Guangxi Electric Power Research Institute

Nanning, China

Guangxi Electric Power Research Institute

Nanning, China
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Wu P.,Shanghai JiaoTong University | Huang W.,Shanghai JiaoTong University | Tai N.,Shanghai JiaoTong University | Liang S.,Guangxi Electric Power Research Institute
Applied Energy | Year: 2017

Microgrid provides an effective approach to utilize distributed renewable energies (DREs). Given the ongoing transformation of distribution system with high penetration of DREs, coordinating and consuming a large amount of distributed generators (DGs) within one single microgrid has become increasingly infeasible. Interconnecting multiple microgrids as a microgrid cluster is an effective way to improve the operation quality of large-scale DG integration. As the keys to the microgrid clusters, the flexible configurations and coordinated operation among multiple microgrids have not been adequately addressed. In order to solve this problem, a novel architecture for multiple microgrids and its coordinated control schemes are designed. Firstly, the advanced microgrid interface named hybrid unit of common coupling (HUCC) is designed and utilized in replacement of the conventional point of common coupling (PCC). The HUCC employs modular multilevel converter (MMC) as its core component and provides both AC and DC interfaces. Then, this paper puts forward a HUCC-based architecture for multiple microgrids where microgrids are grid-connected via the AC interfaces and interconnected via the DC interfaces. Based on the proposed architecture, coordinated control schemes under different operation scenarios are came up with at last. A case study of the HUCC-based multiple microgrids is performed in PSCAD/EMTDC on the basis of the demonstration project in Guangxi, China. The simulation results show that the interconnected microgrids with the proposed architecture and control schemes operates effectively and efficiently under different operation scenarios. The proposed architecture and control schemes not only enhance the large-scale integration of DREs, but realize the optimal use of DGs as well. © 2017 Elsevier Ltd.

Liu Y.,CAS Wuhan Institute of Rock and Soil Mechanics | Li H.,CAS Wuhan Institute of Rock and Soil Mechanics | Xiao K.,Guangxi Electric Power Research Institute | Li J.,CAS Wuhan Institute of Rock and Soil Mechanics | And 2 more authors.
Computers and Geotechnics | Year: 2014

In general, the determination of the factor of safety and the location of the critical slip surface are two major challenges in seismic slope stability analysis. In this paper, a new approach for determining the factor of safety and the corresponding critical slip surface of a layered rock slope subjected to seismic excitations is presented, through a case study based on the combination of the shear strength reduction technique and distinct element method. According to this proposed method, the seismic factor of safety and the critical slip surface of the slope are estimated and compared with those obtained by the pseudo-static approach, combined with the limit equilibrium method. It is found that the factor of safety obtained from the proposed method is slightly greater than that computed by the pseudo-static analysis, with a difference of 4.2%, and that the critical slip surface obtained from the two methods is identical, which confirms the reasonability and feasibility of the proposed method. © 2013 Elsevier Ltd.

Chen X.,Guangxi Electric Power Research Institute | Chen B.,Wuhan University | Tian C.,Wuhan University | Yuan J.,Wuhan University | Liu Y.,Anhui Electrical Power Design Institute
IEEE Transactions on Industrial Electronics | Year: 2012

Magnetically controlled reactors (MCRs) are usually used as three-phase shunt reactors. They have low harmonic distortion independent of the third harmonic current because most three-phase MCRs are delta connected. However, as arc suppression coils, MCRs are operated in the single-phase mode, and the harmonics can be much higher than those of three-phase MCRs. In this paper, the structure and the mathematical model of a two-stage saturable MCR (TSMCR) are proposed. There are two stages with different lengths and areas in the iron cores. The stages saturate at different times when the TSMCR outputs reactive current. The current harmonics of the first saturated stage can be compensated for when the second stage begins to saturate, to reduce the total harmonics of the output current. The mathematical model that reveals the distribution characteristics of the current harmonics for the TSMCR is also presented. A study of the mathematical model indicates that there are two key factors that affect the total current harmonics of the TSMCR. One is the parameter k, which represents the area ratio of the second stage to the first stage. The other one is the parameter m, which represents the ratio of the length of the first stage to the total length of the magnetic valve in the iron core. The simulations and experiments show that the maximum current harmonics of the novel MCR can be limited to 3.61% of the rated output current when k and m are chosen according to the theoretical mathematical model. © 2012 IEEE.

Zeng B.,Hunan University | Teng Z.,Hunan University | Cai Y.,Huawei | Guo S.,Hunan University | Qing B.,Guangxi Electric Power Research Institute
IEEE Transactions on Smart Grid | Year: 2011

An approach for power system harmonic phasor analysis under asynchronous sampling is proposed in this paper. It is based on smoothing sampled data by windowing the signal with the four-term fifth derivative Nuttall (FFDN) window, and then calculating harmonic phasors in the frequency domain with an improved fast Fourier transform (IFFT) algorithm. The applicable rectification formulas of the IFFT are obtained by using the polynomial curve fitting, dramatically reducing the computation load. The FFDN window can effectively inhibit the spectral leakage and the picket fence effect can be modified by the IFFT algorithm under asynchronous sampling, and the overall algorithm can easily be implemented in embedded systems. The effectiveness of the proposed method was analyzed by means of simulations and practical experiments for multifrequency signals with the fluctuation of the fundamental frequency and with the presence of white noise and interharmonics. © 2010 IEEE.

