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Large-scale integration of renewable energy resources in the Alternating Current (AC) grids will have a serious impact on power system operation. The development of the Direct Current (DC) is presented as a solution to overcome some of the negative impacts on massive micro-generation deployment. Over 100 years later, from the time when AC was proving superior over DC, the existing AC electric power grids, equipment, and transmission method facing a big challenge from DC. In this paper, what has changed since Edison and Westinghouse public battle are firstly discussed? Then the high voltage DC (HVDC) transmission system is depicted the developmental history and the system׳s structure, and the HVDC applications based on voltage-source converters (VSCs) combined with the renewable generation are introduced, such as onshore, offshore wind, and City Power Supply. Then, those key technologies are represented. Finally, how to build future electricity grid network and VSCs-HVDC may improve the world is explored, and some recommendations are proposed.

The maximum power point tracking (MPPT) methods for the photovoltaic (PV) power system have been considered by the experts in the whole world. A review of different MPPT methods is discussed in this paper. Firstly, the main methods at uniform radiation that will be deliberated are Hill-Climbing (HC), Incremental Conductance (IncCond), Perturbation and Observation (P&O), Fuzzy-Logic (FL), and Neural Network (NN). However, these existing methods have several drawbacks such as slow tracking speed, low tracking efficiency, which fail to extract maximum power at complex partial shading. Then, the more recent MPPT methods at partial shading are discussed to find the best MPPT control strategy, such as the particle swarm optimization (PSO) algorithm, Cuckoo Search (CS) method, and Fibonacci line search scheme, etc. The advantages and shortcomings of abovementioned MPPT methods are compared to find the optimal MPPT during partial shading conditions. It is imagined that this article will be a source of valuable information for PV professionals to keep abreast with the latest progress in the PV power area, as well as for new researchers to get started on MPPT.

Most of traditional manipulator does not meet experimental requirements of micromanipulation for its large structure and complicated driven mode. Comparatively speaking, using actuating and sensing performance of IPMC gripper can well be applied to specific micro operations and mechanical testing environment. This paper designs one kind of IPMC gripper of actuating and sensing performance based on micro operation and micro assembly, which is applied to grab the cells and fix under a microscope.

The recently-built school buildings have adopted novel heat recovery ventilator and air conditioning system. Heat recovery efficiency of the heat recovery facility and energy conservation ratio of the air conditioning unit were analytically modeled, taking the ventilation networks into account. Following that, school classroom displacement ventilation and its thermal stratification and indoor air quality indicated by the CO2 concentration have been numerically modeled concerning the effects of delivering ventilation flow rate and supplying air temperature. Numerical results indicate that the promotion of mechanical ventilation rate can simultaneously boost the dilution of indoor air pollutants and the non-uniformity of indoor thermal and pollutant distributions. Subsequent energy performance analysis demonstrates that classroom energy demands for ventilation and cooling could be reduced with the promotion of heat recovery efficiency of the ventilation facility, and the energy conservation ratio of the air conditioning unit decreases with the increasing temperatures of supplying air. Fitting correlations of heat recovery ventilation and cooling energy conservation have been presented.

In order to gain the same amplitude、frequency and phase between the output voltage of the inverter and the grid voltage, the phase-locked loop (PLL) technology is widely used in grid-connected photovoltaic (PV) generating system, which is normally used to obtain instantaneous phase information to achieve the grid-connected purpose of PV inverter. The detective accuracy of frequency and phase of the grid voltage is directly affected by the PLL. Two software PLL technologies are compared by using the simulation analysis which is based on the d-q transformation. To provide the basis for the design of grid-connected inverter, the advantages and disadvantages of two software PLL technologies are analyzed under different grid failure conditions, such as one phase voltage dropped, two of three phase voltage (TPV) dropped, grid frequency mutated, and grid voltage offset, etc. Particularly, the appropriate PLL technology can effectively improve the grid-connected ability of PV inverter under the grid voltage offset or unbalance conditions.

This paper introduces the basic principle of the microscopic visual servoing system based on image and summarizes systematically about the researching situation of microscopic visual servo based on image at home and abroad. From three aspects, which are Jacobin matrix calculating, automatic focusing technology of microscopic lens, and microscopic image fusing technology, it proposes some key problems to be urgently solved about the microscopic visual servoing based on image.

The rub-impact fault of Jeffcott rotor system which is generally made of an elastic shaft with supported by two bearings at ends and a lumped mass at the mid-span of shaft is the main research subject of this paper. The mechanical model and finite element model of a lump mass at the mid-span of shaft is set up. The dynamics of it are studied by nonlinear finite element method under the rub-impact conditions, and by investigating the effects of stiffness of stator and the clearance between rotor-stator. From the study results, use finite element method to study the rotor system failure problem is intuitive and convenient, high accuracy, high reliability, can be widely applied.

Today, the large-scale Photovoltaic (PV) power system, connected to grid, is in their advanced development stage and is extremely interest in whole world. The real large-scale PV array can be partially shaded by the shadow of building, cloud, bird and dirt. The output characteristic of PV materials in partially shaded conditions is strong nonlinear, and there are multi local peaks in output power voltage curve, and the only one real peak exists in these local peaks. Certainly, the maximum power point tracking (MPPT) method is very important to extract the as much as possible energy from the costly PV materials. The variant weight Particle Swarm Optimization (PSO) method is proposed to track the real peak by using the excellent multi-peak value optimization characteristic of PSO algorithm. The simulation results shows that the proposed PSO method can improve the response speed and output efficiency of PV materials in partial shading as compared to the conventional Incremental conductance (IC) method.

