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With the objective of discovering the vital line in an electrical power grid (EPG) where the unified power flow controller (UPFC) could be inserted to minimize the severity of overloading (SOL) during contingencies, an investigation into the stiffness of single line contingencies (SLC) on the EPG is presented in this study. An overloading index (OVI) is developed and used in this contribution to arrange the transmission branches of the EPG based on their cruciality and criticality throughout SLC. A harmony search algorithm (HSA), an optimization method, has been adopted to optimally set the parameters of the UPFC to achieve the best minimum SOL of the system at the optimal location. The IEEE 30-bus network was used as the test bed. Results based on the test bed show that placing a UPFC based on the ranking of a well-known contingency severity index (CSI) minimized the SOL to 2.40 × 10 10 as against the 8.05 × 10 5 obtained when the placement is done on the ranking based on the proposed OVI. The minimization of SOL is achieved with a reactance and reactive power of 0.036 p u and 0.096 p u , respectively, of the UPFC. The result also reveals that the proposed OVI identifies with a higher level of precision the vital line in the test bed for placing the UPFC for the purpose of minimizing the SOL during contingencies. [ABSTRACT FROM AUTHOR]

With the objective of discovering the vital line in an electrical power grid (EPG) where the unified power flow controller (UPFC) could be inserted to minimize the severity of overloading (SOL) during contingencies, an investigation into the stiffness of single line contingencies (SLC) on the EPG is presented in this study. An overloading index (OVI) is developed and used in this contribution to arrange the transmission branches of the EPG based on their cruciality and criticality throughout SLC. A harmony search algorithm (HSA), an optimization method, has been adopted to optimally set the parameters of the UPFC to achieve the best minimum SOL of the system at the optimal location. The IEEE 30-bus network was used as the test bed. Results based on the test bed show that placing a UPFC based on the ranking of a well-known contingency severity index (CSI) minimized the SOL to 2.40×1010 as against the 8.05×105 obtained when the placement is done on the ranking based on the proposed OVI. The minimization of SOL is achieved with a reactance and reactive power of 0.036pu and 0.096pu, respectively, of the UPFC. The result also reveals that the proposed OVI identifies with a higher level of precision the vital line in the test bed for placing the UPFC for the purpose of minimizing the SOL during contingencies.

Integrating renewable energy sources like solar power into traditional power systems poses challenges. One such challenge is the effect of renewable power plants, which use power electronics, on the grid’s stability. Specifically, these plants can impact small-signal stability by either damping or exacerbating low-frequency oscillations. This paper introduces a novel Unified Power Flow Controller (UPFC) based damping controller specifically designed for Solar Photovoltaic (PV) integrated power systems. It employs an Arithmetic Optimization Algorithm (AOA) to optimize the UPFC damping controller parameters and mitigate low-frequency oscillations in the power system. The objective function minimizes the Integral Time Absolute Error (ITAE) of speed deviations under varying loading conditions. The proposed technique is utilized simultaneously to control the modulation index of series and phase angle of shunt converters of UPFC. The MATLAB/simulation results obtained effectively from the proposed technique which is actualized and identify both detrimental and beneficial impacts of increased PV penetration for small signal stability performance. The study reveals both the small-signal stability of the system and its response to large disturbances that alter the active power balance and frequency stability. The results of the analysis demonstrated with single and multimachine environment by comparing with the other optimizations like PSO, DE, DE-PSO and GWO, the proposed one is effective for damping out the oscillations. The effectiveness of the proposed damping controller is further confirmed through real-time validation using the OPAL-RT setup. [ABSTRACT FROM AUTHOR]

This article proposes a unified power flow controller with energy (E-UPFC) installed at the renewable energy grid connection node of the transmission network. Compared with other unified power flow controllers (UPFCs), the proposed E-UPFC can not only regulate the power flow on its connected transmission lines, but also suppress the power fluctuations of grid-connected nodes injected with large-scale renewable energy. At the same time, with the installation position of E-UPFC transferred from the transmission line to the node, the original stiff node can be transformed into a flexible node that can regulate the injected power flexibly. First, the PV grid-connected system with E-UPFC is introduced, and its principle of power flow regulation is detailed. In addition, the topology, mathematical modeling, and control strategies of E-UPFC are discussed. Finally, the E-UPFC is applied to the IEEE 3-generator 9-bus system with large-scale renewable energy integration in Matlab/Simulink in order to verify the correctness and feasibility of E-UPFC and its control strategies. [ABSTRACT FROM AUTHOR]

This article addresses the optimality and stability issues of a Tidal power based hybrid power system (HPS). The Tidal system gets destabilized by the uncertain variation of tidal waves and wind input. Stability of the system is restored through the introduction of Unified Power Flow Controller (UPFC) controller. The controller is optimized through the process of configuration of Hyper Spherical Search (HSS) based algorithm. The evaluation of the effectiveness of the suggested controllers is conducted through comparison analyses in order to regulate the voltage profile of the interconnected power network under various loading scenarios. The efficacy of the suggested controllers is assessed by stability analysis utilizing Eigen and Nyquist plots. Further, it is quite evident that optimal tuning is possible in case of the controller where the parameters can create significant impact on the system performance. Consequently, a novel heuristic optimization technique, such as HSS Algorithm are suggested to find the best output of the proposed controller. Finally, by using real-data, the performance as well as robustness of the suggested controller have examined by utilizing a real-time digital simulation platform, specifically the OPAL-RT 5142.

