Advanced Materials Research Vols. 732-733

Abstract: This paper uses Multi-index to assess regional power quality comprehensively. This paper introduces genetic projection pursuit method on power quality comprehensive evaluation. Without human intervention, this method overcomes the traditional power quality comprehensive evaluation method is influenced by subjective factors. Based on this, we put forward improved genetic projection pursuit algorithm. In the process of projection pursuit model and in the field data, changing the maximum normalized to normalization of national standard limit. According to the field experiment data in QingHai province, we assess the results by analysis and comparison with the original method. The improved method is more accurate on power quality comprehensive assessment.

Abstract: This paper established a transformer substation comprehensive optimal planning model considering distribution generation (DG) and different block geographic information factors (GIF), set form, volume, location of existing DG in planning area and transformer substation load-bearing capacity as constraint condition, taking construction cost of distribution transform substation and feeder and operation cost including current supply loss into account, in the meantime, regarding the influence of GIF such as land properties and so on to location and cost of construction with load demand satisfied. Furthermore, influence factors of different block information factor to construction cost were work out by means of interval analytical hierarchy process. On the basis of the established objective function, an particle swarm optimization (PSO) algorithm is proposed to solve the problem in this paper. By empirical study of certain planning area, the proposed model and algorithm are proved to be scientific and effective.

Abstract: In this paper, a fault location method using power quality monitoring data is proposed. The fault location is divided into two classes including fault line recognition and fault distance calculation. Along the each power line in the target network some fictitious fault points are set and the fault voltage of each monitoring bus is calculated. The voltage dip calculation results and the fault line data are matched to form the learning samples and then train the designed fault line recognition BP artificial neural network. The trained neural network searches the fault line when actual fault occurs. After it finishes fault line searching the fault position is calculated using the function of voltage dip amplitude and fault position. The correctness and effectiveness of the proposed method is proved by the simulation results in standard IEEE-14 bus system.

Abstract: With the development of Smart Grid, the permeability of distributed generation (DG) is increased gradually. When a fault happens in systems branch, DG plays a significant role in ensuring a continuous supply to the load points as many as possible. This paper uses ant colony algorithm to achieve distribution network fault reconstruction with distributed generation, in order to guarantee the load points to restore power as many as possible, and the network system having the minimum loss at the same time. The optimization process is divided into two parts: first, In case of DG power supply capacity known, we optimize the capacity of the Island formed on DG, in order to determine the nodes of the island. Then, we optimize the isolated system and the main distribution system separately, in order to find the system radiation structure of minimum network loss. Finally, the IEEE 33 nodes distribution network is used as an example to testify the effectiveness of ant colony algorithm.

Abstract: This main purpose of this paper is to study the implementation of the strategy for breaker failure under the condition of communication exchange in the power system. The method of breaker failure strategy in case of IEC61850 (Communication Networks and Systems in Substations) GOOSE (Generic Object Oriented Substation Event) aims to fast transmit signal to isolate faulty positions for maintaining safety security. The current strategy for breaker failure in substations is to use hardwire solutions to implement related applications for breaker failure. For integrating protective relays in substations, IEC61850 GOOSE schemes can customize a ring construct based on TCP/IP Ethernet to have flexible dispatch of smart grid solutions.

Abstract: This paper provides a framework for smart grid hub. Unlike previous studies exploiting technological challenges, our framework presents the whole steps to construct a smart grid hub, plan operations and develop a business model, and then methodologies to validate the models for each stakeholder.

Abstract: To deal with the problem of large-scale wind power integration and its influence on low frequency oscillation characteristics of Gansu power network, this paper built the low frequency oscillation simulation model with large amount of wind power integration, and proposed an index, namely grid structural weakness degree, based on the damping ratio index, to investigate low frequency oscillation characteristics. The simulation shows that the damping ratio decreases as the wind turbine output increases; and when the damping ratio is lower than 3%, or weakness degree lower than 4, it is more likely to cause low frequency oscillation in Gansu power network, and early-warning should be taken. The analysis provides a reference for low frequency oscillation early-warning and control.

Abstract: In this paper, reliability guarantee strategies for Hengqin were proposed based on reliability affecting factor system and Hengqin needs of high reliability power system and smart grid, and the reliability enhancing degree of these strategies were assessed. Firstly, the indices of reliability were analyzed, and the reliability affecting factor system was built up. Then, combined with the development need of Hengqin power system, four specific reliability guarantee strategies-network structure construction, advanced distribution automation, intelligent operation and maintenance center and the end-line monitoring system-were proposed and the reliability effects were quantitatively assessed. Finally, the reliability effect of the strategies was compared with the reliability goal of Hengqin power system, and the adequacy and completeness of the strategies were verified.

Abstract: How to ensure the security, stability and economic operation of microgrid in different operation modes is a difficult problem of microgrid research. There is active power and reactive power coupling in the regulation of frequencies and voltages because of the line parameter characteristics of microgrid. The defect of the traditional active power-frequency, reactive power-voltage droop control is analyzed and a novel decoupling droop control method for low voltage microgrid is proposed in this paper. At last, the multiple feedback loop control strategy for inverters on the basis of this proposed method and a microgrid simulation model are established. The comparative analysis between the new method and the traditional method based on the simulation results can prove that the proposed control method is simple in design, and it can assure an excellent power quality and realize the reasonable distribution of active power and reactive power between distributed generations.

Abstract: Microgrid and traditional power system are different in terms of operation and control. SCADA reliability directly affects the operational control capacity of the microgrid. Based on the actual needs of the microgrid operation control and energy management, the author designed microgrid SCADA platform, including architecture, information exchange mechanism and data services, and then developed actual microgrid SCADA test platform. Through long-time test, the SCADA platform could achieve reliable microgrid operation and management.