Multi-infeed effective short circuit ratio (MIESCR)is a common index to evaluate the voltage supporting capacity of AC power grid in multi-infeed systems, but its physical significance and applicable scope are not clear enough. In this paper, the multi-infeed system is equivalent to a single-infeed system with the same external characteristics, and the definition of the generalized multi-infeed equivalent effective short-circuit ratio (MEESCR)is proposed. It is proved that effective short circuit ratio (ESCR)and MIESCR are special cases of MEESCR under certain operating conditions after some approximations, and the applicable scope and the error source of MIESCR and ESCR are explained theoretically. The mechanism analysis and PSCAD simulation results show that MEESCR can more accurately evaluate the voltage support capability of AC grid in multi-infeed system compared with MIESCR and ESCR.

This paper analyzes the DC resonance issue of a hybrid double-terminal HVDC system by simplifying the DC side of the MMC into a series-connected LC load and establishing mathematical model of the system. In order to suppress the DC resonance, a new control method is proposed to inject damping into the resonance system. As a result, the DC resonance is eliminated by dynamically adjusting the total number of inserted sub-modules of the MMC, without changing the current and voltage on the AC side. The feasibility and performance of the proposed method are validated by simulations in PSCAD. The control method proposed in this paper can eliminate DC resonance issue of a hybrid HVDC system.

As the key equipment for interconnection between DC power lines with different voltage levels, high-voltage DC/DC converters play an important role. However, the traditional high-voltage DC/DC converters show defects such as the low voltage gains, large volumes and weights, etc. This paper proposes a resonant modular high-gain step-up DC/DC converter (RMHGDC), which operates in resonant mode between submodule capacitors and the arm inductor,features with series-connected submodules for obtaining higher voltage gain. The basic operational principles are analyzed firstly. Based on deduction of the mathematical relation of key parameters of RMHGDC, the high gain control strategy is proposed and studied in detail. An experimental prototype is constructed to verify the feasibilities and effectiveness of the RMHGDC and the proposed control strategies.

Ripple is a typical power quality problem on the DC side of wind power converters, ripple resonance not only affects the power quality of the DC side, in severe cases, it will also endanger the safe and stable operation of wind power systems and their components. This paper introduces the application of film capacitors in the DC side of wind power converters and their actual equivalent circuit model; the influence of the stray parameters of the DC bus and film capacitor of the wind power converter on the ripple current on the DC side is investigated; the failure mechanism of the DC side capacitor of the wind power converter due to the ripple resonance is analyzed, the mathematical expression of its natural resonant frequency is derived. Finally, a simulation model of permanent magnet direct-drive wind power system considering stray parameters is built in Matlab/Simulink, the simulation results verify the theoretical analysis and the correctness of the model.

A new balancing algorithm for double star capacitor bank based on targeting function is proposed in this paper. Firstly, the target center-point is determined by the targeting function, and then the shooting function is used to perform full-coverage and accurate shoot-processing in each round. According to the preset standard unbalance ratio, an optimal set of balancing strategies is finally calculated to achieve the purpose of balance of the double star capacitor bank. Practical program based on the balancing algorithm is formed and applied to practice,which achieves good results and the effectiveness and practical value of the algorithm is verified. This algorithm has the advantages of small amount of calculation, fast convergence and optimal substitution strategy, and has good application prospect and promotion value.

Distributed generation (DG)sources are becoming more prominent in distribution systems due to the incremental demands for electrical energy. Locations and capacities of DG sources have profoundly impacted on the system losses in a distribution network. In this paper, a novel crisscross optimization algorithm(CSO)is presented for optimal location and capacities of DG on distribution systems. The objective is to minimize network power losses, achieve better voltage regulation and improve the voltage stability within the frame-work of system operation and security constraints in radial distribution systems. A detailed performance analysis is carried out on IEEE 33 bus systems to demonstrate the effectiveness of the proposed methodology.

