in non-capture operating mode. These demonstrated that the PCC steady state performance is viable at part loads down to 60%. However, operation in non-capture mode revealed a negative impact on the steam turbine performance, especially on the low pressure (LP) and intermediate pressure (IP) cylinders, as well as the cold end. Suggesting that it is not beneficial to operate in the non-capture mode, regardless of inevitable situations where the PCC or the CO2 compression unit trip.

Treatment and Analysis on Unit Trip Caused by Primary Fan Stall

As a result of incorrect operation causing the stall of primary fan, the pressure of primary air continuously decreased. Therefore, the combustion stability in boiler has been disturbanced greatly, and the generation unit trips due to water-coal ratio imbalance. In this paper, the stall accident resulted from incorrect operation have been analyzed, and correct operation for the fan have been put forward. Namely, the precursory phenomena of stall can be found and eliminated. Correct operations can keep the pressure of primary air stable. It is concluded that adopting the suitable water-coal ratio and air-coal ratio are helpful to keep the unit on safe.

Optimization of FengTai Power Plant 350MW Supercritical Unit Water Supply RB Control Strategy

The improvement of RB is significant for safety of both the power plant and power grid. This paper, took the 2 × 350MW unit of Inner Mongolia Huaneng Power Plant for instance, researched on three ways to improve water supply RB, like taking a proper sliding pressure curve, improving the water supply system and optimizing the boiler combustion. In the research, we succeeded to maintain main parameters of the unit within a safety range during RB operation, and avoided a unit trip accident causing by one single pump’s fault trip. Therefore, the research’s success settled a good base for the unit’s safe and stable operation.

Considerations for Generation in an Islanded Operation

This paper discusses the conceptual design and operation of an isolated power system, recognizing the reality that generator or turbine trips will occur. The level of reserve generating capacity must be set with proper balancing of capital expenditures and operating costs against revenue lost in a production shutdown. The way that reserve capacity is provided is as important as the amount of reserve; seemingly adequate reserve can turn out to be badly insufficient if it is not well distributed across the available reserve sources. The dynamic behavior of reserve capacity, as much as the amount of capacity that is ultimately available, is critical in determining how an isolated facility will behave in the wake of a unit trip or the loss of a grid connection. In this paper, experiences with detailed dynamic simulations of a range of isolated systems are described. These are related to test work and operational incidents that have provided practical calibrations. Based on simulation and experience, some guidelines are offered for configuring generation and selecting strategies for maintaining stability in large, isolated continuous-process facilities.

A Strategy to Improve Voltage Instability in The 30-Bus IEEE Power System Model using Remedial Actions

The analysis of a large interconnection power system, under the severe disturbances such as those that can lead to a voltage collapse (VC), is necessary to develop the performance of the available protection schemes and to avoid critical conditions that can lead to instability or system blackout. In this paper, a Strategy to improve voltage instability in the 30-Bus IEEE power system model as an example to large interconnected power systems. One case study of a large unit tripping is tested and voltage instability was studied. Also, the required remedial actions are considered.

Foraging trip decisions by the streaked shearwater Calonectris leucomelas depend on both parental and chick state

Parents of albatross and shearwater species employ a dual foraging strategy, feeding their chicks quickly in repeated short trips and then restoring their own fuel reserves during longer trips. A decline in parental body condition is believed to trigger longer trips, but chick body condition and age may also play a role. To investigate these factors in the little-studied streaked shearwater Calonectris leucomelas, we monitored the nest attendance of 17 pairs on Mikura Island in 2005 using an automated identification system. We also monitored body mass changes and meal masses of 5 of the 17 pairs using an automated weighing system. Although the birds did not show a clear dual foraging pattern, trip duration varied widely from 1 to 15 days. On average, the birds fed chicks 67.6 g during nighttime meals at 2.74-day intervals. Since meal mass did not depend on trip duration, feeding efficiency (meal mass delivered per unit trip duration) decreased as trip duration increased. Parents accumulated more energy reserves when they took longer trips. Parents appeared likely to initiate longer trips when their body condition declined or chick body condition recovered.