Sharif Digital Repository

As a matter of course, the unprecedented ascending penetration of distributed energy resources, mainly harvesting renewable energies such as wind and solar, is concomitant with environmentally friendly concerns. This type of energy resources are innately uncertain and bring about more uncertainties in the power system context, consequently, necessitates probabilistic analysis of the system performance. Moreover, the uncertain parameters may have a considerable level of correlation to each other, in addition to their uncertainties. The two point estimation method (2PEM) is recognised as an appropriate probabilistic method. This study proposes a new methodology for probabilistic power flow... 

Smartening of contemporaneous power delivery systems in conjunction with the increased penetration of renewable energies (REs), change the way to energize consumers who are willing to maximize their utility from energy consumption. However, there is a high degree of uncertainty in the electricity markets of such systems. Moreover, the unprecedented ascending penetration of distributed energy resources (DERs) mainly harvesting REs is a direct consequence of environmentally friendly concerns. This type of energy resources brings about more uncertainties into power system operation resulting in, necessitates probabilistic analysis of the system performance. In the smarter power markets,... 

As energy resource planning associated with environmental consideration are getting more and more challenging all around the world, the penetration of distributed energy resources (DERs) mainly those harvesting renewable energies (REs) ascend with an unprecedented rate. This fact causes new uncertainties to the power system context; ergo, the uncertainty analysis of the system performance seems necessary. In general, uncertainties in any engineering system study can be represented probabilistically or possibilistically. When sufficient historical data of the system variables is not available, a probability density function (PDF) might not be defined, while they must be represented in another... 

The unprecedented increasing penetration of distributed energy resources, mainly harvesting renewable energies, is a direct result of environmental concerns. These types of energy resources bring about more uncertainties in the power system and, consequently, necessitate probabilistic analyses of the system performance. This paper develops a new approach for probabilistic optimal power flow (P-OPF) by adapting the unscented transformation (UT) method. The heart of the proposed method lies in how to produce the sampling points. Appropriate sample points are chosen to perform the P-OPF with a high degree of accuracy and less computational burden in comparison with the features of other... 

As a matter of course, the unprecedented ascending penetration of distributed energy resources, mainly harvesting renewable energies, is a direct consequence of environmental concerns. This type of energy resource brings about more uncertainties in power system operation and planning; consequently, it necessitates probabilistic analyses of the system performance. This paper develops a new approach for probabilistic load flow (PLF) evaluation using the unscented transformation (UT) method. The UT method is recognized as a powerful approach in assessing stochastic problems with/without correlated uncertain variables. The capability of the UT method in modeling correlated uncertain variables is... 

Control strategies of a microgrid which includes both synchronous generators and converter-based distribution generation (DG) units must be designed such that effective operation of the microgrid is achieved. The main objective of this paper is to develop a high performance control strategy for an islanded medium voltage (MV) microgrid consisting of inverter and non-inverter interfaced DG units. A new control method for the synchronous generator in an islanded microgrid is proposed based on a virtual droop scheme. The proposed strategy can effectively manage the real and reactive powers of the microgrid among the inverter and non-inverter based DG units. The steady state and dynamic... 

This paper presents a long-term dynamic multi-objective planning model for distribution network expansion along with distributed energy options. The proposed model optimizes two objectives, namely costs and emissions and determines the optimal schemes of sizing, placement and specially the dynamics (i.e., timing) of investments on distributed generation units and network reinforcements over the planning period. An efficient two-stage heuristic method is proposed to solve the formulated planning problem. The effectiveness of the proposed model is demonstrated by applying it to a distribution network and comparing the simulation results with other methods and models  

This paper investigates the performance of a smart distribution system comprised of multi-microgrids during emergency conditions. It also proposes a hierarchical scheme for outage management in such a system to enhance the security of supply during contingencies. This goal is achieved through sharing the available generation and storage capacities among different microgrids. In this regard, at first, a well-organized framework is devised in order to introduce the roles and tasks of each player in operation stage of a multi-microgrids system. Based on this framework, the general optimization model that needs to be evaluated in the proposed outage management scheme is formulated. Then, various... 

A linear time-invariant (LTI) robust servomechanism controller for islanded (autonomous) operation of a distributed generation (DG) unit and its local load is proposed. The DG unit utilizes a voltage-sourced converter (VSC) as the interface medium. The controller design is obtained by introducing a new optimal controller design procedure, in conjunction with a proposed non-conservative robustness constraint. The proposed controller utilizes 1) an internal oscillator for frequency control and 2) a robust servomechanism controller (RSC) to regulate the island voltage. Despite uncertainty of the load parameters, the proposed controller guarantees robust stability and pre-specified performance... 

One of the most important issues in the smart grid is to quantitatively assess the impacts of distributed energy resources (DER) on the distribution system reliability. Solar cells (SCs) as developing DERs are normally placed close to the load centers. In this paper, a new algorithm is developed to evaluate distribution system reliability, considering SCs in the vicinity of the end-users. The probabilistic nature of the demand and SC power output are investigated to solve challenges of integrating these intermittent resources with the distribution system. In a smart home, to handle the variation of SC generation, solar load controller (SLC) is utilized to match load and generation of SCs... 

The continuous spread of distributed energy resources (DERs) such as combined heating and power (CHP), diesel generators, boilers and renewable energy sources provide an effective solution to energy related problems to serve the power and heat demands with minimum cost. Moreover, the DERs may play a significant role for supplying power and heat in rural areas, where grid electricity is not available. Also, some dry areas may face water scarcity and salinity problems. So, one important solution is the use of DERs to drive desalination units in order to solve water scarcity and salinity problems. In this study, the optimal scheduling of DERs and reverse osmosis (RO) desalination unit that feed... 

Despite the significant research efforts devoted to the microgrid and smart grid areas, numerous problems related to real world implementations still remain unsolved. The present special issue was announced with the objective of addressing and disseminating state-of-the-art R&D results on microgrids to bring together researchers from both academia and industry with the goal of fostering interactions among stakeholders. In response, 190 two-page extended abstracts were received and considered for the first round of reviews. Authors of about 60 selected abstracts were then invited to submit the full papers in the second round and out of them 27 high-quality manuscripts were ultimately approved... 

In modern power systems, technical virtual power plants (TVPPs) play an important role enabling presence of distributed energy resources (DERs) in electricity markets. In this paper, strategy of using the available energy resources for a TVPP is put under investigation. A new optimization framework is presented for problem of TVPP energy scheduling by taking operational constraints of distribution network into account. In the proposed model, photovoltaic (PV) units and micro turbines along with the electric vehicles (EVs) are scheduled in such a way that the profit of TVPP owner would be maximized. The uncertainty in output generation of PV units is modeled by adopting fuzzy c-means (FCM)... 

Distribution system operator (DSO) has traditionally been responsible for the reliable operation of power distribution systems. The advent of distributed energy resources (DERs) and microgrids in distribution networks has required a new platform for DSOs. The new DSO, which is for the most part an independent agent, is responsible for aggregating a widely dispersed DERs (which include small thermal generation units, energy storage, and demand response) and flexible loads in electricity markets. DSO coordinates and balances the transactive dispatch of supply and demand at the distribution level and links wholesale and retail electricity markets. In this paper, a framework for the day-ahead...