Now showing 1 - 10 of 12
  • Publication
    Information gap decision theory approach to deal with wind power uncertainty in unit commitment
    The renewable energy sources (RES) integration in the electricity supply utilities can reduce the energy procurement costs as well as the environmental concerns. Wind power is the most popular form of RES which is vastly utilized worldwide. This paper proposes a robust model for unit commitment (UC) problem, minimizing the operating costs considering uncertainty of wind power generation. In order to handle the uncertainties arising from volatile nature of wind power, information gap decision theory (IGDT) is utilized, where risk averse (RA) and opportunity seeker (OS) strategies are developed. RA strategy gives a robust decision making tool for handling the severe uncertainty of wind power, whereas the OS strategy makes benefit of possible uncertainties by adjusting the decision variables in a right way. Besides, the impact of demand flexibility (or demand response) on the operation costs is also investigated. The proposed model is examined on the IEEE 118-bus test system, and its benefits over the existing stochastic programming technique is examined. The obtained results demonstrate the applicability of the proposed method to deal with the UC problem with uncertain wind power generation. It is also observed that demand flexibility has positive impacts in both RA and OS strategies.
      503Scopus© Citations 109
  • Publication
    Stochastic Multiperiod OPF Model of Power Systems With HVDC-Connected Intermittent Wind Power Generation
    (Institute of Electrical and Electronic Engineers (IEEE), 2014-02) ;
    This paper presents a new model for a stochastic multiperiod optimal power-flow (SMP-OPF) problem which includes an offshore wind farm connected to the grid by a line-commutated converter high-voltage dc link. The offshore wind farm is composed of doubly fed induction generators (DFIGs), and the DFIG's capability curve is considered in order to obtain a more realistic dispatch for wind farms. The uncertainties of wind power generation are also taken into account using a scenario-based approach which can be adopted by the system operator to obtain the optimal active and reactive power schedules for thermal and wind power generation units. To illustrate the effectiveness of the proposed approach, it is applied on the IEEE 118-bus test system. The obtained results demonstrate the capability of the proposed SMP-OPF model for the determination of the optimal operation of power systems.
      691Scopus© Citations 70
  • Publication
    Distribution networks' energy losses versus hosting capacity of wind power in the presence of demand flexibility
    With the increasing share of renewable energy sources (RES) in demand supply, the distribution network operators (DNOs) are facing with new challenges. In one hand, it is desirable to increase the ability of the network in absorbing more renewable power generation units (or increasing the hosting capacity (HC)). On the other hand,  power injection to the distribution network by renewable resources may increase the active power losses (if not properly allocated) which reduces the efficiency of the network. Thus, the DNO should make a balance between these two incommensurate objective functions. The Demand Response (DR) in context of smart grids can be used by DNO to facilitate this action. This paper provides an approach in which a multi-objective and multi-period NLP optimization model is formulated where the DR is utilized as an effective tool to increase HC and decrease the energy losses simultaneously. In order to quantify the benefits of the proposed method, it is applied on a 69-bus distribution network. The numerical results substantiate that the proposed approach gives optimal locations and capacity of RES, as well as minimum energy losses by load shifting capability provided via DR programs.
      346Scopus© Citations 46
  • Publication
    Risk-Averse Preventive Voltage Control of AC/DC Power Systems Including Wind Power Generation
    Preventive voltage control (PVC) deals with the alert state of power systems, where the system operates in a stable regime but loading margin (LM) is insufficient or some operational constraints have been violated. Hence, the aim of PVC is to ensure a desired LM (i.e. restoration of normal operation state), while minimizing the corresponding control costs. This paper proposes a new stochastic PVC (SPVC) model for power systems operation, taking into account the uncertainties of wind power generation. The uncertainty of wind power generation is handled using scenario based modeling approach. The risk associated with each objective function is handled using conditional value at risk. Voltage set-points of generation units, active power readjustment of predetermined generating units, load reduction of a predetermined load buses, along with the intermittent wind power generation, are employed as control measures in the proposed SPVC approach. Line-commutated converter high-voltage DC (LCC-HVDC) link constraints, doubly fed induction generators’ (DFIGs) capability curves are also considered in the proposed SPVC approach. To illustrate the effectiveness of the proposed approach, it is applied on the IEEE 39-bus test system. The obtained results substantiate the applicability of the proposed SPVC model to ensure secure operation of AC/DC power systems with high penetration of offshore wind farms.
      418Scopus© Citations 32
  • Publication
    Information Gap Decision Theory based OPF with HVDC Connected Wind Farms
    (Institute of Electrical and Electronics Engineers, 2014-12) ; ;
    A method for solving the optimal power flow (OPF) problem including HVDC connected offshore wind farms is presented in this paper. Different factors have been considered in the proposed method, namely, voltage source converter (VSC-HVDC) and line-commutated converter high-voltage DC (LCC-HVDC) link constraints, doubly fed induction generators' (DFIGs) capability curve as well as the uncertainties of wind power generation. Information gap decision theory (IGDT) is utilized for handling the uncertainties associated with the volatility of wind power generation. It is computationally efficient and does not require the probability density function of wind speed. The proposed decision-making framework finds the optimal decision variables in a way that they remain robust against the considered uncertainties. To illustrate the effectiveness of the proposed approach, it is applied on the IEEE 118-bus system. The obtained results validate the applicability of the proposed IGDT-based OPF model for optimal operation of AC/DC power systems with high penetration of offshore wind farms.
