Voltage Stability optimization with Renewable Distributed Generation (RDG) using Index Based planning (IBP) and Genetic Algorithm (GA)

Renewable distributed generators (RDGs) are widely embedded in electrical distribution networks due to their economic, technological, and environmental benefits. However, the main problem with RDGs, photovoltaic generators, and wind turbines, in particular, is that their output powers are constantly changing due to variations in sun irradiation and wind speed, leading to power system uncertainty. Such uncertainties should be taken into account when selecting the optimal allocation of RDGs. The main innovation of this paper is a proposed efficient metaheuristic optimization technique for the sizing and placement of RDGs in radial distribution systems considering the uncertainties of the loading and RDG output power. A Monte Carlo simulation method, along with the backward reduction algorithm, is utilized to create a set of scenarios to model these uncertainties. To find the positions and ratings of the RDGs, the artificial gorilla troops optimizer (GTO), a new efficient strategy that minimizes the total cost, is used to optimize a multiobjective function, total emissions, and total voltage deviations, as well as the total voltage stability boosting. The proposed technique is tested on an IEEE 69-bus network and a real Egyptian distribution grid (East Delta Network (EDN) 30-bus network). The results indicate that the proposed GTO can optimally assign the positions and ratings of RDGs. Moreover, the integration of RDGs into an IEEE 69-bus system can reduce the expected costs, emissions, and voltage deviations by 28.3%, 52.34%, and 66.95%, respectively, and improve voltage stability by 5.6%; in the EDN 30-bus system, these values are enhanced by 25.97%, 51.1%, 67.25%, and 7.7%, respectively.

The transmission of electrical energy using AC started at the end of the 19th century and replaced smaller existing local DC distribution systems. By extending local supply areas and providing energy transfer over longer distances various problems regarding mainly voltage control and stability were observed caused mainly by reactive power unbalances in the systems. Switched reactive power compensation (shunt capacitors, shunt reactors) were primarily used to control the steady state system voltages. Dynamic reactive compensation were based on rotating machines, eg synchronous condensors. In the mid 60's of the 20 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> century first static compensation devices, ie DC controlled reactors (mercury arc bulbs) and thyristor controlled devices (thyristor switched capacitors-TSC, thyristor controlled reactors-TCR) came up. Fast response times, lower losses and less maintenance requirements of thyristor controlled devices resolved the limitations of rotating machines and DC controlled devices. Evaluation of operating losses resulted more and more in the use of Static Var Compensators (SVC) which were built up by combinations of TCR and TSC branches. These shunt devices together with series connected devices TCSC (thyristor controlled series capacitors) provided a base for FACTS (Flexible AC transmission systems). FACTS allows transmission systems to be more efficiently used with regard to improved dynamic system voltage control on one side and higher power transfer capabilities on the other side. In AC transmission systems SVCs are installed presently with a total size of more than 100000 MVA. New power electronic devices (GTOs, IGCT, IGBT) were introduced to the FACTS market and allowed the use of current and voltage source converters (VSC) for providing fast reactive power compensation. With further improvement of controls, development of semiconductors and new arrangements of VSC technology to-days reactive power compensation is a key method to establish a reliable AC power transmission. The paper gives an overview from the early days of reactive power compensation towards the present transmission system situation. It compares early solutions with to-days devices, provides decisive factors for the steps in development of arrangements and discusses advantages of the present devices.

The control of reactive power in any transmission network is important to ensure voltage stability of the entire power grid. Flexible AC Transmission Systems (FACTS) have proven to be efficient in providing controllability to reactive power for voltage stability management. However, the performance of the FACTs devices largely depends on the installation location. A fuzzy logic technique for finding the optimal location for the Thyristor Controlled Series Capacitor (TCSC) and Static Var Compensator (SVC) FACTS devices with specific security indices is proposed in this paper. The proposed indices for SVC placement are the Loss Sensitivity Factor (LSF) and critical voltage, while the considered indices for TCSC placement are the loss sensitivity factor (LSF) and line stability index (LSI). The indices are fuzzified to obtain a suitability index which determines the suitable line(s) and node(s) accordingly. The proposed approach is implemented on the IEEE 30 bus network. The SVC reduced the overall transmission loss by 1.6%, while the TCSC reduced the transmission loss by 4.94 %. The loading margin also improved by 24.87% and 2.92% using SVC and TCSC, respectively. The voltage profile also remained close to 1 p.u under varying load conditions. The results indicate the effectiveness of the proposed technique at reducing transmission loss, improving voltage stability and improving voltage profile simultaneously.

