The ultra-short-term prediction of photovoltaic power system is of great significance to the safe operation of power system. However, the daily and annual periodicity of solar radiation brings strong non-stationary to...
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ISBN:
(数字)9789881563903
ISBN:
(纸本)9781728165233
The ultra-short-term prediction of photovoltaic power system is of great significance to the safe operation of power system. However, the daily and annual periodicity of solar radiation brings strong non-stationary to the photovoltaic power series, which makes it difficult to predict the photovoltaic power series. In order to overcome the problem that the detailed clear sky model relies on a large number of plant parameters, this paper proposes a prediction algorithm based on a modified clear sky model. Firstly, historical data and geographical location of a certain site are utilized to build a modified clear sky model, then the theoretical clear sky power curve fitted by the modified clear sky model are divided by the actual historical power output to get a stabilized time series, finally the method of "online update" is adopted to forecast PV plant power output in the ultra-short-term time horizon (0-4 h). The test results of a photovoltaic power station in Ningxia show that the proposed model can reduce the prediction error of the 4th hour to about 3%.
Paralleling SiC MOSFETs is a popular way to increase the current capacity. However, due to asymmetric layout, device parameter mismatch and other factors, imbalanced switching or dynamic current is observed among the ...
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ISBN:
(数字)9781728158266
ISBN:
(纸本)9781728158273
Paralleling SiC MOSFETs is a popular way to increase the current capacity. However, due to asymmetric layout, device parameter mismatch and other factors, imbalanced switching or dynamic current is observed among the paralleled switches in multi-device paralleling application which results in unequal switching loss, challenging the security and reliability of the system. In this paper, a common-mode choke in the gate loop is proposed and analyzed to suppress the imbalanced switching current induced by asymmetric layout in a half-bridge configuration with a Kelvin-source connection. The mechanism of the proposed method is comprehensively investigated to show that though the common-mode choke is placed in the gate loop, it can also mitigate the imbalanced current caused by asymmetric power loop. And it also shows that only the leakage inductance of the choke is seen in the gate loop and thus the switching speed is not expected to be influenced. The proposed method can be easily extended to multi-device paralleling application and the switching transients is hardly influenced by the common-mode choke. simulation and experimental results are presented to verify the proposed method.
Aimed at power system large-scale blackouts, the paper firstly analyzes the existing problems of current protective relaying and emergency control in power grid. A novel system protection based on local information, p...
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Aimed at power system large-scale blackouts, the paper firstly analyzes the existing problems of current protective relaying and emergency control in power grid. A novel system protection based on local information, protecting both the equipment and power system secure is then proposed, which scheme consists of: identification of fault flow transferring identification, adaptive overload protection and active load shedding strategy. The processes and system structure are introduced, and the following research points are also discussed in this paper.
With high speed data sampling technology development, fault generated high-frequency signals can be got, in which fault generated traveling waves reflects fault location, fault type and faulted equipment so on from di...
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With high speed data sampling technology development, fault generated high-frequency signals can be got, in which fault generated traveling waves reflects fault location, fault type and faulted equipment so on from different ways of traditional power-frequency information. Fault generated traveling waves may help to improve protection relaying. The paper will review fault generated traveling waves and its physical base at first. Then two cases will be presented to exemplify the advantage of traveling waves based protection relaying. One is that fault generated traveling waves with the speed of light can be used to protect UHV long transmission lines independent of capacitive charging current. The other is traveling wave will be applied to detect single-phase-to-ground fault in power distribution system with neutral non-effectively grounded. At last the paper will conclude with implementation of traveling wave based protection relaying.
Forward electricity market has emerged as a pivotal section for the electricity transaction to keep stakeholders away from price risk and electricity shortage. But the forward contract of conventional unit partially l...
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In order to reduce the randomness and fluctuation of wind power, numerical weather prediction is usually used to forecast powergeneration. Due to the redundancy of numerical weather prediction factors, dimensionality...
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Smart substation is the base of smart grid and it is made up of a lot of IEDs (intelligent electric device). Synchronized phasor measurement unit (PMU) plays a very important role in the smart grid, and a great deal o...
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Smart substation is the base of smart grid and it is made up of a lot of IEDs (intelligent electric device). Synchronized phasor measurement unit (PMU) plays a very important role in the smart grid, and a great deal of PMUs have been installed in China. The requirement of PMU in the smart substation is different from traditional substation. This paper introduces that the PMU is suitable for smart substation, there are several details that need to be complemented in IEC 61850 standards, and the paper gives some suggestion to improve it.
Lightning is the major cause of interruptions in power transmission lines. Ultra-high voltage (UHV) AC transmission line has been put into operation in China. Due to the large tower height up to 90 m and the high oper...
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Lighting causes great damage to powersystems due to the stochastic nature of lightning discharges and the vulnerability of lightning leaders to various environments in the process of inception and propagation. In thi...
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The paper proposes faulted feeder selector in power distribution system with neutral non-effectively grounded. At first, the paper presents basic principle of single-phase-to-ground fault feeder selection based on tra...
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