Most of the typical distribution network programmings with distributed new energy utilize passive， conservative programming method to access distributed new energy， which indeed secure the safe of distribution network， but cannot reflect the output characteristics of distributed new energy and cause unnecessary investment on distribution network construction. To solve this problem， this paper proposed active power distribution network programming method based on random chance constrained programming. Firstly， the hard constraint conditions in active power distribution network programming were transformed into soft ones with higher confidence level. Meanwhile， three independent objective functions including the investment cost reflecting the economic benefit， the power loss and the voltage deviation degree reflecting the distribution network power supply security were set to form the multiple-objective active power distribution network planning model based on random chance constrained programming. Then， the model was solved to obtain non-inferior solution Pareto frontier by the improved NSGA-2 （non-dominated sorting genetic algorithm2） combined with the quantum method. On this basis， the TOPSIS （technique for order preference by similarity to ideal solution） was used to sort the non-inferior solution， in order to obtain the optimal solution. Finally， a distribution network with 57 nodes was used as example to verify the feasibility and availability of the proposed method.
Smart grid has become the developing trend of the grid. The information system is an important part supporting the smart grid， whose impact on power grid planning and operation has become increasingly prominent and interaction with the power system has become more and more closely. The traditional distribution network planning methods that neglect this kind of close relationship have been unable to meet the refined planning requirements under the background of smart grid development. This paper discussed the coordination relationships among the distribution network planning， communication system planning and distribution automation planning. Then the thinking framework of the coordinative planning was proposed and the planning model， evaluation index and method of the sub programming problems were further discussed. The research conclusion can provide ideas for the coordinative planning of primary power grid architecture， secondary automatic system and intelligent decision support system in future active distribution network.
Distributed generation （DG） is more and more widely used and gradually connected to the distribution network， whose influence on the distribution network is significant. However， current calculation methods of load supplying capability （LSC） for distribution network do not consider the randomness effects of DG. To solve this problem， LSC model was proposed firstly. With considering the randomness of DG in the probabilistic power flow calculation of Monte Carlo simulation， the improved load factor method and the LSC approximation method with considering voltage and the branch power constraints were applied to calculate the LSC of distribution network. Then the IEEE-33 example of distribution network was used to validate the effectiveness of the proposed model and algorithm， and the LSC variations in different scenarios were simulated. Simulation results show that the DG connected to distribution network can promote the network static safety margin， and the randomness of DG affects the LSC distributed characteristics. Finally the weak link that restricted the LSC promotion was analyzed. It is suggested to add voltage regulator or automatic reactive compensator at low level voltage nodes.
The development of energy revolution and the third industrial revolutions put forward higher requirements for the energy interconnection and information communication in smart grid. Based on the innovation demonstration area construction of Tianjin eco-city smart grid， this paper focused on the development pattern of future power grid， deeply analyzed the development need of smart grid， designed the innovation structure of smart grid with sustainable development， and proposed the planning scheme of energy internet based on virtual power plant and efficiency power plant， as well as the smart energy information service structure based on big data and extensive information interconnection. In order to improve the participation of society and the perception of residents， this paper proposed smart grids construction mode， operation mode， service mode and transaction mode， which could give full play to the platform effect of smart grid and fundamentally change the production and lifestyle of smart city.
The traditional assessments of regional distribution network planning only focus on economy resulting in that the assessments are not comprehensive. To solve the problem， the paper constructed a comprehensive evaluation index system from four aspects of power supply margin， network security， service level and economic benefits， with considering the factors of the technical and economic level and the power responsibility of enterprise in the overall planning scheme of medium-lower voltage distribution network. And the comprehensive evaluation model was built based on the PSV （public service value） model， which could realize the scientific evaluation for the overall planning scheme of medium-lower voltage distribution network. The index system construction and evaluation process follows the principle of differentiation， which designs the evaluation index and set up the index weight and evaluation criterion in differentiation， based on the power supply zone in ‘the guide of planning and design of distribution network’ （Q/GDW 1738-2012）. Meanwhile， the index scoring adopts the comprehensive scoring method of stock value and increment value. So the investment sensitivity difference in different regions caused by the differences in the current situation of network， the power supply demand and the development goals can be solved. Actual examples show that the proposed method can effectively promote the optimal allocation of resource science in medium-lower voltage distribution network planning， and guide the planning direction.
