Using Unified Power Flow Controller Research Articles

Optimized Power Flow Control to Minimize Congestion in a Modern Power System

The growing integration of renewable energy sources (RES) into the power system causes congestion to occur more frequently. In order to reduce congestion in the short term and to make the utilization of the power system more efficient in the long term, power flow control (PFC) in the transmission system has been proposed. However, exemplary studies show that congestion will increase also in the distribution system if the transmission system is expanded. For this reason, the potential of PFC to reduce congestion in a model of a real 110 kV distribution system is investigated. Several Unified Power Flow Controller (UPFC) devices are optimized in terms of their number and placement in the power system, their size, control parameters, and costs, by using a Parallel Tempering approach as well as a greedy algorithm. Two optimization variants are considered, one reducing the number of degrees of freedom by integrating system knowledge while the other does not. It is found that near a critical grid state and disregarding costs, PFC can reduce congestion significantly (99.13%). When costs of the UPFCs are taken into account, PFC can reduce congestion by 73.2%. A basic economic analysis of the costs reveals that the usage of UPFCs is profitable. Furthermore, it is found that the reduction in the solution space of the optimization problem leads to better results faster and that, contrary to expectations, the optimization problem is simple to solve. The developed methods allow not only for the determination of the optimal use of UPFCs to minimize congestion, but also to estimate their profitability.

A UPFC‐based robust damping controller for optimal use of renewable energy sources in modern renewable integrated power systems

This paper proposes coordinated design of wide-area damping controller (WADC) in the presence of renewable energy resources in a large-scale power system. To tackle with constant and time-varying delays in wide-area system, a robust criterion based on H∞ has been used for the coordinated WADC design. By using an auxiliary function in Lyapunov function, conservatism of linear inequality matrix (LMI) is reduced, such that larger delay margin and larger feasibility region is obtained in the presence of delays. The wind farms here are composed of doubly-fed induction generator (DFIG) and squirrel-cage induction generator (SCIG), which are connected to common bus of photovoltaic (PV) system by using unified power flow controller (UPFC). Then, the renewable energy units are integrated with 10 and 16-machine power systems. Afterwards, by identifying oscillating modes, the coordinated design of WADC is carried out for rotor-side-converter (RSC) in DFIG, DC/AC converter in the PV units, shunt converter (SHC) in UPFC, and power system stabilizer (PSS). Different scenarios of power system operating conditions are considered to evaluate performance of the proposed approach. The simulations in power system analysis toolbox (PSAT) and programming in MATLAB demonstrate effectiveness of the conducted method.

Improving the dynamic performance of grid connected wind farms using modern UPFC

Reliable power from Wind energy is one of the promising non-conventional energy sources for the future. But the fluctuating nature of wind introduces power quality problems affects the stability of the entire grid. Another issue is that power system grid is non-linear dynamic system which needs plenty of real and reactive power to provide its load and power loss is unreliable. Nowadays Flexible AC Transmission Systems (FACTS) controllers are handling a transmission line power surges which magnify the entire grid operation. This manuscript aims at reducing the power quality issues using Unified Power Flow Controller (UPFC) which is interconnected at the Point of Common Coupling (PCC) to improves the transmission ability of the system and enhance the dynamic response of ac grids. The distortions in the waveform are reduced by the proper switching of the semiconductor devices of the UPFC. The switching is controlled using a PI controller with current controlled Pulse Width Modulation (PWM). The gains of the PI controller are tuned using Modified Particle Swarm Optimization Technique (MPSO). The power quality is then analyzed with Total Harmonics Distortion (THD) and the performance is simulated in SIMULINK/MATLAB. These results are acquired by means of modified Particle Swarm Optimization (MPSO), to demonstrate the superiority of the proposed method, the simulation conceded out on grid connected wind power system with Proportional Integral Controller, Fuzzy Logic Controller, Artificial Bee Colony Algorithm and Modified Particle swarm Optimization.

