Showing papers on "Forced outage published in 2015"

Flexible transmission expansion planning associated with large-scale wind farms integration considering demand response

Abstract: With increasing large-scale wind farms being integrated into the power grids, transmission expansion planning (TEP) increasingly requires more flexibility to account for the intermittency as well as other uncertainty factors involved in the process. In this study, a probabilistic TEP model is proposed for planners to tackle the variability and uncertainty factors associated with grid connected wind farms. Both load forecast and wind power output uncertainties are considered in the proposed model. Other factors considered in the model include the forced outage rates of transmission lines and generators, and the wind speed correlation between wind farms. Moreover, the incentive-based demand response (IBDR) program is introduced as a non-network solution instead of the conventional network expansion approaches. The utilities will pay IBDR providers for their contributions to peak demand reduction. The proposed TEP model can find the optimal trade-off between transmission investment and demand response expenses. The hierarchical Bender's decomposition algorithm integrated with Monte Carlo simulation is employed to solve the proposed model. Case studies are given using the Garver's six-bus system and the IEEE-reliability test system to show the effectiveness of the method.

Optimization of grid connected micro-grid consisting of PV/FC/UC with considered frequency control

Abstract: In this paper, ultracapacitors are used as short-term storages for the frequency control of grid-connected microgrid that consists of photovoltaic panels, fuel cells, and the battery packs as long-term storages. Fuel cells and battery packs have delays in load tracking; therefore, ultracapacitors are used to compensate for the sudden power fluctuations in the microgrid that occur due to the output power uncertainty of the PV arrays and the loads required in the microgrid, as well as the sudden interruption of the main grid. The microgrid consists of interruptible and uninterruptible loads. When the total produced power in the microgrid, in addition to the purchased power from the grid, cannot satisfy the demand, first, the interruptible loads, and then the uninterruptible loads, are interrupted. In this paper, the forced outage rate of each component and some notions of the reliability are considered for the microgrid. To ensure the system's reliability, the uncertainty of the PV power and load demand is considered.

Evaluation of Reliability Parameters in Micro-grid

Abstract: Evaluation of the reliability parameters in micro-grids based on renewable energy sources is one of the main problems that are investigated in this paper. Renewable energy sources such as solar and wind energy, battery as an energy storage system and fuel cell as a backup system are used to provide power to the electrical loads of the micro-grid. Loads in the micro-grid consist of interruptible and uninterruptible loads. In addition to the reliability parameters, Forced Outage Rate of each component and also uncertainty of wind power, PV power and demand are considered for micro-grid. In this paper, the problem is formulated as a nonlinear integer minimization problem which minimizes the sum of the total capital, operational, maintenance and replacement cost of DERs. This paper proposes PSO for solving this minimization problem.

On-line fault monitoring system for hydroelectric generators based on spectrum analysis of the neutral current

Abstract: An on-line fault monitoring diagnostic system for hydroelectric generators based on spectrum analysis of neutral current is presented. Hydroelectric generators are fundamental elements in the power train at hydroelectric power plants and require an adequate diagnostic analysis. Unexpected generator failures can lead to a significant financial effect owing to the elevated costs of emergency repairs and lost revenues caused by forced outage extended periods. Determining the actual operating conditions of a generator is a crucial phase in assessing the risk of failures. The on-line instrumentation fault monitoring diagnostic system uses a simplified electrical model of fault simulation in order to help interpret the harmonic sources in the neutral current. Field measurement results proved that the spectrum analysis model for detecting mechanical faults is effective.

Operational statistic risk assessment for power systems under extreme weather conditions

Abstract: Since the power systems become complicated, the probability and perniciousness of multi-concurrent outages keep rising, especially under some extreme weather conditions like typhoon. Thus, operational risk assessment methods are very useful for system operation to evaluate the reliability of power grids under extreme weather. To calculate the forced outage rate (FOR) for components, common reliability evaluation methods use physical models, which analyze the physical relationship between probabilities of outages and one main weather factor. However, because extreme weather contains several factors and the interaction of these factors is hard to be modeled, physical models are not appropriate for risk assessment with extreme weather. To solve this problem, a statistic method is proposed to evaluate the risk of power systems under extreme weather, and a typhoon case is tested with proposed method in a real large-scale power grid of China.

