Power System Studies

With large amounts of distributed energy resources interconnecting to the power grid and other non-transmission alternatives competing with traditional grid solutions, energy developers, utilities, regulators, and system operators alike depend on power system studies to maintain the security and dependability of the electric grid. RLC maintains a high level of security and confidentiality throughout the studies process using security software and internal procedures and is competent in handling Critical Energy Infrastructure Information (CEII).

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Power System Studies?

Distribution System Studies

The future distribution systems will look different than those of the past. There will be many more distributed resources and both resources and loads will need to be managed in real-time by a coordinated controller. Our engineers are prepared to help utilities and developers figure out how to make this all work, and have performed hundreds of distribution system renewable resource interconnection impact studies, including equipment design upgrades. We are proficient with ASPEN, SKM, PSCAD, Synergi, EasyPower, PowerTools for Windows and CYME for completing these analyses. We understand the issues associated with unbalanced loads and are experienced at solving voltage profile, voltage flicker, effective grounding, anti-islanding, power factor, short circuit, reverse power flow and other interconnection challenges. In addition, we perform PSCAD analyses for Risk of Islanding (ROI), Ground Fault Over Voltage (GFOV), Load Rejection Over Voltage (LROV), Under Frequency Load Shedding (UFLS), and Control Interaction per IEEE 1547-2018. Our strengths are complemented by a strong system protection group.

Typical Studies Performed:

Feasibility Studies
System Impact Studies
Long-Term Dynamic and Transient Analyses
Curtailment Analyses (8,760 Analyses)
Load Addition Analyses
Motor Start Analyses
Reliability Analyses
IEEE 1453 Flicker Analyses
Protection and Coordination Studies

We have performed numerous Distributed Resource (DR) interconnection studies for utilities throughout New England. Distributed Generation (DG) interconnection studies are performed to determine modifications to the distribution feeder and project to comply with state tariff requirements, IEEE 1547 and utility standards. These potential modifications are determined by several different analyses:

Short Circuit Analysis
Effective Grounding Analysis
Steady State Analysis (Voltage Profile, Thermal Capacity Analysis and Reverse Powerflow)
Transient/Stability Analysis (ROI, LROV, GFOV, UFLS, Control Interaction)
Voltage Flicker Assessment
Anti-Islanding Determination of Direct Transfer Trip (DTT)
Protection Coordination
Design Review
Operating Guides
Special Studies (Long Term Dynamic, Transient Analysis, Custom Modeling)

Distributed Resource Interconnection Studies Performed:

Hundreds of Interconnection System Impact Studies
Benchmarking Models for ISO Interconnection Application
DER Hosting Capacity Analyses
Curtailment Analyses (8,760 Analyses)
DER Coordination Studies
DER System Operating Guide Development
Custom Power Electronics Modeling in CYME
CHP and Anaerobic Digester Synchronous Generator Impact Studies
Voltage Needs Assessment of a Distribution System with Impacts of DR
Model Creation/Cleanup/Validation
Witness Testing

We have performed Non-Transmission Alternative (NTA) analyses as part of solutions studies in Maine. These assessments considered alternatives to “transmission only” solutions and were developed to address reliability needs at both the local and regional system levels.

NTA analyses establish the critical load, within a defined region, that triggers the requirement for load reduction resources. The assessment determines the location and effective amount of NTA resources needed to maintain each region’s net load below the applicable critical load level and eliminate reliability violations within the region. NTA resources may be required during transmission maintenance outages or during day-to-day operations to address identified reliability concerns. We also estimate the transmission construction cost savings that could be potentially realized by developing these NTA resources.

We have developed NTA solutions to displace the need for significant transmission improvements in the following Maine areas:

Mid-Coast Region
Portland Region

The growth of wind and other renewable energy sources, notably solar, has been brisk the last few years and is likely to continue. We have analyzed the integration of dozens of these resources onto both transmission and distribution systems. We have also analyzed interconnections of small and large wind farms, performed siting and interconnection studies for solar systems and performed interconnection studies for battery storage installations. Our team also performed congestion analyses for renewable resources, both near the source and for moving large quantities of renewable energy over long distances.

Transmission System Studies

Our engineers are experts at performing transmission system studies that include steady state, stability, short-circuit, transient switching and congestion analyses. Tools that we use for these analyses are PSS/E, TARA, PSLF, PSCAD, ATP and our own specialized programs. Our client list includes large investor-owned utilities, Independent System Operators (ISO) and merchant power plant developers.

Typical Studies Performed:

Generation System Impact
Generator Feasibility
Transmission System Expansion and Operations
Non-Transmission Alternative Analysis
Congestion Analysis
DER Cluster Studies
Power System Protection
NERC Modeling, Testing and Documenting for MOD-025, -026, -027, -032, and TPL-001
Capacitor Bank Switching and Application

We have performed congestion analyses for several clients, helping them determine the amount of energy that would be curtailed for deliveries that they want to make over long distances. We have developed a proprietary model that performs hourly calculations of energy curtailment based on a bubble diagram and energy balance equation approach. Input assumptions are specified at a high level allowing for quick turnaround of analyses of different scenarios. Results are summarized every month.

