Liu Li-qun’s research while affiliated with Taiyuan University of Science and Technology and other places

Environmental pollution and greenhouse gas emissions are becoming significant environmental issues in China, thus the sustainable development and revival of the country is impossible using the conventional path of encouraging economic growth at the expense of the environment. In response to the global warming, the prices of the traditional energy rise considerably, and a series of environmental problems, China must improve its own mode of economic development. Hundreds of Chinese cities have billions of square meters of buildings and most industry and the annual energy demand is an astronomical figure. China's government is facing increasing pressure in the low carbon international backdrop, and the low carbon city becomes the inevitable developmental direction of Chinese city in the foreseeable future. The description is first centered on energy structure/energy consumption per unit/urbanized status, and urban energy consumption status, and then concerned with the efforts and measures of Chinese government, to realize the energy saving. Finally, we present the developmental prospect and barriers and the promotion measures related to the low carbon city under the government policy, financial incentives and funding supports, etc.

An efficient maximum power point tracking (MPPT) algorithm is important to increase the output efficiency of a photovoltaic (PV) generate system. The conventional perturbation and observation (PO) MPPT algorithm is impossible to quickly acquire the maximum power point (MPP), and the tracking course is very difficulty under veil weather conditions, and the essential reason is not known the actual values of the n and Io. It is well-known that the different solar cells have different n and Io. Theoretical and simulative results show that a piece of solar cell has same photocurrent under different n and Io conditions. A new combined perturb and observe (PO) method is described in order to acquire the actual n and I. Then an improved PO maximum power point tracking method is described which based on the actual n and Io, and the tracking bound is reduced, and the tracking speed is rapid to compare with the conventional PO method. Furthermore, it is simple and can be easily implemented in digital signal processor (DSP). The simulation results verified the correctness and validity of MPPT method.

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.

An efficient Maximum Power Point Tracking (MPPT) algorithm is important to increase the output efficiency of a photovoltaic (PV) generate system. The conventional method have some problems in that it is impossible to quickly acquire the generation power at the maximum power (MP) point, i.e., the efficiency of electric power generation is very low, and the amount of electric power generated by solar cell is always changing with weather conditions. Normally, the different solar cells have different diode factor (n) and reverse saturation current (Io). Theoretical and simulative results show that the approximately linear relationship exists between the optimal output current and the short-circuit current, and if the weather conditions are sameness, a piece of solar cell have same photocurrent under different diode factor n and reverse saturation current Io conditions. A new combined perturb and observe (PO) method is described in order to acquire the actual diode factor and reverse saturation current. This paper describes a rapid maximum power point tracking method which is based on the actual n and Io. An expiatory program is applied to acquire the actual maximum power point. The correctness and validity of expiatory coefficients is verified through simulation. The simulation results verified the correctness and validity of MPPT algorithm.