Flexible Alternating Current Transmission System Research Articles

Simulation of the influence of STATCOM on power system losses

The supply of growing electricity demand is possible through continuous technological advances and the expansion of national and international electrical systems. This scenario could introduce voltage drops and consequent changes in the reactive power flow throughout the electrical network. In order to control these problems, various strategies have been developed as a solution to improve the transport and distribution of electrical energy. One of them is the Flexible Alternating Current Transmission System (FACTS), and more specifically the STATic synchronous COMpensator (STATCOM). This paper investigates the influence and effectiveness of STATCOM to mitigate the losses in the transmission lines and its impacts on bus voltage drops. The simulations are performed using the software DIgSILENT PowerFactory and the results showed that STATCOM reduces the power system losses in an interval of 23.86% until 32.86%, and in addition, the STATCOM decreases the annual energy cost by 7.82% in the implemented test case.

Use FACTS elements to improve energy exchange between countries in response to the high penetration of variable renewable energy

Integrating Variable Renewable Energy sources (VRE) into Electric Power System (EPS) requires optimizing the synergy between VRE characteristics, PES flexibility elements, and local Electric Market operations. However, during advanced integration phases, where VRE accounts for a significant portion of the system’s energy, and in the face of stability issues caused by energy excess, cross-border energy exchange appears to be one of the most effective solutions for Energy Management. In this investigation, to highlight the role of Flexible Alternative Current Transmission Systems (FACTS) elements to ensure the required flexibility in these energy exchange operations, a modeling strategy Methodology was implemented in MATLAB and SIMULINK to design a Static Var Compensator (SVC) and simulate its connection to a high-voltage power line between Turkey and Syria, observing its response these changes in load flow. This investigation contributes to the VRE integration strategy, identifying FACTS elements as a solution to manage excess energy and achieve efficient energy exchange.

Loss reduction of transmission lines using PSO-based optimum performance of UPFC

Transmission line losses are one of the essential topics and issues in power systems research. Several methods and techniques have been used to reduce these losses, and one of these modern techniques is flexible alternating current transmission systems (FACTS). In this paper, one of the most important types of this technology, the unified power flow controller (UPFC), was used to reduce losses in the Iraqi national grid (ING) 400 kV. This paper presents an efficient method for minimizing losses of transmission lines in the ING system (400 kV) 46-bus approach. A particle swarm optimization (PSO)-based optimum proportional-integral (PI) controller with UPFC was proposed to obtain the optimal location of UPFC and optimum parameters of the PI controller to achieve the objective function of the research. MATLAB coded the algorithm. The Newton-Raphson method was employed to perform load flow analysis. The results showed that the best place for UPFC is buses (14-17) named BGE4 (Baghdad)-AMN4 (Baghdad), and the total active power and reactive power losses decreased from 727.4593 to 579.3874 MW and from 5155.9 to 3971.1 MVAR, respectively and also led to voltage regulation.

Investigation of the Transfer Capability of the Nigerian 330 kV, 58-bus Power System Network using FACTS Devices

Over the years, the Nigerian power system is beset with lingering problems, which include severe power losses, as well as very low transfer capability of the transmission network to evacuate power from generating stations to the load at the distribution level. Presently, the Nigerian power industry is undergoing restructuring, especially in the generation and distribution systems. In view of the deregulation of electricity distribution and marketing, the traditional practices of the Nigerian power system are undergoing changes to address the identified problems in the existing power system. Specifically, better utilization of the existing power transmission network to improve on the system transfer capability and minimize cost is one of the key focuses of the deregulation agenda. This work deals with the enhancement of transfer capability of Nigerian 58-bus, 330kV network using FACTS (Flexible Alternating Current Transmission System) devices. FACTS devices are used for controlling transmission voltage, power flow, reducing reactive power losses, and damping of power system oscillations for high power transfer capability. Three FACTS devices; Thyristor Controlled Series Compensator (TCSC), Unified Power Flow Controller (UPFC), and Interline Power Flow Controller (IPFC) were used to investigate the transfer capability of the Nigerian 58-bus power system network. NEPLAN was employed in this work to model the Nigerian 58-bus system and optimally placed the FACTS devices at the weakest buses that were found out through the computation for available transfer capability (ATC) after continuation power flow (CPF) simulation was completed. MATLAB codes were developed and used to calculate power transfer capability of the network without and with FACTS devices. Comparing the three FACTS devices, the results obtained showed that UPFC enhanced the power transfer capability of the network than TCSC and IPFC.