To accelerate the reliability evaluation of large-scale complex distribution networks, an improved algorithm based on secondary node optimized numbering is proposed. Firstly, the node is numbered sequentially to improve the search efficiency. Then a virtual node is added in each branch, which can eliminate the impact of switch type in both ends of the branches and reduce the required memory. Finally, the distribution network is represented in sections according to the switch type in the branch. And the failures are enumerated based on section as a unit. The optimized numbering of the section can avoid the repeated work in deep-first search for the front circuit breaker. As a result, the time cost of searching is significantly reduced and the computation efficiency is improved. Meantime, the occupancy rate of CPU is also reduced. The RBTS-BUS6 test system and an actual large-scale complex distribution network are used to verify the accuracy and effectiveness of the proposed method and its high practical value of engineering.

This paper aims at the application of artificial intelligence technology in the field of electric energy metering. Starting from the research progress of artificial intelligence platform construction project of China Southern Power Grid Electric Energy Data Center, this paper builds an interactive big data artificial intelligence platform. The platform mainly classifies the structure into electric energy data access layer, intelligent algorithm layer and interactive business application layer. Firstly, through the overall overview of the platform architecture, this paper clarifies the hierarchical relationship and the main contents contained in each layer. Secondly, it introduces the function, design concept and internal logic of electric energy data access layer and intelligent algorithm layer. Finally, the paper focuses on the interactive business application layer and briefly describes the implementation of the system. The interactive business application layer describes in detail several main interactive modes used in the system, and explains how to combine with the electric energy artificial intelligence platform business to improve the convenience and interactivity for the electric power workers using the system.

During the heating season in Northeast China, using electric boilers to coordinate the heating network and power grid is of great significance to reduce wind curtailment. Considering the constraints of conventional unit power, wind power, and thermal power from heat storage, combined heat and power (CHP) unit, electric boiler, this paper presents an optimal economic dispatching model of electric and thermal power system with wind power based on the stage electric and thermal regulation performance of electric boilers and the objective function of minimizing total operation cost and wind curtailment cost. By analyzing the heat network balance of CHP unit heating, CHP unit + heat storage equipment heating, CHP unit + heat storage equipment+electric boiler heating, three different scenarios of wind power including heat-fixed power, non-electric boiler and electric boiler are constructed, and the effects of heat storage and electric boiler on the discarded air and coal consumption are compared and studied. Finally, the CPLEX toolbox is used to validate the effectiveness of the method in a 6-node thermoelectric system, and the optimal combined operation mode of thermoelectric power is proposed.

The safe operation of transmission lines is often threatened by hidden dangers in line corridors such as illegal buildings, tree barriers and large illegal construction vehicles. Aiming at the problems of limited working conditions, small monitoring range and low accuracy of current line corridor hidden danger detection methods, this paper presents an improved line corridor hidden danger detection method based on U-net semantics segmentation network, trains the model based on a small amount of satellite remote sensing image data, and achieves fast and accurate detection of hidden dangers in line corridors, the detection accuracy is 85%. The experimental results show that the proposed method has a good detection effect for corridor hidden dangers and improve the level of intelligent detection of hidden dangers in transmission line corridors.

With the continuous advancement of China’s electricity market construction, a complete comprehensive evaluation system and method for electricity market plays an important role in ensuring that the electricity market can operate safely, stably, efficiently and reliably. Fully considering the principles of index system construction and the rules of market design, this paper constructs a complete comprehensive evaluation index system of electricity market from four dimensions: fairness, safety, economy and environmental friendliness. Meanwhile, based on the multi-level fuzzy evaluation method, the Guangdong mid and long-term electricity market public data is employed as an example to verify the effectiveness of the index system. The results show that the constructed comprehensive evaluation index system is applicable.

In order to solve the problems of energy depletion and environmental pollution, internet plus smart energy (Energy Internet)is more and more attention by domestic experts, scholars and governments. This paper first summarizes the concept of Energy Internet and the development at home and abroad, and briefly describes the reasons and related contents of Energy Internet attention. Secondly, the background and conditions of the development of Energy Internet in Guangzhou are analyzed, including the basic conditions, driving force and development focus. Thirdly, according the characteristics of Guangzhou, the construction plan and construction effectiveness of Guangzhou energy demonstration project are proposed. Finally, the challenges and development trends of Guangzhou Energy Internet development is analyzed, and countermeasures and suggestions are put forward. The research results of this paper can provide reference for future internet energy construction in Guangdong, Hong Kong and Macao Dawan District.