The active distribution network （ADN） provides an effective solution for large-scale integration and high-efficient utilization of renewable energy sources under the background of low-carbon economy, which is strategic significant to promote the optimization and adjustment of energy structure in China. The functional characteristics of ADN was analyzed, then the development objective, contents and effect of both domestic and oversea demonstration projects were introduced. After analysis the insufficient of traditional ADN planning, key technical issue of ADN planning was explored in this paper. Furthermore framework and critical factors of ADN planning method were proposed. It is pointed that engineering practice should develop from frame structure, distribution automation, intelligent communication network, information platform and intelligent power utilization, development direction and principle are put forward as well.
With the increasing integration of distributed energy resources（DER） and electric vehicles（EV）, the intelligent home and demand side response are being gradually popularized. As a result, the operation and planning complexity of distribution system are significantly enhanced. Moreover, the higher demands of power supply make the system optimization more difficult. As one development mode of the future distribution system, active distribution network begins to attract more and more attention. Its concept and management system are introduced, and the operation and planning strategy are reviewed including the present situation as well as the current concerns. Finally, the development trends are sorted out from three aspects： the source-network-demand interaction, the multi-period coordination, and the multi-layer distributed strategy.
Integrated energy system （IES） can provide an effective solution to solve the low security, insufficient self-healing capability, and low utilization rate of energy equipment problems under the background of low-carbon economy, which has a significant potential to support the optimization and adjustment of China’s energy structure. Firstly, the basic concept of IES and its main features are given in detail. Then, considering the valuable IES construction experience around the world and the current status of China’s energy resources, some key issues about China’s IES from the prospective of national level, regional level, and terminal level are discussed. Also, the corresponding suggestions are proposed.
The large scale penetration of distributed generation will reshape electric distribution systems from a passive energy receiver to an active bi-directional energy network with flexible generation, transmission, storage and distribution. The evolution of a passive distribution system to an active distribution cannot be realized without advanced technologies. Therefore this paper provide a thorough review towards existing literatures from 6 aspects, i.e. protection, operation and control, system planning, integration of information communication systems and energy policy. Suggestions of future work are proposed based on the review, which can act as important reference to related scholars and engineers.
As an effective approach to connect the distributed generation to the grid and to supply energy to remote areas and islands, microgrids present wide application prospect. It’s impossible to build a microgrid without the help of efficient method of planning and design of microgrids. However, the access of renewable energy sources and energy storage system to power system results in a great difference between the planning and design method of microgrid and the one of traditional power system. The paper presents the key steps of planning and design of microgrids on the technique side, reviews the state-of-the-art techniques of planning models, solving algorithms and softwares related to this field, and at the same emphatically discusses the coupling between planning and operation of microgrids, the calculation of reliability and the main planning softwares. Finally, from the perspectives of microgrids themselves, integrated energy network and coordinated planning with distribution system, some proposals on the methods of planning and design of microgrids are proposed.
Traditional distribution networks undertake the function of distributing energy and providing electricity consumption, therefore the flowtransferringis unilateral. The increasing amount of distributed generation （DG） in todays highly complex restructured power networks change it to bidirectional flow. Due to the randomness and intermittence of DG, flow fluctuates wildly in a degree, which makes the distribution infrastructure cannot work in economical and efficient ways. For the better energy transferring ability of DG, provide high-quality power, Beijing Power Grid build the controllable and observable active distribution（ADN） in energy transferring and distribution operator system field, for the entire energy consumption of high-permeability DG, achieve the aim of efficient energy use and high-quality and high-reliability power supply.
Traditional distribution networks undertake the function of distributing energy and providing electricity consumption, therefore the flowtransferringis unilateral. The increasing amount of distributed generation （DG） in todays highly complex restructured power networks change it to bidirectional flow. Due to the randomness and intermittence of DG, flow fluctuates wildly in a degree, which makes the distribution infrastructure cannot work in economical and efficient ways. For the better energy transferring ability of DG, provide high-quality power, Beijing Power Grid build the controllable and observable active distribution（ADN） in energy transferring and distribution operator system field, for the entire energy consumption of high-permeability DG, achieve the aim of efficient energy use and high-quality and high-reliability power supply.
