Advanced Metering Infrastructure (AMI) combines two way communication and smart metering technologies. It can record customer’s load profiles, and thus provide system wide sensing and measuring capability to utilities. Data analytics based on AMI are emerging hotspots for utility in big data applications. Summarizing the functions of the smart meter first, this paper makes a brief description of smart meter data analytics. Then several examples of smart meter data analytics in distribution network branch impedance estimation, power flow calculation and volt/var optimization are explained in detail to show that great benefit may be available for utilities in application of smart meter data analytics.

It is a dispensable step for many electromagnetic compatiblity problems to calculate the mutual impendance between the overhead and the underground conductors in a multi-layered soil. To this end, an efficient approach is proposed in this paper. The expression of the mutual impedance, which contains a complex highly oscillatory semi-infinite integral, is divided into two parts intentionally in the first place, i.e., the definite and the tail integral respectively. The definite integral is calculated using the proposed moment functions after fitting the integrand into a serial of spline functions, and the tail integral is replaced by an exponential integral with an asymptotic integrand. The advantage of the proposed approach is that the calculation of oscillatory integral is completely avoided due to the fact that the moment function is evaluated analytically. Numerical examples justify the proposed approach in many cases with different combination of parameters. The proposed approach can be used in the electromagnetic compatibility analysis between overhead and underground conductors.

This article summarizes the design and development of DC-DC autotransformer(DC AUTO), a new type of DC-DC converter. The prior art of DC AUTO is firstly described, and then the development of DC AUTO and its supported technologies are summarized. Analogy between AC autotransformer and DC autotransormer is investigated. The converter cost and power loss ratio of DC AUTO with bidirectional DC fault isolating capability are studied. A number of extended technologies such as multiport DC AUTO, hybrid DC AUTO, unidirectional DC AUTO and grid interconnector are summarized, pointing out that under low and medium stepping ratio, the DC AUTO technology is able to replace the conventional DC/AC/DC technology.

Bushing fault is one of the prime reasons causing transformer faults, among which the failure rates caused by humidified insulation is in the first place, and correlative researches have verified that moisture is a key factor leading to paper oil insulation degradation, therefore, it is of great significance to research the influence of moisture on condenser bushing’s dielectric property. Oil-impregnated paper condenser core samples with different initial moisture contents are prepared, then an accelerated thermal aging laboratory test is carried out, and dielectric loss characteristics interval integral model is established. Results show that the integral values of ageing time and dielectric loss within the feature region comply with the linear rule, and the integral breadth of moisture and dielectric loss within feature region still comply with linear rule, which means that the integral value of dielectric loss can reflect the aging degree of insulation, the results of this paper provides a basis for further analysis on dielectric loss based oil-impregnated paper condenser bushing aging assessment and on insulation aging acceleration caused by moisture.

Faults happened on AC filter sub-bank circuit breakers (CB) would endanger the safe and stable operation of the power system. It’s necessary to analyze the factors influencing the insulation of arc-extinguishing chamber by simulation and calculation of the CBs to identify the causes of CB faults. Considering structure symmetry, a 3D calculation model including moving/static contact, porcelain coat, SF₆ gas and air package, is established by Solidworks software for one of the double breaks of 550 kV ceramic post breaker. Simulations of the 3D stactic electric field are carried out using ANSYS under five conditions: normal break, metal particles on porcelain, metal particles suspended between two arc contacts, metal particles on arc contact, and increasing inner diameter of porcelain. Results show that the maximum electric field happens 7.5 ms after arc is blown out, metal particles on arc contact will significantly increase the electric field intensity, CB insulation faults can be effectively reduced by raising the SF₆ gas pressure properly and using metal particle absorption measures.

In order to solve the problem of data sharing, equipment versatility, network congestion and other issues in the current power transmission and transformation equipment online monitoring network, based on the technology of Internet of Things, this paper employs a two-level communication network structure of an access network and an aggregation network to design communication network of substation and transmission lines, solving the problem of communication network congestion by the traffic control and redirection of the aggregation network. Heterogeneous double network dual channel design method is proposed to improve the communication network fault tolerant ability and realize a together application of on-line monitoring equipment and assets inspection. Simulation calculation reveales that long distance point to point communication, single jump distance relay, stable bandwidth and bit error rate are better meet the requirements. A design scheme of wireless Mesh+OPGW fiber is proposed as an effective means for transmission lines to realize on-line monitoring signal remote transmission, and tested and verified on site.

