A review of optimal planning active distribution system:Models, methods, and future researches

Due to the widespread deployment of distributed energy resources (DERs) and the liberalization of electricity market, traditional distribution networks are undergoing a transition to active distribution systems (ADSs), and the traditional deterministic planning methods have become unsuitable under the high penetration of DERs. Aiming to develop appropriate models and methodologies for the planning of ADSs, the key features of ADS planning problem are analyzed from the different perspectives, such as the allocation of DGs and ESS, coupling of operation and planning, and high-level uncertainties. Based on these analyses, this comprehensive literature review summarizes the latest research and development associated with ADS planning. The planning models and methods proposed in these research works are analyzed and categorized from different perspectives including objectives, decision variables, constraint conditions, and solving algorithms. The key theoretical issues and challenges of ADS planning are extracted and discussed. Meanwhile, emphasis is also given to the suitable suggestions to deal with these abovementioned issues based on the available literature and comparisons between them. Finally, several important research prospects are recommended for further research in ADS planning field, such as planning with multiple micro-grids (MGs), collaborative planning between ADSs and information communication system (ICS), and planning from different perspectives of multi-stakeholders

Smart Operation of Four-Quadrant Electric Vehicle Chargers in Distribution Grids

Many policies and programs adopted in the context of climate change mitigation and substitution of fossil fuels are contributing to the continuous development and growth of Electric Vehicles (EVs) in urban mobility systems, reaching 1.26 million units on the roads through the end of 2015. Even though the increasing number of EVs will create problems in distribution systems, which can be mitigated using smart charging strategies, there will also be economic opportunities for EV owners to provide services to the grid while their vehicle are parked and plugged in, a concept known as Vehicle-to-Grid (V2G). Most of the studies on V2G have concentrated on the provision of services such as frequency regulation or spinning reserves, which may reduce the battery life because of the required extra charging/discharging cycles, and little attention has been paid to the possibility of providing reactive power control services to the grid by using the ac/dc converter and the dc link capacitor available in most advanced chargers, a practice that does not compromise the vehicle battery life. These kinds of chargers, which are known as four-quadrant EV chargers due to the capability of being operated in all quadrants of the P-Q plane, can be used in distribution networks to improve the power factor and help regulate voltage, thus facilitating larger EV penetrations, as discussed in this thesis. In the first part of this thesis, a new average model of a single-phase, four-quadrant EV charger is developed. The steady-state and step responses of the proposed model for different P-Q requests, corresponding to the operation in the four quadrants of the P-Q plane, are used to validate its performance against a four-quadrant EV charger prototype. The model is shown to be useful for efficient time-domain simulations and studies that include a number of EV chargers, such as EV integration studies in Low-Voltage (LV) distribution networks. A practical case study is presented to demonstrate and test the performances of the four-quadrant charger and its model, investigating the voltage interactions of several chargers in an LV residential network during the provision of three vehicle-to-grid (V2G) strategies for active and reactive power. In the second part, a novel three-stage algorithm to coordinate the operation of four-quadrant EV chargers with other volt/var control devices in Medium-Voltage (MV) and LV distribution feeders is proposed. The first stage of the algorithm is operated on a day-ahead basis and defines the Load Tap Changer (LTC) and capacitor schedules while minimizing the peak load associated with EVs in the distribution system. The second and third stages update their operation every five minutes, to fairly allocate the aggregated and individual EV loads in the MV and LV feeders, respectively, while minimizing active power losses and voltage deviations. The proposed technique is applied to CIGRE's North-American MV and LV benchmark systems to demonstrate its ability to properly allocate EV loads, and improve distribution system performance in terms of losses and voltage profiles

Expansion planning of power distribution systems considering reliability : a comprehensive review

One of the big concerns when planning the expansion of power distribution systems (PDS) is reliability. This is defined as the ability to continuously meet the load demand of consumers in terms of quantity and quality. In a scenario in which consumers increasingly demand high supply quality, including few interruptions and continuity, it becomes essential to consider reliability indices in models used to plan PDS. The inclusion of reliability in optimization models is a challenge, given the need to estimate failure rates for the network and devices. Such failure rates depend on the specific characteristics of a feeder. In this context, this paper discusses the main reliability indices, followed by a comprehensive survey of the methods and models used to solve the optimal expansion planning of PDS considering reliability criteria. Emphasis is also placed on comparing the main features and contributions of each article, aiming to provide a handy resource for researchers. The comparison includes the decision variables and reliability indices considered in each reviewed article, which can be used as a guide to applying the most suitable method according to the requisites of the system. In addition, each paper is classified according to the optimization method, objective type (single or multiobjective), and the number of stages. Finally, we discuss future research trends concerning the inclusion of reliability in PDS expansion planning