Bus RTS Research Articles

Multi-objective optimization of reactive power dispatch problem using fuzzy tuned mayfly algorithm

The recent multi-objective optimization problems are very complex which require an effective and robust evolutionary method for obtaining a global Pareto-optimal solutions. Most of these multi-objective evolutionary techniques are population-based methods which usually work on random search approaches and often trapped into local minima during their execution. A new fuzzy tuned mayfly algorithm (FTMA) is presented in this paper, to obtain the Pareto-optimal solutions for any complex multi-objective power system problem. It has a self-adapting global exploration capability to get the best Pareto-optimal solutions by varying two crucial parameters i.e., crossover (Pc) and mutation Pm probabilities. Moreover, a model of Pareto-dominance is employed to rank non-dominating solutions to maintain the diversity within the populations. The proposed evolutionary approach is examined on a standard ZDT benchmark test suite and its algorithmic performance is statistically compared with a few of the recent optimization techniques such as NSGA-II, NSGA-III, MMODE, MOAVOA and MMA algorithm. It is further applied to minimize two distinct objective functions (i.e., total transmission loss and voltage stability index) for IEEE-118 bus system and IEEE-24 bus RTS. A comprehensive statistical analysis is presented for the obtained numerical results, which proves that proposed FTMA has better convergence with better solution diversity in comparison to the other competing algorithms. A comprehensive analysis based on statistical results reveal that the proposed FTMA is superior for obtaining better non-dominating pareto-fronts as compared to other competing methods.

Ecological Robustness-Oriented Grid Network Design for Resilience Against Multiple Hazards

Power systems are critical infrastructure for reliable and secure electric energy delivery. Incidents are increasing, as unexpected multiple hazards ranging from natural disasters to cyberattacks threaten the security and functionality of society. Inspired by resilient ecosystems, this paper presents a resilient network design approach with an ecological robustness (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ECO</sub> )-oriented optimization to improve power systems' ability to maintain a secure operating state throughout unknown hazards. The approach uses R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ECO</sub> , a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">surprisal</i> -based metric that captures key features of an ecosystem's resilient structure, as an objective to strategically design the electrical network. The approach enables solvability and practicality by introducing a stochastic-based candidate branch creation algorithm and a Taylor series expansion for relaxation of the R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ECO</sub> formulation. Finally, studies are conducted on the R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ECO</sub> -oriented approach using the IEEE 24 Bus RTS and the ACTIVSg200 systems. Results demonstrate improvement of the system's reliability under multiple hazards, network properties of robust structure and equally distributed power flows, and survivability against cascading failures. From the analysis, we observe that a more redundant network structure with equally distributed power flows benefits its resilience.

Wind-Hydro Combined Bidding Approach for Congestion Management Under Secured Bilateral Transactions in Hybrid Power System

After restructuring of power system, independent system operator is facing a big challenge to manage operations on transmission networks due to growing renewables share and involvement of large market players in power system operation. Among all renewables, wind power has the most stochastic nature and faces penalties due to mismatch in its initial power committed and final power delivered. Also, wind power plants are generally located at remote areas and need longer transmission lines for power delivery. This leads to congestion of transmission lines and poses a threat to security and safety of power system. To manage congestion on transmission lines, this paper proposes a novel rescheduling based combined bidding approach for wind integrated hybrid (pool + bilateral) power system. Congestion management problem has been formulated as mixed integer non-linear programming problem incorporating proposed combined bidding approach with an objective to reduce total congestion management cost through rescheduling of wind and hydro units on the basis of their combined up and down generation cost bids. The hydro units that have lowest operating cost and fast turn-on time have been used in coordination with wind units to alleviate congestion cost. Secured bilateral transactions have been confirmed while implementing the combined bidding approach for congestion management. Performance of proposed strategy has been analyzed by demonstrating it on modified IEEE-24 bus RTS system.

Effect of SVC installation on loss and voltage in power system congestion management

&lt;span&gt;In this paper, a new hybrid optimization technique is proposed namely Adaptive Embedded Clonal Evolutionary Programming (AECEP). This idea comes from the combination part of the clone in an Artificial Immune System (AIS) and then combined with Evolutionary Programming (EP). This technique was implemented to determine the optimal sizing of Flexible AC Transmission Systems (FACTS) devices. This study focused on the ability of Static Var Compensator (SVC) is used for the optimal operation of the power system as well as in reducing congestion in power system. In order to determine the location of SVC, the previous study has been done using pre-developed voltage stability index, Fast Voltage Stability Index (FVSI). Congested lines or buses will be identified based on the highest FVSI value for the purpose of SVC placement. The optimizations were conducted for the SVC sizing under single contingency, where SVC was modeled in steady state analysis. The objective function of this study is to minimize the power loss and improve the voltage profile along with the reduction of congestion with the SVC installation in the system. Validation on the IEEE 30 Bus RTS and IEEE 118 Bus RTS revealed that the proposed technique managed to reduce congestion in power system.&lt;/span&gt;

