CERTS Microgrid Test Bed 
Dolan Technology Center

The CERTS Microgrid Test Bed is located at American Electric Power (AEP) Company’s Walnut Test Facility, pictured below, and designed to demonstrate the CERTS Microgrid Concept, which is an advanced approach for enabling the integration of multiple distributed energy resources (DER) into an electric utility’s distribution system/power grid.

The background and basis for this R&D Project are as follows:

  • The Consortium for Electric Reliability Technology Solutions (CERTS) was formed in 1999 to research, develop, and disseminate electric reliability technology solutions in order to protect and enhance the reliability of the U.S. electric power system under the emerging competitive electricity market structure. The founding members include four DOE National Labs (Lawrence Berkeley National Laboratory (LBNL), Sandia National Laboratory (SNL), Oak Ridge National Laboratory (ORNL), and Pacific Northwest National Laboratory (PNNL); NSF’s Power Systems Engineering Research Center; and the Electric Power Group. Currently, CERTS is conducting public interest research for the DOE Office of Electricity Delivery and Energy Reliability and California Energy Commission (CEC) Public Interest Energy Research program.
  • AEP shares a common vision of the potential for advanced technologies within the electric power industry, in particular the increasing value of DER, and has developed a unique research and testing facility, offering opportunities to test equipment, such as generation, energy storage and power quality devices at its Dolan Test Facility and Walnut Test Facility.
  • TECOGEN, Inc. has a core competence in manufacturing and installing combined heat & power generation (CHP) equipment at commercial and industrial sites in the U.S. market.
  • Youtility, Inc. has a core competence in designing and installing distributed power electronics for inverter-based systems.
  • Northern Power Systems has a core competence of engineering, designing and installing electric power systems at commercial and industrial sites in the U.S. market.
  • University of Wisconsin has technical knowledge of electric power systems in their power engineering program, has investigated, modeled and assessed the concept of establishing microgrids which would be interconnected to an electric utility’s distribution system/power grid.

The CERTS Microgrid Concept is an advanced approach for enabling integration of, in principle, an unlimited quantity of DER (e.g., distributed generation (DG), energy storage, etc.) into the electric utility grid. A key feature of a microgrid, is its ability to separate and isolate itself from the utility system, during a utility grid disturbance. This is accomplished via intelligent power electronic interfaces and a single, high-speed, switch which is used for disconnection from the grid and synchronization to the grid. During a disturbance, the DER and corresponding loads can autonomously be separated from the utility’s distribution system, isolating the microgrid’s load from the disturbance (and thereby maintaining high level of service) without harming the integrity of the utility’s electrical system/power grid. Intentional islanding of DER and loads has the potential to provide a higher level of reliability than that provided by the distribution system as a whole. Thus, when the utility grid returns to normal, the microgrid automatically synchronizes and reconnects itself to the grid, in an equally seamless fashion.

What is unique about the CERTS Microgrid is that it can provide this technically challenging functionality without extensive (i.e., expensive) custom engineering. In addition, the design of the CERTS Microgrid provides a high level of system reliability and great flexibility in the placement of DER within the microgrid. The CERTS Microgrid offers these functionalities at much lower costs than traditional approaches by incorporating peer-to-peer and plug-and-play concepts for each component within the microgrid.

The original concept was driven by two fundamental principles:

  1. A systems perspective was necessary for customers, utilities, and society to capture the full benefits of integrating DER into an energy system; and
  2. The business case for accelerating adoption of these advanced concepts will be driven, primarily, by lowering the first cost and enhancing the value of Microgrids.

Each innovation was created specifically to lower the cost and improve the reliability of small-scale DG systems (i.e., installed systems with capacities ranging from less than 100kW to 1000kW). The goal was to increase and accelerate realization of the many benefits offered by small-scale DG, such as their ability to supply waste heat at the point of need or to provide a higher level of power quality to some but not all loads within a facility. From an electric utility perspective, the Microgrid Concept is attractive because it recognizes the reality that the nation’s distribution system is extensive, aging, and will change over time. The CERTS Microgrid Concept enables high penetration of DG systems without requiring re-design or re-engineering of the utility’s distribution system.

Prospective applications of the CERTS Microgrid include industrial parks, commercial and institutional campuses, situations that require uninterrupted power supplies and high power quality, CHP systems, greenfield communities, and remote applications. In short, wherever economic and DG co-location considerations indicate the need for multiple DG units within a (or among) site, the CERTS Microgrid offers the potential for a much more reliable, flexible, and lower cost solution compared to traditional engineering approaches for integrating DG.