This paper primarily focuses on an investigative study on allocating Flexible AC transmission system (FACTS) devices on radial distribution systems. The FACTS device that is used in this paper is static var compensator (SVC). In this paper, SVC is placed on each bus except substation bus and study the results to find the best location for allocation. A design of SVC was done by fixed reactance method. The total power loss of network and voltage of nodes have been analyzed for each allocation and the sequences of each implementation have been compared to find the best location of SVC. The proposed algorithm has been executed on IEEE 33-bus and 69-bus standard test systems.

Design and installation of a ±250 kVAr D-STATCOM for a distribution substation

With increasing focus on economical as well as environmentally friendly means for mass transit, rail transport is gaining renewed momentum in many parts of the world. This means investing in novel rail infrastructure as well as upgrading and electrifying existing facilities. The TEN (Trans-European Network) program within the European Union is but one current example of the importance attributed to more and better mass transit all over the world. The feeding of heavy rolling stock from AC grids will in many cases cause unacceptable voltage drops as well as unsymmetry between phases of the feeding grid. A traditional way to improve the situation would be to build additional power transmission lines and/or step up the feeding voltage to a higher level. This, however, may be undesirable or even impossible, for cost reasons as well as for environmental reasons. FACTS devices offer means of remedy within the existing feeding grid, restoring grid symmetry as well as voltage stability, and also mitigating harmonic distortion emanating from rolling stock. FACTS devices such as SVC (Static Var Compensator) and STATCOM (Static Compensator) are well proven and commercially available today. The paper treats dynamic load balancing of grids supplying power to rail transport, as well as dynamic voltage support and harmonic mitigation, by means of SVC as well as STATCOM.

Voltage stability is an important issue in power system operation. Flexible AC transmission systems, so-called FACTS devices, help to improve voltage stability and minimize real power losses. The effectiveness of FACTS devices depend on their proper location and rating. This paper presents a method, based on line flow sensitivity factors such as bus voltage stability index and line voltage stability index, to find suitable locations of multi-type FACTS devices. Also this paper proposes an application of particle swarm optimization (PSO) and harmony search algorithm (HSA) in optimizing the rating of FACTS devices. The proposed approaches are evaluated with three different objective functions namely, minimization of real power loss, improvement of voltage profile and enhancement of voltage stability. The performance of proposed methods is analyzed on IEEE 14 bus system by implementing FACTS devices such as static var compensator (SVC), thyristor controlled series capacitor (TCSC) and unified power flow controller (UPFC).The analysis shows that there is a reduction in real power loss and improvement in voltage stability and voltage profile of the system after employing FACTS devices. It also shows that both real power loss and bus voltage stability index (BVSI) have been reduced more with FACTS ratings obtained from PSO than with that from HSA.

This Voltage stability problems increasing day by day because of demand increase. It is very important to analyze the power system with respect to voltage stability. Location of FACTS devices is important for the enhancement of voltage stability. This paper investigates the voltage stability analysis of 14 bus systems by optimally locating Flexible AC Transmission System (FACTS) devices. Shunt and series FACTS controllers are introduced in the weakest bus and its effectiveness is assessed by comparing voltage profile and loading margins enhancement. It is shown that best location for static voltage stability margin is the “weakest bus” of the system. Continuation power flow (CPF) is done with PSAT (power system stability analysis Toolbox).

The Thyristor Controlled Series Compensator (TCSC) and Static Var Compensator (SVC) are variable impedance Flexible AC Transmission Systems (FACTS) Controllers. A combination of the TCSC and the SVC installation is proposed to acquire superior performance for the power system. The coordination between the two pieces of equipment is designed with the SVC treated as the supplement of the TCSC. When operation of the TCSC is constrained by the inherent limitation of equipment, such as due to the firing-angle limitation of the thyristors, the adjustable SVC can supply the auxiliary support to improve the overall performance. The voltage and angle stability margins can be greatly improved with the compatible control schemes of the TCSC and the SVC.