This research presents a new method to improve the ability of small-scale microgrids to maintain stability during temporary disturbances. This is achieved by combining a simplified Unified Power Flow Controller (UPFC) configuration with a low-pass filter (LCL) in the Distributed Generation (DG) unit. The DG unit consists of a Photovoltaic (PV) system that is linked to the grid via a dc-dc buck converter and inverter. The dc-dc converter ensures a consistent output voltage that is linked to the inverter, which produces the necessary ac voltage to power the grid. The downsized Unified Power Flow Controller (UPFC) with a Low Capacitance-Inductance (LCL) filter utilizes the Direct Current (DC) connection of the Distributed Generation (DG) unit to generate an appropriate series voltage. This voltage is then injected into the power line to enhance transient stability. In order to get the highest level of system stability while minimizing expenses, a nonlinear discrete-time Hamilton- Jacobi-Bellman (HJB) optimal control approach is used. The control strategy is specifically developed to optimize the functioning of the microgrid, with the primary goal of decreasing the total cost associated with stability improvement. The cost function is estimated by using a Neural Network that utilizes the weighted residual approach. The simulation results confirm the efficacy of the suggested model and control method. The integration of the DG unit, LCL, and UPFC architecture exhibits exceptional efficacy in attenuating oscillations within the system. This study adds to the progress in comprehending and using decreased UPFC structures in microgrid setups, presenting a feasible approach to achieve improved stability and dependability in distributed power systems. [ABSTRACT FROM AUTHOR]

In regards to present power system setup, this article presents a frequency stabilization of hybrid power system (HPS) assimilated with distributed generation (DG) resources, conventional thermal, geo‐thermal and electric vehicle (EV). The insertion of appropriate system non‐linearities in addition to the intermittency in renewable based generation sources leads to a more practicality into the developed HPS. For such systems, a vigorous control action with swift responding controllable device are an instantaneous requirement. In this view, a cascaded fractional order proportional‐derivative (foPD)‐multi‐stage fractional order proportional integral derivative (MSfoPID) (cascaded foPD‐MSfoPID) as secondary controller is explored for frequency stabilization of HPS. Further, the established power system is provided with erratic load deviations. The influence of EVs on frequency and tie‐line power fluctuations are examined comprehensively. Moreover, the outcome of unified power flow controller (UPFC) device as flexible AC transmission system (FACT) device for system dynamic control are illustrated. Further, sensitivity examination is exhibited to examine the resiliency of proposed cascaded foPD‐MSfoPID controller parameters for deviances in solar irradiance and number of vehicles. Finally, a proposed secondary controller is tested in case studies on standard IEEE‐39 bus system and four‐area hybrid power system. [ABSTRACT FROM AUTHOR]

Purpose. To guarantee proper operation of the system, the suggested method infers the loss of a single transmission line in order to calculate a contingency rating. Methods. The proposed mathematical model with the machine learning with particle swarm optimization algorithm has been used to observe the stability analysis with and without the unified power flow controller and interline power flow controller, as well as the associated costs. This allows for rapid prediction of the most affected transmission line and the location for compensation. Results. Many contingency conditions, such as the failure of a single transmission line and change in the load, are built into the power system. The single transmission line outage and load fluctuation used to determine the contingency ranking are the primary emphasis of this work. Practical value. In order to set up a safe transmission power system, the suggested stability analysis has been quite helpful.

This paper proposes a voltage stability and loadability improvement model of power systems by incorporating the optimal placement of flexible alternating current transmission systems (FACTS) using an artificial neural network (ANN) called OPFANN. The key aspect of this model is to identify the weakest lines which having the most probability of voltage collapse utilized for placing FACTS devices. As installing a new power system network with rapidly increasing power demand cannot be possible, the operator usually operates the power system close to the stability limit. In this regard, continuous monitoring and improvement of system voltage stability and loadability of the existing system are vital issues for energy management systems nowadays. However, the proposed OPFANN introduces a more straightforward and faster scheme for voltage stability monitoring systems using ANN. Intelligent and reliable data samples have been designed to train the ANN based on two line voltage stability indices (LVSI) techniques. Compared with other works, OPFANN effectively improves voltage stability and loadability at the load point by installing the unified power flow controller (UPFC) FACTS devices to the weakest lines. OPFANN can provide information on voltage collapse points using ANN and reduce the further computational cost of LVSI. Finally, OPFANN ensures faster and more secure operation of the power system. [ABSTRACT FROM AUTHOR]

