Intelligent Power Quality Monitoring Concept: 4 Applications | Electricity

There are many applications for the intelligent power quality monitoring concept.

Some of the more important applications are listed in this article: 1. Industrial Power Quality Monitoring Applications 2. Power System Performance Assessment and Benchmarking 3. Applications for System Maintenance, Operations and Reliability 4. Power Quality Monitoring and the Internet.

1. Industrial Power Quality Monitoring Applications:

a. Energy and demand profiling with identification of opportunities for energy savings and demand reduction.

b. Harmonics evaluations to identify transformer loading concerns, sources of harmonics, problems indicating misoperation of equipment (such as converters), and resonance concerns associated with power factor correction.

c. Voltage sag impacts evaluation to identify sensitive equipment and possible opportunities for process ride-through improvement.

d. Power factor correction evaluation to identify proper operation of capacitor banks, switching concerns, resonance concerns, and optimizing performance to minimize electric bills.

e. Motor starting evaluation to identify switching problems, inrush current concerns, and protection device operation.

f. Short-circuit protection evaluation to evaluate proper operation of protective devices based on short-circuit current characteristics, time-current curves, etc.

2. Power System Performance Assessment and Benchmarking:

a. Trending and analysis of steady-state power quality parameters (voltage regulation, unbalance, flicker, harmonics) for performance trends, correlation with system conditions (capacitor banks, generation, loading, etc.), and identification of conditions that need attention.

b. Voltage sag characterizing and assessment to identify the cause of the voltage sags (transmission or distribution) and to characterize the events for classification and analysis (including aggregation of multiple events and identification of sub-events for analysis with respect to protective device operations).

c. Capacitor-switching characterization to identify the source of the transient (upline or downline), locate the capacitor bank, and characterize the events for database management and analysis.

d. Performance index calculations and reporting for system benchmarking purposes and for prioritizing of system maintenance and improvement investments.

3. System Maintenance, Operations and Reliability:

a. Locating faults. This is one of the most important benefits of the monitoring systems. It can improve response time for repairing circuits dramatically and also identify problem conditions related to multiple faults over time in the same location.

b. Capacitor bank performance assessment. Smart applications can identify fuse blowing, can failures, switch problems (restrikes, reignitions), and resonance concerns.

c. Voltage regulator performance assessment to identify unusual operations, arcing problems, regulation problems, etc.

d. Distributed generator performance assessment. Smart systems should identify interconnection issues, such as protective device coordination problems, harmonic injection concerns, islanding problems, etc.

e. Incipient fault identifier. Research has shown that cable faults and arrester faults are often preceded by current discharges that occur weeks before the actual failure. This is an ideal expert system application for the monitoring system.

f. Transformer loading assessment can evaluate transformer loss of life issues related to loading and can also include harmonic loading impacts in the calculations.

g. Feeder breaker performance assessment can identify coordination problems, proper operation for short-circuit conditions, nuisance tripping, etc.

4. Power Quality Monitoring and the Internet:

Many utilities have adopted power quality monitoring systems to continuously assess system performance and provide faster response to system problems. It is clear that intranet and internet access to the information has been key to the success of these systems. An example of a completely Web based power quality monitoring system is the result of research initiated by TVA and EPRI.

Specifications for the system were developed with the help of all the members of the EPRI Power Quality Target group to support the variety of applications which must be supported by such a system. The result was a modular system with a completely open architecture so that it can be interfaced with a wide variety of platforms. After helping with the development of the system, TVA is deploying the Web-based monitoring systems at important customers and substations throughout their system.

TVA distributors are also taking advantage of the system. It already had an extensive power quality monitoring system in place, and the new system is integrated with the existing monitoring system infrastructure at the central data management level (enterprise level). This provides the capability to provide system-wide analysis of the power quality information.

The future of these systems involves integration with other data-collection devices in the substation and the facility. Standard interfaces like the Power Quality Data Interchange Format (PQDIF) and COMTRADE are used to share the information, and standard protocols like UCA are used for the communications. The intelligent applications described will be applied at both the substation level and at the enterprise level, as appropriate.

Summary and Future Direction:

Power quality monitoring is fast becoming an integral component of general distribution system monitoring, as well as an important customer service. Power producers are integrating power quality monitoring with monitoring for energy management, evaluation of protective device operation, and distribution automation functions. The power quality information should be available throughout the company via the intranet and should be made available to customers for evaluation of facility power conditioning requirements.

The power quality information should be analyzed and summarized in a form that can be used to prioritize system expenditures and to help customers understand the system performance. Therefore, power quality indices should be based on customer equipment sensitivity.

The SARFI index for voltage sags is an excellent example of this concept. Power quality encompasses a wide range of conditions and disturbances. Therefore, the requirements for the monitoring system can be quite substantial.

The information from power quality monitoring systems can help improve the efficiency of operating the system and the reliability of customer operations. These are benefits that cannot be ignored. The capabilities and applications for power quality monitors are continually evolving. Ongoing development and new applications are described on various Internet sites.