An efficient Maximum Power Point Tracking (MPPT) control method is important to increase the output efficiency of a photovoltaic (PV) material. The output power of PV power system depends on local irradiance conditions. The output characteristics of large-scale PV materials under partial shading conditions have multiple maximum power points, which make the tracking of the actual maximum power point (MPP) a difficult task. A novel combined fuzzy and perturb and observe (PO) control method is suggested to extract maximum power from the PV materials under these conditions. The ability of the proposed method and its increased performance as compare with the traditional fuzzy control method is evaluated by means of experimental tests performed on a real PV power system and based on the MSP430x44x microcontroller.

The price of photovoltaic (PV) materials and wind generating system (WGS) materials is costly, and the stand-alone PV or WGS can not steadily supplied electric power for end user, fortunately, solar power and wind power can compensate well for one another under various locations and climatic conditions, an efficient maximum power point tracking (MPPT) method for hybrid solar-wind electricity materials is important to extract maximum power from wind and solar energy because of the costly price of PV and WGS. The fuzzy MPPT method is used to track the maximum power point (MPP) of distributed small WGS and PV and hybrid solar-wind system. In order to decrease the output oscillation, the immune response feedback principle (IRFP) is used to improve the track speed and response speed and robust of output characteristic of electricity materials, the results displayed that the immune theory can effectively improve the performance and the stability of electric power of stand-alone or hybrid generating materials.

The steady and maintainable electric power provides the development momentum of a country's industrialization, which is indispensable to every country at present. It is well known that China is the largest developing country in the world. With the rapid development of economy and society, energy demand of Chinese society is increasing in an incredible speed, i.e., the annual accumulative total capacity of electric energy is about 0.1 billion kW, and the most of them is provided by the fossil fuel resource, and the share is about 90% in China. Certainly, it is a very inappropriate energy structure, so the sustainable development of country is impossible in future, the status must be improved in order to achieve sustainable development. Fortunately, China has large country area, and there are abundant solar resources. Development and application of solar energy have been regarded by the government and ordinary people, and they thought that solar energy can provide more and more electric energy in future, and more and more actual examples have been applied in the last decades, which are supported by central government and local governments. This paper discusses the distribution zone and current developmental situation of solar energy in China. Then, some application practice is described, such as solar energy greenhouse, solar energy hearth, solar water heater, solar lighting system, solar water pump, distributed generation (DG), grid-connect photovoltaic generation (GPG) and wind–solar hybrid system. The policies and law of China central government and local governments are described in the following paragraph. At the end, the developmental prospect of photovoltaic (PV) in future China and the development barriers and recommendations are introduced.

China is the largest developing country in the world. At present, more and more energy demand gives immense pressure to Chinese government. The inappropriate energy structure must be improved by Chinese government in order to achieve the sustainable development of economy and society. Development and application of renewable energy, such as wind energy, solar energy, biomass energy, etc., have been regarded by the government and the local people in the past 10 years, and more and more actual examples have been established, which are supported by government and plants in China. It is well known that there are abundant wind and solar resources in China. This paper presents the distribution zone and development and application practice status in China. However, a common drawback is existing in the stand-alone wind energy and solar energy generating power system, which is the unpredictable output electric power, and the output power depends on the unpredictable weather and climatic changes. Fortunately, the wind–solar hybrid generation system can partially overcome the problems. The conventional structure and key technology of stand-alone wind–solar hybrid generating system, the current status and outlook of wind–solar hybrid energy system are presented in the paper, for example, the city road lighting system, distributed generation, photovoltaic (PV) water pumping for irrigation, etc. At the end, the policies and laws of China central government and local governments are described, and the development barriers and recommendations are introduced.

An efficient Maximum Power Point Tracking (MPPT) method is important to increase the output efficiency of a photovoltaic (PV) generate system. It is well-known that the different photovoltaics have different n and Io. The conventional MPPT algorithm is impossible to quickly acquire the maximum power point (MPP), and the essential reason is not known the actual values of the n and Io. Theoretical and simulative results show that a piece of photovoltaic has same photocurrent, and the optimal output current and voltage are different under different n and Io conditions. Perturb and observe (PO) method is used to acquire the actual n and I. Then an easy maximum power point tracking algorithm is described which based on the actual n and Io. Furthermore, it is simple and can be easily implemented in digital signal processor (DSP). The maximum power point tracking course became a calculation course by using DSP base on the known coefficient. The simulation results verified the correctness and validity of MPPT method.

According to the difficulty of urban bus stop planning, a method which is based on optimization theory is introduced. First, the minimum passengers’ total traveling time model base on the shortest stop distance is adopted to calculate the optimum stop distance and determine the number of bus stops. Then, the bus stop coverage rate model is used to predict the development scale of urban bus stop. Finally, based on a comprehensive analysis of these two models, the rational development scale of urban bus stop is determined. The method has been applied in Zhanjiang’s public traffic planning, the experiment shows that the method is brief and easy, it has some real work significance to public traffic planning.