Bi-level Multi-objective Joint Planning of Distribution Networks Considering Uncertainties

With the increasing penetration of photovoltaics in distribution networks,the adaptability of distribution network under uncertainties needs to be considered in the planning of distribution systems.In this paper,the interval arithmetic and affine arithmetic are applied to deal with uncertainties,and an affine arithmetic based bi-level multi-objective joint planning model is built,which can obtain the planning schemes with low constraint-violation risk,high reliability and strong adaptability.On this basis,a bi-level multi-objective solution methodology using affine arithmetic based non-dominated sorting genetic algorithm II is proposed,and the planning schemes that simultaneously meet economy and adaptability goals under uncertainties can be obtained.To further eliminate bad solutions and improve the solution qualities,an affine arithmetic based dominance relation weakening criterion and a deviation distance based modification method are proposed.A 24-bus test system and a 10 kV distribution system of China are used for case studies.Different uncertainty levels are compared,and a sensitivity analysis of key parameters is conducted to explore their impacts on the final planning schemes.The simulation results verify the advantages of the proposed affine arithmetic based planning method.

Motion planning for redundant prismatic-jointed manipulators in the free-floating mode

This paper investigates the motion planning of redundant free-floating manipulators with seven prismatic joints. On the earth, prismatic-jointed manipulators could only position their end-effectors in a desired way. However, in space, the end-effectors of free-floating manipulators can achieve both the desired orientation and desired position due to the dynamical coupling between manipulator and satellite movement, which is formally expressed by linear and angular momentum conservation laws. In this study, a tractable algorithm particle swarm optimization combined with differential evolution （PSODE） is provided to deal with the motion planning of redundant free-floating prismatic-jointed manipulators, which could avoid the pseudo inverse of the Jacobian matrix. The polynomial functions, as argument in sine functions are used to specify the joint paths. The co- efficients of the polynomials are optimized to achieve the desired end-effector orientation and position, and simulta- neously minimize the unit-mass-kinetic energy using the redundancy. Relevant simulations prove that this method pro- vides satisfactory smooth paths for redundant free-floating prismatic-jointed manipulators. This study could help to recognize the advantages of redundant prismatic-jointed space manipulators.

BP Plans to Sell Stake in Chinese Joint Venture

BP,the UK energy group,is planning to sell one of its biggest Chinese investments,by disposing of its 50percent stake in the SECCO petrochemicals plant near Shanghai.BP is the latest western oil company to curtail activity in China,as energy groups reel from low crude and petrochemical prices.China’s slow liberalization

Analysis of System Value Evolution Trends of Energy Storage in Decarbonization Process

With the continuous expansion of the scale of renewable energy installation,the demand for energy storage has increased significantly.However,there are significant differences in the value of energy storage in different scenarios,and the phenomenon of diminishing marginal benefits of energy storage is becoming more apparent.Therefore,themulti-dimensional value evolution trend of energy storage has become a key issue.This study selects indicators from three dimensions of energy storage:low-carbon emission reduction,smoothing wind and solar power fluctuations,and saving generation costs,quantifying the economic,environmental,and technical values of energy storage.This forms a quantitative evaluation system for energy storage value.By comparing the calculated system values under different energy storage capacities,the marginal value evolution trend of energy storage is obtained.Meanwhile,considering factors such as the utilization rate of renewable energy,the change in energy storage value under different scenarios is analyzed.The results show that the value of long-duration energy storage is significantly affected by the energy storage capacity.Specifically,when the charge-discharge efficiency of longduration energy storage reaches 0.6 or above,the system value increases significantly.Additionally,appropriately reducing the cost of energy storage capacity also helps to improve its system value.

Review of Key Problems Related to Integrated Energy Distribution Systems

Integrated energy distribution system(IEDS)is one of the integrated energy and power system forms,which involves electricity/gas/cold/heat and other various energy forms.The energy coupling relationship is close and complex.IEDS is the focus of regional energy internet research and development at home and abroad.Compared with the traditional power distribution system,IEDS through the multi-energy coupling link comprehensive utilization,effectively improve the distribution system economy,safety,reliability,flexibility and toughness,but also to ease the regional energy system environmental pressure.IEDS is an important direction for the future development of energy systems,and its related research and practice on China’s energy system development also has important practical and strategic significance.This paper summarizes the related researches of the IEDS and explores the energy operation characteristics and coupling mechanisms.What’s more,the integrated model of IEDS is summarized.On these bases,this paper discusses and prospects some key issues such as joint planning,optimization control and security analysis,state estimation and situational awareness and generalized demand side management.

THREE BROTHERS BAND TOGETHER

Three years have elapsed since the synergetic development of the BeijingTianjin-Hebei（Jing-Jin-Ji）region was first put forward as a major national strategy by Chinese President Xi Jinping in February2014.Xi called for the coordination and integration of the economic zone surrounding Beijing. Now, a fledging Capital Economic Circle is taking shape.