Optimal Siting and Sizing of FACTS in Distribution Networks Using the Black Widow Algorithm

The problem regarding the optimal placement and sizing of different FACTS (flexible alternating current transmission systems) in electrical distribution networks is addressed in this research by applying a master–slave optimization approach. The FACTS analyzed correspond to the unified power flow controller (UPFC), the thyristor-controlled shunt compensator (TCSC, also known as the thyristor switched capacitor, or TSC), and the static var compensator (SVC). The master stage is entrusted with defining the location and size of each FACTS device using hybrid discrete-continuous codification through the application of the black widow optimization (BWO) approach. The slave stage corresponds to the successive approximations power flow method based on the admittance grid formulation, which allows determining the expected costs of the energy losses for a one-year operation period. The numerical results in the IEEE 33-, 69-, and 85-bus grids demonstrate that the best FACTS device for locating in distribution networks is the SVC, given that, when compared to the UPFC and the TCSC, it allows for the best possible reduction in the equivalent annual investment and operating cost. A comparative analysis with the General Algebraic Modeling System software, with the aim to solve the exact mixed-integer nonlinear programming model, demonstrated the proposed BWO approach’s effectiveness in determining the best location and size for the FACTS in radial distribution networks. Reductions of about 12.63% and 13.97% concerning the benchmark cases confirmed that the SVC is the best option for reactive power compensation in distribution grids.

Review of FACTS technologies and applications for accelerating penetration of wind energies in the power system

AbstractConventional energy resource problems made power system planners apply more renewable energy sources (RESs) in the power system. RESs have a significant impact on fulfilling the world's energy demand, protecting the environment at least in the exploration phase, and providing energy reliability as well as security for the new generation of power grids. In this regard, wind power generation is considered a promising solution. However, by increasing the share of wind power generation units in the power sector, some challenges, such as voltage problems, transient stability, increasing system losses, and line congestions can occur. Consequently, an alternative solution is required to accelerate wind power units' connections to the grid by preventing the problems caused by the penetration of wind power. In this regard, Flexible Alternating Current Transmission Systems (FACTS) devices can play an important role while they can improve power grid dynamic performance. This paper presents a review of the optimization techniques applied to accelerate the penetration of wind energy by exploiting FACTS devices. The topic identifies the objectives and optimization formulations, as well as schemes and models available in the published literature. This survey gives noteworthy insights to the researchers to cover available solutions in these regards. The literature in the field is summarized in different aspects, such as FACTS technology, objective functions, constraints, optimization methods, planning or operation purposes, and load flow types. At each aspect, a comparison is derived to recognize the most important issues. The result of the review is the finding of future work and contributions which can be done in the field of wind energy integration acceleration using FACTS devices and the output of the paper can be used as a guide for researchers to find a new path for research in this area.

Mitigating Low-Frequency Oscillations and Enhancing the Dynamic Stability of Power System Using Optimal Coordination of Power System Stabilizer and Unified Power Flow Controller

The integration of a flexible alternating current transmission system (FACTS) and a power system stabilizer (PSS) can increase dynamic stability. This paper presents the enhancement of power system dynamic stability through the optimal design of a power system stabilizer and UPFC using an ant lion optimization (ALO) technique to enhance transmission line capacity. The gained damping ratio, eigenvalue and time domain results of the suggested ALO technique were compared with a base case system, ALO-based PSS and ALO-based PSS-UPFC to test the effectiveness of the proposed system in different loading cases. Eigenvalues gained from an ant lion approach-based UPFC with a PSS and a base case system are compared to examine the robustness of the ALO method for various loading conditions. Thus, this paper addresses the mechanism regarding the power system dynamic stability of transmission lines by integrating the optimal size of a PSS and UPFC into the power system. Therefore, the main contribution of this manuscript is the optimal coordination of a power system stabilizer, power oscillation damper and unified power flow using ant lion optimization for the mitigation of low-frequency oscillation.