Tang Q.,Hunan University | Teng Z.,Hunan University | Gao Y.,Hunan University | Zhou Y.,Guangxi Electric Power Research Institute
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012

To realize high-accuracy measurement of voltage flicker, a kind of voltage flicker measurement method using the square demodulation method based on S-transform was presented. S-transform principles were briefly introduced; the computational process of voltage flicker using the square demodulation method was simplified; and the voltage flicker measurement scheme using the S-transform-based square demodulation method was given. The S-transform is applied for the time-frequency analysis of voltage flicker signals. The frequency domain characteristic given in S-matrix was used for computing the magnitude of the voltage flicker. Based on the high frequency spectrum amplitude, the starting and ending moments of the voltage flicker were estimated. Simulation experiment results verify the feasibility and accuracy of this algorithm. Furthermore, a voltage flickermeter based on virtual instrument technology was developed, and its structure and main front panel were given. The operation results show that the meter has advantages of convenient operation and reliable measurement. © 2012 Chinese Society for Electrical Engineering.

Lu Z.,Hunan University | Luo A.,Hunan University | Jiang W.,Guangxi Electric Power Research Institute | Xu X.,Hunan University
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2012

The new method of operating an inverter to imitate a synchronous generator for circulating current restraint is motivated and developed. Based on the comparison with the traditional droop control method, detail analysis is done on the principles of decoupling between the equivalent line impedance and output reactive power and the advantage of the new method to improving the accuracy of the load power distribution is described. In order to reduce voltage and frequency difference between the paralleled inverters when no-load operating, minor amendment is used to the droop control coefficient to meet the demand of load power distribution between different rated power inverters and circulation suppression and adding differential link to improve the control delays caused by power calculation. Simulation and experiment are done in a small-scale experimental micro-grid system which contains two inverters in parallel. The results are given to verify that the circulation inhibitory is effective in a variety of conditions.

Zeng B.,Guangxi Electric Power Research Institute | Teng Z.,Hunan University | Zhou Y.,Guangxi Electric Power Research Institute
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2012

In this paper, the spectral characteristics of the cosine window are analyzed and an improved FFT method for harmonic analysis based on the even order cosine window (EOCW) is proposed. The rectification formulae of the frequency, amplitude and phase of the fundamental and harmonics are obtained by using the least squares fitting method. Simulation results indicate that, the precision in calculating harmonic parameters can be highly improved by the proposed algorithm, no matter with the fundamental frequency varies and the presence of interharmonics. The proposed algorithm is suitable for harmonic analysis under nonstationary situations and the correctness of which is verified by the application in embedded system.

Zeng B.,Guangxi Electric Power Research Institute | Zhou Y.,Guangxi Electric Power Research Institute | Teng Z.,Hunan University | Li G.,Guangxi Electric Power Research Institute
International Journal of Electrical Power and Energy Systems | Year: 2013

A new class of windows, the even order cos α(x) window (EOCW), is proposed. The main-lobe and side-lobe behaviors of the EOCWs are studied. A EOCW-based weighted dual-point interpolated discrete Fourier transform (WDIpDFT) algorithm for calculating power system harmonic parameters under nonstationary situations is given. The EOCW has a low peak side-lobe level and a high side-lobe decaying rate. Leakage errors and harmonic interferences are thus reduced considerably by weighting samples with the EOCW. The rectification formulae of frequency, amplitude and phase of the fundamental and harmonics were obtained by using the polynomial curve fitting method. The EOCW-based WDIpDFT algorithm is free of solving high order equations, and the overall method can be easily implemented in embedded systems. The effectiveness and correctness of the proposed method were analyzed by means of computer simulations and practical experiments for multi-frequency signals with the variance of the fundamental frequency, the fluctuation of the harmonic voltage as well as with white Gaussian noise. © 2012 Elsevier Ltd. All rights reserved.

Sun Y.,Guangxi Electric Power Research Institute | Wang Z.,Wasion Group Ltd.
2011 2nd International Conference on Mechanic Automation and Control Engineering, MACE 2011 - Proceedings | Year: 2011

In order to optimize the allocation of energy resources, reduce enterprises' electrical energy consumption and achieve the goals of energy conservation and emission reduction, the electrical energy consumption monitoring platform is designed in this paper. With its high transmission rate, real-time online and resource-efficient, GPRS has been widely used in the energy consumption monitoring system. Utilizing the feature of GPRS, this paper designs a wireless energy consumption monitoring system. The system has the function of data acquisition, statistical analysis and prediction which makes it be the base of electrical energy consumption management system. © 2011 IEEE.

Xue Z.,Guangxi Electric Power Research Institute | Cheng S.,Guangxi Electric Power Research Institute
Dianwang Jishu/Power System Technology | Year: 2012

As the precondition of checking the calculation of tower strength and examining conductor stresses and clearances to ground of spans, the unbalanced tension of ice-covered transmission line should be computed. In view of such features of the mathematical model for unbalanced tension of ice-covered transmission line as high dimension and strong nonlinearity, the Trust Region optimization algorithm that possesses strong robustness is chosen to solve the model. Results of calculation and a lot of simulation show that using this algorithm the high-precision solutions of stresses of spans, increments of spans and increments of height differences can be obtained. After the validation of the model and the accuracy of the algorithm, the percentages of maximum unbalanced tensions in different ice areas and under different unbalance rates are computed, and the variation law of unbalanced tension with the factors such as safety coefficient, length of suspension insulator string and height differences of spans is further analyzed. Results of this research could be used to optimization design, safety operation and fault analysis of ice-covered transmission lines.

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