Intelligent Electronic Devices Increase Availability, Power Quality in Power Distribution Networks

Until recently, power distribution networks have operated in a simple, unidirectional flow. Rising overall consumption and a growing share of renewable generation are two factors changing these operational needs. Wind power and solar generation often take place closer to customers, making power networks multidirectional. To operate these growing unidirectional and multidirectional distribution networks in an efficient and economical way, a more comprehensive approach is essential that involves new smart grid technologies for monitoring and automating the distribution network.

Current Situation

Many power distribution networks are, or soon will be, under threat from unpredictable, inclement weather conditions or aging infrastructures. In addition, renewable power generation such as photovoltaic (PV), wind power and biomass are starting to directly feed into distribution networks. Consumers are evolving and the distribution network is changing into a multidirectional network that requires new automation to prevent overload situations and outages. There are, therefore, new challenges to address:
• Prevention of outages to avoid losses of earnings and/or penalties,
• Reduction of power losses,
• Maximized utilization of medium-voltage (MV) equipment (capacity utilization and life span),
• Low-voltage (LV) stabilization to stay within tolerances,
• Demand response or better modulation according to power production, and
• Asset management.
An ideal approach to distribution automation would not target only one of these challenges, but would address all major application issues.

Reduction of Brownouts or Blackouts

Two main factors should be considered: the reduction of the outage frequency and the reduction of the outage duration. Currently, the use of remote terminal units (RTUs) has reduced outage durations by nearly 50 percent on average. Adding spring-loaded or motor-driven load breakers can reduce the outage duration to minutes.
The RTU, combined with fault indicators, informs the substation automation system of the short circuit current flow on the faulty segment. Based on network topology and related algorithms, the substation automation system in the primary station will automatically isolate the faulty section and close the normal open switch in the ring structure. By reclosing the infeed switch at the primary substation, the procedure for service restoration will be completed. This usually takes just one to two minutes.
It is now known that using intelligent electronic devices (IEDs) with combined protection and RTU functionality is the next level of automation, and there are new systems that are able to clear a distribution fault and re-establish power from another source in less than 300 milliseconds.

See more at: http://www.utilityproducts.com/articles/print/volume-16/issue-01/product-focus/alternative-power-construction/intelligent-electronic-devices-increase-availability-power-quality-in-power-distribution-networks.html