Performance analysis of a desalination plant as a single unit with mandatory shutdown during winter

Abstract: The aim of this paper is to present a reliability and availability analysis of a desalination plant as a single unit. The plant operates round the clock for water production and the complete plant is under shut down state for 30 days during winter season for annual maintenance. The water supply during the shutdown period is maintained through ground water and storage system. Any failure or annual maintenance brings the plant to a complete halt and the plant goes under forced outage state. Tripping statesare also noted which requires only servicing. For the present analysis, seven years failure data has been extracted from operations and maintenance reports of a desalination plant in Oman. Measures of the plant effectiveness have been obtained using semi-Markov processes and regenerative point techniques

Wind power integrated power system spinning reserve optimizing method taking wind power overflow into consideration

Abstract: The invention discloses a wind power integrated power system spinning reserve optimizing method taking wind power overflow into consideration. The wind power integrated power system spinning reserve optimizing method taking wind power overflow into consideration comprises integrating a system uncertainty risk analyzing method and a cost-benefit analyzing method under multi-scenario probability to establish a unit commitment model taking wind power overflow into consideration, by improving a multi-scenario probability-based risk analyzing method capable of simultaneously taking load, wind power predication uncertainty and unit forced outage into consideration, can take the wind power overflow into consideration when computing system load loss risks, and by calculating the target of routine unit generation cost and minimum expected outage cost through cost-benefit analysis, obtains optimized spinning reserve capacity. The wind power integrated power system spinning reserve optimizing method takes wind power overflow into consideration and accordingly can comprehensively take system operation economical benefits into consideration during determining of system spinning reserve to achieve low operation cost.

New Robotic Technologies for Inspecting Two Pole Electric Generators while the Rotor Remains in Place

Abstract: The electric generator is a highly stressed plant component requiring periodic inspection and maintenance to reduce the risk of a costly forced outage. This paper briefly introduces two new robotic technologies for performing fast and reliable inspections of two pole electric generators with minimal mechanical disassembly requirements. The first robotic system is designed to inspect within the generator rotor and stator air gap, while the second robotic system is designed to inspect the generator retaining rings. An overview of the design and construction of each system is provided, along with an explanation of the capabilities and benefits they bring to the power station owner.

Distributed generation unit allocation utilizing expert system with reliability and voltage sag consideration

Abstract: The advent of distributed generation (DG) units has posed many problems to the planning and operation of distribution networks (DS). The selection of the “best” site for the DG installation is a major problem in this context. Different strategies and methods have been developed in the recent years which deal with this problem. However, Complexity of solutions and inadequate manipulation have hindered their utilization by DS planners. This paper presents a robust and practical tool which helps the distribution network planner in getting the best possible location of DG unit taking into account both reliability of supply and voltage sag problems. The method suggested uses knowledge-base expert system (ES) to help in selecting the appropriate locations. The method suggested is based on economic and technical considerations. It investigates with economic loss due to both voltage sag and forced outage of DS components. It concerns with the effect of location of the added DG on the overall network performance during both steady-state when a forced outage occurring on one or more component of the DS and transients after sudden short-circuit. Using ES avoids mathematical complications of solving complex analytical model. By judicious rule-base ES, selection of optimum locations becomes clear and simple. The suggested method is explained and implemented through practical distribution network and its effectiveness is tested and discussed.

Shorting-time transmission line maintenance scheduling method based on Credibility Theory

Abstract: Scheduling transmission line maintenance is important to the operation of power system. Traditionally, transmission line maintenance scheduling formulated as a stochastic programming problem, which cannot express operation risk accurately. In terms of Short-term transmission line maintenance scheduling, line forced outage rate is based on (100km·year)−1. In other words, in the same region, the longer the transmission line with the same voltage level is, the higher the forced outage rate is. However, this is not conform to the actual. The power system contains twofold uncertainty, consisting of random and fuzzy. Therefore, we need to evaluate random and fuzzy of the maintenance plan comprehensively. Credibility Theory provides a comprehensive assessment for the fuzziness and randomness, which is the key to solve the problem that traditional line maintenance scheduling model is not applicable to practice. In this paper, combined with the IEEE-RBTS system, the model and algorithm of short-term transmission line maintenance scheduling based on credibility theory is presented.