A transient stability analysis method for wind power system with thyristor controlled phase shifting transformer based on branch potential energy index

With the growing usage of renewable energy technologies like wind power and photovoltaics, and the increased integration of FACTS (Flexible Alternating Current Transmission System) devices into the power system, the transient characteristics of the evolving power system undergo changes that require appropriate analysis methods. As a new type of FACTS device, TCPST (Thyristor Controlled Phase Shifting Transformer) is introduced to facilitate the superior operation of renewable energy sources by controlling the power flow of access branches. From the perspective of branches, the dynamic characteristics of renewable energy sources and TCPST might be uniformly studied and simply calculated in the transient stability analysis. Therefore, the paper proposes a transient stability analysis method for wind power systems with TCPST based on the branch potential energy index. First, considering the variation characteristics of branch potential energy, this paper employed the stability index to analyze the transient stability of branches and the system by finding vulnerable lines. Then, based on the stability index, the paper investigates the influence of wind turbine removal, the installation and control parameter adjustment of TCPST on the transient stability of wind power systems. The simulation results in PSAT demonstrate that the removal of a proper amount of wind turbine post-fault and the installation of TCPST can improve the transient stability of the wind power system. Furthermore, it can also be improved by reasonably adjusting the TCPST control parameters. All simulation results are verified by the time domain simulation method.

A Proposed Supercapacitor Integrated with an Active Power Filter for Improving the Performance of a Wind Generation System under Nonlinear Unbalanced Loading and Faults

This study proposes the integration of a supercapacitor (SC) with the DC link of a three-phase four-wire active power filter (APF) by using an interfaced three-level bidirectional buck-boost converter controlled by the fuzzy control approach. APF is a flexible alternating current transmission system (FACTS) device that enhances power quality in the electrical network by reducing the load current harmonics and compensating the reactive power. Regulating the DC voltage of the APF’s DC link and absorbing fluctuations in compensated reactive power during disturbances are the major objectives of the integration of an SC circuit to APF. The studied model is a wind farm of Gabal El-Zeit with a total capacity of 580 MW, connected to unbalanced nonlinear loads. The Gabal El-Zeit wind farm is divided into three projects with a capacity of 240 MW, 220 MW, and 120 MW. The model is simulated by the MATLAB/SIMULINK program, and the effectiveness of the proposed methodology is proved by applying different types of faults such as single-line-to-ground, double-line-to-ground, and three-line-to-ground faults. In addition, an additional SC circuit with a two-level converter is connected to the generators coupled to the wind turbines to enhance the performance of the wind farm during disturbances. The results show that SC-integrated APF can reduce the harmonic distortion and compensate the reactive power for high or low inductive loads. Also, it can regulate the DC voltage and absorb the fluctuations in the reactive power during faults. Finally, the performance and the stability of the overall electric system are improved.

Analysis of Influence of Vertical Vibration on Natural Heat Convection Coefficients from Horizontal Concentric and Eccentric Annulus

Renewable energy is crucial for reducing emissions and meeting future energy demands. However, due to concerns regarding intermittent supply, integrating RE into a multi-microgrid system might pose various power system problems, for instance, unstable electrical power output. As a result, increased load reactive power demands result in voltage losses during peak load demand. Therefore, it can be minimized by utilizing Flexible Alternating Current Transmission System (FACTS) devices in electrical networks, which are designed to strengthen the stability and control of power transfer and act as a controller for the AC transmission specification, which also provides speed and flexibility for certain applications. By identifying the need to implement solutions that can sustain the electric power quality of a microgrid, this paper presents a review of various method approaches which could be used to evaluate the impact of integrating the multi-microgrid systems with FACTS devices for voltage profile improvement and real power loss reduction in power system. In this paper, a comprehensive study is carried out for optimum multi-microgrid placement, considering the minimization of power losses, enhancement of voltage stability, and improvement of the voltage profile. An attempt has been made to summarize the existing approaches and present a detailed discussion that can help the energy planners decide which objective and planning factors need more attention for optimum locations and capacity for multi-microgrid and FACTS devices.