Traditional distribution network needs to pay more investment costs but with less economic returns in order to meet the requirements of load growth and the high penetration of distributed energy resources. The initiative of active distribution system is to change the traditional distribution system planning for its planning objectives, to maximum the possible use of existing assets, which can greatly improve the cost-effectiveness of the investments. This paper discusses the main factors affecting the distribution system planning, such as the main difference between active and passive distribution network distribution network, the impact of the qualitative data analysis and control mode as well as the active distribution system planning model, and then explains the impact of the external conditions on distribution network planning, finally, green and brown networks with different requirements for active distribution system planning is provided, which could provide a good foundation for active distribution system planning studies in China.
In this paper, basic concept and characteristics of distributed photovoltaic generation （DPG） were first introduced. However, integrating more and more DPG into distribution grid may have adverse effects on distribution grid, while conventional distribution grid also constrains the wide application of DPG. Both issues were discussed in details. To address these issues, active distribution network（ADN） technology was applied and analyzed. On this basis, the key technologies of ADN were summarized. Finally, several typical combined applications of DPG and ADN were given. Moreover, coordinated development of these two technologies in policy planning, technical requirements and demonstration were emphasized.
Active distribution network construction relies on the development of key technologies such as on-grid and operation control of large-scale intermittent renewable energy, interaction of charging and discharging facilities with grid and smart electricity use. With the increased popularity of electric vehicle,the random charging behavior of large-scale EV users in time and space will increase the uncertain influencal factors in power grid operation. The research mainly studied the influence of electric vehicle charging mode on grid daily load curve. Through analyzing the probability distribution of electric vehicle users’ driving habits, a load model of electric vehicles was established according to the charging power and energy demand characteristics. Then the influence of electric cars in uncontrolled and coordinated charging modes was compared. The comparison was done by simulation with the actual charging station operating data, which verified the active role of coordinated charging in active distribution network.
To solve the influence of distributed generation （DG） on the fault location and voltage quality of distribution network, the influence of various DGs on the short-circuit current were analyzed. The adaptation range of traditional distribution automation system was obtained, in which the fault location was based on the fault current distribution. An improved fault process strategy was proposed to meet the requirement of much larger amount of DGs connection, based on the coordination of the reclosing procedure and DG escaping after faults. The influences of DGs on the voltage deviation and voltage fluctuation of distribution network were analyzed. The judging condition to meet the requirements of voltage quality without the control of DG was proposed. The DG that could not accord with the judging condition could be monitored by distribution automation system to meet the requirements of voltage quality. The examples show that the proposed method is feasible.
As a novel “Source-Net-Load” ternary structure of distribution system, active distribution network （ADN） is the main technical mean to solve the large-scale and high penetration of distributed energy in near future. This paper focused on the overall architecture and key features of ADN, elaborated the technique concepts of ADN and proposed scientific and complete evaluation index system for ADN, including the characteristic indexes of intermittent energy sources grid-connection, ADN control and operation. The quantitative analysis of “reason-process-result” of ADN was carried out with using these indexes, which had important guiding significance and reference value to the choice of the technical route and implementing scheme of ADN.
As many factors must be considered when distributed generation （DG） integrating the distribution,an efficient method for evaluating distribution network is proposed in this paper. According to the feature of wind power and solar power, normal distribution of wind speed and light intensity is established to calculate their output power and the reliability of network. Taking the economy, quality of service, safety and environment efficiency into consideration, this paper established the evaluation system and summarize the calculating methods. The indices under different situations are calculated based on the IEEE RBTS-Bus6 system. Fuzzy analytic hierarchy process （FAHP） was adopted to obtain the quantitated comprehensive evaluation results. The evaluation results show that multiple DG integrating into grid could promote the indices efficiently.
The active distribution network （ADN） provides an effective solution for the high penetration of distributed generators. The change of control and operation mode has made the microgrid operation different from that in traditional mode. In this paper, the influerice of ADN operation mode on the microgrid reliability was analyzed and a reliability model of component was built. Based on Monte Carlo simulation a reliability evaluation algorithm for ADN containing microgrids was discussed, and the reliability of modified IEEE RBTS was evaluated with this algorithm. Moreover, the system reliability in different situations were compared and analyzed. The evaluation results have shown that microgrids in the ADN operation mode will effectively improve the power supply reliability.
Based on the analysis of the characteristics of fault current, this paper analyzed how distributed electric resources impacted the relaying protection of distribution networks. According to the actual performances of the protections and the countermeasures need，the impact of the DER to the protection is classified as three levels, no substantial impact, moderate impact and serious impact. According to the maximum fault contribution of the DERs in a line, a simple assessment method is presented. To prove the feasibility and efficiency of this method, examples are given.