A Heuristic Approach for Economic Dispatch Problem in Insular Power Systems

Abstract: Insular power systems are characterized by their isolated geographical location, which makes their interconnection with other power systems a challenging task. Moreover, these islands have important renewable resources that allow the reduction of generation costs and greenhouse gas emissions (GHE). To guaranty the quality, flexibility and robustness of the electrical framework, the representation of renewable power forecasting error by scenario generation or even the implementation of demand response tools have been adopted. In this paper, the failure events of a specific unit are considered according to its capacity. Then, using the forced outage rate, the probability of each failure event is computed. Results of energy not supplied and fuel consumption cost are determined by applying probabilistic concepts, while the final results are obtained by fitting and evaluating a nonlinear trend line carried out using the previous results, resulting in a proficient computational tool compared with classical ones.

Study on Optimization of Peak Load Shifting in Zhongshan Power Supply Bureau and Development of the Support System

Abstract: Starting with industrial power customers’ behavior of Zhongshan Power Supply Bureau, this paper studies the electrical behavior and production characteristics, and implements staggering power consumption optimization. Then an optimization method is proposed, which could guarantee the peak load shifting effect, and at the same time could reduce the influence on users. In this way, peak load shifting could reduce outage time and get industrial customers’ understanding and support compared to the former way. And with the peak load shifting support system, manpower could be cut down. Based on the optimization of peak load shifting scheme, the limited power could be used in the most efficient enterprise. The improvement of peak load shifting will reduce industrial customers’ forced outage frequency as well as the influence on the normal production of the industrial customers, and help the power supply bureau put the customers first, providing quality services.

Short-term and multi-state reliability model for an industrial gas turbine

Abstract: This paper presents a short-term, multi-state reliability model for an industrial gas turbine. A new method is introduced to define the state boundaries. The transition intensities between any two states are determined from actual operation data and a Markov chain embedded in the operation data. The Chapman Kolomogorov equation corresponding to N-states is given. The equation can be applied to any gas turbine system. In the current paper, it is applied to a power plant having two identical 5.2 MW (nominal capacity at ISO condition) Siemens Taurus 60S gas turbines. The specific model included droop and isochronous modes of operation. The results show that the forced outage rates for the two gas turbines converge to 0.513 and 0.2661, respectively, when t��. Such a model will be applicable for short term planning of the operation of gas turbines hence contributing to a saving in life-cycle or maintenance cost. © 2006-2016 Asian Research Publishing Network (ARPN).

Reliability Evaluation of Wind Power Plant Using Matlab

Abstract: Wind is a clean source of electricity as it doesn’t produce harm to environment. But the output obtained from wind resource is uncertain. Power output from the wind electric conversion system is variable. Hence the main objective of this project is to develop a method to evaluate the reliability of output power obtained from wind electric conversion system The approach used here involves the simplified reliability model for the wind energy conversion system. In this methodology, four factors are calculated which are wind availability factor, constant power output factor, variable power output factor, factors for mechanical failure. In order to calculate these factors turbine design parameters such as shape factor (β), which is dependent on the height of the tower and station, Scale factor (α), which is nearer to the average wind speed are considered. These parameters are determined using weibull distribution. For the reliability evaluation, plants considered in this project are Jajikalgudda, Kappatagudda, Seegegudda, and Chitradurga The procedure centers on the determination of Forced outage rate. Sensitivity graphs for the several key parameters are plotted in MATLAB.

Risk-based transmission lines importance calculation under ice storm weather

Abstract: A risk-based transmission lines importance calculation method is proposed under ice storm to identify the importance of icing lines to system operation in this paper. The model of forced outage rate of icing line is established by load-strength interference theory. Then risk functions of demand not supplied and power failures are established. The concept of transmission lines' global sensitivity of risk functions is proposed to quantify the influence of icing lines to system operation by analysis of variance decomposition. The quasi-Monte Carlo method based on Sobol' sequence is used to calculate global sensitivity of icing lines. The proposed method is tested on the system of IEEE RTS79. The results show that different lines have various importance to system risk and the importance sorting of icing lines could be a feasible tool to help arrange the deicing work.