Irradiance changes caused by clouds movement are the main factors, which lead to mutation of photovoltaic power. In order to increase the accuracy of the ultra-short-term photovoltaic power prediction, based on of clo...
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Irradiance changes caused by clouds movement are the main factors, which lead to mutation of photovoltaic power. In order to increase the accuracy of the ultra-short-term photovoltaic power prediction, based on of clouds images, the cloud identification for sky images is one of the primary aspects for improving photovoltaic power accuracy. A cloud identification model for sky images is established based on Otsu. Firstly, a series of sky images are collected by Total Sky Imager (TSI) with the regions of clouds and sky are distinguished. Secondly, the color features (based on RGB values) of pixels in sample images and the spectral and texture features of the whole image are extracted; Finally, we established a cloud identification model for sky images based on Otsu according to the clouds' and sky areas' division and the general characteristics featured by pixels and images. The simulated results show that the model in this paper can identify the clouds in a sky images effectively.
There may be complex interaction between the converter controlsystems of wind power and MMC-HVDC, which will lead to sub-/super-synchronous oscillation and threaten the safe and stable operation of the system. The re...
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There may be complex interaction between the converter controlsystems of wind power and MMC-HVDC, which will lead to sub-/super-synchronous oscillation and threaten the safe and stable operation of the system. The relevant events have been reported in Guangdong Nan'ao, Shanghai Nanhui and Zhangbei projects. Rudong offshore wind power project is the first offshore wind power transmission system in China, and it is still under construction. Therefore, it is of great significance to carry out the research on the risk analysis and suppression measures of sub-synchronous oscillation in Rudong wind power MMC-HVDC system. First, the time-domain simulation model of Rudong wind power MMC-HVDC system is built in the PSCAD/EMTDC simulation model. Then, the effects of the number of wind turbine generators, wind power output and the parameters of MMC-HVDC controller on the sub-/super-synchronous oscillation characteristics of the system are further analyzed. Finally, the suppression measures based on supplementary frequency dependent gain control are proposed, the application position of the controller is discussed, and the parameter optimization method of the controller is given. The research content provides a certain guiding significance for the operation and control of Rudong wind power MMC-HVDC.
The operation risk may increase with the high penetration of wind power, but the calculation of risk indices is complex and nonlinear, which makes it difficult to incorporate the risk constraints into the conventional...
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ISBN:
(数字)9781728177175
ISBN:
(纸本)9781728177182
The operation risk may increase with the high penetration of wind power, but the calculation of risk indices is complex and nonlinear, which makes it difficult to incorporate the risk constraints into the conventional unit commitment (UC) model. This paper focuses on accurately handling the risk constraints instead of approximate exponential decay rules, and proposes an iteration-correction methodology to solve risked-constrained UC of powersystems with wind power. The proposed method calculates the risk indices based on the PJM method, and modifies the minimum reserve demand in each iterative step if the risk indices exceed the limits. A dynamic iterative speed-up equation is given to decrease the elapsed time. The case studies based on the actual system of China are conducted to validate the effectiveness. Compared with the conventional reserve limit, the precise and optimal reserve decision is made under different risk levels, and the proposed UC has merits of less cost and lower risk.
The paper mainly focuses on the communication problem based on IEC61850 communication protocol. As in the process level communication system: MU (Merging Unit)-Switch-DIPC (Digital Integrated Protection and control sy...
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The paper mainly focuses on the communication problem based on IEC61850 communication protocol. As in the process level communication system: MU (Merging Unit)-Switch-DIPC (Digital Integrated Protection and control system), the stability of SMV packets transmission is very important. The transmission delay of the process level communication is the key problem that may restrict the protection algorithm and capability. In the meantime, GPS synchronization problem of MUs, protection capability of the integrated protection device and stability of SMV message transmission based on the existing DIPC(DIP-01) system will also be discussed in the paper. Through the experiment and analysis, the paper gives out the key factors that lead to the message transmission delay and packets loss. The work at last gives out some primary ideas to improve the protection capability.
Recently solar photovoltaic (PV) powergeneration increases rapidly all over the world. Because of variability, uncertainty, stability and reliability of power system with high penetration of PV generation faces chall...
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According to the demand of 126kV intelligent switch with intelligent operative box, an intelligent terminal device by using cooperation control of embedded CPU (STM32F103ZET6 ARM) and Field Programmable Gates (Cyclone...
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According to the demand of 126kV intelligent switch with intelligent operative box, an intelligent terminal device by using cooperation control of embedded CPU (STM32F103ZET6 ARM) and Field Programmable Gates (Cyclone II EP2C8Q208C8 FPGA), which is up to the IEC61850 standard, is designed in this paper. Research program of the device is discussed. Starting from the modularization structure design, function of each module, circuit design and implementation method were introduced in detail. A hardware platform was established according to the design. Finally, the article confirmed the correctness of the hardware platform primarily through experimental method.
The offshore wind power has been gaining increasing attention in recent years. Low-frequency alternating current (LFAC) transmission is emerging as a promising technology with specific advantages for offshore wind pow...
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ISBN:
(数字)9798350375558
ISBN:
(纸本)9798350375565
The offshore wind power has been gaining increasing attention in recent years. Low-frequency alternating current (LFAC) transmission is emerging as a promising technology with specific advantages for offshore wind power transmission. This paper discusses the structure and control of the offshore wind power transmission system based on LFAC. In order to enhance the support for the power system, grid-forming control can be implemented on both sides of the modular multilevel matrix converter (M3C) used in LFAC. Additionally, the capacitor voltage control of M3C is briefly introduced. Furthermore, power reserve control is utilized to enable wind turbines to participate in primary frequency regulation. Finally, the effectiveness of the designed control system is verified through simulation using PSCAD/EMTDC, further demonstrating the efficacy of the strategy.
Insulator is an important component of outdoor insulation systems. It works in complex environments and faces a series of problems such as surface contamination, loss of hydrophobicity, accumulation of surface charges...
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The stochastic differential equation (SDE)-based random process models of volatile renewable energy sources (RESs) jointly capture the evolving probability distribution and temporal correlation in continuous time. It ...
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In deregulated electricity markets, generation companies with the aim of maximum revenue need to provide trading strategies to the electricity trading market, which contributed to a self-scheduling model. When conside...
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