Intelligent Power Dispatch Optimization: A Genetic Algorithm Approach with Unified Power Flow Controller

In this paper, multi – type Flexible AC Transmission System (FACTS) devices are optimally located for enhancing the loadability of an existing power network within the security margins. Line Stability Index is used to determine the critical lines of the system in increased loading of transmission lines and is used to determine the optimal location of FACTS devices. Differential Evolution Algorithm (DE) is used to determine the optimal location and control parameter settings of the FACTS devices. Among the various FACTS devices, Unified Power Flow Controller (UPFC) and Thyristor Controlled Series Capacitor (TCSC) are chosen and modeled for steady state studies. IEEE- 30 bus test system is used for simulation studies and the results are compared with Genetic Algorithm (GA) to show the advantage and feasibility of the DE approach. Further the results demonstrate that the system loadability can be increased by optimal location and control parameter settings of the multi – type FACTS devices.

In this paper, a fully fledged optimal power flow (OPF) algorithm with flexible AC transmission systems (FACTS) devices has been developed and presented aiming at the advancement of how FACTS equipment impacts on the security and economy of the wider power network. The proposed modelling uses Newton’s method along with Lagrangian multipliers, leading to an ecient algorithm that can handle practical power networks independence of initial settings of FACT controllers parameters. Newton’s method provides a suitable vehicle for incorporating the newly developed nonlinear, linearized FACTS models. In this paper, mainly a firing angle-based thyristor controlled series compensators (TCSC) model, a coordinated two-voltage source unified power flow controller (UPFC) model have been developed and presented in details and can easily be extended to other modern FACTS devices such as interline power flow controller (IPFC) and generalized unified power flow controller (GUPFC). The proposed model has capability of converting multi-objective functions into single objective and also can be extended to multiple multi-type FACTS devices. The performance of the proposed model has been validated for IEEE 30 bus system and the solutions so obtained are presented in detail.

In this paper, a hybrid tabu search and simulated annealing (TS/SA) approach is proposed to minimize the generator fuel cost in optimal power flow (OPF) control with multi-type of flexible AC transmission systems (FACTS) devices. The problem is decomposed into the optimal setting of FACTS parameters subproblem that is searched by the hybrid TS/SA approach and the OPF with fixed FACTS parameters subproblem that is solved by the quadratic programming (QP). Four types of FACTS devices are used: thyristor-controlled series capacitor (TCSC), thyristor-controlled phase shifter (TCPS), unified power flow controller (UPFC), and static VAr compensator (SVC). Test results on the modified IEEE 30 bus system with multi-type of FACTS devices indicate that the proposed hybrid TS/SA approach can obtain better solutions and require less CPU times than genetic algorithm, SA, or TS alone. Using multi-type of FACTS devices results in less total generator fuel cost than using individual FACTS device.

Voltage instability and voltage collapse have been considered as a major threat to present power system networks due to their stressed operation. It is very important to do the power system analysis with respect to voltage stability. Flexible AC Transmission System (FACTS) is an alternating current transmission system incorporating power electronic-based and other static controllers to enhance controllability and increase power transfer capability. A FACTS device in a power system improves the voltage stability, reduces the power loss and also improves the load ability of the system. FACTS have made the power systems operation more flexible and secure. Amongst the several FACTS controllers, the Unified Power Flow Controller (UPFC) is most effective to improve the enhancement of voltage stability and reduces the power loss. This study investigates the application of Particle Swarm Optimization (PSO) to find sizing of Unified Power Flow Controller (UPFC) device to minimize the voltage stability index, total power loss, load voltage deviation, and cost of FACTS devices to improve voltage stability in the power system. A new model is proposed in this thesis to improve existing power-based model by using the Norton Equivalent Theorem. The proposed model can be integrated with the Equivalent Current Injection (ECI) power flow model easily. By ECI algorithm, it is much quickly and precisely to implement power flow calculations. Finally It is observed from the results that the voltage stability margin is improved, the voltage profile of the power system is increased and real power losses also reduced by optimally sizing UPFC device in the power system. Index Terms: Voltage stability, Unified Power Flow Controller (UPFC), Equivalent -Current Injection (ECI), Modified particle swarm optimization (MPSO)

New approach for optimal UPFC placement using hybrid immune algorithm in electric power systems

