Bharat Bhargava

Arc furnace flicker measurements and control

The results of arc flicker investigations and harmonic measurements taken on a 55 MW arc furnace are presented. The arc furnace has been in operation since 1976 and has a 65 MVAr static VAr system (SVS) installed to improve the customers power factor, reduce the voltage fluctuations. and arc furnace flicker. Although the SVS improved the power factor and reduced the voltage fluctuations and incandescent lamp flicker, it caused considerable fluorescent flicker, which was specially noticeable at some remote locations about ten miles away. >

Synchronized Phasor Data Based Energy Function Analysis of Dominant Power Transfer Paths in Large Power Systems

Many large interconnected power systems such as the U.S. eastern interconnection and the U.S. western power system are characterized by many power transfer paths or interfaces with high loading. Disruptions of these transfer paths frequently lead to increased loading on neighboring transfer paths, which themselves will become less secure and could cause further disruptions. State estimators have limited performance under large system disruptions, because of low sampling rates and potentially poor solution quality due to topology errors. Furthermore, disruptions in external power systems cannot be readily seen by control room operators because most state estimators only use reduced models for external systems. A system of well-placed phasor measurement units (PMUs) that provide voltage and current magnitude and phase at a high sampling rate can provide useful system dynamic security information. In this paper we apply energy function analysis using phasor data to monitor the dynamic status of power transfer paths. The ideas will be illustrated using actual data captured by several PMUs in the U.S. western power system

Application of an energy source power system stabilizer on the 10 MW battery energy storage system at Chino substation

Southern California Edison (SCE) installed a 10 MW battery energy storage system (BESS) at its Chino substation facility in 1988. The BESS facility has been in operation for six years and has been used for load leveling and peaking functions. The BESS power conversion system was built with the then state of the art technology and has a very fast response rate when changing power output of the batteries. SCE installed an energy source power system stabilizer (ESPSS) to test the concept of providing damping of power system swings using the ESPSS. The ESPSS basically modulates the power output/input of the energy storage batteries to respond to system frequency deviations caused by power system oscillations. The ESPSS differs from a conventional power system stabilizer. It is designed to change the power output of the power source rather than the voltage or the reactive power output. While installing the ESPSS several upgrades to the BESS were made to improve reliability. Installation of the ESPSS on the battery enables SCE to test the concept of system stabilization using power source output modulation instead of reactive power modulation. The energy storage batteries provide an easy test bed for conducting field tests and response of the ESPSS to system disturbances. This paper discusses the BESS, the ESPSS and presents recorded results from system disturbance monitoring and field tests conducted on the ESPSS and the batteries.

Synchronized Phasor Measurement System project at Southern California Edison Co

This paper presents the Synchronized Phasor Measurement Technology project at Southern California Edison (SCE). SCE has been working aggressively on this technology for the last four years and has installed several phasor measurement units (PMUs) and a phasor data concentrator (PDC) on its system. The data from the PMUs is now being collected and being used for analysis of system disturbances. SCE is continuing to work on this technology with Bonneville Power Administration to implement it for real-time monitoring and will work with other Western Systems Coordinating Council (WSCC) members for information exchange. It is believed that the technology has great potentials for monitoring the system stability and may be, useful in avoiding major system disturbances like the one that occurred on August 10, 1996 in WSCC.

Voltage Stability Analysis of a Multiple-Infeed Load Center Using Phasor Measurement Data

Voltage stability is a security concern for modern power systems. It can be analyzed using detailed or equivalent models. In this paper a new approach is presented for voltage stability analysis using synchronized phasor measurement data. Simple equivalent models of the interconnected system and load side at a measurement point are estimated from the data, and then used for calculating PV curves and predicting the stability limit. Two different models are proposed, and compared based on the analyses performed on the event recordings from US western power system. Minimal modeling and formulation makes the method suitable for online calculations. The models are continuously updated to reflect the effects of different system components and changes