Transmission line losses are a crucial and essential issue in stable power system operation. Numerous methodologies and techniques prevail for minimizing losses. Subsequently, Flexible Alternating Current Transmission Systems (FACTSs) efficiently reduce transmission losses, and the Unified Power Flow Controller (UPFC) is a reactive power compensation controller. The parameter strength of the proportional–integral (PI) controller was calibrated with the Marine Predator Algorithm (MPA), a recent metaheuristic algorithm. An MPA-based optimum PI controller with a UPFC evaluates the optimal location of the UPFC and PI controller parameters to accomplish the desired research objective. The power rating of the UPFC was determined depending on the voltage collapse rating and power loss and an evaluated performance analysis of the MPA–PI-controlled UPFC on a modified IEEE-30 bus transmission network in MATLAB Simulink code. The Newton–Raphson method was used to perform the load flow analysis. Hence, the proposed MPA–PI controller was examined in contrast to preferred heuristic algorithms, the Artificial Bee Colony (ABC) and Moth Flame Optimization algorithms (MFO); the results showed that the MPA–PI controller exhibited better performance with an improved voltage profile and surpasses active power losses with the optimal placement of the UPFC device under different loading conditions. The active power loss, considering a UPFC with the proposed algorithm, reduced from 0.0622 p.u to 0.0301 p.u; consequently, the voltage profile was improved in the respective buses, and the loss percentage reduction during a 100% base load was 68.39%, which was comparatively better than the ABC and MFO algorithms. [ABSTRACT FROM AUTHOR]

This article presents the design of unified power flow controller (UPFC) damping controllers based on Propo rtion al-De rivat ive (PD)-type lead-lag (PD type LL) controllers for dampening low-frequency oscillations in a power system. The proposed PD type Lead Lag based UPFC uses hybridized of Whale and Moth-Flame Optimization Algorithms (WMFOA) to tune controller parameters is compared with MFO, WMFOA, and particle swarm optimization (PSO) tuned controllers for damping low frequency oscilliations. The eigenvalue analysis of time domain simulation has been demonstrated to show the effectiveness of transient stability improvement of PD type LL UPFC controller of the power system. The results analysis reveals that hybridizing of WMFOA tuned WMFOA PD type LL UPFC has excellent capability in damping power system low-frequency oscillations. The same test model type-2 fuzzy lead-lag-based UPFC damping controller transient stability improvement performance is compared to PD type LL controller of the same power system. It is demonstrated with four alternative control signal-based UPFC damping controllers are evaluated under a variety of disturbances and variation of parameters of the power system. The damping function of the UPFC with various alternative control signals is investigated using a linearized modified Phillips-Heffron model of a power system with a UPFC controller implemented. [ABSTRACT FROM AUTHOR]

Purpose. In this paper an allocation methodology of Flexible Alternating Current Transmission Systems (FACTS) controllers, more specifically, the Unified Power Flow Controller (UPFC) is proposed. As the penetration of Renewable Energy Sources (RESs) into the conventional electric grid increases, its effect on this location must be investigated. Research studies have shown that the uncertainty of RESs in power generation influences the reactive power of a power system network and consequently its overall transmission losses. The novelty of the proposed work consists in the improvement of voltage profile and the minimization of active power loss by considering renewable energy sources intermittency in the network via optimal location of UPFC device. The allocation strategy associates the steady-state analysis of the electrical network, with the location and adjustment of controller parameters using the Whale Optimization Algorithm (WOA) technique. Methodology. In order to determine the location of UPFC, approaches are proposed based on identification of a line which is the most sensitive and effective with respect to voltage security enhancement, congestion alleviation as well as direct optimization approach. The optimum location of UPFC in the power system is discussed in this paper using line loading index, line stability index and optimization method. The objective function is solved using the WOA algorithm and its performance is evaluated by comparison with Particle Swarm Optimization (PSO) algorithm. Results. The effectiveness of the proposed allocation methodology is verified through the analysis of simulations performed on standard IEEE 30 bus test system considering different load conditions. The obtained results demonstrate that feasible and effective solutions are obtained using the proposed approach and can be used to overcome the optimum location issue. Additionally, the results show that when UPFC device is strategically positioned in the electrical network and uncertainty of RES is considered, there is a significant influence on the overall transmission loss and voltage profile enhancements of the network.

Abstract The optimal location and setting of the unified power flow controller (UPFC) along with power plant generators' output parameters to enhance power systems reliability in the presence of uncertain variables are determined in this paper. For this purpose, the expected power not served (EPNS) is used as a reliability index based on the total required load shedding at all buses in case of single contingencies such as the outage of lines or generators. The EPNS and components of system's normal operating conditions such as active power losses, voltage deviation index (VDI), as well as economic components, namely, the cost of power generation and UPFC allocation, are taken into consideration in the objective function. The particle swarm optimization (PSO) algorithm optimizes this objective function. Afterward, the firefly algorithm (FA) determines the minimum quantity of required load shedding based on all possible solutions obtained by PSO. Because of the probabilistic nature of loads and renewable generations like wind power generation (WPG), an accurate probabilistic assessment is essential. Therefore, the two‐point estimate method (2PEM) is used, and its performance is compared with the Latin hypercube sampling (LHS) method. The proposed solution method is evaluated on the IEEE 14‐bus and the IEEE 57‐bus test systems and results are discussed.

