Distributed generation and its impact on power grids and microgrids protection
The National Institute of Standards and Technology, NIST, is assigned by the US Department of Energy, DoE, to drive Smart Grid developments and harmonization efforts in the power industry. Distributed Generation has been identified as one of the important areas for the Smart Grid developments. Multiple generation sources, bi-directional power flow, power flow time co-ordination and management bring significant benefits and challenges for the existing and emerging power grids and microgrids. In particular, the effect of distributed generation on protection concepts and approaches needs to be understood, and accounted for. This paper describes distributed generation concepts, applications and scenarios. Benefits and challenges are discussed and analyzed on a number of real life examples. Special considerations are provided on ensuring security and dependability, as well as on protection parameterization and coordination.
Solar generation control with time-synchronized phasors
Solar-energy-based photovoltaic (PV) systems are a quickly growing source of distributed generation (DG) and connect to the power distribution system. PV-based DG poses challenges to grid reliability and power quality. One critical challenge is islanding control. Research is underway to devise best practice methods for anti-islanding for all power mismatch conditions. Synchrophasors provide an accurate means to detect islanding conditions by enabling precise, time-synchronized wide-area measurements. This paper presents an islanding detection system for PV-based DG. The system utilizes synchrophasor data collected from local and remote locations to detect the islanded condition. The paper shows how synchrophasors are used to control the DG during such conditions. It also discusses the power system modeling using a Real Time Digital Simulator (RTDS®) and closed-loop testing of the synchrophasor-based islanding detection system, which includes the PV-based inverter and the power distribution system. The effectiveness of the system was experimentally tested on a live power system.
Contractor Failure: Analysis
The possibility exists for any construction contractor to fail to filfill the contract requirements associated with a facility. Contractor failure occurs when a contractor is unable to perform his/her contractual duties, thus requiring the facility owner to invoke the contract's nonperformance clause. This paper provides aggregate contractor business failure statistics and outlines potential causes for failure. A framework to identify and quantify the associated costs is also introduced. Several case studies are presented to examine the cause and cost of failure and the means by which the facilities were completed. Alternatives available for project completion when contractor failure occurs are discussed. Recommendations to identify and monitor contractors at high risk for failure are outlined as well. This paper provides facility owners with a greater awareness of the possibility of contractor failure, how to quantify costs of contractor failure, and avoidance techniques.