Team Participants & Responsibilities:
Collectively, Team participants agreed to: 1) establish a multi-source inverter based Microgrid Test Bed interconnected to an electric utility’s typical distribution circuit/system; and 2) perform various mutually agreed tests of the Microgrid Concept control scheme to demonstrate functionality and compatibility with the operation of a typical distribution circuit/system.

Team responsibilities which include key elements for development, successful testing and deployment of CERTS Microgrids in the U.S. follow:

  • CERTS – The LBNL coordinated research, contracted and funded activities for the CERTS Microgrid Test Bed Project.
  • SNL – The SNL coordinated and managed the integration of multiple supplier activities, associated with the establishment and implementation of test programs developed for the CERTS Microgrid Test Bed.
  • TECOGEN Inc. – TECOGEN provided three separate and complete Gen-set packages for the CERTS Microgrid Test Bed. Each Gen-set package includes an engine, generator, and a separate three-phase inverter, developed by Youtility, Inc. The inverters provide both the CERTS Microgrid control requirements and the TECOGEN engine management requirements. The inverters have undergone factory testing to exercise the CERTS control algorithms, prior to shipping inverters to TECOGEN’s plant; and each generation package has undergone a complete factory acceptance test at TECOGEN’s plant to ensure proper design and operation of the total integrated package (i.e., engine, inverter and associated controls).
    Tecogen.com & Youtilityinc.com
  • Northern Power Systems – NPS provided engineering, design details and wiring prints of the complete Microgrid Test Bed; switchgear cabinets; a static switch; sensing equipment for data logging, protection and energy management systems; protection equipment; data logging equipment; plus motor load and test/fault load equipment. This equipment was installed in cabinets for outdoor use and factory tested at NPS plant facility. In addition, the static switch, developed by S&C Electric Company, included the CERTS Microgrid controls requirements and NPS included this switch in their factory acceptance test plan.
  • After successful factory acceptance testing, the switchgear, equipment, associated controllers, and cabinets were packaged and shipped for installation at AEP’s Walnut Test Site in Groveport, Ohio. In addition, NPS developed and provided the initial commissioning test plan, as well as the initial CERTS Microgrid Test Plan, which was provided to Team Participants for input and revision.
  • University of Wisconsin – The University of Wisconsin provided technical direction and expertise associated with the algorithms developed for the CERTS Microgrid Test Bed Project. These algorithms promote a systems approach which views DER and associated customer load as a subsystem or a Microgrid. In concept, during disturbances on an electric utility’s distribution system/power grid, the DER and corresponding customer load can be separated and isolated (i.e., islanded) from the distribution grid without harming the integrity of the electrical system and providing a higher level of reliability to the customer.
  • AEP – The Walnut Test Facility was selected and utilized to accommodate the CERTS Microgrid Test Bed. AEP made provisions at the site to accommodate the three Gen-sets from TECOGEN which were received and installed in a Gen-set Enclosure, provided by AEP to protect equipment from weather related conditions. In addition, AEP provided the engine’s cooling, exhaust, and air ventilation systems in the enclosure for the three Gen-sets; power and auxiliary power transformers; power and control cables in conduit; and connected equipment according to the wiring prints provided by NPS. During construction of the Test Bed, AEP received and installed switchgear, equipment, associated controllers, and cabinets from NPS. Following construction, AEP provided technical and utility expertise in the assessment of site commissioning tests, as well as the development of the CERTS Microgrid Test Plan.

CERTS Microgrid Test Bed Overview
An electrical 1-line diagram (in PDF format) of the CERTS Microgrid Test Bed follows.

Picture below shows the south exterior view of Gen-set Enclosure with three 112.5kVA inverter transformers which connect each Gen-set/inverter, within the Enclosure, to the Microgrid Test Bed. The electrical panels, attached to the exterior wall of the Enclosure, include the load side breaker and visible disconnect switch for each Gen-set. In addition, the electrical breaker panel and 45kVA transformer on the right provides auxiliary power to equipment inside the Gen-set Enclosure and Gen-set coolant system.

Picture below shows the north exterior view of the Gen-set Enclosure with one engine coolant system, connected to each of the three Gen-set engines within the Enclosure. Three engine exhausts and sound suppressors are mounted on the roof with three ventilation exhaust fans mounted on the wall of the Enclosure. In addition, the main natural gas supply is shown with gas pressure regulated from one 250 psi source down to three individual 10psi sources, which are connected to each Gen-set.

Picture below shows a portion of the interior of the Gen-set Enclosure with one of the two-door Gen-set/inverter cabinets on the right with the engine and generator located on the back-side of this cabinet. A DC/DC surge module is connected to each Gen-set and for this unit is mounted on the lower left wall. In addition, this picture shows the engine coolant expansion tank, mounted on the upper wall.