Optimal Power Flow Using a Hybrid Improved Harris Hawks Optimization Algorithm-Pattern Search Method

The optimal power flow (OPF) problems for effective power system planning and operations are solved using a hybrid Improved Harris Hawks Optimization and Pattern Search (PS) (hIHHO-PS) algorithm in this research. The OPF problem is considered minimization of non-convex active power generation fuel cost (NAPGFC), total active power losses (TPL), shunt capacitor cost (SCC), voltage variation (VD), and maximization of social welfare (SW) and loadability factor (LF) objective functions. The proposed hIHHO-PS algorithm was tested on different benchmark test functions (unimodal (UM), multi-modal (MM), and fixed-dimension MM functions) and IEEE 30 bus test system, and obtained results are validated with existing algorithms. These results show the proposed hIHHO-PS algorithm outperformed the others. Further, to enhance the OPF results, optimally place the multi-line Flexible Alternating Current Transmission System (FACTS) devices (unified power flow controller (UPFC) and generalized unified power flow controller (GUPFC)) using severity index. Furthermore, test the effects of control modes of multi-line UPFC and GUPFC devices on OPF results. These results show the multi-line FACTS devices with control mode enhance the OPF results, especially GUPFC in control mode operation.

Optimal Placement and Size of SVC with Cost-Effective Function Using Genetic Algorithm for Voltage Profile Improvement in Renewable Integrated Power Systems

Given the concern for maintaining voltage stability in power systems integrated with renewable power systems due to a mismatch in generation and demand, there remains a need to invoke flexible alternating current transmission system (FACTS) devices in the distribution network. The present paper deals with identifying the locations of placement of a static var compensator in an experimental IEEE 14-bus system; the voltage drop in different buses in an IEEE 14-bus system is calculated by the standard formula. The total voltage drop in the network (TVDN) is also calculated as a reference. The ranking of buses in order of decreasing voltage drop is made, and the weak buses are identified as those showing the maximum or near-maximum voltage drop for the installation of a Static Var Compensator (SVC). The optimum usable size is calculated using a Genetic Algorithm approach to optimize the installation cost. After size optimization, installing a 2 MW solar generator is considered for the weak and most potential bus, which suffers from voltage drops or power loss. Based on the generator at the weakest bus, the total power loss in the network is calculated and compared with a similar method to assess the efficiency of the proposed model. Thus, the voltage stability enhancement problem is solved by applying a Genetic algorithm (GA) to optimize SVC size and using the Total Voltage Drop in Network (TVDN) method to identify weak buses in the systems. It is found that the performance of the proposed system is comparable with another existing system. It is further observed that a gain in power loss to 6.56% is achievable by adopting the proposed strategy, and the gain is better than the other system.

Optimal placement of STATCOM using a reduced computational burden by minimum number of monitoring units based on area of vulnerability

AbstractVarious Flexible Alternating Current Transmission System (FACTS) devices are used to improve the power quality and reliability of power system. In addition to the technical constraints, the installation and maintenance costs limit the exploitation of such devices. To maximize the efficiency of FACTS, the least possible number of devices must be placed optimally in the network. In this vein, many types of research have been conducted to offer optimal placement solutions. Although these methods lead to optimal placement, they usually suffer from a huge amount of computational burden. Therefore, here, an intelligent optimal placement approach is presented, focusing on reducing computational volume. For this aim in the suggested method, the monitoring buses are limited, while monitoring other buses is carried out using an estimation approach. To avoid increasing calculations for this selection, applying the worst fault condition instead of all fault types, the least number of monitoring buses are selected. Moreover, high‐risk zones are indicated for each monitoring bus so that by applying different fault conditions in only these areas, the study is conducted, which results in an additional decrement in computational burden. Finally, the optimal placement problem is solved by employing the genetic algorithm.