Loss Minimization in Optimal Reactive Power Planning (ORPP) Based on Whale Optimization Algorithm

The key of RPP is the optimal allocation of reactive power considering location and size. This paper presents the loss minimization in optimal reactive power planning (ORPP) based on Whale Optimization Algorithm (WOA). The objective is to minimize transmission loss by considering several load conditions at bus 3, bus 15 and bus 21. Reactive Power Scheduling (RPS) and Transformer Tap Changer Setting (TTCS) were set as the control variables. Validation was conducted on the IEEE 30 Bus RTS. Results from the study indicate that the proposed WOA can minimize transmission loss better than Evolutionary Programming (EP).

IMLANNs for Congestion Management in Power System

In this paper, Integrated Multi-Layer Artificial Neural Networks (IMLANNs) model has been developed for congested line prediction in a power system. The master characteristic of an ANN is the superiority to achieve complicated input-output mappings through a learning procedure, without exhaustive programming efforts. The IMLANNs model was developed to predict the congested lines in a power system. Before the IMLANNs model is developed, a case study was selected to receive an early result in power system load current during normal condition and contingency based on heavily loaded term. In order to optimize the architecture of the neural network and minimize the computational effort, but those state variables with major impact on the power system are selected as inputs. A pre-developed index, namely Fast Voltage Stability Index (FVSI) is employed as a benchmark to identify the locations declared as congested lines. This indicator was produced which aims for an analytic thinking, sustainable power system when an excessive load was imposed on the power system network. In addition, voltage collapse can be identified when the index is approaching 1.000 or unity. The value of FVSI is chosen as the targeted output in the IMLANNs model. The strength of the proposed IMLANNs model has been validated on the IEEE 30- Bus RTS. Results obtained from the study demonstrated that the proposed IMLANNs is feasible for congested line prediction, which in turns beneficial to power system operators in the planning unit of a utility.

Chaotic Local Search Based Algorithm for Optimal DGPV Allocation

The advent of advanced technology has led to the increase of electricity demand in most countries in the world. This phenomenon has made the power system network operate close to the stability limit. Therefore, the power utilities are looking forward to the solution to increase the loadability of the existing infrastructure. Integration of renewable energy into the grid such as Distributed Generation Photovoltaic (DGPV) can be one of the possible solutions. In this paper, Chaotic Mutation Immune Evolutionary Programming (CMIEP) algorithm is used as the optimization method while the chaotic mapping was employed in the local search for optimal location and sizing of DGPV. The chaotic local search has the capability of finding the best solution by increasing the possibility of exploring the global minima. The proposed technique was applied to the IEEE 30 Bus RTS with variation of load. The simulation results are compared with Evolutionary Programming (EP) and it is found that CMIEP performed better in most of the cases.

ATC Determination with Heuristic techniques and Comparison with Sensitivity based Methods and GAMS

Transmission system works like express highways to evacuate the power generation in remote areas to the load centres. The assessment of the capability of the network to carry power is essential not only from the security point of view but also from commercial use reserving transactions in a competitive electricity market. The main contribution of the paper is i) An evaluation of ATC with heuristic techniques viz. Genetic Algorithm, Particle Swarm Optimization, and Firefly Algorithm, ii) The comparison with Generalized Algebraic Modeling System software (GAMS), iii) Comparison of the results obtained with sensitivity based methods Viz. AC/DC PTDFs based approach. The results have been determined for intact and line contingency cases taking simultaneous as well as single transaction cases. The results have been obtained for IEEE 24 bus RTS.

Composite power system reliability evaluation using modified minimal cut set approach

The composite power system reliability analysis is generally based on minimal path or cut enumeration, tracing of power flow paths from which the related reliability indices are calculated. The minimal cut set is a popular method in the reliability analysis for simple and complex configurations. Average availability of power supply at the consumer end is one of the reliability assessment parameter. This paper is concerned about the evaluation of this reliability index. A step by step procedure for a modified minimal cut set method is explained in this paper using IEEE 6 bus, 14 bus and Single area IEEE RTS 96 system. The proposed algorithm is easy to program and can be applicable to any system. The proposed algorithm is validated with the Classical Node Elimination method, Step by Step algorithm using Conditional Probability and Monte Carlo Simulation method. The proposed technique is tested with a practical example taken from Roy Billinton paper (Reliability evaluation in distribution and transmission systems).