This article proposes a unified power flow controller with energy (E-UPFC) installed at the renewable energy grid connection node of the transmission network. Compared with other unified power flow controllers (UPFCs), the proposed E-UPFC can not only regulate the power flow on its connected transmission lines, but also suppress the power fluctuations of grid-connected nodes injected with large-scale renewable energy. At the same time, with the installation position of E-UPFC transferred from the transmission line to the node, the original stiff node can be transformed into a flexible node that can regulate the injected power flexibly. First, the PV grid-connected system with E-UPFC is introduced, and its principle of power flow regulation is detailed. In addition, the topology, mathematical modeling, and control strategies of E-UPFC are discussed. Finally, the E-UPFC is applied to the IEEE 3-generator 9-bus system with large-scale renewable energy integration in Matlab/Simulink in order to verify the correctness and feasibility of E-UPFC and its control strategies.

Devices referred to as FACTS are utilized extensively in the process of making power system more secure. The UPFC, which contains both shunt and series correction, is one of the FACTS devices that is considered to be among the most successful. The placement of the FACTS device and the values that are selected for its parameters both have a role in determining how successful the device is in reducing security risks. In this study, the ACO approach is presented as a means of optimally positioning UPFC in order to improve the consistency of the power system in the occurrence of single contingencies, also known as an N-1 contingency. In order to guarantee the integrity of the system, the simulation is run on test systems based on the IEEE 6 bus and the IEEE 14 bus, taking into account line overloads and voltage destructions on the bus. This strategy has a two-pronged approach. In the beginning, a N-1 contingency test is carried out based on the severity ranking, and after that, an ACO algorithm is used to install UPFC in the ideal location in order to reduce the severity. In order to further verify the suggested method, the results are matched with the traditional NLP-IP method. This comparison reveals that the new strategy is better in terms of assuring the safety of power systems.

Purpose. To guarantee proper operation of the system, the suggested method infers the loss of a single transmission line in order to calculate a contingency rating. Methods. The proposed mathematical model with the machine learning with particle swarm optimization algorithm has been used to observe the stability analysis with and without the unified power flow controller and interline power flow controller, as well as the associated costs. This allows for rapid prediction of the most affected transmission line and the location for compensation. Results. Many contingency conditions, such as the failure of a single transmission line and change in the load, are built into the power system. The single transmission line outage and load fluctuation used to determine the contingency ranking are the primary emphasis of this work. Practical value. In order to set up a safe transmission power system, the suggested stability analysis has been quite helpful. [ABSTRACT FROM AUTHOR]

An optimization approach for two-area power system with Unified Power Flow Controller (UPFC) is proposed in this paper. The proposed method is the Atomic Orbital Search (AOS) approach. The proposed approach is applied to achieve full utilization of UPFC and keeps the parameters uncertain. The multivariable PI controller is utilized to control the system controller and eliminates the negative interaction of the controllers. The proposed approach combines the two subsystems by converting algebraic subsystem using differential approximation, which leads to a nonlinear system. The proposed approach provides efficient voltage regulation and quicker damping of inter-area mode oscillations. The proposed UPFC controller eliminates generator oscillation and fault condition, which guarantee the stability of the system as well as provides dynamic power flow control under the tie-line. At last, the proposed method is simulated on MATLAB platform and compared with existing methods. From this comparison, it is shown that the proposed approach provides less oscillation than the existing approach. [ABSTRACT FROM AUTHOR]

Due to the inconsistent nature of the system, the power system uncertainties put forward numerous operational challenges that lead to enhanced risk. Also, minimizing the predictability of the power system makes the operational decisions becomes more challenging and undesirable. Therefore, optimal location, with the real and apparent power flow of a Unified Power Flow Controller (UPFC), is accomplished for enhancing the rate of predictability and minimizing the loss. In this paper, a novel Taylor Spider Monkey-Teaching Learning (TSMO-TL) algorithm is proposed which is the integration of two optimization algorithms namely the Taylor spider monkey as well as the teaching-learning algorithm. Here, the novel TSMO-TL algorithm is employed to optimize the location for situating the UPFC by the objective function (i.e. active power loss and active power flow predictability index). In addition to this, the TSMO-TL approach attains the optimal UPFC placement by considering the input bus voltage, line loss as well as angle. Finally, the proposed TSMO-TL algorithm is utilized in the IEEE-57 bus system to determine its effectiveness. Then the novel TSMO-TL method proved the effectiveness of the system with respect to active power loss, power flow predictability index as well as computational time. • The real and apparent power flow of a unified power flow controller is accomplished. • To enhance predictability using Taylor spider monkey-teaching learning algorithm. • To optimize location for situating UPFC in accordance with the objective function. • To evaluate active power loss, power flow predictability index, computational time. • TSMO-TL algorithm is utilized in IEEE-57 bus system to determine its effectiveness. [Display omitted] [ABSTRACT FROM AUTHOR]