The Impact of Integrating Multi-Microgrid System with FACTS Devices for Voltage Profile Enhancement and Real Power Loss Reduction in Power System: A Review

Renewable energy is crucial for reducing emissions and meeting future energy demands. However, due to concerns regarding intermittent supply, integrating RE into a multi-microgrid system might pose various power system problems, for instance, unstable electrical power output. As a result, increased load reactive power demands result in voltage losses during peak load demand. Therefore, it can be minimized by utilizing Flexible Alternating Current Transmission System (FACTS) devices in electrical networks, which are designed to strengthen the stability and control of power transfer and act as a controller for the AC transmission specification, which also provides speed and flexibility for certain applications. By identifying the need to implement solutions that can sustain the electric power quality of a microgrid, this paper presents a review of various method approaches which could be used to evaluate the impact of integrating the multi-microgrid systems with FACTS devices for voltage profile improvement and real power loss reduction in power system. In this paper, a comprehensive study is carried out for optimum multi-microgrid placement, considering the minimization of power losses, enhancement of voltage stability, and improvement of the voltage profile. An attempt has been made to summarize the existing approaches and present a detailed discussion that can help the energy planners decide which objective and planning factors need more attention for optimum locations and capacity for multi-microgrid and FACTS devices.

Application of whale algorithm optimizer for unified power flow controller optimization with consideration of renewable energy sources uncertainty

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.

Traveling Wave-Based Fault Localization in FACTS-Compensated Transmission Line via Signal Decomposition Techniques

Modern power systems are structurally complex and are vulnerable to undesirable events like faults. In the event of faults in transmission line, accurate fault location improves restoration process, thereby enhancing the reliability of the overall system. Fault location methods (FLMs) are tools which assist in identifying fault locations quickly. However, the accuracy of these FLMs gets affected in the presence of flexible alternating current transmission system (FACTS) devices. Therefore, in this work, the performance of four different signal decomposition techniques aided traveling wave aided FLMs are qualitatively compared in the context of fault localization in FACTS-compensated systems. FLMs based on intrinsic time decomposition (ITD), empirical mode decomposition (EMD), S-transform (ST), and estimation of signal parameters via rotational invariance technique (ESPRIT) are investigated. The accuracy of FLMs is tested for different cases of series, shunt, and series-shunt FACTS-compensated systems. A 500 kV system employed with 100 MVAr FACTS device is used for simulation. The instant of arrival wave at end of transmission line is from all aforementioned FLMs. The obtained ATWs are used in fault localization. Further, the associated percentage errors are calculated. The results suggest that EMD and ESPRIT-based FLMs are more accurate than others.

Optimal power flow solution with current injection model of generalized interline power flow controller using ameliorated ant lion optimization

<span lang="EN-US">Optimal power flow (OPF) solutions with generalized interline power flow controller (GIPFC) devices play an imperative role in enhancing the power system’s performance. This paper used a novel ant lion optimization (ALO) algorithm which is amalgamated with Lévy flight operator, and an effectual algorithm is proposed named as, ameliorated ant lion optimization (AALO) algorithm. It is being implemented to solve single objective OPF problem with the latest flexible alternating current transmission system (FACTS) controller named as GIPFC. GIPFC can control a couple of transmission lines concurrently and it also helps to control the sending end voltage. In this paper, current injection modeling of GIPFC is being incorporated in conventional Newton-Raphson (NR) load flow to improve voltage of the buses and focuses on minimizing the considered objectives such as generation fuel cost, emissions, and total power losses by fulfilling equality, in-equality. For optimal allocation of GIPFC, a novel Lehmann-Symanzik-Zimmermann (LSZ) approach is considered. The proposed algorithm is validated on single benchmark test functions such as Sphere, Rastrigin function then the proposed algorithm with GIPFC has been testified on standard IEEE-30 bus system.</span>