Güç sistemlerinin sürekli ve geçici durum çalışmalarında Esnek AC İletim Sistemi (FACTS) cihazları tercih edilmektedir. FACTS cihazları içerisinde kontrol etme yeteneği en güçlü olan Birleştirilmiş Güç Akışı Kontrolü (UPFC)’dir. UPFC bara gerilimlerini reaktif güce bağlı olarak kontrol ederken, iletim hattını empedans ve akıma göre kontrol etmektedir. Bu çalışmada, Uluslararası Elektrik Elektronik Mühendisliği (IEEE) 14 baralı güç sisteminde UPFC’nin statik ve dinamik gerilim kararlılığı analizleri gerçekleştirilmiştir. Sürekli ve geçici durum için gerilim kararlılığı çalışma limitlerinin geliştirilmesi ve sistemin kararlı bölgede kalması için UPFC ile birlikte Enerji Depolama Sistemi (EDS) elemanlarından yakıt hücresi kullanılmıştır. UPFC-EDS ile sistemin gerilim-maksimum yüklenme parametre değerlerinin yanı sıra bara gerilim profilleri analiz edilmiştir. UPFC ile yakıt hücresinin birlikte kullanılması durumunda sistemin yüklenme parametre değerinin arttığı ve bara gerilim profillerinin iyileştiği görülmüştür.

UPFC (Unified power flow controller) is one of the most powerful and complex FACTS (Flexible AC transmission system) devices in a power system today. It is primarily used for simultaneous or independent control of real and reactive power in transmission lines for flexible, reliable and economic operation and loading of power systems. In this paper, the effectiveness of UPFC has been explored in transmission system network when subjected to three phase to ground fault condition. The comparison has been made between VSI (Voltage Source Inverter) based UPFC and ZSI (Z-Source Inverter) based UPFC. From the results so obtained, it has been established that the performance of ZSI based UPFC is superior as compared to that of VSI based UPFC.

The introduction of the flexible AC transmission system (FACTS) in the power system reduces the losses, reduces the cost of the generation, improves the stability and also improves the load capability of the system. Some application of the Flexible AC transmission system (FACTS) technologies to existing high voltage power system has proves the use of FACTS technology may be a cost effective option for power delivery system enhancement. Amongst various power electronic devices unified power flow controller (UPFC) may be considered to be a capable of regulating the power flow and minimizing the power loss simultaneously. Since for the cost effective application of the FACTS technology a proper selection of the number and the placement of these devices is required. The main aim of this paper is to propose the methodology based on the genetic algorithm, able to identify the optimal number and the location of the UPFC devices in an assigned power system network for maximizing system capabilities. In order to validate the usefulness of the approach suggested here is , a case study using a IEEE 30-bus power system is presented and discussed.

Ensuring the transient stability of the power system networks is one of the prime challenges in the highly interconnected power systems. Though the low-frequency oscillations are not very harmful initially, failure to damping out may lead the system to go out of synchronism. The employment of flexible AC transmission systems (FACTS) devices may suppress these oscillations effectively in addition to the enhancement of power transfer capability. Among many FACTS devices, unified power flow controller (UPFC) is one of the most sophisticated ones. Tuning the parameters of power system stabilizer (PSS) coordinated with UPFC for a stable system is a multi-objective optimization problem. This paper aims to optimize the parameters of power system stabilizer (PSS) of power network incorporating UPFC using support vector regression (SVR) in real time to damp out the small signal oscillations hence to enhance the transient stability. System eigenvalues obtained from SVR tuned UPFC coordinated PSS and the fixed gain conventional PSS are compared to investigate the efficacy of the proposed technique for different loading conditions. Besides, time domain simulation comparison proves the superiority of the proposed technique over the conventional one. Furthermore, the statistical performance measures for training and testing datasets provide confidence on the developed SVR model.

The demand for electricity is increasing day by day and we have to produce more electrical energy to meet the load demands. Most of the experts prefer to extend the existing electrical networks over building the new network with greater costs. In this paper, the implementation of the flexible AC transmission systems (FACTS) devices in a simple electrical network is described. FACTS devices enhance power transfer capacity of the line without laying out new transmission line. These devices also protect the system from overloading in case of any contingency in the electrical network. Moreover, this paper describes the impacts of FACTS devices on improving the voltage stability and power handling capability of a transmission line. The proposed methods for the controllable flow of active and reactive power in a transmission line are also elaborated. A simple electrical system is examined to explain the improvement in the constraints of power system using FACTS devices.

