• Journal of Electrical Engineering and Technology
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• 제4권4호
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• pp.492-498
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• 2009

The placement of the UPFC is the major concern to ensure the full potential of utilization in the transmission network. Voltage stability enhancement with the optimal placement of UPFC using stability index such as modal analysis, Voltage Phasor method is made and the loss minimization including UPFC is formulated as an optimization problem. This paper proposes particle swarm optimization for the exact real power loss minimization including UPFC. The implementation of loss minimization for the optimal location of UPFC was tested with IEEE-14 and IEEE-57 bus system.

• Advances in Energy Research
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• 제4권4호
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• pp.255-274
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• 2016

This paper presents a novel symbiotic organisms search (SOS) algorithm to optimize both real power loss (RPL) and voltage stability limit (VSL) of a transmission network by controlling the variables such as unified power flow controller (UPFC) location, UPFC series injected voltage magnitude and phase angle and transformer taps simultaneously. Mathematically, this issue can be formulated as nonlinear equality and inequality constrained multi objective, multi variable optimization problem with a fitness function integrating both RPL and VSL. The symbiotic organisms search (SOS) algorithm is a nature inspired optimization method based on the biological interactions between the organisms in ecosystem. The advantage of SOS algorithm is that it requires a few control parameters compared to other meta-heuristic algorithms. The proposed SOS algorithm is applied for solving optimum control variables for both single objective and multi-objective optimization problems and tested on New England 39 bus test system. In the single objective optimization problem only RPL minimization is considered. The simulation results of the proposed algorithm have been compared with the results of the algorithms like interior point successive linear programming (IPSLP) and bacteria foraging algorithm (BFA) reported in the literature. The comparison results confirm the efficacy and superiority of the proposed method in optimizing both single and multi objective problems.

• KIEE International Transactions on Power Engineering
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• 제4A권2호
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• pp.58-68
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• 2004

This paper presents an optimal routing algorithm (ORA) for maximizing voltage stability as well as for minimizing power loss in radial power systems. In the proposed ORA, a novel voltage stability index (VSI) for real-time assessment is newly introduced based on the conventional critical transmission path framework. In addition, the suggested algorithm can automatically detect the critical transmission paths resulting in voltage collapse when additional real or reactive loads are added. To implement an effective ORA, we have developed an improved branch exchange (IBE) method based on a loss calculation index and tie-branch power flow equations, which are suggested for real-time applications. The proposed algorithm has been tested with IEEE test systems as well as a large-scale power system in Korea to demonstrate its effectiveness and efficiency.

• 대한전기학회논문지:전력기술부문A
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• 제53권5호
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• pp.266-274
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• 2004

This paper presents a scheme for the interconnection of dispersed generator systems(DGs) based on load .unbalance and load model in composite distribution systems. Groups of each individual load model consist of residential, industrial, commercial, official and agricultural load. The unbalance is involved with many single-phase line segment. . Voltage profile improvement and system loss minimization by installation of DGs depend greatly on how they are placed and operated in the distribution systems. So, DGs can reduce distribution real power losses and replace large-scale generators if they are placed appropriately in the distribution systems. The main idea of solving fuzzy goal programming is to transform the original objective function and constraints into the equivalent multi-objectives functions with fuzzy sets to evaluate their imprecise nature for the criterion of power loss minimization, the number or total capacity of DGs and the bus voltage deviation, and then solve the problem using genetic algorithm. The method proposed is applied to IEEE 13 bus and 34 bus test systems to demonstrate its effectiveness.

• 전기학회논문지
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• 제61권6호
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• pp.797-803
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• 2012

In this paper, for minimizing the real-time operating load losses of the power transformer, a SCADA optimum operating system was developed, and the economic analyses on the test operation were performed. Transformer loss DB which reflects the economic integration operation criteria was constructed by referring the transformer manufacturer's loss data(iron loss, copper loss). Based on the loss DB, each substation transformer real-time loss was calculated according to the size of the transformer loads, and if integration or separation transformer operating conditions minimizing the loss are met, then a window pops-up and the dispatcher performs the substation equipments operation according to the procedure provided by this system. With the existing SCADA main program, the relation database of the substation facilities and integration/separation operation algorithm were developed and applied to Auto MTR Processor and pconn Processor Task module. Seven stations test data for seven months were analyzed for the economic analyses, and the results showed that Cost-Benefit ratio was 2.64, and IRR(Internal Rate of Return), 36%, which asserted the economic justification of the proposed system.

• 전기학회논문지
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• 제58권11호
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• pp.2079-2088
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• 2009

The optimal operation in distribution system is to select tie switches considering important elements(Load balance, Loss minimization, Voltage drop, Restoration index..) in distribution system. Optimal Tie Switches Selection is very important in operation of distribution system because that is closely related with efficiency and reliability. In this paper, a new algorithm considering important elements is proposed to find optimal location of tie switches. In the case study, the proposed algorithm has been testified using real distribution network of KEPCO for verifying algorithm and complex network for applying future distribution network.

• ETRI Journal
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• 제6권4호
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• pp.31-36
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• 1984

This paper presents an efficient method for real power loss minimization and for improvements in voltage profiles. This method is accomplished by optimal control of reactive power in the system. The problem is formulated as an optimization problem, suitable for solution by linear programming technique. After establishing the objective function for minimizing the system losses with the help of linearised sensitivity relationships of control variables, i. e., the transformer tap position, generator terminal voltages and switchable reactive power sources. The linear programming technique is used to determine the optimal adjustments to the above variables, simultaneously satisfying the constraints. The proposed algorithm has been tested on a sample system and the result is presented and discussed.

• 전기학회논문지
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• 제57권10호
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• pp.1681-1687
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• 2008

This paper shows application of optimal reconfiguration algorithm for distributing power system to KEPCO system for loss minimization and load balancing. That is, it suggests additional algorithm to check potential problems caused in case of theoretical algorithm being applied to real system and recover from them. Also, comparing the results of reconfiguration algorithm Tabu-Search Algorithm applied to current KEPCO distribution power system and those of Branch Exchange Algorithm using initial operation point suggested in this paper, it shows how much the results are improved in aspects of load balancing, loss reduction and calculating time.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.125-127
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• 2008

This paper shows application of optimal reconfiguration algorithm for distributing power system to KEPCO(Korea Electric Power Corporation) system for loss minimization and load balancing. That is, it suggests additional algorithm to check potential problems caused in case of theoretical algorithm being applied to real system and recover from them. Also, comparing the results of reconfiguration algorithm Tabu-Search Algorithm applied to current KEPCO distribution power system and those of Branch Exchange Algorithm using initial operation point suggested in this paper, it shows how much the results are improved in aspects of load balancing, loss reduction and calculating time.

• 전기학회논문지
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• 제58권4호
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• pp.671-678
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• 2009

This paper presents target operation voltage guidelines of each voltage control area considering both voltage stability and economical efficiency in real power system. EMS(Energy Management System) data, Real-time simulator, shows not only voltage level but lots of information about real power system. Also this paper performs optimal power flow calculation of three objective functions to propose the best target operation voltage. objective function of interchange power flow maximum and active power loss minimization stand for economical efficiency index and reactive power reserve maximum objective unction represents stability index. Then through simulation result using optimazation technique, the most effective objective function is chosen. To sum up, this paper divides voltage control area into twelve considering electric distance characteristics and estimate or voltage level by the passage of time of EMS peak data. And through optimization technique target operation voltage of each voltage control area is estimated and compare heir result. Then it is proposed that the best scenario to keep up voltage stability and maximize economical efficiency in real power system.