Showing 11 results for Allocation
A. Kazemi, Sh. Jadid, H. Andami,
Volume 3, Issue 1 (1-2007)
Abstract
Transmission loss allocation in very large networks with multiple interconnected
areas or countries is investigated in this paper. The main contribution is to propose a
method to calculate the amount of losses due to activity of each participant in the multi area
markets. Pricing of cross-border trades in Multi area systems is often difficult since
individual countries may use incompatible internal transmission pricing regimes, and they
are usually unwilling to disclose any sensitive information about their own systems.
A new methodology based on the loss formula concept for allocating electric losses to
generators and loads is presented in this paper. The only data required are the power flows
and characteristics of tie-lines and PV Ward equivalent model of area networks from border
nodes point of view. Proposed methodology is tested on the IEEE 118 node network which
is divided into three areas, each with a different internal transmission pricing methodology.
In the proposed methodology no information is required about individual loads, generations
or detailed internal networks. It is also shown to be simple, transparent and very fast and it
can deal effectively with multiple pricing policies.
A. Falahati, M.-R. Ardestani,
Volume 4, Issue 1 (1-2008)
Abstract
A low complexity dynamic subcarrier and power allocation methodology for
downlink communication in an OFDM-based multiuser environment is developed. The
problem of maximizing overall capacity with constraints on total power consumption, bit
error rate and data rate proportionality among users requiring different QOS specifications
is formulated. Assuming perfect knowledge of the instantaneous channel gains for all users,
a new simple algorithm is developed to solve the mentioned problem. We compare the sum
capacity, proportionality, and computational complexity of the proposed algorithm with the
one presented by Wong et al. Numerical results demonstrate that the proposed algorithm
offers a performance comparable with Wong’s algorithm, yet complexity remains low and
proportionality constraint will be tightly satisfied. As well, the proposed algorithm can
provide a flexible trade-off between complexity, capacity and proportionality constraint.
M. Ghayeni, R. Ghazi,
Volume 6, Issue 2 (6-2010)
Abstract
This paper presents a method to allocate the transmission network costs to users
based on nodal pricing approach by regulating the nodal prices from the marginal point to
the new point. Transmission nodal pricing based on marginal prices is not able to produce
enough revenue to recover the total transmission network costs. However, according to the
previous studies in this context, this method recovers only a portion of transmission costs.
To solve this problem, in this paper a method is presented in which by considering the
direction and amount of injected power in each node the marginal price is regulated to the
new price, in such a way as the nodal pricing can recover the total transmission network
costs. Also the proposed method is able to control the cost splitting between loads and
generators in accordance with the pre-specified ratio. The proposed method is implemented
on both IEEE 24-bus and 118-bus test systems and the obtained results are reported.
M. Ghayeni, R. Ghazi,
Volume 6, Issue 4 (12-2010)
Abstract
This paper proposes an algorithm for transmission cost allocation (TCA) in a large power system based on nodal pricing approach using the multi-area scheme. The nodal pricing approach is introduced to allocate the transmission costs by the control of nodal prices in a single area network. As the number of equations is dependent on the number of buses and generators, this method will be very time consuming for large power systems. To solve this problem, the present paper proposes a new algorithm based on multi-area approach for regulating the nodal prices, so that the simulation time is greatly reduced and therefore the TCA problem with nodal pricing approach will be applicable for large power systems. In addition, in this method the transmission costs are allocated to users more equitable. Since the higher transmission costs in an area having a higher reliability are paid only by users of that area in contrast with the single area method, in which these costs are allocated to all users regardless of their locations. The proposed method is implemented on the IEEE 118 bus test system which comprises three areas. Results show that with application of multi-area approach, the simulation time is greatly reduced and the transmission costs are also allocated to users with less variation in new nodal prices with respect to the single area approach.
M. R. Baghayipour, A. Akbari Foroud,
Volume 8, Issue 1 (3-2012)
Abstract
This paper presents a method to improve the accuracy of DC Optimal Power Flow problem, based on evaluating some nodal shares of transmission losses, and illustrates its efficiency through comparing with the conventional DCOPF solution, as well as the full AC one. This method provides three main advantages, confirming its efficiency:
1- It results in such generation levels, line flows, and nodal voltage angles that are more accurate than the conventional DCOPF solution.
2- Like the previous DCOPF problem, the new method is derived from a non-iterative DC power flow algorithm, and thus its solution requires no long run time.
3- Its formulation is simple and easy to understand. Moreover, it can simply be realized in the form of Lagrange representation, makes it possible to be considered as some constraints in the body of any bi-level optimization problem, with its internal level including the OPF problem satisfaction.
S. Najafi Ravadanegh,
Volume 10, Issue 1 (3-2014)
Abstract
Optimal distribution substation placement is one of the major components of optimal distribution system planning projects. In this paper optimal substation placement problem is solved using Imperialist Competitive Algorithm (ICA) as a new developed heuristic optimization algorithm. This procedure gives the optimal size, site and installation time of medium voltage substation, using their related costs subject to operating and optimization constraints. A multistage and pseudo-dynamic expansion planning is applied to consider dynamic of the system parameters for example, load forecasting uncertainty, asset management and geographical constraints. In order to evaluate the effectiveness of the proposed method a sensitivity analysis of ICA parameters on obtained results is done. A graphical representation of obtained results is used to show the efficiency and capability of the proposed method both from the planning view and graphical aspects. The results show the efficiency and capability of the proposed method which has been tested on a real size distribution network.
