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 were initially slow to support interconnection, then carefully honored it while observing the benefits. Many utilities, committed to protecting the planet, are preparing to ramp up the interconnection of DER technologies within the next decade.
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.
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 PBE power quality expert engineers before DER systems are interconnected to the grid. Many utilities are now requiring permanent remote PQ monitoring instruments be installed at DER sites over a specific kVA to ensure they are kept abreast of any change in the operation of the site that could place the power system at risk.
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. PBE 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 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 the PQ monitor installed at the site through high-performance cellular data modems through the Internet to PBE’s Power Quality Monitoring Center in Sevierville, Tennessee. PBE’s 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. PBE’s software can be used to allow customers to upload their own data from any PQ monitor. PBE can also provide engineering and technical support to A&E firms to electrical design of DER interconnections, PV systems, protective relaying and witness testing.
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. PBE, 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. PBE’s services can be extended to one DER system at one site or multiple DER systems at multiple sites. PBE’s 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. PBE’s can be used to allow customers to upload their own data from any PQ monitor.
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 PBE 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. PBE 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. PBE 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.
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