Evaluating and comparing profitability of bulk storage systems in unit commitment and optimal power flow operation frameworks

An energy storage system (ESS) is a promising tool for improving the power system's technical and economical functionalities. This device possesses diverse applications in terms of system operation and planning. One of the main applications of the ESS in the power system operation, specially a large scale unit, is defined as load leveling. To this end, in the literature, various ESS models are integrated into two main power system operation frameworks, i.e., optimal power flow (OPF) and unit commitment (UC). But the question is that in which framework the obtained benefit from the load leveling by ESS is maximum and why. In other words, should ESS units schedule before generating unit commitment (UC) or after OPF and how. In this context, this paper performs three works. First, it proposes OPF and UC frameworks integrated with large scale ESS units. Second, the proposed models are implemented with identical parameters. Third, the obtained results are considered with respect to various outcomes, especially operation cost. This study is implemented on an IEEE 24 bus RTS system. The simulation results are analyzed and compared with respect to various parameters, and relevant conclusions are drawn based on the results.

ATC enhancement in electricity markets with GUPFC and IPFC – A comparison

Available transfer capability (ATC) needs to be declared well in advance by the system operator to reserve transactions and avoid any congestion in the network. In this paper, an optimal power flow based approach has been utilized for bilateral/multi-transactions deregulated environment to obtain the ATC. The ATC has been obtained with generalized unified power flow controller (GUPFC) and interline power flow controller (IPFC) for intact and line contingency cases. The impact of ZIP load model has been evaluated on the ATC with both the devices. The main contribution of the paper is the comparison of the ATC obtained with. GUPFC and IPFC for intact and contingency cases with constant P,Q load model and ZIP load model. The results have been determined for intact and line contingency cases taking simultaneous as well as single transaction cases. The results obtained are also compared with DC/AC and PTDFs. The proposed method have been applied for IEEE 24 bus RTS.

Design of joint active and reactive power reserve market: a multi‐objective approach using NSGA II

A joint active and reactive power reserve market is presented in this study. Reactive and active powers are closely related through some issues such as load flow equations, network line current limitations and synchronous generator capability curve. The proposed solution deals with simultaneously determining of optimal capacities of active and reactive power reserve after administration and settlement of active and reactive power markets separately. Three following objectives would be met in the proposed joint market while satisfying constraints of network and producing units in all contingencies: i Minimising cost of required simultaneous active and reactive power at each contingency. ii Minimising unsupplied energy due to lack of active power at each contingency. iii Minimising unsupplied energy due to insufficiency of reactive power. IEEE 24 bus RTS system is used for evaluation of the proposed market and results have been compared with those from traditional separate active power reserve markets.

Congestion Management Solution for Hybrid System Considering Voltage Stability Margin

In deregulated structure, power system network has become more complex with free trades amongst GENCOs and DISCOs and with increasing penetration of Renewable Energy Sources. These complexities might impose risk on security and stability of the network especially during congestion hours. This paper presents an economical and secure congestion management approach, in hybrid power system; by considering linear piece-wise hydro model and probabilistic wind generation model. Impact of wind participation in congestion management and bidding's effect on congestion cost has been analyzed. Minimization of congestion cost has been formed as major objective and problem has been formulated as Mixed Integer Non Linear Programming (MINLP) problem which has been tested on modified IEEE-24 bus RTS system. Locational dependence of congestion cost and a comparison of VSM based approach with conventional congestion management approach have also been presented.

Fast Voltage Stability Index (FVSI) Based Technique for Congestion Management Assessment

This paper presents a voltage stability assessment based approach to determine the congested line with optimal sizing and location. FVSI, a voltage stability index is chosen as the indicator for congested line identification, while particle swarm optimization technique (PSO) is used for optimal location and sizing of FACTs devices installation. Congested line is identified by increasing the reactive load at chosen load buses until they reach the maximum loadability level. PSO is applied for identifying the optimal location and sizing of FACTs devices as the compensating device. Results obtained from the implementation on IEEE 30 Bus RTS revealed that the proposed technique can manage the congestion subject to various disturbances.

