Advanced Materials Research Vols. 960-961

Abstract: This paper proposes an improved droop control strategy. Its principle is an introduction of feed-forward bias currents based on conventional droop control, which makes the inverter work as grid supporting sources in the grid connected mode. When the main grid voltage suffers any variation, the inverter will respond with variation of active power and reactive power, so that it can restore the main grid voltage and frequency and increase stability of the main grid. In the island mode, the proposed control method can allocate load power proportionally as expected and make soft changes between island mode and grid connected mode. At last, verify the effectiveness and reasonableness of the proposed control strategy through simulation.

Abstract: As an important part of Smart Grid, smart metering attracts more and more attention all over the world. It is the way for energy consumer to sense the benefit of smart grid directly. Smart meter is an advanced energy meter that measures consumption of electrical energy providing additional information compared to a conventional energy meter. This paper discusses various applications and technologies that can be integrated with a smart meter. Smart meters can be used not only from the supply side monitoring but also for the demand side management as well. It plays an important role to monitor the performance and the energy usage of the grid loadings and power quality. In addition, This paper gives a comprehensive view on the benefit of smart metering in power network such as energy efficiency improvement.

Abstract: Self-healing is an important feature of smart distribution grid. Self-healing control for smart distribution grid covers risk prevention and operation optimization before accidents, in addition, it covers fault location, fault isolation and power restoration. The research of self-healing control theory, risk assessment, fault diagnosis and safety warning for smart distribution grid provides technical supports to help build a safe, reliable, efficient, high-quality, flexible and compliant smart distribution grid.

Abstract: Smart grid puts forward high requirements for the equipment to access authentication, which achieves openness and real-time performance in mart grid. The users’ identities need to protect, in the meanwhile, identity authentication and data encryption should be efficient. According to the characteristics of smart grid, this paper proposed an identity-based aggregation signcryption scheme which combined pseudonymous ID with batch verification. The scheme adopted the pseudonym technology to achieve the user identity anonymity, and adopted the signcryption to complete digital signature and encryption in one time. This paper presented the aggregation signcryption for different multiple users by dynamic equation, which can compromise the security and computation overhead to meet the requirements of smart grid. This scheme can reduce the computational burden of aggregators with security of communication data. Moreover, this scheme solved the difficult problem of the management of pseudonymous ID, and improved the efficiency of the whole system. Therefore, this scheme meets the requirement of real time and high efficiency in smart grid.

Abstract: This paper presents a fitting degree-based multi-fault location algorithm for complex large power grid utilizing wide-area information. Firstly, fault injection current of the equivalent fault points is used in the equivalent model. Then the correlation matrix is formed by the network topology and associated nodal injection current and a network is formed to determine the location of faults. When multiple faults occur, the addition of the current of each two fault lines is calculated and the real-time current is measured. Then by calculating the minimum of fitting degree between two current values, fault line and virtual fault location can be determined. The simulation results of 10-generator 39-bus system verify the validity and feasibility of this algorithm.

Abstract: With the development of the smart grid , information network securityassessment affects the safe operation of the smart grid . In this paper, theimproved credibility theory and analytic hierarchy process , combined withstructural features of the smart grid network , From the wide area network ,access network, enterprise local network , local area network and the CPN-siteand home users to assess the impact of the five aspects of information networksfor smart grid security operation. And make the case for more security strategyto improve the reliability of the smart grid operation , thus providing a basisfor guiding the development and safe use of electricity grid users .

Abstract: Massive applications of the power electronic devices and non-linear loads lead to various power quality problems during the microgrids grid-connecting. Aiming at improving power quality of micro-grid, the structure of SCs’ main circuit and control circuit are designed. The model of super-capacitor energy storage system (SCESS) is established. A simulation model of micro-grid is also built up by using MATLAB and the simulation is conducted for different situations. Moreover, under Goldwind micro-grid platform, according to the result of MATLAB modeling and simulation, the SCESS effectively improves the transient power quality of the system.

Abstract: Insulator leakage current contains important information which can reflect the condition of insulators. However, it is always swallowed by many other noises which hinder us to get precise signals. Wavelet transform is a kind of new method which has been widely used in signal-de-noising because of its good frequency effect. However, suitable wavelet bases should be used to guarantee better effect. In this paper, we compared three groups of wavelet basis: db/coif/sym in hunt for the most relative suitable wavelet basis for insulator leakage current signal. Experiment results prove the conclusion later.

Abstract: The induced voltage generated by AC submarine cables would effect the normal operation of communication cables nearby. The paper calculated the induced voltage generated by AC submarine cable according to formula and procedures related to magnetic induction. The maximum parallel length between submarine cable and communications table was calculated under horizontal arrangement, and shielding effect was taken into account to the impact of the results. The causes of various induced voltage on communication cable were analysed under normal operation and various fault conditions. The results show that the induced voltage on communication cable is proportional to the parallel length and inversely proportional to parallel spacing. When the parallel length does not exceed a certain value, the induced voltage is in the allowable range and will not affect the normal operation of the communication cable.

Abstract: With the development of electric power system, Power-frequency Magnetic Field (MF) has become a matter of concern recently. In order to speed up the computation and modeling process, the small-scale experimental technique and simplified model for air-core reactors are introduced as a novel way to assess the MF of air-core reactors in this paper. Firstly, the scaling rules of the parameters for air-core reactors are summarized. Then, the scaling rules modification is put forward to reduce the error. Thirdly, three simplified models were established for air-core reactors, including one loop model, two loops model and three loops model. It is concluded after that the two loops model in configuration 2 can be considered as the optimal simplified model.