Unified Power Flow Controller In Power System Research Articles

LQR and LQG based optimal switching techniques for PSS and UPFC in power systems

Selection of better optimized unified power flow controller (UPFC) control inputs along with simultaneous coordinated design of power system stabilizer (PSS) is a challenge in the present scenario of power systems. Hence, in this paper, four sets of experiments performed are presented. First set of experiments are without disturbance scenario where switching is done using linear quadratic regulators (LQR’s). Second set is for power systems with disturbances using linear quadratic gaussian (LQG). Switching control algorithms presented here are tested on the single machine infinite bus (SMIB) linearised Phillips Heffron model of power system using MATLAB/SIMULINK® platform.

Load Curtailment Sensitivity Indices Through Optimal Placement of Unified Power Flow Controller

The optimal power flow (OPF) is one of the key tasks to be performed in the complicated operation and planning of a power system. Directing the power in such a way that the lightly loaded branches are loaded to reduce the system load curtailment is an option which can be achieved by making use of FACTS devices. This paper proposes a set of load curtailment sensitivity indices for optimal placement of Unified Power Flow Controller (UPFC) in power system network. An OPF formulation considering the minimization of load curtailment requirement as an objective has been developed in this paper to study the impact of optimal placement of UPFC. The effectiveness of the proposed method has been tested on IEEE-14 bus test system. The obtained results have been presented in terms of change in system load curtailment with respect to changes in UPFC controller parameters for the best location. The optimal location of UPFC in a line has been decided based on the calculated sensitivity indices. Conclusion is made on different results to see the benefit of UPFC in power system.

Efficient and optimal approach for location and parameter setting of multiple unified power flow controllers for a deregulated power sector

This study presents an efficient approach to optimal allocation of unified power flow controller (UPFC) in a pool and bilateral power market. The optimisation technique has been used with an objective to maximising social welfare (SW) by suitable location, number and rating of the UPFC in power system working under a deregulated environment. The proposed method accurately evaluates SW by determining locational marginal pricing based on the marginal cost theory. The impact of the UPFC on system real power losses has also been investigated. The effectiveness of the proposed optimal technique has been tested on the 39-bus New England system with addition of four bilateral transactions.

Application of Multi Objective Technique to Incorporate UPFC in Optimal Power Flow using Modified Bacterial Foraging Technique

A modified bacterial foraging technique is applied to solve the multi-objective optimal power flow problem with unified power flow controller (UPFC). The introduction of UPFC in power system improves the stability and it is one of the crucial factors for effective modern power systems. Effective means for controlling and improving power flow is done by installing fast reacting devices such as a Unified Power Flow Controller (UPFC).The application of modified bacterial foraging technique is applied to find optimal location of unified power flow controller to achieve solution of optimal power flow and this problem is formulated by multi-objective optimization using bacterial foraging technique. The optimal power flow problem is used to minimize the overall cost functions, which include the total active and reactive production cost function of the generators and installation cost of UPFCs and also the OPF constraints are generators, transmission lines and UPFCs limits are included. Modified Bacterial foraging algorithm and multi-objective optimization technique is applied to the problem with use of controllable UPFC devices is proposed. The specified power flow control constraints due to the use of UPFC devices are included in the OPF problem in addition to these normal conventional constraints. The sensitivity analysis is carried out for the location of UPFC devices. This provides an enhanced economic solution with the use of controllable of UPFC devices. Simulations are performed modified IEEE 4 bus and IEEE 30 bus system for optimal location of UPFC and the results obtained are encouraging and will be useful in electrical restructuring.

Optimal placement of UPFC in power systems using immune algorithm

This paper presents the application of immune algorithm (IA) to find optimal location of unified power flow controller (UPFC) to achieve optimal power flow (OPF) and congestion management. Objective function in the OPF, that is to be minimized, is the overall cost functions, which includes the total active and reactive production cost function of the generators and installation cost of UPFCs. The OPF constraints are generators, transmission lines and UPFCs limits. In power system, it may not always be possible to dispatch all of the contracted power transactions due to congestion of the transmission corridors. We propose IA method to minimize the objective function under all equality and inequality constraints. Simulations are performed on 4-bus, IEEE 14-bus and IEEE 30-bus test systems for optimal location of UPFC and the results obtained are encouraging and will be useful in electrical restructuring.

Application of the normal forms to analyze the interactions among the multi-control channels of UPFC

One of the most important features of the unified power flow controller (UPFC) is its multiple control functions, which are implemented by multiple controllers. However, recent simulation studies have demonstrated the existence of the dynamic interactions among different controller channels of UPFC, i.e. power flow controller, AC voltage controller and DC voltage controller. This paper is concerned with the application of the normal forms to analyze the interactions among the multi-controller channels of UPFC in power systems. Moreover, a non-linear interaction index is developed to investigate the interactions among these UPFC controllers. The employed approach has been applied to two test systems: a single machine infinite bus power system (SMIB) and the New England test power system (NETPS). The simulation results validate the proposed approach.