In the restructured electricity markets, transmission usage, usage costs, and loss allocation are critical issues for recovering network embedded and maintenance costs from network users. However, because of the integration of the flexible alternating current transmission system (FACTS) and the occurrence of power system contingencies, this allocation is more complex and critical from the utility's perspective, as it may cause volatility in transmission network costs. In this work, the unified power flow controller (UPFC) is utilized to show the effect of its integration on the system cost and cost allocation. Further, contingency conditions are common in power systems. Therefore, for determining usage, usage cost, and loss allocation volatility under UPFC‐integrated system and N‐1 contingency conditions, this work utilized a power flow tracing‐based transmission usage allocation technique. Reliability factors are used to determine transmission line flows in the event of a failure. Furthermore, contingency line flows are employed to assess transmission tariff volatility in terms of risk premiums. The cost of transmission utilization is recovered using a modified MW‐mile technique. The devised approach was put to the test on a 6‐bus system and an IEEE 14‐bus system. [ABSTRACT FROM AUTHOR]

Copyright of Electric Power Automation Equipment / Dianli Zidonghua Shebei is the property of Electric Power Automation Equipment Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction. In recent years, numerous non-renewable and renewable energies are connected to the grid to meet the demand. Also, transient variation with loads poses the shortcomings for generating units, transmission and distribution networks. In this regard, the study on choice of suitable load modelling is essential to predict the system characteristics. The aspect of the research design is a ZIP load model, which, when combined with contingency criteria and constant-impedance, constant-current, and constant-power loads, produces realistic and long-term load representations. Purpose. The proposed technique, infers the single transmission line outage for obtaining the contingency ranking to ensure the system behavior. Methods. The proposed mathematical model with hybrid line stability ranking index has been used for observing the stability analysis with and without considering unified power flow controller. Results. The power system involves many unpredictable conditions or contingency conditions like single transmission line outage, double transmission line outage, generator outage and load variations. This paper mainly focuses on the single transmission line outage for obtaining the contingency ranking. Practical value. The recommended stability analysis has been very beneficial in establishing a secure transmission power system.

With the sharp increase in fluctuant sources in power systems, the deterministic power flow (DPF) calculation has been unable to meet the demands of practical applications; thus, the probabilistic method becomes indispensable for the reliable and stable operation of power systems. This paper adopts the probabilistic power flow (PPF) method, which is a Monte Carlo simulation (MCS) based on the Latin hypercube sampling (LHS) method, to analyze the uncertainties of power systems. Specifically, the available load supply capability (ALSC) based on the branch loading rate is used to analyze the safety margin of the whole system, while the improved power flow entropy is introduced to quantify the equilibrium of power flow distribution. The repeated power flow (RPF) calculation is combined with the PPF method, and, hence, the probabilistic repeated power flow (PRPF) method is proposed to calculate the power flow entropy at the initial state and the probabilistic ALSC. To flexibly control the power flow, the unified power flow controller (UPFC) is added to the AC power system. The different control coefficients of UPFC are set to reveal the relationship between power flow entropy and available load supply capability under the stochastic scenarios. Finally, the modified IEEE14 test system is used to study the adjustment abilities of UPFC. With consideration of uncertainties in the test case, the positive effect of UPFC on the power flow entropy and the probabilistic ALSC under stochastic scenarios is deeply studied. [ABSTRACT FROM AUTHOR]

The compact design of a fuzzy distance relay, which includes its impact on using a unified power flow controller in a power system, has been adopted as the object of the study. Traditional power system grids have increasingly widely used flexible alternating current transmission system devices in recent years to increase power system stability when faults, unbalance, and sudden changes in load occur. This plays a role in improving power quality, power factor corrections, and power flow control. A unified power flow controller is one of these devices that is most used, popular and meets these benefits, but it simultaneously gives a different change in the apparent impedance of the protection system due to its design. To overcome these issues, the proposed novel design of a fuzzy distance relay is made with the assistance of MATLAB® Simulink and Neuro-Fuzzy Designer. The proposed design work was divided into three parts, the first without fault and the second one including four scenarios without using and using a unified power flow controller in different transmission line locations. The design was carried out in the third part after collecting all input output data sets. This paper offers an efficient design method, which depends on the input value of the observed apparent impedance, also known as resistance (R), and reactance (X). The output is a trip signal to the circuit breaker when a fault occurs. The advantages of the proposed design are a fast-clearing time of 1.42 ms, and working when utilizing a unified power flow controller in different locations; the results show a fast clearing although the long impedance trajectory for some cases. The fast fault clearing will make the system more stable and overcome the maloperation of the distance relay. [ABSTRACT FROM AUTHOR]

