C. Subramani

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.

Particle Swarm Optimization Algorithm to Find the Location of Facts Controllers for a Transmission Line

The main purpose of this project is to find the optimal location of FACTS controllers in a multi machine power system using particle swarm optimization (PSO). Using the proposed method, the location of FACTS controller, their type and rated values are optimized simultaneously. Among the various FACTS controllers, Thyristor Controlled Series Compensator (TCSC) and Unified Power Flow Controller (UPFC) are considered. The proposed algorithm is an effective method for finding the optimal choice and location of FACTS controller and also minimizing the overall system cost, which comprises of generation cost and the investment cost of the FACTS controller using PSO and conventional Newton Raphsons power flow method. A MATLAB coding is developed for Enhanced Genetic Algorithm. In order to verify the effectiveness of the proposed method, IEEE 14- bus system is used.

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).

Analysis and experimental investigation for grid-connected 10 kW solar PV system in distribution networks

In this paper, the dynamic performance of a grid connected photovoltaic (PV) power system of a distribution networks is studied and experimental results are presented. Due to oscillating nature of the PV power plant, the grid integration requires stable and steady power injection with good power quality (PQ). Hence, the PQ analysis has been carried out under different climate conditions at 10 kW Solar Power Plant (SPP). This SPP can operate in grid connected or in isolated mode. The proposed PV power plant system is modelled and its performance is studied. This integrating model is composed of boost converter, maximum power point tracking (MPPT) control, inverter and filter design. It also explains the behaviour of system response whether it is stable and unstable condition. It is analyzed that the presence of high penetrated grid connected solar PV system will exhibit low PQ issues like voltage variations and harmonics. To study this effect a 10 kW SPP is developed for verifying the performance of the system.

Stability Index Based Voltage Collapse Prediction and Contingency Analysis

Voltage instability is a phenomenon that could occur in power systems due to stressed conditions. The result would be an occurrence of voltage collapse leading to total blackout of the system. Therefore, voltage collapse prediction is an important part of power system planning and operation, and can help ensure that voltage collapse due to voltage instability is avoided. Line outages in power systems may also cause voltage collapse, thereby implying the contingency in the system. Contingency problems caused by line outages have been identified as one of the main causes of voltage instability in power systems. This paper presents a new technique for contingency ranking based on voltage stability conditions in power systems. A new line stability index was formulated and used to identify the critical line outages and sensitive lines in the system. Line outage contingency ranking was performed on several loading conditions in order to identify the effect of an increase in loading to critical line outages. Correlation studies on the results obtained from contingency ranking and voltage stability analysis were also conducted, and it was found that line outages in weak lines would cause voltage instability conditions in a system. Subsequently, using the results from the contingency ranking, weak areas in the system can be identified. The proposed contingency ranking technique was tested on the IEEE reliability test system.

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.

Line outage contingency screening and ranking for voltage stability assessment

This paper presents the voltage stability based weak area clustering techniques in power system. The techniques employed voltage stability analysis (VSA) and Line outage contingency analysis (LOCA). From the VSA and LOCA, the most critical lines in a system during stressed condition are identified. A predeveloped voltage stability index was utilized as an indicator to voltage stability condition of the system. The weak areas formed by the lines are identified as the most critical lines. The results show that the lines which are identified as the weak lines from stability analysis. The proposed technique was implemented on IEEE reliable test system and the results show that distinct weak areas were identified when the system was closed to the stressed Condition.

Application of integrated wind energy conversion system (WECS) and photovoltaic (PV) solar farm as Statcom to regulate grid voltage during night time

This paper presents the concept of utilizing photovoltaic (PV) solar farm (SF) as flexible ac transmission system controller-static synchronous compensator, to regulate the point of common coupling voltage during night time when the SF is not producing any active power. The proposed control will enable increased connections of WECS to the grid. MATLAB/Simulink based simulation results are presented for validation of the system.

Voltage stability improvement using “Sen” transformer

This paper covers the modelling of the standard IEEE 14 bus system using the MATLAB package. The basic system is tested under large and small disturbances to study the dynamic behaviour of the system and the stability margins associated with the different configurations of the system. As a suggested solution to increase stability margins of the system, Sen transformer is added, modelled and tested to show the effect of the controller on the different stability margins under both large and small disturbances.