With the development of smart grid, the self-healing ability of protection device becomes much more important. Pilot protection is of good selectivity, but it needs a highly reliable communication network. Once the co...
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ISBN:
(纸本)9781785618260
With the development of smart grid, the self-healing ability of protection device becomes much more important. Pilot protection is of good selectivity, but it needs a highly reliable communication network. Once the communication line between two devices is out of work, pilot protection will be forced out of operation. Since there are many ring structures in communication network, circuitous routes can be found to help pilot protection remain operational. In this paper, ant colony algorithm (ACA) are used to find the optimal circuitous route, and simulation results show the method is fast and accurate. To the actual communication network of powersystem, each node is just connected to a few other nodes, so the search process often come to dead ends. Use penalty functions can reduce the probability of coming to a dead end and improve the algorithm efficiency. The whole route accelerating penalty function is most efficient.
Wind-photovoltaic-energy storage (ES) hybrid generating system has numerous reactive power sources. It is crucially important for coordinated control of these reactive power sources. According to the test results, the...
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In this paper, the reliability of the rolling bearing fault feature extraction based on casing vibration signals is discussed. Through the fault simulation experiment of rolling bearing, the vibration data of the oute...
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Insufficient power capacity for peak load regulation has caused loss of wind power accommodation in China.A regulation capacity market is under consideration to encourage more peak regulation service,thus how much the...
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Insufficient power capacity for peak load regulation has caused loss of wind power accommodation in China.A regulation capacity market is under consideration to encourage more peak regulation service,thus how much the market would be is important for each participant.A new peak-load regulation capacity planning method is proposed for long-term market based on the wind power curtailment evaluation model using probabilistic production *** method is suitable for the situation in the planning stage without the knowledge of detailed sequences of load and renewable power,and includes modeling of two peak load regulation measures,increasing the adjustable capacity and to shift some long-lasting units to on/off cycling units.A typical area in China is studied in the paper to evaluate the actual effects of different measures.
The unavoidable wind power forecast error results in the pervasive uncertainty in powersystem economic *** order to solve optimization problem such as economic dispatch with random variables,the commonest and simples...
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The unavoidable wind power forecast error results in the pervasive uncertainty in powersystem economic *** order to solve optimization problem such as economic dispatch with random variables,the commonest and simplest method is using a deterministic value to replace this random *** kinds of predictions are used such as maximumlikelihood approximation,expectation and *** study analyses the effect of these prediction choices on uncertainty of powersystem via comparing their statistical *** is shown that when the wind power output is very volatile,the quality of these prediction choices is not ***,a simplified three-unit thermal system and a tenunit system are studied for illustrating the consequence of statistical inconsistency.
Travelling wave (TW) differential protection fully utilizes the fault information contained in TW at both terminals of a transmission line, so it's a protection with high reliability and high selectivity. However,...
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ISBN:
(纸本)9781785618260
Travelling wave (TW) differential protection fully utilizes the fault information contained in TW at both terminals of a transmission line, so it's a protection with high reliability and high selectivity. However, because TW differential protection needs a large amount of communication, it cannot be put into practical use. This paper proposes a TW differential protection which is based on equivalent travelling wave (ETW). Fault information is not lost during the process of getting ETW, so the proposed protection has the same reliability and selectivity with traditional TW differential protection. Because only several modulus maxima are needed to be sent to the opposite terminal, the traffic is largely reduced and the protection can operate much more rapidly. Extensive simulations validate the proposed protection.
Purpose Due to existence of skin effect under rotational excitation, especially to high-frequency motors and power transformers run at the frequency of hundreds or even thousands of hertz, core losses will increase si...
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Purpose Due to existence of skin effect under rotational excitation, especially to high-frequency motors and power transformers run at the frequency of hundreds or even thousands of hertz, core losses will increase significantly, which may cause local overheating damage, and the efficiency and longevity will be decreased. The purpose of this paper is to accurately calculate the rotational anomalous loss in electrical steel sheets. Design/methodology/approach The influence of skin effect to rotational anomalous loss coefficient is described in detail. Based on the rotational core losses calculation approach, the transformed coefficient and parameters of rotational anomalous loss are determined in accordance with experimental data obtained by using 3D magnetic properties testing system. Then, a variable loss coefficient calculation model of rotational anomalous loss is built. Meanwhile, a separation of the total 2D elliptical rotation experimental core losses is worked out. Findings The two methods are analysed and compared qualitatively. It should be noted that the novel calculation model can be more effectively presented anomalous loss features. Moreover, quantitative comparisons between 2D elliptical rotation and alternating core losses have achieved beneficial conclusions. Originality/value Transformed rotational anomalous loss coefficient and parameters of electrical steel sheets considering skin effect are determined. Based on that, a novel calculation model evaluating 2D elliptical rotation anomalous loss is presented and verified based on the experimental measurement and the separation of the total 2D elliptical rotation core losses. The 2D elliptical rotation core losses separation method and quantitative comparison with alternating excitation are helpful to engineering application.
Aiming at the characteristics of the casing vibration acceleration signal of rotating machinery with rubbing fault, a diagnosis method based on EMD (empirical mode decomposition) and Hilbert envelop spectrum is put fo...
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This paper presents a measurement-based solution for low frequency oscillation(LFO) analysis in both real time monitoring and off-line case study. An online LFO property discrimination method is developed first,which ...
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This paper presents a measurement-based solution for low frequency oscillation(LFO) analysis in both real time monitoring and off-line case study. An online LFO property discrimination method is developed first,which alternately uses empirical mode decomposition(EMD)/Hilbert transform(HT) and square calculation to process the measurement data. The method magnifies the variation trend of oscillating variables to accurately discriminate the property of the oscillation. Subsequently, an oscillation source locating method for the forced oscillation(FO) and a strongly correlated generator identification method for the weak damping oscillation(WDO) are proposed. Finally, numerical study results on a test system of the isolated Changdu grid in Tibet validate the proposed methods.
The prediction method based on the partition of weather types has been widely used in photovoltaic prediction. Here, the temporal characteristics of PV data is studied, the physical meaning of the sequential differenc...
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The prediction method based on the partition of weather types has been widely used in photovoltaic prediction. Here, the temporal characteristics of PV data is studied, the physical meaning of the sequential difference sequences is analysed, and a characteristic index system including sequential characteristics index is proposed. The weather types are partitioned based on self-organising map neural network algorithm. Case study shows that the partition method is helpful to improve the discrimination of weather types and to improve prediction accuracy.
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