Mostafa Kheshti

Modeling and Fault Analysis of Doubly Fed Induction Generators for Gansu Wind Farm Application

Wind power is developing rapidly as a means of handling the worlds energy shortage and associated environmental problems. The Gansu provincial wind energy resources have around 237-GW wind power potential in China. In this paper, a study on key technologies of Hexi 750-kV power transmission line protections has been carried out. The project includes some characteristics, such as large-scale wind power, long-distance EHV lines, and so on. We used 49.5-MW doubly fed induction generator (DFIG) wind turbines in this project and different situations when a fault occurs in the presence of DFIG are studied and investigated. By the aid of stator-flux-oriented vector strategy, the system is modeled in PSCAD/EMTDC software on the basis of the real information from the wind farm site. The fault analysis is studied while the fault location is changed and the crowbar protection is ON/OFF. The data and information have been obtained by field experience of the wind farm in Gansu province. Also, the matrix pencil algorithm has been applied as a novel method in this project. This analysis can ease the protection issues and push the schedule to the next steps. With these results, we are able to adapt our system with smart grids and provide some novel methods to stabilize and control the wind farm.

A Phase Selection Method for Wind Power Integration System Using Phase VoltageWaveform Correlation

The fault characteristics of the wind power system, which are reflected in the weak feed features, variation of system impedance, frequency deviation, and non-sinusoidal waveform, will cause the inadaptation of traditional phase selectors to a wind power integration system. In this paper, a new phase selection principle based on the waveform correlation of transient voltage is proposed, which is valid for relay protection of intermittent solar or wind power plants. First, the characteristics of transient voltage of various fault types are deduced according to their boundary conditions. And on this basis, the correlations between the fault transient voltages of every two phases can be acquired. With the differentiated waveform correlations of different fault types, the fault phase selection criterion based on correlation coefficient is formed accordingly. Because it depends on the waveform characteristics of fault transient voltages, the new phase selector is not influenced by the wind power systems fault characteristics and it can select the correct fault phase quickly with high sensitivity. The proposed novel phase selection criterion is verified by the PSCAD-based simulation results and field fault recording data of the wind power integration system.

A study on hybrid solar thermal and geothermal power plant as a key development for Shaanxi province in China

The Challenging issues such as soaring energy demand, environment protection and pollutants rate would be some of the major problems for coming years in China, because peak energy demand is gaining field with economic growth. Consequently, energy infrastructures and its consumption are gradually pushed in a higher amount. Facing the obvious future energy crisis in advance, this paper presents the renewable energy technologies by means of geothermal energy and its hybrid solar-geothermal energy to ensure energy demand capability response in China. Focusing on the Shaanxi province, it can be benefited from enormous advantages of this clean energy. Shallow and deep geothermal energy added to an introduction of hybrid solar-geothermal approach are studied to bring this concept as one of the feasible approaches for sustainable development in the region.

Optimal overcurrent relay coordination in distribution network based on Lightning Flash Algorithm

Purpose Distribution network protection is a complicated problem and mal-operation of the protective relays due to false settings make the operation of the network unreliable. Besides, obtaining proper settings could be very complicated. This paper aims to discuss an innovative evolutionary Lightning Flash Algorithm (LFA) which is developed for solving the relay coordination problems in distribution networks. The proposed method is inspired from the movements of cloud to ground lightning strikes in a thunderstorm phenomenon. LFA is applied on three case study systems including ring, interconnected and radial distribution networks. The power flow analysis is performed in Digsilent Power Factory software; then the collected data are sent to MATLAB software for optimization process. The proposed algorithm provides optimum time multiplier setting and plug setting of all digital overcurrent relays in each system. The results are compared with other methods such as particle swarm optimization and genetic algorithm. The result comparisons demonstrate that the proposed LFA can successfully obtain proper relay settings in distribution networks with faster speed of convergence and lower total operation time of relays. Also, it shows the superiority and effectiveness of this method against other algorithms. Design/methodology/approach A novel LFA is designed based on the movements of cloud to ground lightning strikes in a thunderstorm. This method is used to optimally adjust the time multiplier setting and plug setting of the relays in distribution system to provide a proper coordination scheme. Findings The proposed algorithm was tested on three case study systems, and the results were compared with other methods. The results confirmed that the proposed method could optimally adjust the relay settings in the electric distribution system to provide a proper protection scheme. Practical implications The practical implications can be conducted on distribution networks. The studies provided in this paper approve the practical application of the proposed method in providing proper relay protection in real power system. Originality/value This paper proposes a new evolutionary method derived from the movements of cloud to ground lightning strikes in thunderstorm. The proposed method can be used as an optimization toolbox to solve complex optimization problems in practical engineering systems.

The study of comprehensive transmission line fault location method for smart substations

As traveling wave fault location cannot be applied due to the low sampling rate in smart substation, a novel algorithm of transmission line fault location for smart substation is proposed in this paper. When there is a transmission line fault, the algorithm can select the best fault location method in the conventional single-ended frequency fault location methods, and then get a value that is the closest to the fault. The conventional frequency fault location methods have various sources of error, and fault location result is affected by power source, the opposite system impedance, transition resistance and other parameters. In the different fault case, every method has different location accuracy, namely the most accurate location method is always varying with varying parameters. In this paper, firstly we construct a large number of training samples of transmission line fault, secondly, the rough set theory is used to reduce training samples and find the intrinsic relationship between fault location and system parameters. When transmission line has a fault, this algorithm can search for a most accurate fault location method by k-Nearest Neighbor method and finally give the most credible fault distance. The results of ATP simulation an RTDS simulation shows that the algorithm can successfully keep away from the method of larger system error and select the optimal method and greatly improve the fault location accuracy.