This paper presents an application of a flexible AC transmission system (FACTS) device as additional control in reactive power (VAR) optimization problem and analyzes the impact on system loss minimization. The adopted FACTS device is a new static VAR compensator (SVC). The general SVC consists of internal devices, and local devices, and the operation mode of the general SVC model is voltage control mode only. The new SVC model controls local, remote, internal and external devices simultaneously. It has two modes of operation: (1) Voltage control mode; and (2) Q control mode. This paper analyzes the functions of the new SVC, and implements them in the practical power systems. The impact of VAR optimization with new SVC model on loss minimization is also discussed by comparing it with VAR optimization with general SVC model as well as VAR optimization without SVC model.

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)

This paper introduces an adaptive terminal voltage regulation of a standalone self excited induction generator using flexible AC transmission systems (FACTS). FACTS in the form of static VAR compensator (SVC) is introduced. SVC is used to regulate the terminal voltage of self excited induction generator-based (SEIG) wind generator working with variable speed and load. Since, the wind generator operates over a wide range of operating conditions; the terminal voltage of the induction generator is not regulated. This terminal voltage is controlled by adapting the value of the excitation capacitance of SVC using artificial neural networks (ANN) and adaptive neuro-fuzzy inference systems (ANFIS). Changing the excitation capacitance is performed by controlling the firing angle of SVC under different operating conditions to control the terminal voltage. A mathematical model of SEIG with variable load and speed along with SVC is developed and simulated in MATLAB to get the excitation capacitance required for voltage control. Simulation results are used to train both ANN and ANFIS for on-line prediction of the suitable firing angles required to control the terminal voltage of the system under these operating conditions. Results signify the supremacy of ANFIS over ANN in terms of performance measures.

&lt;span&gt;The rise in demand for electricity and the high cost of constructing new power networks reckons optimal utilization of electric power overloading and excessive power transfer along transmission lines, high losses, voltage instability, poor power quality, reliability issues. Flexible AC transmission system (FACTS) boosts the static and dynamic performance of power systems. Although efficient power transmission by improving power quality and voltage profile enhancement is controlled using the FACTS devices the placement, types, and sizing are important parameters to be optimized for the power system. This paper develops the economic multiple FACT placements and sizing solution during N-1 contingency conditions. Placement and sizing being the stochastic problem meta-heuristic algorithm genetic algorithm (GA) is used and applied on the standard IEEE 9 bus system. MATLAB-based simulation is developed for economic placement of multiple FACTS and single FACTS devices in different scenarios (without FACTS devices, with single FACTS devices, and with multiple FACTS devices). Both static VAR compensators (SVC) and thyristor-controlled series capacitors (TCSC) are used (either single or multiple) to optimize the transmission loss and total cost. The results show that transmission loss and cost reduction with 70% compensation is working better with about 0.1 MW lesser loss in many cases.&lt;/span&gt;

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.

The increasing demand for reliable and high-quality electrical power has led to the development of advanced techniques for controlling power flow in transmission networks. Flexible AC Transmission Systems (FACTS) are key technologies designed to enhance the controllability and stability of AC power systems. Among FACTS devices, the Static VAR Compensator (SVC) is widely used to regulate voltage, improve power factor, and maintain system stability under varying load conditions. This project focuses on the design and implementation of a Static VAR Compensator for improving voltage stability and reactive power management in an AC transmission system. The SVC achieves rapid reactive power compensation using thyristor-controlled reactors (TCRs) and thyristor-switched capacitors (TSCs), allowing dynamic adjustment to changing system conditions. By maintaining voltage within desired limits, the SVC enhances the reliability, efficiency, and operational flexibility of the transmission network. The project includes simulation and analysis of the SVC in different loading scenarios to demonstrate its effectiveness in reducing voltage fluctuations, improving power quality, and minimizing transmission losses. The implementation of SVC in a transmission system represents a cost-effective solution for modern power systems, enabling better control of power flow and contributing to the stability of the electrical grid.