ATC with ZIP load model – A comprehensive evaluation with third generation FACTS in restructured electricity markets

In this paper, an optimal power flow based approach has been applied for multi-transactions in deregulated environment for ATC determination with third generation FACTS devices. The main contribution of the paper is (i) OPF based approach for evaluation of ATC with multi-transactions, (ii) ATC enhancement with third generation FACTS devices viz. Static Compensator (STATCOM), Static Synchronous Series Compensator (SSSC), and Unified Power Flow Controller (UPFC) for intact and line contingency cases (iii) Impact of ZIP load on ATC determination and comparison of ATC obtained with ZIP load model and constant P,Q load model, (iv) Comparison of ATC obtained with DC/AC-PTDFs based method along with FACTS devices for comparison. The results have been determined for intact and line contingency cases taking simultaneous as well as single transaction cases for IEEE 24 bus RTS.

A stochastic framework for reactive power procurement market, based on nodal price model

A new modified nodal pricing method is presented in this paper to calculate reactive power price. This article tries to solve the problems of traditional nodal pricing methods to be able to consider opportunity and availability costs for the generators. A modified model of generators reactive power production cost has been used in OPF objective function considering normal and contingency conditions. Availability cost would be estimated considering the volume of network demand from the generators in contingency states through probability calculations. This cost would be paid to all the units that possibly will needed to produce reactive power in contingency states. Purvey of required availability of generation units to deal with emergency conditions, encouraging providers to invest in critical areas in the network and fair distribution of reactive power production costs over several producers are some advantages of the proposed method. The proposed method is tested on IEEE 24 bus RTS and is compared with the uniform pricing method.

ATC determination with FACTS devices using PTDFs approach for multi-transactions in competitive electricity markets

Available transfer capability (ATC) is an important indicator for accommodating further transactions over and above already existing commitments. With flexible AC transmission system (FACTS) deployment in a system for better utilization, the ATC information quantification is essential. ATC enhancement with these devices can play an important role in an efficient and secure operation of competitive markets. The main objective of the paper is: (i) power transfer distribution factors determination with FACTS devices, (ii) ATC determination for bilateral/multi-lateral transactions based on PTDFs with FACTS devices, (iii) optimal location of FACTS devices based on power flow sensitivity corresponding to transactions, and (iv) comparison of ATC obtained with DC PTDF based approach. The results have been determined for intact and line contingency cases without and with FACTS devices. The proposed method have been tested on IEEE 24 bus RTS.

ATC Enhancement with SVC and TCSC Using PTDF Based Approach in Deregulated Electricity Markets

In this paper, power transfer distribution factor based on AC load flow has been proposed for multi-transaction environment in the presence of FACTS devices viz. SVC and TCSC. The method can be implemented for any number of transactions occurring simultaneously between sellers and buyer buses with FACTS devices. The results have been determined for intact and line contingency cases. The results have also been obtained with DC method for comparison under intact and contingency cases. The proposed method have been applied for IEEE 24 bus RTS.

Comparison of UPFC and SEN Transformer for ATC enhancement in restructured electricity markets

Available transfer capability (ATC) is an important indicator of remaining transfer capability in the transmission network for its commercial use in a competitive electricity market. In this paper, an optimal power flow based approach has been proposed for multi-transactions deregulated environment. The ATC has been obtained with unified power flow controller (UPFC) and Sen Transformer (ST) for intact and line contingency cases. The impact of ZIP load model has been evaluated on ATC with both devices. The main contribution of the paper is the comparison of ATC obtained with UPFC and Sen Transformer for intact and contingency cases with constant P,Q load model and also taking impact of ZIP load model. The results have been determined for intact and line contingency cases taking simultaneous as well as single transaction cases. The results have also been obtained with DC/AC PTDFs method for comparison. The proposed method have been applied for IEEE 24 bus RTS.

ACPTDF for Multi-transactions and ATC Determination in Deregulated Markets

Abstract—Available transfer capability in the transmission network has become essential quantity to be declared well in advance for its commercial use in a competitive electricity market. Its fast computation using DC load flow based approach is used worldwide for on line implementation. Many authors have proposed the ATC calculation based on DC/AC load flow approach. In this paper, AC PTDF based approach has been proposed for multi-transaction cases using power transfer sensitivity and Jacobian calculated with three different methods. The methods can be implemented for any number of transactions occurring simultaneously. The results have been determined for intact and line contingency cases taking multi-transaction/simultaneous as well as single transaction cases. The main contributions of the paper are: (i) ATC determination for multi-transactions environment, (ii) ATC determination and comparison with three approaches of PTDF calculations, (iii) LODFs with line contingency cases for multi-transaction environment and thereby ATC determination. The results have also been obtained with DC method for comparison. The proposed method have been applied for IEEE 24 bus RTS. Keywords: Available transfer capability, AC load flow, AC power transfer distribution factors , line outage contingency, line outage distribution factors, multi-transactions, simultaneous transactions. DOI: http://dx.doi.org/10.11591/ijece.v1i1.61 Full Text: PDF