Voltage Profile Improvement of a Disturbed Electric Power System using UPFC Compensation

The major objective of using flexible alternating current transmission systems (FACTS) devices in an interconnected electric power transmission network is to improve the parameters of the transmission line. This study presents the voltage profile improvement and power loss reduction of the Nigeria 330 kV transmission network using the unified power flow controller (UPFC) as an optimal FACTS device. The study utilized the power systems analysis toolbox (PSAT) 2.1.10 that is embedded in MATLAB 2017a to model the Nigeria 330 kV transmission network that consists of 9 generating stations, 31 buses and 42 transmission lines. The Newton Raphson load flow algorithm was used to carry out the load flow study using data obtained from the transmission company of Nigeria. Voltages less than 0.95pu (313.5kV) were assumed to be low voltage while those greater than 1.05pu (346.5kV) were assumed to be high voltage. A base case load flow study was carried out without the use of UPFC to determine weak buses. The outcome of the base case simulation without the use of the UPFC showed that seven buses were operating outside the lower operating limit. After compensation using the UPFC, the operating voltages at each of the buses were found to be within the stated limit. Findings from the study show that the weak buses occurred as a result of the long distances between the transmission lines and the generating stations. The transmission line losses were found to have been reduced from 71.66MW to 32.95MW and from 76.7MVAR to 41.89MVAR respectively.

EAF Arc Stability Through the Use of UPFCs

The use of a unified power flow controller (UPFC) to improve the power transfer in an EAF is investigated. The implemented equipment used techniques of hardware-in-the-loop to determine the required specific characteristics of the UPFC to improve the stability of the arc. The arc is mainly responsible for the conversion of electromagnetic power into thermal power and heat transfer. The stability studies of power networks help in improving the stability of the arc. These are the topics covered in this paper. This research also shows how it is possible to achieve an increment of the stability of the arc with the enhancement of the power quality between the main transformer and the distribution system through the decrease of the THD I , unbalance, and flicker.

Smart Enhancement of UPFC Performance in Transmission Systems Using BPSO and ANNC

The power disturbances in the transmission system can be controlled and reduced by using unified power flow controller (UPFC). UPFC is used for controlling power flow in electrical transmission system. In this paper an algorithm for optimizing and smart controlling of UPFC, using an artificial neural network controller (ANNC) and a Binary Particle Swarm Optimization (BPSO), is proposed for smarting transmission system. The proposed algorithm controls the parameters of the UPFC. Therefore, a best performance of the UPFC is achieved and the transmission losses are minimized at different load conditions and variation of generation. Matlab is used for simulating the proposed algorithm and the test system. The results show that the UPFC using the proposed algorithm effectively act the proposed requirements.

An Optimal FACTS Device Allocation for Improving the Power Loss Factors in IEEE 9 Bus System

This paper deals with power quality improvement by using Unified Power Flow Controller (UPFC), Static Synchronous Series Compensator (SSSC) and Second Generation of FACTS Static Compensator (STATCOM) according to change of the reactive and real power of the load, a suitable high response compensator is needed. UPFC, (Thyristor controlled tap changer) TCTC, (Thyristor Controlled Series Capacitor) TCSC, SSSC, STATCOM and SVC are the compensators belonging to FACTS devices. this paper used UPFC (Unified Power Flow Controller), STATCOM (Static Compensator) and static synchronous Series compensator (SSSC). there are three such compensators belonging to FACTS devices. Models for the UPFC, SSSC, and STATCOM are analysis using MATLAB Simulink. The simulation results of nine bus system with UPFC, SSSC, and STATCOM are presented. MATLAB codes are utilized for the implementation of the three FACTS devices in the Newton – Raphson algorithm. Power flow control was evaluated for nine bus system.

INVESTIGATION WITH TCSC, SSSC AND UPFC OF STATIC VOLTAGE STABILITY IN ZIP LOAD MODELING

Maximum loading parameter-voltage in power systems of the nonlinear load modeling relation is important for static voltage stability. In this study, the effects on static voltage stability of static impedance, current, and active power (ZIP) load modeling in 5 buses power system are investigated. As maximum load analysis, Thyristor Controller Series Compensator (TCSC) Static Synchronous Seri Compensator (SSSC) and Unified Power Flow Controller (UPFC) from Flexible AC Transmission System (FACTS) devices are used. The impacts of ZIP load modeling on different parameter values were evaluated in terms of voltage-maximum loading parameters. Besides, voltage profile of 5 buses power system with TCSC, SSSC and UPFC in different parameter values was examined. Particularly, with use of UPFC has shown that static voltage stability is more effective and maximum load parameter value is increased.

Impacts and benefits of UPFC to wind power integration in unit commitment

Unified Power Flow Controller (UPFC) is recognized as the most powerful flexible AC transmission systems (FACTS) device for power system operation. This paper addresses how UPFC explores the transmission flexibility and facilitates the integration of uncertain and volatile wind power generation. To this end, a comprehensive unit commitment (UC) model with UPFC and uncertain wind power generation is proposed. Then, some metrics are introduced to evaluate the impacts of UPFC on the reliability, security and economy of power system operation. Further, different dispatch strategies of UPFC are compared to provide helpful guidances on making full use of UPFC to hedge against uncertainties. In addition, facing the challenging mixed-integer non-linear non-convex problems, approximate models are proposed to provide a starting point to solve the problems efficiently. All these models are easy to adapt to other types of FACTS devices. Illustrative numerical results are provided.