The compact design of a fuzzy distance relay, which includes its impact on using a unified power flow controller in a power system, has been adopted as the object of the study. Traditional power system grids have increasingly widely used flexible alternating current transmission system devices in recent years to increase power system stability when faults, unbalance, and sudden changes in load occur. This plays a role in improving power quality, power factor corrections, and power flow control. A unified power flow controller is one of these devices that is most used, popular and meets these benefits, but it simultaneously gives a different change in the apparent impedance of the protection system due to its design. To overcome these issues, the proposed novel design of a fuzzy distance relay is made with the assistance of MATLAB® Simulink and Neuro-Fuzzy Designer. The proposed design work was divided into three parts, the first without fault and the second one including four scenarios without using and using a unified power flow controller in different transmission line locations. The design was carried out in the third part after collecting all input-output data sets. This paper offers an efficient design method, which depends on the input value of the observed apparent impedance, also known as resistance (R), and reactance (X). The output is a trip signal to the circuit breaker when a fault occurs. The advantages of the proposed design are a fast-clearing time of 1.42 ms, and working when utilizing a unified power flow controller in different locations; the results show a fast clearing although the long impedance trajectory for some cases. The fast fault clearing will make the system more stable and overcome the maloperation of the distance relay. [ABSTRACT FROM AUTHOR]

Copyright of Electric Power Automation Equipment / Dianli Zidonghua Shebei is the property of Electric Power Automation Equipment Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electric Power Automation Equipment / Dianli Zidonghua Shebei is the property of Electric Power Automation Equipment Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose. In this paper an allocation methodology of Flexible Alternating Current Transmission Systems (FACTS) controllers, more specifically, the Unified Power Flow Controller (UPFC) is proposed. As the penetration of Renewable Energy Sources (RESs) into the conventional electric grid increases, its effect on this location must be investigated. Research studies have shown that the uncertainty of RESs in power generation influences the reactive power of a power system network and consequently its overall transmission losses. The novelty of the proposed work consists in the improvement of voltage profile and the minimization of active power loss by considering renewable energy sources intermittency in the network via optimal location of UPFC device. The allocation strategy associates the steady-state analysis of the electrical network, with the location and adjustment of controller parameters using the Whale Optimization Algorithm (WOA) technique. Methodology. In order to determine the location of UPFC, approaches are proposed based on identification of a line which is the most sensitive and effective with respect to voltage security enhancement, congestion alleviation as well as direct optimization approach. The optimum location of UPFC in the power system is discussed in this paper using line loading index, line stability index and optimization method. The objective function is solved using the WOA algorithm and its performance is evaluated by comparison with Particle Swarm Optimization (PSO) algorithm. Results. The effectiveness of the proposed allocation methodology is verified through the analysis of simulations performed on standard IEEE 30 bus test system considering different load conditions. The obtained results demonstrate that feasible and effective solutions are obtained using the proposed approach and can be used to overcome the optimum location issue. Additionally, the results show that when UPFC device is strategically positioned in the electrical network and uncertainty of RES is considered, there is a significant influence on the overall transmission loss and voltage profile enhancements of the network. [ABSTRACT FROM AUTHOR]

The optimal location and setting of the unified power flow controller (UPFC) along with power plant generators' output parameters to enhance power systems reliability in the presence of uncertain variables are determined in this paper. For this purpose, the expected power not served (EPNS) is used as a reliability index based on the total required load shedding at all buses in case of single contingencies such as the outage of lines or generators. The EPNS and components of system's normal operating conditions such as active power losses, voltage deviation index (VDI), as well as economic components, namely, the cost of power generation and UPFC allocation, are taken into consideration in the objective function. The particle swarm optimization (PSO) algorithm optimizes this objective function. Afterward, the firefly algorithm (FA) determines the minimum quantity of required load shedding based on all possible solutions obtained by PSO. Because of the probabilistic nature of loads and renewable generations like wind power generation (WPG), an accurate probabilistic assessment is essential. Therefore, the two‐point estimate method (2PEM) is used, and its performance is compared with the Latin hypercube sampling (LHS) method. The proposed solution method is evaluated on the IEEE 14‐bus and the IEEE 57‐bus test systems and results are discussed. [ABSTRACT FROM AUTHOR]

In this paper, modified dragonfly algorithm (MDA) with ant lion optimization (ALO) based Load Flow Analysis (LFA) with hybrid power flow controller in comparison with unified power flow controller is established. The proposed technique is exemplify at enhanced search ability, random reduction and decreased complexity. Here, search behavior of dragonflies is updated to ALO algorithm. Hence, the combination of these two optimization algorithm is named as MDA2LO technique. In this paper, load flow studies are suggested with obtain voltage, real and reactive power and load angle in each bus of power system to divide their steady state circumstances utilizing MDA2LO approach. The proposed system is actualized on MATLAB/Simulink working platform. The proposed study is experienced at IEEE 30 and 14 bus system. The performance of proposed system is compared to previous method like salp swarm algorithm-firefly (SSA-FF), combination of modified salp swarm optimization algorithm and moth-flame optimization called CMSSMFO and dragonfly algorithm (DA).The result accuracy (RA) of proposed and existing method is also analyzed. The RA of the proposed hybrid system is 52.7699% and SSA-FF is 9.665%, CMSSMFO is 11.995%, DA is 10.721%. Overall, the comparison outcomes decide the benefit of proposed system and confirm their potential for resolving these issues. [ABSTRACT FROM AUTHOR]