A. R. Soofiabadi, Dr. A. Akbari Foroud,
Volume 11, Issue 2 (6-2015)
Abstract
This paper develops a method for nodal pricing and market clearing mechanism considering reliability of the system. The effects of components reliability on electricity price, market participants’ profit and system social welfare is considered. This paper considers reliability both for evaluation of market participant’s optimality as well as for fair pricing and market clearing mechanism. To achieve fair pricing, nodal price has been obtained through a two stage optimization problem and to achieve fair market clearing mechanism, comprehensive criteria has been introduced for optimality evaluation of market participant. Social welfare of the system and system efficiency are increased under proposed modified nodal pricing method.
N. Okati, M. R. Mosavi, H. Behroozi,
Volume 13, Issue 4 (12-2017)
Abstract
Node cooperation can protect wireless networks from eavesdropping by using the physical characteristics of wireless channels rather than cryptographic methods. Allocating the proper amount of power to cooperative nodes is a challenging task. In this paper, we use three cooperative nodes, one as relay to increase throughput at the destination and two friendly jammers to degrade eavesdropper’s link. For this scenario, the secrecy rate function is a non-linear non-convex problem. So, in this case, exact optimization methods can only achieve suboptimal solution. In this paper, we applied different meta-heuristic optimization techniques, like Genetic Algorithm (GA), Partial Swarm Optimization (PSO), Bee Algorithm (BA), Tabu Search (TS), Simulated Annealing (SA) and Teaching-Learning-Based Optimization (TLBO). They are compared with each other to obtain solution for power allocation in a wiretap wireless network. Although all these techniques find suboptimal solutions, but they appear superlative to exact optimization methods. Finally, we define a Figure of Merit (FOM) as a rule of thumb to determine the best meta-heuristic algorithm. This FOM considers quality of solution, number of required iterations to converge, and CPU time.
M. Ghayeni,
Volume 15, Issue 4 (12-2019)
Abstract
In this paper, the new approach for the transmission reliability cost allocation (TRCA) problem is proposed. In the conventional TRCA problem, for calculating the contribution of each user (generators & loads or contracts) in the reliability margin of each transmission line, the outage analysis is performed for all system contingencies. It is obvious that this analysis is very time-consuming for large power systems. This paper suggests that this calculation should be done only for major contingencies. To do this, at first, the contingency filtering technique (CFT) is introduced based on the new economic indices that quantify the severity of each contingency to determine the critical contingencies. Then the results of contingency filtering are used in the TRCA problem. The simulation results are reported for the IEEE 118-bus test system. The obtained results show that by application of CFT in TRCA problem, the simulation time is greatly reduced, but the percentage of error remains within an acceptable limit.
M. Hosseinpour, J. Sadeh,
Volume 16, Issue 3 (9-2020)
Abstract
Increasing the short circuit current due to the penetration of distributed generations (DGs) in various voltage levels and meshed topology is a basic problem in power systems. Using fault current limiter (FCL) is an efficient approach to mitigate the exceeded short circuit levels. In this paper, a new approach is presented for multiple FCLs locating to decrease short circuit levels in meshed networks with several subsystems and multi-level voltages. Modified hybrid genetic algorithm (GA) and sensitivity analysis (SA) are used to determine the type, number, location, and voltage level of FCLs. Also, an effective sensitivity index is proposed, which can reduce the search space for optimal allocation. This method suggests the optimal allocation with the least investment cost in multi-level voltages networks according to the FCL costs. The proposed method is evaluated in the IEEE 30-bus, 57-bus, and 300-bus test systems. Numerical results indicate the accuracy and efficiency of the proposed method.
T. Agheb, I. Ahmadi, A. Zakariazadeh,
Volume 17, Issue 3 (9-2021)
Abstract
Optimal placement and sizing of distributed renewable energy resources (DER) in distribution networks can remarkably influence voltage profile improvement, amending of congestions, increasing the reliability and emission reduction. However, there is a challenge with renewable resources due to the intermittent nature of their output power. This paper presents a new viewpoint at the uncertainties associated with output powers of wind turbines and load demands by considering the correlation between them. In the proposed method, considering the simultaneous occurrence of real load demands and wind generation data, they are clustered by use of the k-means method. At first, the wind generation data are clustered in some levels, and then the associated load data of each generation level are clustered in several levels. The number of load levels in each generation level may differ from each other. By doing so the unrealistic generation-load scenarios are omitted from the process of wind turbine sizing and placement. Then, the optimum sizing and placement of distributed generation units aiming at loss reduction are carried out using the obtained generation-load scenarios. Integer-based Particle Swarm Optimization (IPSO) is used to solve the problem. The simulation result, which is carried out using MATLAB 2016 software, shows that the proposed approach causes to reduce annual energy losses more than the one in other methods. Moreover, the computational burden of the problem is decreased due to ignore some unrealistic scenarios of wind and load combinations.