Preventive Security-Constrained Optimal Power Flow Considering UPFC Control Modes

The successful application of the unified power flow controller (UPFC) provides a new control method for the secure and economic operation of power system. In order to make the full use of UPFC and improve the economic efficiency and static security of a power system, a preventive security-constrained power flow optimization method considering UPFC control modes is proposed in this paper. Firstly, an iterative method considering UPFC control modes is deduced for power flow calculation. Taking into account the influence of different UPFC control modes on the distribution of power flow after N-1 contingency, the optimization model is then constructed by setting a minimal system operation cost and a maximum static security margin as the objective. Based on this model, the particle swarm optimization (PSO) algorithm is utilized to optimize power system operating parameters and UPFC control modes simultaneously. Finally, a standard IEEE 30-bus system is utilized to demonstrate that the proposed method fully exploits the potential of static control of UPFC and significantly increases the economic efficiency and static security of the power system.

Design of Robust UPFC Based Damping Controller Using Biogeography Based Optimization

<p>In this paper a new optimization algorithm, the biogeography based optimization (BBO) is employed to design a robust power oscillation damping (POD) controller using unified power flow controller (UPFC). The controller that is used to damp low frequency oscillation is designed over a wide range of operating points using two different objective functions. The obtained controllers are then verified through time-domain simulation over different loading conditions with different system uncertainties introduced.</p>

Enhancement of Power Transfer Capability of Interconnected Power System Using Unified Power Flow Controller (UPFC)

Enhancement of Power Transfer Capability of Interconnected Power System Using Unified Power Flow Controller (UPFC)

Power Flow Control and Voltage Profile Improvement Using Unified Power Flow Controller (UPFC) in a Grid Network

Power Flow Control and Voltage Profile Improvement Using Unified Power Flow Controller (UPFC) in a Grid Network

Optimal power flow with UPFC using security constrained self-adaptive differential evolutionary algorithm for restructured power system

Abstract The restructuring of the power industry begins with the 21st century and this restructuring of the power system requires a careful analysis because of the nature of the real-time operations. For the restructuring power system (RPS), the self-adaptive differential evolutionary (SADE) algorithm is proposed for enhancing and controlling the power flow using Unified Power Flow Controller (UPFC) under practical security constraints (SCs). The new formulas for the tuning parameters of Differential Evolutionary technique are designed in such a manner that they become automatically adaptive throughout the whole iteration. The UPFC is modeled considering losses of the both converters, transmission loss in UPFC and losses of the coupling transformers. The unique mathematical modeling of the cost function is developed considering practical SCs. The proposed algorithm and other evolutionary algorithms are applied on the IEEE standard and ill-conditioned test systems. With and without UPFC, the power flow and line losses are observed for the three sets of user-defined active and reactive power. The use of UPFC not only enhances the power flow but also reduces the total line losses. Comparing characteristics, convergence rate, success rate for all cases, the best performances are observed for the proposed Security Constraint SADE (SCSADE) algorithm.

Performance Investigation of D-Q Model for PI and Fuzzy Controller Based UPFC

– The unified power flow controller (UPFC) is the most versatile and complex power electronic equipment that has emerged as the indispensable equipment for the control and optimization of power flow in electrical power transmission system. In this manuscript is investigated the control of real and reactive power flow through a transmission line with the use of UPFC at the sending end. Computer simulation using MATLAB Simulink is done and the behavior of the UPFC is studied. In the UPFC based control of transmission line parameter control systems, it is observed that whenever the SSSC sources some real power into the transmission line it is manifested as a voltage drop across the DC link. Reactive power demand is indicated as fall in the bus bar AC voltage. The fall of the DC link voltage is an indication of real power demand from the receiving end. Similarly a fall of the bus bar AC voltage is an indication of reactive power demand from the receiving end. Fuzzy Logic and PI controllers are used in this works, the control of DC voltage, AC voltage and power transfer.

