Bus Voltage Stability Index Research Articles

Optimal Location of Capacitor in a Radial Distribution System Using New Hybrid Method

This paper solves the problem of optimal sizing and locations of capacitors in radial distribution system using a new hybrid method combining a new stability index and a genetic algorithm to improve the loss, voltage and stability planes. The Bus Voltage Stability Index BVSI is used to determine the locations and the genetic algorithm GA to calculate the size. The GA-BVSI analytical-metaheuristic method, compared with existing methods, is more suitable and recommended for operators who are faced with the problem of sizing capacitors to improve the technical performance of their network. Keywords: Optimal sizing and locations; Capacitors; Radial distribution system; New stability index;Hybrid method.

Enhancement of Voltage Stability by Optimal Placement of Shunt Compensation using Bus Voltage Stability Indices and Reactive Power Margin

Voltage stability problem has caused several blackouts in many countries in recent years. Impending voltage instability has been a significant threat to modern power system's security and reliability. Moreover, the operation and planning of large interconnected power systems is becoming increasingly complex as power demand rises, posing a security risk to the grid. Appropriate efforts to improve power system security and increase voltage stability margin should be planned to keep the system secure. This work investigates the voltage stability of a power system with and without a shunt capacitor. The bus voltage stability index, L index, is used to measure the distance of the power system to its stability limit in order to assign the shunt capacitor. The L-index for a particular load state is computed for all load buses, and the greatest L-index indicates the system's approach to voltage collapse. The system's load ability margin is being traced utilizing a static voltage stability evaluation approach, i.e., PV and QV curve analysis. The minimal power loss approach is used to calculate the optimal capacitor size. The effect of shunt compensation was simulated, and the results with and without compensation were compared. The IEEE-9 bus system was employed in this work, and the system was simulated using MATLAB and Power World Simulator. The result demonstrates that the shunt capacitor enhances voltage stability by injecting the appropriate reactive power.

Enhancing the performance of Transmission Lines by FACTS Devices using GSA and BFOA Algorithms

Flexible Alternating Current Transmission System devices have numerous applications in electrical transmission lines like improvement of voltage stability, reactive power compensation, congestion management, Available Transfer Capacity enhancement, real power loss reduction, voltage profile improvement and much more. The effectiveness of these FACTS devices is enhanced by the placement of these devices in the transmission lines. The placement is based on transmission line sensitivity factors such as Bus voltage stability index and line voltage stability index. This research article focuses on optimizing the location, number and ratings of FACTS devices using Evolutionary Algorithms like Bacterial Foraging Algorithm and Gravitational search algorithm. FACTS devices such as Static Var Compensator, Thyristor Controlled Series Capacitor and Unified Power Flow Controller are placed on IEEE 14 bus and IEEE 30 bus systems for reducing the real power loss in the transmission system. The results show that the performance of the transmission lines is enhanced more using Bacterial Foraging Algorithm than Gravitational Search Algorithm.

Network Structure-Based Critical Bus Identification for Power System Considering Line Voltage Stability Margin

Voltage security assessment of power system is an important and all-inclusive aspect of power system operation and preventive control actions. Fast and accurate detection of critical components of the power system is one essential approach for preventing the occurrence of voltage collapse phenomenon. Over the years, several approaches for voltage collapse point identification and prevention have been widely studied using the continuous power flow approach, minimum singular value of eigenvalues, Jacobian matrices, and power transfer concept. In this work, critical node (bus) identification based on power system network structure is proposed. In this approach, the power system is treated as a multidimensional graph with several nodes (buses) linked together by the transmission lines. An improved line voltage stability margin estimator which is based on active and reactive power changes in a power system is used as the weight of each transmission line and an adaptation of the degree of centrality approach is used to determine the criticality of the system buses. A comparative analysis with other bus voltage stability indices is presented to test the suitability of the proposed approach using the IEEE 14, 30, 57 and 118 bus test systems.

Stability issues in presence variable distributed generation into radial distribution network

Related to environmental issues resulting from the use of traditional energy sources, drive usage of renewable energy is increasing. Changes in the structure of the network will certainly affect the changes in voltage stability. In this paper, discuss the impact of the stability after distributed generation penetration whose its output intermittent relatively. The simulation based PSAT software and tested into IEEE 30 bus system. Observation of voltage deviation and SVSI-index on some load buses in conditions before and after integration of wind generation. Load condition is a very determining factor of bus voltage stability index. This relates to the active power and reactive power needs that must be injected by DG penetration.

Voltage stability index-based reactive power compensation scheme

Abstract Reports of various committees set up to review the 2003 North American major power outages pointed out that a major exacerbating factor has been lack of situational awareness by power system operators. To improve reactive power compensation and contribute to the mitigation of power outages associated with the present near-limit operated commercialized grid, a bus voltage stability (BVS) index based reactive power compensation scheme has been developed. BVS index is a hybrid voltage stability computation model involving the two machine modeled L-index and a complex power Π -transmission line structure modeled Ls-index developed by the authors. The current regional wheeling of power across transmission distance far beyond the two machine model has necessitated the development of a novel Ls-index model suitable for long lines. The composite scheme was then incorporated into Newton–Raphson’s (N–R) power flow which encompasses multiple shunt devices (multi-shunt). This arrangement provided a knowledge based system for power system monitoring. Results obtained from applying the developed models and schemes in the IEEE 300 bus system with zoning and under varying operating conditions showed the system’s capability to provide improved system monitoring and optimal compensation based on availability.

Comprehensive Evaluation Index on Voltage Fluctuation and Stability Considering Wind Power Generators

In this paper, voltage fluctuation and stability analysis of critical buses was performed using multiple indexes to power system with wind farm connected. Considering the intermittency and randomness of wind speed, this paper constructed three voltage fluctuation indexes according to the characteristic of voltage random distribution. Bus voltage stability index was also calculated with the help of PV and QV curves in the paper. The simulation analysis performed in the DIgSILENT/PowerFactory basing on three machines nine nodes system with double-fed wind farm was carried out to reveal the impacts of wind generation uncertainty on voltage fluctuation and stability.