The researches on power grid environmental problems are little at home and abroad， and the environmental planning of regional power grid is lacking of framework system guidance. In view of the above facts， this paper firstly analyzed the characteristics of the environmental planning of power grid， and then preliminarily established the method framework of the environmental planning for regional power grid. The method framework pays more attention to the overall upgrade of regional ecological environment quality， uses basic theories of environmental planning as guide to recognize the environmental impact of power grid system comprehensively， and design the planning scheme in different ways according to the classification of environmental problems. Taking the ‘13th Five-Year’ environmental planning of Zhuhai power grid as example， this paper defined the land occupation， electromagnetic radiation and other key problems that should be focused on， based on the present situation analysis of Zhuhai power system environmental， and put forward the planning schemes for three kinds of environmental problems in ecological environment， ecological landscape and environmental quality， as well as the priority implementation projects aimed at key issues. According to the investment benefit evaluation， the area substations cover， electromagnetic radiation and noise value will reach the corresponding national standards， and the environmental impacts of power grid will reduce overall， after the implementation of the proposed planning.
Power system interconnections bring primary economic advantages. However， certain technical problems occur with the size expansion of synchronous grids， such as grid dispatching and low frequency oscillation. From technical viewpoints， this paper proposed three basic constraints to determine reasonable size of synchronous grids， including the frequency stability constraint， the minimum frequency constraint of low frequency oscillations and the synchronous support effect disappearance constraint. The research results indicate that steady frequency deviation index has higher requirements for synchronous grid size than that of transient frequency deviation index. Therefore the frequency stability constraint of synchronous grid can be calculated according to the deviation index of steady frequency. Fast excitation control contributes negatively to generator damping in low frequency spectrum， and the lower oscillation frequency the worse of damping effect is. The total damping of generators with power system stabilizer （PSS） tends to be negative when the frequency is lower than 0.3 Hz， and the lower oscillation frequency the worse of damping effect is. The synchronous power coefficient represents synchronous support effect. The synchronous support effect disappears when the steady angle difference of any two generators is larger than 90° within the synchronous grid. Based on the general structures of synchronous grids， the research conclusion in this paper has guiding significance to the interconnection method of actual power grids and grid scale determination.
To eliminate the relevance among similar evaluation indexes of power network planning scheme， a new comprehensive evaluation method of planning scheme based on the Choquet capacity and integral was presented. Firstly， the Choquet capacity was used to measure the non-additive relevance indexes because of the non-additive measure characteristics. Then， a comprehensive evaluation result was attained based on the Choquet integral with the relevance removed. On the other hand， the profit of power network investment is uncertain， and the risk preferences of various decision-makers in addressing the uncertainties are considered in economic evaluation. So the appropriate utility function should be used to describe the risk preferences of decision-makers. Risk premium based on the Choquet integral was firstly employed to measure the reduced part of the profit for the risk elimination of decision-makers. Then， the comprehensive profit obtained by decision-makers subjective expectation with considering risk preference was employed as the result of the comprehensive evaluation of economic indexes. Finally， the evaluation and decision table of power network planning was established based on the economic and reliability indexes. The numerical example results show that the proposed method can provide reasonable evaluations for power network planning schemes.
KEYWORDS： microgrid|distributed generation|droop control|isolated island operation|power flow calculation|three-phase unbalance
To clear the NO release law under the interaction of oxygen-enriched combustion and biomass/coal co-combustion， this paper studied the NO release characteristics during biomass/coal co-combustion process in oxygen-enriched atmosphere， and discussed the influence law of atmosphere， temperature， biomass blending ratio， coal type and biomass type on NO release characteristics， with using homemade iso-thermal TGA and pollutants synchronous measurement system. The results show that two peaks and conversion of NO in oxygen-enriched atmosphere are less than that in air atmosphere when Yangquan coal blending 20% corn cob at 21% oxygen concentration. As oxygen concentration increasing， the NO release rate curve is changed from two peaks to one peak， and the NO conversion of samples increases. As the biomass blending ratio increasing， the NO conversion shows a decreasing tendency. The NO conversion of samples increases with the temperature rising. The NO conversion decreases when coal blending corn cob；and the NO conversion decreases when Yangquan coal blending biomass.