Abstract In the restructured electricity markets, transmission usage, usage costs, and loss allocation are critical issues for recovering network embedded and maintenance costs from network users. However, because of the integration of the flexible alternating current transmission system (FACTS) and the occurrence of power system contingencies, this allocation is more complex and critical from the utility's perspective, as it may cause volatility in transmission network costs. In this work, the unified power flow controller (UPFC) is utilized to show the effect of its integration on the system cost and cost allocation. Further, contingency conditions are common in power systems. Therefore, for determining usage, usage cost, and loss allocation volatility under UPFC‐integrated system and N‐1 contingency conditions, this work utilized a power flow tracing‐based transmission usage allocation technique. Reliability factors are used to determine transmission line flows in the event of a failure. Furthermore, contingency line flows are employed to assess transmission tariff volatility in terms of risk premiums. The cost of transmission utilization is recovered using a modified MW‐mile technique. The devised approach was put to the test on a 6‐bus system and an IEEE 14‐bus system.

Introduction. In recent years, numerous non-renewable and renewable energies are connected to the grid to meet the demand. Also, transient variation with loads poses the shortcomings for generating units, transmission and distribution networks. In this regard, the study on choice of suitable load modelling is essential to predict the system characteristics. The aspect of the research design is a ZIP load model, which, when combined with contingency criteria and constant-impedance, constant-current, and constant-power loads, produces realistic and long-term load representations. Purpose. The proposed technique, infers the single transmission line outage for obtaining the contingency ranking to ensure the system behavior. Methods. The proposed mathematical model with hybrid line stability ranking index has been used for observing the stability analysis with and without considering unified power flow controller. Results. The power system involves many unpredictable conditions or contingency conditions like single transmission line outage, double transmission line outage, generator outage and load variations. This paper mainly focuses on the single transmission line outage for obtaining the contingency ranking. Practical value. The recommended stability analysis has been very beneficial in establishing a secure transmission power system. References 19, tables 8, figures 3. [ABSTRACT FROM AUTHOR]

The unified power flow controller (UPFC) helps to control the power flow, but its outage due to the abnormal state is a threat to power systems. In this paper, based on the proportion of the random failure, the transition rates of the abnormal state are newly derived. The impact of the routine test (RT) on the transition rates is quantified. The state space models of the UPFC based on voltage-source converter (VSC) and modular multilevel converter (MMC) are extended with the states introduced by the RT. The frequency and duration method is used to aggregate the states. The sensitivities of the availability and outage frequency of the UPFC with respect to the failure rates of the components are newly derived to find the vulnerable component and the optimal RT interval. The numerical results show that the RT reduces the probability of the abnormal state, reduces the failure duration, and improves the availability of the UPFC. [ABSTRACT FROM AUTHOR]

Transmission line losses are a crucial and essential issue in stable power system operation. Numerous methodologies and techniques prevail for minimizing losses. Subsequently, Flexible Alternating Current Transmission Systems (FACTSs) efficiently reduce transmission losses, and the Unified Power Flow Controller (UPFC) is a reactive power compensation controller. The parameter strength of the proportional–integral (PI) controller was calibrated with the Marine Predator Algorithm (MPA), a recent metaheuristic algorithm. An MPA-based optimum PI controller with a UPFC evaluates the optimal location of the UPFC and PI controller parameters to accomplish the desired research objective. The power rating of the UPFC was determined depending on the voltage collapse rating and power loss and an evaluated performance analysis of the MPA–PI-controlled UPFC on a modified IEEE-30 bus transmission network in MATLAB Simulink code. The Newton–Raphson method was used to perform the load flow analysis. Hence, the proposed MPA–PI controller was examined in contrast to preferred heuristic algorithms, the Artificial Bee Colony (ABC) and Moth Flame Optimization algorithms (MFO); the results showed that the MPA–PI controller exhibited better performance with an improved voltage profile and surpasses active power losses with the optimal placement of the UPFC device under different loading conditions. The active power loss, considering a UPFC with the proposed algorithm, reduced from 0.0622 p.u to 0.0301 p.u; consequently, the voltage profile was improved in the respective buses, and the loss percentage reduction during a 100% base load was 68.39%, which was comparatively better than the ABC and MFO algorithms.