Railway electrification systems and configurations

Several different type of railway traction electric power system configurations have been used in the USA and all over the World. The choice of the system depends on the train service requirements, such as commuter rail, freight rail, light rail, train loads and the electric utility power supply. The railway electrification load is one of the most difficult kinds of load to be fed by an electric utility and presents a challenge both for the railway company and the utility. For the utility, it requires over sized substation facilities and may result in power quality deterioration for its other customers. These utility challenges have been met using different methods for the different railway electrification system configurations. Some countries have used low frequency (15-20 Hz) railway electrification systems to maximize the efficiency and reduce costs, while the others have maintained the 50/60 Hz frequency and have developed high voltage innovative designs to meet these challenges. The low frequency railway electrification system option has been used in European countries and US for almost a century and has provided satisfactory operation. With the modern day power electronics technology available for frequency conversion and the high power quality demanded by the utility power customers, the low frequency systems could be an increasingly viable option to provide an affordable and desirable railway electrification systems.

Monitoring power system dynamics using phasor measurement technology for power system dynamic security assessment

This paper describes the SCE phasor measurement system, and its usefulness in monitoring the inter-area oscillations occurring in the WECC system and reviews some of the power system operation events recorded by the synchronized phasor measurement system (SPMS).

Use of Synchronized Phasor Measurement system for monitoring power system stability and system dynamics in real-time

This paper / presentation is discussing the use of Synchronized Phasor Measurement Technology, which is now being used for monitoring power system status and dynamic transient event recording at Southern California Edison (SCE)off-line and in Real-time. This real time monitoring system is expected to enhance the Transmission system reliability and provide wide area visibility of the WECC system. The SPMS can enable SCE to monitor AC-DC power transmission system reliability and improve reliability by monitoring the phase angles and oscillations at several substations and two remote DC terminals. The system could be used for real-time control in future. SCE has been working aggressively on this Synchronized Phasor Measurement technology for over last twelve years and has installed a network of Phasor Measurement Units (PMUs), obtains data from eighteen Phasor Measurement Units (PMUs) and has installed two Phasor Data Concentrators (PDC) on its system. The data from the PMUs/PDCs is now being collected and being used for monitoring and analysis of the system events.

Effectiveness of pre-insertion inductors for mitigating remote overvoltages due to shunt capacitor energization

Pre-insertion inductors have been introduced as a cost-effective alternative to pre-insertion resistors for controlling capacitor bank energization overvoltages. The results of a system study investigating remote overvoltage mitigation methods for shunt capacitor switching show that pre-insertion inductors are not always as effective as pre-insertion resistors. A parametric study is performed to determine the effectiveness of pre-insertion inductors for controlling remote overvoltages, such as those at the end of open-ended lines or transformer-terminated lines. The results show that the pre-insertion inductors used for controlling remote overvoltages may become completely ineffective for certain system conditions. This finding is explained in terms of the physical phenomena. >

Monitoring voltage stability with real-time dynamics monitoring system (RTDMS®)

Monitoring and maintaining voltage stability in real-time is extremely important for operating a power system reliably. Inadequate voltage support was a contributing factor in several major blackouts in North America, including the 1996 Western Interconnection and the 2003 North East US /Canada blackout. The RTDMS enables monitoring of voltage stability over a wide area using SynchroPhasor technology. The high resolution data provided by synchrophasor technology is time-synchronized and the RTDMS provides for the wide area visualization of key metrics of the electric power grid across a wide area covering multiple control areas, including visualization using synchronized phasor measurements. The RTDMS application has the capability to monitor voltage stability over a wide area in real-time, enabling operators to quickly identify the location of voltage instability, and based on this information, operators can take corrective actions to prevent voltage collapse conditions. The RTDMS tool monitors the current voltage levels as well as the voltage sensitivity or the rate of change of voltage with respect to power (PV curve sensitivity) at multiple locations and alerts the operators if the voltage deviation or the sensitivity exceeds a set threshold. Additionally, the RTDMS application displays the voltage and angle contour plots for the entire interconnection. This presentation/paper presents the voltage stability monitoring capabilities of the RTDMS tool with illustrations of some practical examples.