As data models of smart substations, most SCD(substation configuration description) models contain only secondary device model information in project implementation. Based on IEC 61850, a panoramic view modeling technology of primary and secondary equipment in substation is proposed. By integrating the SSD model, prudential model, phasor measurement unit (PMU) model and other professional data model into the panoramic SCD model, a unified platform for intelligent substation data information is established. Based on the new panoramic model data integration platform, the advanced applications of data fusion such as data identification of multi-source data, topology analysis, quality identification of electric quantity data, alarm intelligent analysis of the substation are mainly researched and realized, which can improve the data exchange efficiency and intelligent operation management level of substation.

The wide deployment of TD-LTE power wireless private network in smart grid demands an efficient and reliable security protection system. An end-to-end security protection system is presented for TD-LTE power wireless private network, in which specific methods are utilized to guarantee the security of access, transmission, core networks (three domains), user, control, management plane (three planes) and equipment, network, service layer (three layers), thus reducing the security risks brought by the open wireless channel, shared wireless network and mobile wireless terminal, and ensuring the safe end-to-end transmission and the reliable operation of the system.

This paper proposes a simple but precise method to measure the zero sequence parameters among four lines on the same tower. The 4 cases of two phase systems using the four lines on the same tower are assembled, then the open circuit and short circuit impedances of positive and zero sequences of these two phase systems are measured. Based on which,the equivalent distributed impedance and admittance for each case are estimated. Finally, the mutual inductance and coupling capacitance, as well as self parameters of zero sequence can be calculated.

With considerations of the uncertainties on wind power/load prediction errors and random outages of generators, a day-ahead assessing model is presented to assess wind power integration capability on the basis of operation senario optimaztions. The model presented here is a typical multi-objectively optimization formulation, and its two optimization objects, i.e., wind power integating capacties maximization and generating costs minimzation are inherently conflicting each other and can not get their optimal results simultaneously. Non-dominated sorting genetic algorithm (NSGA) is utilized to obtain Pareto optimal result set of the formulation, from which, day-ahead minimum and maximum wind power injection amounts can be obtained. On the basis of Pareto optimal result set obtained by NSGA, average generation costs and average wind power integration costs with respect to different wind power injection amounts are calculated and analyzed. Simulation results on IEEE 118-node systems justified the formulation and solving technique presented in this paper. Wind power injection amounts and their costs can provide supports for day-ahead dispatching decision.

Identifying disturbances timely and accurately is greatly helpful to take proper anticipatory actions to eliminate the disturbances and avoid blackouts. In this paper, the wavelet multi-resolution analysis based method is proposed to identify power system disturbances. The energy of wavelet coefficients is used as a criterion to choose optimal wavelet function and decomposition scale, which are used for obtaining the maximum wavelet coefficients by identifying the frequency signals from wide area measurement system (WAMS). The maximum wavelet coefficients are then selected to be the indicators for disturbance identifying. The detailed procedure and effectiveness of the proposed method is demonstrated by simulations of a 10-machine 39-bus system. A software system has been developed for an actual power system based on the method and the measured disturbances to validate the effectiveness and feasibility of the method and software.

When interior point method is used to solve the problem of reactive power optimization in large scale power system, the feasible solution may not be obtained because of the unreasonable part of the constraint conditions. In this paper, a practical relaxed reactive optimal power flow method (Relax ROPF) is proposed to restore the solvability of reactive optimization by interior point method. In the iterative process, the ill-condition constraint which causes failure of OPF can be automatically identified, the problem is restored by introducing minimum relaxation into those ill-condition constraints. Test results on IEEE 39-bus system and an actual power grid show that the proposed method can identify unfeasible constraints very well, and can effectively restore the optimal power flow.