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Consulting Services

Pterra was founded to provide premier consulting services exclusively for the electric power industry. Most of Pterra engagements are per diem, best effort contracts with an agreed upon scope of work, schedule, set of deliverables and budget limit. 

Scopes of Work

Following are typical Scopes of Work for Pterra's engagements:

Distributed Generation Integration -  Integrating renewables such as photovoltaic cells, wind turbines and fuel cells in distribution systems.  Pterra’s analyses may include assessment of islanding issues, steady state power flow, voltage regulation, short-circuit impact, protective relaying and coordination, power quality (flicker and harmonic), power factor control, system stability, grounding, and ground fault overvoltage.

Strategic Assessment - Technical and management advice based on our knowledge and experience and focused on future investments involving power generation, equipment, transmission and distribution grids. 

Network Studies - Large-scale network analysis and application of power flows, short circuit, contingency analysis, stability simulations and other power engineering calculations.  An example power flow study report: West African Power Pool Report .

Voltage Control and Reactive Power Studies - These studies may have objectives such as: avoiding voltage collapse, specification of static var devices and sizing and allocation of capacitors.  A sample study: South Island Grid Upgrade Project Dynamic Voltage Stability Study.

Fatal Flaw studies - assess the transmission requirements for a new power project using a quick but accurate analysis.  Identify potential transmission fatal flaws before you get too far along on project development. 

Site Assessment - compare the transmission impacts for several interconnection points for a proposed project. 

Feasibility studies - assess the thermal and voltage requirements to interconnect a proposed power project using a specific model of the transmission network closest to that used in an impact study, and taking into account sensitivity to other power projects under development and contingencies that determine specific impacts. 

Interconnection Studies - In support of new generation or transmission interconnection.  Studies may include contingency analysis, short circuit calculation, stability simulation, transfer analysis, torsional and prony analysis, power quality and switching transient analyses.

Links to sample Pterra impact studies posted on the web: Sheffield Wind Farm, Vermont, Combined Cycle Plant in Louisiana, and Wind Farm in Carson County, Texas.

Expert Testimony - Our staff members have provided expertise in proceedings before the Federal Energy Regulatory Board, state commissions, private and commercial arbitration and civil cases.  From white papers, technical opinions, to direct and oral testimony, Pterra has provided that strong expertise, experience and knowledge that made for vital and decisive proceedings.  Sample report: On Designation of National Corridors.

Model Development - Special models for new devices and processes, or models that are not available in a standard library.  Pterra will help you write a special user model compatible with the most popular software.  Share functionality without giving away proprietary information. Examples of model development include static var compensator with high-speed capacitor switching, synchronous motors and composite load models.

Analytical Studies

As part of its overall project engagement or as standalone tasks, Pterra conducts the following types of analysis:

Power flow analysis to determine thermal and voltage capabilities on an electrical circuit or grid. This may also include contingency analysis to determine impacts of outages, power factor tests to determine adequacy of voltage support, and transfer limit analysis to measure power injection capacity.

Short circuit analysis to determine fault levels. This may include breaker-by-breaker analysis for substations, and protection relay setting and coordination.

Positive sequence dynamic simulations to determine transient and dynamic stability of synchronous systems. The analysis may also be applied to voltage stability and collapse assessment.

Three-phase electromagnetic transient simulations, also known as EMTP studies applied to simulate transient overvoltages, capacitor switching, recovery of voltage, subsynchronous resonance, among others.

Harmonic analysis to determine the magnitude of harmonics in an electrical circuit or grid, and design filters.

Flicker analysis to measure the variation of voltage as it can be tolerated or perceived by electric customers.

Relay coordination - for transmission and distribution circuits to set and adjust relay protection and sensitivity.

Insulation coordination the necessary and sufficient insulation characteristics of the various network components in order to obtain uniform withstand to normal voltages and to overvoltages that the study system may experience.

Ground overvoltage and grounding bank application to determine appropriate size and rating ensuring sufficient protection against high voltages without reducing the sensitivity of relays.

Capacitor sizing and switching analysis to determine the potential overvoltages that a capacitor bank may be exposed to as a function of its planned interconnection, operation and use.  Analysis includes measurement of outrush currents.  Typical application is to determine type of switching and need for pre-insertion resistors.

Islanding assessment is conducted for distribution circuits for which there are planned distributed generation resources.  The assessment determines any changes to protection schemes and potential operating conditions that may be a concern from the aspect of islanding.

Transient recovery voltage simulations determine if circuit breakers can withstand the high voltage stresses coming from various switching events.