In the presence of nonlinear response created by power electronics-based compensators, reliable fault detection and classification by distance protection relays is a major concern. The unified power flow controller (UPFC) has a dynamic characteristics that causes stability and protection issues. A intrinsic time decomposition (ITD) based strategy is proposed for addressing this issue. A differential energy based detection index computed using ITD and adaptive thresholding technique is employed such that unerring fault detection is achieved wherein faulty phases of a UPFC compensated transmission line are well pointed out. Various fault and non-fault cases considering critical power system conditions are analysed for power systems with varying configurations modelled using EMTDC/PSCAD. A comparison of the current detection method to recently proposed techniques reveals the benefits and feasibility of the presented detection strategy, which has been proved to be accurate and efficient. – Unit protection of UPFC-compensated lines irrespective of compensation mode and level. – Intrinsic Time Decomposition based detection index using current signal to detect faults. – Accurate identification and discrimination of fault and non-fault events. – Adaptive threshold technique immune to power system structure. The executional burden time is near about 5 ms. [ABSTRACT FROM AUTHOR]

This paper presents Sensitivity constrained placement of unified power flow controller (UPFC) considering active-power flow sensitive index (APFSI) and static voltage stability index (STATIC-VSI) to minimize active-power losses and to improve power transmission capacity. The sensitive factors are derived with respect to voltage, phase angle and current to formulate APFSI. Transmission line impedance parameters along with active and reactivepower flow measurements are considered to formulate static-VSI. Sensitivity constrained differential evolutionary (SCDE) algorithm is proposed for parameter setting through which power control and minimization of losses in system can be achieved. Testing is performed on IEEE-5, 14 and 30-bus networks in MATLAB and results indicate that SCDE is robust optimization technique compared to conventional method and genetic algorithm (GA). [ABSTRACT FROM AUTHOR]

A wind turbine, battery energy storage system, and photo-voltaic system are the three main sources included in this work as hybrid renewable energy systems (HRESs). To alleviate power quality (PQ) issues, i.e., swell, sag, harmonics, interruption, and fluctuation, a unified power flow controller (UPFC) is utilized in this paper. The major goal of this research is to compensate the load demand, mitigate the PQ issues, and reduction of cost as well as power flow along with IEEE-14 bus system. In HRESs, the PQ issues are mitigated by utilizing a novel hybrid optimized technique called GWO-CS approach-based UPFC. By utilizing the hybrid optimized technique, the PID controller is employed to drive the pulse width modulation of this UPFC. Numerous PQ issues like fluctuations, interruptions, estimation of harmonics, sags, and swells are evaluated in this paper by validating the enactment of the presented methodology, and also this technique is simulated in MATLAB/Simulink to analyze the outcomes. Moreover, to validate the efficacy of the proposed method, the presented technique is compared with the conventional approaches, i.e., GWO, PSO, and hybrid PSO-based GWO. [ABSTRACT FROM AUTHOR]

This paper presents enhancement of power system dynamic stability while equipped with both unified power flow controller and doubly fed induction generator by using LMI technique. We have used all UPFC (Unified Power Flow Controller) main basic PI controllers and its POD (Power Oscillation Damping) supplementary controller. More complete model of DFIG (Doubly Fed Induction Generator) and both RSC (Rotor Side Converter) and GSC (Grid Side Converter) dynamics with their controllers have considered too. These two devices controllers have simultaneously co-ordinate and optimized with compromising between their control variables parameters. PSO (Particle Swarm Optimization) algorithm has used to optimize an objective function based on Eigen values and damping ratio to reach to best parameters and variables of controllers of both of UPFC and DFIG. LMI (Linear Matrix Inequality) have applied to whole system linearized model to reach to optimally modified eigenvalues. Within steady state and dynamic study we considered practical line thermal capacity and UPFC power rating too. Simulation results in 39-bus 10-machine Ne-England power systems ilustrate the capability of applied method. The results demonstrated that coordinated control of these two devices beside using LMI tend to more damping of system modes oscillation and more stability in power system.

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In this manuscript, a hybrid HUA‐GPC strategy with unified power flow controller (UPFC) is proposed to enhance that security of power system under the condition of transmission and/or generator failure. The proposed hybrid strategy is joint implementation of Human urbanization algorithm (HUA) and Giza Pyramids Construction (GPC) and commonly named as HUA‐GPC approach. GPC approach is utilized to develop that search behavior of HUA. The main aim of the proposal is the operation and control of electrical system is to satisfy the demand continuously in the absence of failures. A new severity function is created with transmission line loads and bus voltage magnitude deviations. The proposed function and generation fuel cost are evaluated in contingency conditions of transmission line (s) and/or generator (s). System safety in contingency conditions is evaluated with optimal power flow issue. To improve system safety in contingency conditions in the presence of UPFC, it is essential to recognize an optimal position to install this device. To recognize an optimal UPFC position, in this proposal, a HUA‐GPC technique depending on line overload sensitivity index (LOSI) is evolved. The LOSI is assessed for every transmission lines in contingencies. An energy injection model based on UPFC voltage source, incorporation process and optimal location recognition approach depending on line overload sensitivity indices is proposed. The constraints are the constraints of equality and inequality. The proposed approach is then performed on the MATLAB/Simulink work platform and the efficiency is compared with existing strategies. The quality of the solution for the proposed system is analyzed in terms of best aptitude, worst aptitude, mean aptitude, SD, coefficient of variation and the error of best is 1110936.01, 1097382.12, 1107656.56, 1051.98, 0.075, and 0.82. [ABSTRACT FROM AUTHOR]