Power Quality Impact Studies

Utilities

Electric utilities are increasing their engagement in the interconnection and use of distributed generation (DG) technologies across the grid. Also referred to as distributed energy resource (DER) systems, DERs include small-scale power generation and storage technologies in the range of one kW to 10,000 kW. DER technologies provide an alternative to or an enhancement of the traditional electric power system. Examples include combined heat and power (CHP) also referred to as co-generation and tri-generation systems, fuel cells, hybrid power systems (solar hybrid and wind hybrid systems), micro combined heat and power (MicroCHP), microturbines, photovoltaic (PV) systems (rooftop and land-based), reciprocating engines, wind power systems, hydro power (wave power) and waste-to-energy systems. DER storage systems include PV storage, electric vehicle-to-grid and flywheels. While some states and utilities are more aggressive in the adoption of DG equipment, some of the states and utilities that have been slow to support interconnection are now beginning to put plans into action.

Regardless of the technology and application, installation of DER systems can have negative impacts on the power system and customer facility electrical systems. If DER systems are not engineered into existing power systems, power quality problems will occur. The IEEE 1547 standard, “Standard for Interconnecting Distributed Resources with Electric Power Systems” is a standard published by the IEEE to provide a set of criteria and requirements for the interconnection of DG resources into the electric power grid. Since the first IEEE 1547 standard (IEEE 1547.1) was approved in 2003, six sister IEEE 1547 standards have been developed and published. The table below is a list of these standards, their publication year and a brief description of each.

IEEE 1547 Standard

Published

Brief Description

1547.1

2005

Describes the testing of the interconnection in order to determine whether or not the DG installation conforms to standards.

1547.2

2008

Provides a technical background of the standard.

1547.3

2007

Details techniques for monitoring of DER systems.

1547.4

2011

Guide for the design, operation and integration of conforming systems.

1547.5

 

Designed for DER systems larger than 10 MVA

1547.6

2011

Describes practices for secondary network interconnections.

1547.7

2013

Provides distribution impact studies for DER interconnection.

 

Utilities must be concerned with how DER systems might impact the PQ of their power grids. Concerns regarding the effects of voltage distortion on the power grid is an example of a PQ impact. The effects of undervoltage, overvoltage, voltage sags, voltage swells and voltage fluctuations (flicker) on grid PQ are also typical reasons why PQ impact studies should be carried out by Electrotek power quality expert engineers before DER systems are interconnected to the grid.

Architecture & Engineering Firms

Consulting engineering firms have become more involved in engineering projects regarding the interconnection and maintenance of DER systems to power grids. The majority of A&E firms are not staffed and equipped to conduct on-site PQ investigations at candidate interconnection points and at existing interconnection points where an installed DER system may be experiencing PQ problems or causing PQ problems for their area electric power systems. Electrotek power systems and PQ expert engineers can provide the engineering expertise to conduct on-site PQ field investigations. Our technical field engineering staff can travel to a potential interconnection point or an existing point where a DER system may be causing a PQ problem to its area power grid. Remote PQ monitoring using advanced Dranetz PQ monitoring equipment can be installed at any potential or existing DER site.

In addition to multiple channels of interconnection voltage and current, other critical DER system data such as temperature, speed and other controls- and performance-related voltages and currents can also be monitored simultaneously. All of this data can be downloaded from Dranetz monitors through high-performance cellular data modems through the Internet to Electrotek’s Power Quality Monitoring Center in Knoxville, Tennessee and Beverly, Massachusetts. Electrotek’s PQView® PQ data management and analysis software can be used to manage and analyze data from multiple DER systems on large sites and DER systems on multiple sites separated by 100’s of miles. Electrotek’s PQWeb® can be used to allow customers to upload their own data from any PQ monitor. Electrotek can also provide engineering and technical support to A&E firms to electrical design of DER interconnections, PV systems, protective relaying and witness testing.

Equipment Manufacturers

While DER equipment manufacturers are likely equipped and staffed to conduct PQ monitoring and investigations at sites where their equipment is installed, their capabilities to manage and analyze large amounts of PQ data and other DER system data simultaneously may be limited. Electrotek, operating as an independent third-party engineering consulting firm, has built strong relationships with US utilities and international utilities. Our detailed understanding of all types of utility power distribution systems can be used by DER equipment manufacturers to solve complex power system and PQ problems. Electrotek’s services can be extended to one DER system at one site or multiple DER systems at multiple sites. Electrotek’s PQView® PQ data management and analysis software can be used to manage and analyze data from multiple DER systems on large sites and DER systems on multiple sites separated by 100’s of miles. Electrotek’s PQWeb® can be used to allow customers to upload their own data from any PQ monitor.

End Users

Owners of DER equipment installations may not be equipped to address power system and PQ problems at sites when they occur. Companies who manage and operate DER system assets for investors have similar needs. Due to the fast growth of DER installations such as rooftop PV arrays and ground-based PV farms and other DER technologies, electric utilities—transmission and distribution companies, may not be properly informed or not informed at all regarding plans to install DER systems. DER owners and asset management companies can call upon Electrotek to serve as an independent third-party power systems and PQ engineering consulting firm to help them keep utilities informed regarding future installations until an installation is complete. Electrotek is very knowledgeable regarding the information utilities require to help ensure DER installations occur without problems and remain successful energy sources for utilities and their customers. Electrotek can help owners and asset management companies understand that information is required, guide them and help them gather and prepare information to keep utilities informed.