Subranshu Sekhar Dash

Voltage Profile Improvement Using FACTS Devices: A Comparison between SVC, TCSC and TCPST

If the reactive power of the load is changing rapidly, then a suitable fast response compensator is needed Static VAR Compensator (SVC) thyristor control series compensator (TCSC) and thyristor control phase shift transformer (TCPST) is such a compensator which belongs to FACTS family. The ultimate objective of applying reactive shunt compensation in the line is to improve the voltage profile. The inclusion of the FATCS devices in the circuit improves the reactive power in the line. FACTS are successfully simulated and the results show the voltage profile improvement.

Voltage Quality Improvement Using DVR

The problem of voltage sags and Swells and its severe impact on sensitive loads is well known. To solve this problem, custom power devices are used. One of those devices is the Dynamic Voltage Restorer (DVR), which is one of the most efficient and effective modern custom power devices used in power distribution networks. This paper described DVR principles and voltage correction methods for balanced and/or unbalanced voltage sags and swells in a distribution system. Simulation results were presented to illustrate and understand the performances of DVR under voltage sags/swells conditions. The results obtained by simulation using MATLAB confirmed the effectiveness of this device in compensating voltage sags and swells with very fast response (relative to voltage sag/swell time).

A PD-type Multi Input Single Output SSSC damping controller design employing hybrid improved differential evolution-pattern search approach

A novel PD type MISO controller is proposed for SSSC based damping controller.Hybrid improved DE and PS approach is proposed to optimize the controller parameters.In improved DE, control parameters F and CR are varied during optimization runs.Both single machine infinite bus and multi-machine power systems are considered.Comparative results are provided to show the superiority of the proposed design approach. In this paper, a Proportional Derivative (PD)-type Multi Input Single Output (MISO) damping controller is designed for Static Synchronous Series Compensator (SSSC) controller. Both local and remote signals with associated time delays are chosen as the input signal to the proposed MISO controller. The design problem is formulated as an optimization problem and a hybrid Improved Differential Evolution and Pattern Search (hIDEPS) technique is employed to optimize the controller parameters. The improvement in Differential Evolution (DE) algorithm is introduced by changing two of its most important control parameters i.e. Scaling Factor F and Crossover Constant CR with an objective of achieving improved performance of the algorithm. The superiority of proposed Improved DE (IDE) over original DE and hIDEPS over IDE has also been demonstrated. To show the effectiveness and robustness of the proposed design approach, simulation results are presented and compared with DE and Particle Swarm Optimization (PSO) optimized Single Input Single Output (SISO) SSSC based damping controllers for both Single Machine Infinite Bus (SMIB) power system and multi-machine power system. It is noticed that the proposed approach provides superior damping performance compared to some approaches available in literature.

Non Linear Control of STATCOM

This paper presents an investigation on a voltage regulator for parallel operated isolated synchronous generators supplying 3-phase 4-wire loads driven by constant speed prime mover like diesel engine, bio-mass, gasoline, hydro turbine unit etc. The proposed voltage regulator is realized using a STATCOM (static compensator) for providing the reactive power compensation, and load balancing. Three single-phase thyristors based VSC along-with three single-phase transformers and self supporting DC bus is used as a voltage controller for supplying 3-phase 4-wire loads. The neutral point of the load is achieved using neutral point of the excitation capacitors and primary windings terminal of the transformers. The proposed isolated electrical generating system is modeled and simulated on MATLAB using Simulink and PSB (Power System Blockset) toolboxes. The performance of proposed voltage controller for isolated synchronous generators is demonstrated while feeding loads.

A novel fuzzy logic controller for STATCOM to improve power system stability

This paper presents an application of Single-input Fuzzy Logic Controller (SFLC) to determine the control signal of a Static Compensator (STATCOM) synchronous for improvement of power system stability. This compensation scheme is relevant to Flexible AC Transmission systems (FACTSs) technology which is used worldwide to improve system dynamic performance. STATCOM improves the damping of electromechanical oscillations when used in transmission systems. The SFLC uses only one input variable which is called as signed distance. The SFLC has the advantages of reduced number of rules. Thus, generation, estimation and tuning of control rules are much easier while comparing with the existing conventional Fuzzy Logic Controllers (FLCs). The proposed control method is applied to control the AC and DC bus voltage of a STATCOM connected at a load bus in a Single Machine Infinite Bus (SMIB) System and also to improve the power system stability.

Economic emission OPF using hybrid GA-Particle swarm optimization

This paper presents a Hybrid Genetic Algorithm (HGA) Particle Swarm Optimization (PSO) approach to solve Economic Emission Optimal Power Flow problem. The proposed approach optimizes two conflicting objective functions namely, fuel cost minimization and emission level minimization of polluted gases namely NOX , SOX and COx simultaneously while satisfying operational constraints. An improved PSO which permits the control variables to be represented in their natural form is proposed to solve this combinatorial optimization problem. In addition, the incorporation of genetic algorithm operators in PSO improves the effectiveness of the proposed algorithm. The validity and effectiveness have been tested with IEEE 30 bus system and the results show that the proposed algorithm is competent in solving Economic Emission OPF problem in comparison with other existing methods.

Thyristor Controlled Series Capacitor as an Optimizer in an Electrical Market

This paper presents an overview over different areas where FACTS devices can improve transmission system efficiency especially under the condition of liberalized electricity markets. Furthermore, a network example, is shown where the installation of Thyristor Controlled Series Capacitor (TCSC) increases the transfer capacity into a region considerably while maintaining security margins. This can help to reduce or even eliminate congestion in a transmission network.

Transient Stability Enhancement of a Multi-Machine System Using BFOA

The Static Synchronous Compensator (STATCOM) is the typical Flexible AC Transmission System (FACTS) devices playing a vital role as a stability aid for the large transient disturbances in a multi-machine power system. This paper deals with the design of STATCOM with two different controllers installed in a multi-machine power system. The disturbances are created in the multi-machine system and the results obtained are analyzed. The results proved the supremacy of the feedback linearizing controller tuned by Bacterial Foraging Optimization Algorithm (BFOA) of STATCOM over the power system stabilizer (PSS) equipped with PI Proportional-Integral controller of STATCOM.

Enhanced discrete differential evolution to determine optimal coordination of directional overcurrent relays in a power system

This paper presents an enhanced differential evolution technique to solve the optimal coordination of directional overcurrent relays in a power system. The most vital task when installing directional relays on the system is selecting suitable current and time settings such that their fundamental protective functions are met under the requirements of sensitivity, selectivity, reliability and speed. Coordination of directional over current relays can be formulated as a linear or non-linear problem taking into account the discrete value for the time dial settings and the pickup current settings. The results are compared with different algorithms on a test system and are presented in this paper.

Comparison of PSO tuned feedback linearisation controller (FBLC) and PI controller for UPFC to enhance transient stability

An Unified Power Flow Controller (UPFC) is a typical Flexible AC Transmission System (FACTS) device playing a vital role as a stability aid for large transient disturbances in an interconnected power system. This paper deals with the design of Feedback Linearising Controller (FBLC) tuned by PSO for UPFC.The disturbances are created in the SMIB system and the results are simulated. The results proved the supremacy of the Power System Stabilizer (PSS) equipped with FBLC over the PSS equipped with Proportional Integral (PI) controller.