UPFC with series and shunt FACTS controllers for the economic operation of a power system

This paper presents the application of Genetic Algorithm (GA) and Differential Evolution (DE) technique for the minimization of transmission loss and simultaneous reduction in the operating cost of the system using Flexible AC Transmission System (FACTS) devices. Three types of FACTS devices, Thyristor Controlled Series Compensator (TCSC), Static VAR Compensator (SVC) and Unified Power Flow Controller (UPFC) are considered for this purpose. Optimal placement of FACTS devices in the heavily loaded power system reduces transmission loss, control reactive power flow, improves voltage profile of all nodes and also reduces operating cost. The system is reactively loaded starting from base to 200% of base reactive load and the system performance is observed without and with FACTS devices. The proposed technique is applied on IEEE 30-bus system for the optimal setting of FACTS devices. Finally, how system performance is improved with the use of UPFC along with other series and shunt FACTS controller is illustrated.

Stability Improvement in Power Systems Using Unified Power Flow Controller (UPFC)

Flexible AC transmission system (FACTS) is a system composed of static equipments used for ac transmission of electric energy to improve the power transfer capability and to enhance controllability of interconnected network. Unified Power Flow Controller (UPFC) is the most widely used FACTS device for providing fast acting reactive power compensation on high voltage electricity transmission network. This paper deals with the designing of Adaptive Neuro Fuzzy Inference controller (ANFIC) and fuzzy based Particle Swarm Optimization (PSO) controller for the performance analysis of UPFC. The controller have been designed and tested for controlling the real and reactive power of UPFC. Fuzzy-PI controller is used to control the shunt part of UPFC. The system response under high short circuit level is tested on 5-bus system and 118-bus system. Computer simulation by MATLAB/SIMULINK has been used to verify proposed control strategies.

Application of UPFC for enhancement of voltage profile and minimization of losses using Fast Voltage Stability Index (FVSI)

Application of UPFC for enhancement of voltage profile and minimization of losses using Fast Voltage Stability Index (FVSI)Transmission line loss minimization in a power system is an important research issue and it can be achieved by means of reactive power compensation. The unscheduled increment of load in a power system has driven the system to experience stressed conditions. This phenomenon has also led to voltage profile depreciation below the acceptable secure limit. The significance and use of Flexible AC Transmission System (FACTS) devices and capacitor placement is in order to alleviate the voltage profile decay problem. The optimal value of compensating devices requires proper optimization technique, able to search the optimal solution with less computational burden. This paper presents a technique to provide simultaneous or individual controls of basic system parameter like transmission voltage, impedance and phase angle, thereby controlling the transmitted power using Unified Power Flow Controller (UPFC) based on Bacterial Foraging (BF) algorithm. Voltage stability level of the system is defined on the Fast Voltage Stability Index (FVSI) of the lines. The IEEE 14-bus system is used as the test system to demonstrate the applicability and efficiency of the proposed system. The test result showed that the location of UPFC improves the voltage profile and also minimize the real power loss.

Low-frequency power oscillation damping enhancement and voltage improvement using unified power flow controller (UPFC) in multi-machine power system

The problem of low-frequency power swings is a matter of concern for power systems engineers in the operation and planning of power systems. Therefore, this paper is an investigation of the use of unified power flow controller (UPFC) that is suitably tuned to improve the damping of low frequency power oscillations present in Nigerian grid system. A large disturbance is initiated, during simulation in PSAT, in the network to induce nonlinear oscillations of the power system in order to ascertain the damping effect of UPFC. The dynamic responses of the system simulated show that the system is well damped and is stabilized at minimal time which confirms the robustness of the UPFC. Finally, a comparative study in a typical transient stability problem on IEEE 14-bus system using a UPFC model and the Nigerian high voltage interconnected system is used to illustrate the concepts presented in this paper. Key words: Power oscillation damping, power systems, unified power flow controller (UPFC), flexible AC transmission system (FACTS) devices, low frequency oscillation

All Nodes Voltage Regulation and Line Loss Minimization in Loop Distribution Systems Using UPFC

Voltage regulation and line loss minimization in distribution networks are challenging problems, particularly when it is not economic to upgrade the entire feeder system. This paper presents a new method for achieving line loss minimization and all nodes voltage regulation in the loop distribution systems, simultaneously, by using unified power flow controller (UPFC), one of the most important FACTS devices. First, the line loss minimum conditions in the loop system are presented. Then, load voltage regulation is applied under line loss minimum conditions. Reference voltage of the controlled node is determined based on the assumption that this voltage can subsequently improve all node voltages to be within the permissible range. Also, the proposed control scheme of the UPFC series converter, to regulate all node voltages under line loss minimization, is presented. The effectiveness of the proposed control scheme has been experimentally verified.