Y. M. Atwa

Optimal Allocation of ESS in Distribution Systems With a High Penetration of Wind Energy

Environmental concerns and fuel cost uncertainties associated with the use of conventional energy sources have resulted in rapid growth in the amount of wind energy connected to distribution grids. However, based on Ontarios standard offer program (SOP), the utility has the right to curtail (spill) wind energy in order to avoid any violation of the system constraints. This means that any increase in wind energy production over a specific limit might be met with an increase in the wind energy curtailed. In spite of their cost, energy storage systems (ESSs) are considered to be a viable solution to this problem. This paper proposes a methodology for allocating an ESS in a distribution system with a high penetration of wind energy. The ultimate goal is to maximize the benefits for both the DG owner and the utility by sizing the ESS to accommodate all amounts of spilled wind energy and by then allocating it within the system in order to minimize the annual cost of the electricity. In addition, a cost/benefit analysis has been conducted in order to verify the feasibility of installing an ESS from the perspective of both the utility and the DG owner.

Reliability Evaluation for Distribution System With Renewable Distributed Generation During Islanded Mode of Operation

Keen interest in the development and utilization of wind-based distributed generations (DGs) has been currently observed worldwide for several reasons. Among those is controlling the emission of environmentally harmful substances, limiting the growth in energy costs associated with the use of conventional energy sources and encouraging the independent power producers for participation in the electricity market system. One of the most important issues is to quantitatively assess the impact of such type of DGs on the distribution system reliability. This paper presents a probabilistic technique to evaluate the distribution system reliability utilizing segmentation concept and a novel constrained Grey predictor technique for wind speed profile estimation.

Adequacy Evaluation of Distribution System Including Wind/Solar DG During Different Modes of Operation

Keen interest in the development and utilization of renewable distributed generation (DG) has been currently observed worldwide. The reliability impact of this highly variable energy source is an important aspect that needs to be assessed as renewable power penetration becomes increasingly significant. Distribution system adequacy assessment including wind-based and solar DG units during different modes of operation is described in this paper. Monte Carlo simulation (MCS) and analytical technique are used in this work with a novel utilization of the clearness index probability density function (pdf) to model the solar irradiance using MCS. The results show that there is no significant difference between the outcomes of the two proposed techniques; however, MCS requires much longer computational time. The effect of islanding appears in the improvement of the loss of load expectation (LOLE) and loss of energy expectation (LOEE).

Supply Adequacy Assessment of Distribution System Including Wind-Based DG During Different Modes of Operation

Keen interest in the development and utilization of wind-based distributed generation (DG) has been currently observed worldwide. The reliability impact of this highly variable energy source is an important aspect that needs to be assessed as wind power penetration becomes increasingly significant. Distribution system adequacy assessment including wind-based DG units during different modes of operation is described in this paper. Monte Carlo simulation (MCS) and analytical technique are used in this work with a new implementation of the islanding mode of operation in the assessment. The results show that there is no significant difference between the outcomes of the two proposed techniques; however, MCS requires much longer computational time. Moreover, the effect of islanding appears in the improvement of the loss of load expectation (LOLE) and loss of energy expectation (LOEE).

Reliability Assessment of Distribution Systems Considering Telecontrolled Switches and Microgrids

Telecontrol of distribution switching devices is recognized as a major means for reducing interruption duration after a fault occurrence in modern distribution systems, since it allows one to isolate the faulted sections and to restore the healthy ones as quickly as possible. In order to reduce interruption frequency as well, it is necessary to increase the number of series automatic circuit breakers. Further benefits in terms of service continuity improvement can be obtained by allowing islanded operation of relatively small portions of distribution network (microgrids) in the presence of distributed energy resources in order to supply the local load autonomously during upstream faults. This paper aims to describe an innovative systematic method and its related analytical formulation to evaluate distribution system reliability indices accounting for advanced operation practices such as those based on telecontrol and islanding.

Distribution system loss minimization using optimal DG mix

In this paper a probabilistic-based model is proposed to determine the optimal mix of different types of renewable distributed generation (DG) units (i.e. wind-based DG and solar DG) to minimize the annual energy losses in the distribution system without violating the system constraints. Beta and Rayleigh probability density functions have been utilized to estimate the random behavior of the solar irradiance and wind speed, respectively; whereas IEEE-RTS system has been applied to describe the load profile. The problem is formulated as a mixed integer non-linear programming (MINLP); with an objective function to minimize the distribution system annual energy losses. This proposed technique has been applied to a typical rural distribution system with different scenarios including all possible combinations of renewable resources. The results show that a significant reduction in the annual energy losses is achieved for all the proposed scenarios.

Effect of wind-based DG seasonality and uncertainty on distribution system losses

Typically the planning problem formulation of the distribution system integrated with wind-based DGs only considers the peak load and treats the wind-based DG as a constant power supply with a rating based on its capacity factor. However, in reality there are more factors that vary continuously and cause the system losses to vary accordingly. Two of these analyzed parameters which significantly affect the output of wind-based DGs are: wind speed profile variations and load profile variations. Therefore, in this paper a new practical study will be conducted to calculate the actual energy losses in a distribution system with embedded wind-based DGs. Two proposed scenarios will be proposed; the first one will be based on the estimation of the wind speed profile utilizing a proper probability density function (pdf), while the load will be assumed to be constant at its estimated average value. In the second scenario a more accurate method will be used to calculate the energy losses in the system. This method will utilize the actual time based wind and load data. These scenarios will be applied to a typical distribution system with wind-based DGs already located in predetermined locations.