Ashok Sundaram

Distance estimation technique for single line-to-ground faults in a radial distribution system

A simple yet powerful algorithm to estimate the distance to a single line-to-ground fault on a distribution feeder is proposed. The algorithm is implemented in a power monitor instrument and the estimation of distance is made within the instrument itself. The algorithm is designed to work where the only available data to the instrument are a single point measurement taken at the substation and the positive and zero-sequence impedance of the primary feeder. The single point measurement consists of three-phase voltage and current waveforms. Network topology data are not available to the algorithm. The new technique accommodates computational power and data constraints while maintaining adequate accuracy of the measurements.

Controller hardware-in-the-loop validation for a 10 MVA ETO-based STATCOM for wind farm application

This paper reports experimental validation of a Static Synchronous Compensation (STATCOM) by controller hardware-in-the-loop (CHIL) testing with a real-time digital simulator (RTDS). The controller is designed and developed for a 10 MVA STATCOM for voltage regulation at the PCC of a 50 MW wind farm connected to a 69kV utility grid. Emitter Turn-off (ETO) thyristors are switching devices in the multilevel inverter. The STATCOM controller was developed for a cascade multilevel inverter and has been validated on a laboratory test-bench. The CHIL testing of the controller is done with detailed scaled model of the 50 MW wind farm and 69kV utility system. The experimental results from the RTDS for both steady state and dynamic changes in the STATCOM output validate the STATCOM controller design and performance.

Testing of a controller for an ETO-based STATCOM through controller hardware-in-the-loop simulation

The testing of a controller for a proposed 10 MVA STATCOM through hardware-in-the-loop experimentation is described in this paper. The electrical environment into which the STATCOM is to be inserted, including a significant portion of the utility network and a nearby wind farm are simulated using a large-scale digital real time electromagnetic transients simulator. The STATCOM controller is interfaced to the simulation, providing firing pulses to the simulated STATCOM and receiving feedback of system voltages and currents. Notional wind speed data is used to simulate realistic behavior of the wind farm. This paper presents preliminary results of the ongoing testing of the controller under the most realistic system conditions.

Implementation and validation of a Five-Level STATCOM Model in the RTDS small time-step environment

In this paper, the implementation issues of a five-level STATCOM model in RTDS small time-step environment are studied. The five-level STATCOM is modeled by two small time-step VSC models and connected by a three-phase cross card Bergeron transmission line. With appropriate transmission line parameters, little voltage and current distortion is found on voltages and currents along the transmission line. The effectiveness of the STATCOM model is verified by comparing the simulation results of a test system modeled on RTDS to the results of the model from Matlab/Simulink/SimPowerSystems. The sensitivity study of the power loss provides valuable information on the actual and artificial power loss of the STATCOM model. In addition, harmonics analysis further validates the STATCOM model. From the power loss and the comparative study, the effectiveness of the STATCOM model is verified for use in a Control-Hardware-In-Loop (CHIL) testing of the STATCOMs controller.

Capacitor bank predictive maintenance and problem identification using conventional power quality monitoring systems

Functional specifications for an automated capacitor bank predictive maintenance system that works with a conventional power quality monitoring system, are described in This work. This system uses raw power quality monitoring data to automatically evaluate and characterize transient disturbances and system conditions associated with the operation of capacitor banks, i.e., during energization, deenergization, and when the capacitor bank is in service. The system is composed of six rule based modules. The main characteristics and requirements of each module are described. An example output of this predictive maintenance system is provided in order to illustrate the utility and adaptability of the system. A brief discussion of the future system development plans concludes the paper.

A Computational Study of the Thermal Performance of a 15 kV Solid State Current Limiter Cooled by Immersion in Mineral Oil

This paper outlines the thermal performance of a unique liquid-cooled 15 kV/4000 A Solid State Fault Current Limiter (SSFCL) developed by Silicon Power of Malvern, PA with support of EPRI. The design features an extremely high power system which consumes 96 kW of power in a one phase configuration. The system is submerged in mineral oil coolant and the waste heat is dissipated by internal liquid convection and subsequently through an external radiator system driven by a centrifugal pump. This project numerically explores the effects of various design parameters on the heat dissipation and the resulting effect on the operating temperature of several components within the system.Copyright

A Computational Study of the Thermal Performance of a 69 kV Solid State Current Limiter Submerged in FR3 Dielectric Coolant

This paper presents the results of thermal modeling of a unique 69 kV 3000A Solid State Fault Current Limiter (SSFCL) developed by Silicon Power of Malvern, PA with support of EPRI. The development of the Solid State Fault Current Limiter is expected to modernize power distribution systems through the use of small-scale solid-state power devices. The use of this new design is expected to increase reliability and functionality while reducing footprint. However, as the footprint is reduced, the heat flux for the system is increased, leading to the significant possibility of device failure due to thermal excursions if the heat load is not properly managed. The high heat loading requires the use of aggressive thermal management in the form of liquid cooling of the electronics. This system features 288 kW of waste heat in the three phase system. The system is submerged in FR3 dielectric coolant and the desired thermal management system is liquid natural convection within the tank and shed to the ambient through an external finned array system. This project explores the feasibility of this system design.Copyright