The stability and the transmission ability of a power system can be improved using a Flexible AC Transmission Systems (FACTs) devices. Amongst the various types of FACTs devices, Unified Power Flow Controller (UPFC) provides better controlover the power flow in the transmission line and also increases the stability of the system. At the same time, it also effectively suppress the low frequency oscillations by controlling the voltage and power. Hence in this work, a linearized power system with an UPFC is evaluated. This proposed fuzzy-based UPFC controller affords an effective damping control. The results obtained through simulation shows that the proposed UPFC with fuzzy controller is more effective compared to that of conventional PID controllers. Â

Flexible AC Transmission System (FACTS) controllers are advanced power electronic devices employed in electrical power systems to enhance system stability, reliability, and power transfer capabilities. These controllers enable dynamic and flexible control of various transmission parameters such as voltage, current, impedance, and phase angle, thereby improving the overall power system performance. FACTS devices are broadly classified into series, shunt, series- series, and series-shunt configurations, each designed to manage reactive power and regulate voltage either by injecting voltage in series or current in shunt with the transmission line. Well-known FACTS devices include Static Var Compensators (SVC), Static Synchronous Compensators (STATCOM), Thyristor Controlled Series Capacitors (TCSC), Static Synchronous Series Compensators (SSSC), and Unified Power Flow Controllers (UPFC), each serving specific roles in power flow control, voltage regulation, and transient stability enhancement. The integration of these controllers provides significant benefits such as increased transmission line capacity, improved voltage stability, minimized transmission losses, and damping of power system oscillations. They are capable of rapid response during transient disturbances, effectively mitigating voltage collapses and enhancing system resilience against faults and contingencies. FACTS controllers not only improve steady-state operational parameters but also address dynamic stability and transient conditions, enabling power systems to operate closer to their stability limits while maintaining security. Their deployment helps avoid costly infrastructural expansions by optimizing existing transmission assets, which is critical given environmental and economic constraints. Recent advances in semiconductor technologies and control algorithms have made FACTS devices more reliable, efficient, and adaptable to modern grids, including renewable integration and deregulated power markets. In summary, FACTS controllers play a vital role in modern power systems by providing flexible, efficient, and reliable solutions for power flow management, voltage control, and system stability enhancement, thereby supporting the evolving demands of today's complex electrical networks.

A generalized approach for determination of optimal location and performance analysis of FACTs devices

Flexible AC Transmission Systems (FACTS) play a vital role in enhancing the stability, efficiency, and reliability of modern power systems. With the increasing complexity of power grids due to the integration of renewable energy sources, effective control of power flow, voltage regulation, and stability improvement are critical challenges. FACTS devices, such as Static Synchronous Compensator (STATCOM), Unified Power Flow Controller (UPFC), and Thyristor- Controlled Series Capacitor (TCSC), offer advanced solutions to mitigate these challenges by providing dynamic voltage control, reactive power compensation, and congestion management. This paper presents a comprehensive analysis of various FACTS devices, focusing on their control strategies, applications, and impact on improving power system performance. Simulation results demonstrate the effectiveness of FACTS devices in maintaining voltage stability, optimizing power flow, and minimizing transmission losses, ultimately contributing to a more efficient and resilient power grid.

With recent development of power electronics technology, power system stability enhancement and optimal power flow control by using flexible AC transmission system (FACTS) devices have so far been studied. The FACTS devices to relieve multiple constraints can also make it possible to enhance Available Transfer Capability (ATC) without construction of new transmission lines. In this paper, a new method for improving transient stability by unified power flow controller (UPFC) is proposed. Then the proposed method is applied to an OPF control by using UPFC for avoiding multiple constraints. The new OPF method is used for enhancement of ATC taking into account transient stability constraints as well as overload and steady-state stability constraints. The OPF problem is formulated to minimize total inverter capacity of UPFC. Effectiveness of the proposed method is shown by numerical examples for 3-machine 9-bus system and 10-machine 47-bus system.