Power Planning for a Reliable Southern African Regional Grid

Southern Africa has suffered from multiple power disruptions in the past decade due to inadequate electrical generation capacity, as well as load developments in locations that were not suitably planned for. Southern African countries are able to have reliable, sustainable, and efficient electrical power grids. The use of power interconnections for exchange power, especially for long-distance transmission networks, is important. Installing a suitable high-voltage alternating current (HVAC) with a high-voltage direct current (HVdc) will improve the active–reactive power compensation when transmitting electrical power over long distances (when transmitting bulk power is possible). Flexible alternating current transmission system (FACTS) devices are typically combinations of shunt and series converters. These approaches are capable of improving the power stability and voltage while allowing power to be transferred with minimal losses to an alternating current transmission system for the power exchange. In this article, two HVDC line-commutated converter (LCC) links, i.e., Angola–Namibia and Aggeneys–Kokerboom, were applied to minimize losses from 2657.43 to 2120.91 MW, with power setpoints of 1000 and 600 MW, respectively. The 2500 and 475 MVAr SVCs were used to control the voltage instabilities at Namibia and Mozambique substations, respectively. The use of HVdc to reduce losses and FACTS devices to enhance controllability and power transfer is extremely effective, particularly in long transmission lines transporting bulk power.

Voltage stability and power loss minimization with UPFC using heuristic and hybrid heuristic methods

Present-day power systems have highly complex and stressed operating conditions owing to insufficient reactive power to meet the required power demand. This leads to increased real power and reactive power losses, as well as voltage instability within a power system. To achieve the flexible operation of the power system, Flexible Alternating Current Transmission System (FACTS) devices have been employed. The optimal location of FACTS devices influences the system's performance and significantly affects line/bus reactive power flows. Consequently, the line or bus voltage profiles have been improved, leading to a reduction in power losses. Particle Swarm Optimization (PSO) heuristic methods and HFPSO Hybrid heuristic methods have been used to identify the weakest bus/branch for the suitable placement of UPFC devices, improving voltage stability. This paper discusses a more significant reduction in power losses in a MATLAB environment. Flexible Alternating Current Transmission System (FACTS) devices address reactive power challenges in power systems and enhance operational flexibility. Strategic placement using Particle Swarm Optimization (PSO) and HFPSO Hybrid methods identifies weak points, optimizing Unified Power Flow Controller (UPFC) placement for improved voltage stability. UPFC integration strategically reduces real and reactive power losses, improving power transmission efficiency. This enhances line and bus voltage profiles, addressing instability and significantly reducing overall power losses. The paper offers a detailed analysis of the power system, highlighting the synergy between FACTS devices, heuristic optimization, and power loss reduction. Simulations in MATLAB validate the proposed methodology, demonstrating a noteworthy improvement in power system performance.

Optimal Allocation of STATCOM to Enhance Transient Stability Using Imperialist Competitive Algorithm

With the daily expansion of global energy consumption, developing the power grids is of uttermost importance. However, building a new transmission line is costly and time-consuming, so utilizing the same lines with possible higher transmission capacity is very cost-effective. In this regard, to increase the capacity of the transmission lines, the flexible alternating current transmission system (FACTS) has been widely used in power grids in recent years by industrialized countries. One of the essential topics in electrical power systems is the reactive power compensation, and the FACTS plays a significant role in controlling the reactive power current in the power grid and the system voltage oscillations and stability. When a static synchronous compensator (STATCOM) is embedded in a power system to increase the bus voltage, a supplementary damping controller can be designed to enhance the system oscillation damping. Given the expansion of the grids in the power system, the complexity of their optimization and the extraordinary ability of the imperialist competitive algorithm (ICA) for solving such problems, in this paper, the ICA has been used to determine the optimal position and size of the FACTS devices.