      647Scopus© Citations 98
  • Publication
    Optimal multi-area generation schedule considering renewable resources mix: a real-time approach
    (Institute of Engineering and Technology (IET), 2013-09) ;
    One of the key role players in deregulated electricity markets is a retailer. This study proposes a multi-area dynamic economic dispatch (MA-DED) model for a retailer, taking into account hydrothermal generating units, wind power generation and power pool market, to supply the overall demand of the system for a given horizon. The uncertainties in wind power generations, energy prices and demand of the system are also modelled to make the proposed approach more practical in case of real-time operation of practical power systems. Scenario-based approach is adopted for uncertainty modelling. In order to make the proposed MA-DED applicable in real-time operation of power systems, optimality condition decomposition (OCD) technique is employed along with parallel computation ability. The proposed approach is examined on two interconnected power networks, to demonstrate its applicability for real-time scheduling of joint thermal and undispatchable renewable energy resources. DED, multi-area, OCD, real-time, uncertainty modelling, scenario-based approach.
      474Scopus© Citations 42
  • Publication
    Gas Network's Impact on Power System Voltage Security
    Due to the energy linkage between electricity and gas networks, assessing the voltage security of the electricity system without considering the practical constraints of both systems, may lead to unrealistic values of loading margins (LM). This work proposes a model for investigating the impact of gas networks on the voltage security of electric transmission networks. The overall objective is to maximize the LM of the electricity network while satisfying all relevant constraints in both gas and electricity networks such as hourly line pack of gas pipelines, reactive power capability limits of generators, and complementarity constraints representing the generators active/reactive power limits based on the capability curves, power flow equations at both current operation, and security limit points. Three (small, medium, and large) case studies are presented as the applications of the proposed model for LM maximization in power systems that are highly coupled with gas networks. The obtained results corroborate the impact of both gas and electrical networks operation constraints such as voltage and reactive power limits, nodal gas pressure limits, gas network loading as well as the line pack phenomenon of gas pipelines on the LM of power systems.
      143Scopus© Citations 1
  • Publication
    Stochastic Real-Time Scheduling of Wind-Thermal Generation Units in an Electric Utility
    (Institute of Electrical and Electronics Engineers, 2015-01-05) ; ;
    The objective of the dynamic economic dispatch (DED) problem is to find the optimal dispatch of generation units in a given operation horizon to supply a prespecified demand while satisfying a set of constraints. In this paper, an efficient method based on optimality-condition-decomposition technique is proposed to solve the DED problem in real-time environment while considering wind power generation and pool market. The uncertainties of wind power generation, as well as the electricity prices, are also taken into account. The aforementioned uncertainties are handled using a scenario-based approach. To illustrate the effectiveness of the proposed approach, it is applied on 40 and 54 thermal generation units and a large-scale practical system with 391 thermal generation units. The obtained results substantiate the applicability of the proposed method for solving the real-time DED problem with uncertain wind power generation.
      493Scopus© Citations 21
  • Publication
    Energy Hub Management with Intermittent Wind Power
    The optimal energy management in energy hubs has recently attracted a great deal of attention around the world. The energy hub consists of several inputs (energy resources) and outputs (energy consumptions) and also some energy conversion/storage devices. The energy hub can be a home, large consumer, power plant, etc. The objective is to minimize the energy procurement costs (fuel/electricity/environmental aspects) subject to a set of technical constraints. One of the popular options to be served as the input resource is renewable energy like wind or solar power. Using the renewable energy has various benefits such as low marginal costs and zero environmental pollution. On the other hand, the uncertainties associated with them make the operation of the energy hub a difficult and risky task. Besides, there are other resources of uncertainties such as the hourly electricity prices and demand values. Hence, it is important to determine an economic schedule for energy hubs, with an acceptable level of energy procurement risk. Thus, in this chapter a comprehensive multiobjective model is proposed to minimize both the energy procurement cost and risk level in energy hub. For controlling the pernicious effects of the uncertainties, conditional value at risk (CVaR) is used as risk management tool. The proposed model is formulated as a mixed integer nonlinear programming (MINLP) problem and solved using GAMS. Simulation results on an illustrative test system are carried out to demonstrate the applicability of the proposed method.
      299Scopus© Citations 66
  • Publication
    Imperialist competitive algorithm for solving non-convex dynamic economic power dispatch
    Dynamic economic dispatch (DED) aims to schedule the committed generating units' output active power economically over a certain period of time, satisfying operating constraints and load demand in each interval. Valve-point effect, the ramp rate limits, prohibited operation zones (POZs), and transmission losses make the DED a complicated, non-linear constrained problem. Hence, in this paper, imperialist competitive algorithm (ICA) is proposed to solve such complicated problem. The feasibility of the proposed method is validated on five and ten units test system for a 24 h time interval. The results obtained by the ICA are compared with other techniques of the literature. These results substantiate the applicability of the proposed method for solving the constrained DED with non-smooth cost functions. Besides, to examine the applicability of the proposed ICA on large power systems, a test case with 54 units is studied. The results confirm the suitability of the ICA for large-scale DED problem.
      608Scopus© Citations 115