Short Circuit Analysis
Effective Grounding Analysis
Steady State Analysis (Voltage Profile, Thermal Capacity Analysis and Reverse Powerflow)
Transient/Stability Analyses (ROI, LROV, GFOV, UFLS, Control Interaction)
Voltage Flicker Assessment
Anti-Islanding Determination of Direct Transfer Trip (DTT)
Protection Coordination
Design Review
Operating Guides
Special Studies (Long Term Dynamic, Transient Analysis, Custom Modeling)

Distributed Resource Interconnection Studies Performed:

Hundreds of Interconnection System Impact Studies
Benchmarking Models for ISO Interconnection Application
DER Hosting Capacity Analyses
Curtailment Analyses (8,760 Analyses)
DER Coordination Studies
DER System Operating Guide Development
DER Cluster Studies to assess Transmission and Sub-Transmission Impacts
CHP and Anaerobic Digester Synchronous Generator Impact Studies
Voltage needs assessment of a Distribution System with Impacts of DR
Model Creation/Cleanup/Validation
Witness Testing

We have performed numerous interconnection studies for ISO-New England and the New York ISO. Interconnection studies are performed to determine generation and transmission project requirements and reliability enhancements. These potential upgrades are determined by several different analyses:

Steady State (Voltage and Thermal) N-1 and N-1-1 Analyses
Transient Stability N-1 and N-1-1 Analyses
Fault Duty and Short Circuit Ratio Analyses
Facility and System Impact Studies
DER Cluster Studies
Site Assessment/Hosting Capacity Analyses

Impact Studies Performed:

Kibby Mountain Wind Farm (132 MW)
Oakfield Wind Farm (148 MW)
Bull Hill Wind Farm (34 MW)
Northern Pass (HVDC Line)
Grand Isle Intertie (HVDC Line)
Bayonne Energy Center (130 MW)
Long Island Offshore Wind Project (550 MW)
Bay State Offshore Wind (840 MW)
Quebec – Maine Interconnect ETU (1,200 MW)

We have performed Non-Transmission Alternative (NTA) analyses as part of solutions studies in Maine. These assessments considered alternatives to “transmission only” solutions were developed to address reliability needs at both the local and regional system levels.

We developed NTA solutions to displace the need for significant transmission improvements in the following Maine areas:

Mid-Coast Region
Portland Region

The power system in the United States is changing. Non-traditional solutions to power system needs are becoming more common. These new solutions include more renewable resources on the generation side and Non-Transmission Alternatives (NTA) on the transmission side. Microgrids and distributed resources may become the norm. A key driver of decisions about these non-traditional solutions is economics. Our engineers have the experience and background to analyze the economics considering construction costs, market congestion and revenue requirement perspectives.

Power System Economics Studies Performed:

Construction Cost Estimates for Transmission Projects in Maine
Construction Cost Estimates for Projects in New Hampshire
Comparison of Revenue Requirements for DC and AC Interconnection Options in the Boston Area
Revenue Requirement Comparison of Transmission Solutions to NTAs
Congestion Analyses in Maine and New York
Curtailment Analyses (8,760 Analyses)

We have performed a variety of regional planning studies in the New England and New York areas. Our engineers have also performed needs assessments, alternative solutions studies, proposed plan application studies (for project approval), identification of the year of need, critical load level determinations, material modification determinations and construction sequence analyses. Specialties include steady state N-1 and N-1-1 analyses, transient stability analyses, and short circuit analyses to provide thorough and comprehensive analyses.

Regional Planning Studies Performed:

Maine Power Reliability Program (MPRP)
New England East-West Solution
New Hampshire/Vermont
Greater Boston
Pittsfield/Greenfield
Eastern Connecticut
Southwest Connecticut
Greater Hartford/Central Connecticut

We have supported our clients with several transfer limit assessments over the years. Transfer limits define the maximum amount of power that can be shipped from one area of the electric grid to another (usually from generation to load pockets of the grid) without violating the region’s performance criteria. To accomplish this, several different types of analyses are conducted; typically thermal, voltage and stability studies, and are simulated for conditions with the electric grid intact as well as conditions where critical elements are out of service. These studies could be initiated on a periodically following many small changes to the system or could be initiated following substantial changes to the system.

Transfer Capability Analyses Completed:

Maine Transfer Limit Upgrades from MPRP
Northern New England Transfer Limits
Bulk Power System Determination

The growth of wind and other renewable energy sources, notably solar, has been brisk the last few years and is likely to continue. Our engineers have analyzed the integration of dozens of these resources onto both transmission and distribution systems. We analyzed interconnections of small and large wind farms, performed siting and interconnection studies for solar systems and performed interconnection studies for battery storage installations. We also performed congestion analyses for renewable resources, both near the source and for moving large quantities of renewable energy over long distances.

Interconnection Studies

The growth of solar, wind and battery renewable energy sources have been brisk the last few years and are likely to continue their high penetration of both small- and large-scale projects. We analyze the integration of these resources onto both transmission and distribution systems through interconnection studies and studies for emerging technologies. In addition, we perform congestion analyses to study moving large quantities of renewable energy over long distances. We have performed hundreds of distribution system studies for utilities throughout the United States, with a wide breadth of industry software knowledge.

Typical Studies Performed:

Generation System Impact
Distributed Resource Interconnection Studies
Distribution System Studies
Interconnection Studies
Transmission System Studies
Hosting/Injection Capacity Analyses
Distributed Energy Resource Cluster Studies
EMT Analyses