Power System Studies

Purpose and Value of Power System Studies

On Grid Engineering leverages advanced modeling and simulation tools to conduct thorough power system studies. These analyses ensure electrical designs balance reliability, cost, and regulatory compliance. By identifying system limitations, optimizing configurations, and validating protective schemes, we deliver robust solutions tailored to our clients’ needs.

Rather than relying on assumptions, our engineers determine which studies yield actionable insights and apply industry-leading software to generate accurate results. This approach uncovers hidden issues early and informs critical design decisions.

Load Flow / Power Flow Analysis

Load flow studies model current and voltage profiles across the network under various operating scenarios. Our services include:

• Steady-State Load Flow: Calculating bus voltages, real/reactive power flows, and losses to validate system performance.
• Contingency Analysis: Assessing N-1 and N-2 scenarios to ensure grid security during equipment outages.
• Voltage Regulation Studies: Evaluating tap changer settings, capacitor banks, and reactive support requirements.
• Optimal Power Flow (OPF): Minimizing generation costs or losses while meeting operational constraints.
• Distribution System Modeling: Analyzing radial or networked feeders for balanced loading and minimal voltage drop.
• Power Factor Correction & Reactive Power Management to minimize losses and utility penalties.

Short-Circuit / Fault Current Studies

Short-circuit analysis determines fault levels to specify equipment ratings and protection settings. Key activities include:

• Three-Phase, Line-to-Line, Single-Phase, and Ground Fault Calculations to characterize potential fault currents.
• Equipment Rating Verification: Ensuring breakers, fuses, and busbars withstand prospective fault levels.
• Transformer Inrush and Generator Contribution Assessments for accurate fault modeling.
• Neutral Grounding & System Grounding Studies: Designing grounding resistors or Reactors to limit ground fault currents.
• Protective Device Coordination: Aligning fault clearing times between upstream and downstream devices.

Arc Flash & Electrical Safety Studies

Arc flash assessments identify hazard levels and safe working distances to protect personnel. Our methodology includes:

• Incident Energy Calculation in Accordance With IEEE 1584 and NFPA 70E Guidelines.
• Arc Flash Boundary Determination: Defining minimum safe approach distances for workers.
• Labeling & PPE Recommendations: Providing equipment labeling and personal protective equipment requirements.
• Shock Hazard Analysis: Evaluating step and touch potential to minimize accidental exposure risks.
• Maintenance & Mitigation Measures: Suggesting arc-resistant switchgear, speed controllers, or fault current limiting solutions.

Protection Coordination Studies

Relay coordination studies ensure selective tripping to isolate only faulted sections, improving system stability. Our coordination process includes:

• Time-Current Characteristic (TCC) Curve Development for overcurrent, distance, and directional relays.
• Coordination Margin Analysis: Verifying minimum operating time gaps between relays under fault conditions.
• Zone of Protection Definition: Setting pickup thresholds and time delays for feeder, transformer, and bus differential protection.
• Adaptive Protection Schemes: Implementing real-time adjustments based on network topology changes.
• Documentation of Relay Settings and Coordination Reports for regulatory and operational use.

Grounding & Earthing Studies

Proper grounding ensures safety and system reliability. Our grounding services include:

• Grounding Grid Design & Analysis Using CDEGS or Equivalent Software Tools.
• Step & Touch Potential Evaluations to ensure personnel safety around substation equipment.
• Grounding Electrode System Design for buildings, substations, and transmission structures.
• Lightning Protection & Surge Mitigation Strategies to protect assets from transients.
• Earthing Component Sizing: Specifying grounding conductors, rods, and mats based on soil resistivity surveys.

System Loss Studies

We evaluate system efficiency and losses across the entire electrical architecture to optimize design and ensure compliance:

• MV Cable Loss Studies: Voltage drop, I²R losses, and optimization of conductor size and routing
• LV & DC Cable Loss Analysis: String-level and combiner-to-inverter losses for PV, and rack-to-PCS losses for BESS
• Loss Allocation Studies: Partitioning losses between project phases (e.g., contracted vs. uncontracted capacity)
• Reactive Power Impact on Losses: Loss variations under different PF and dispatch conditions
• Annual Energy Yield Impacts: Translation of electrical losses into annual production and revenue loss

Insulation Coordination Studies

We ensure proper equipment insulation withstand levels under normal and transient conditions to reduce risk of insulation failure:

• BIL Selection & Validation: Equipment insulation coordination per IEEE/IEC guidelines
• Surge Arrester Sizing: Placement and rating selection to clamp switching and lightning surges
• Clearance & Creepage Review: Verification of minimum phase-to-ground and phase-to-phase distances
• Overvoltage Evaluation: Analysis of switching transients and resonance conditions
• Cable Termination & Bushing Coordination: Ensuring withstand levels match insulation system ratings

Lightning Risk Assessment Studies

We provide engineering-based lightning risk assessments to support design decisions and compliance with industry standards such as NFPA 780 and IEC 62305:

• Site Risk Evaluation: Assess site-specific lightning exposure based on regional flash density, equipment layout, and installation location
• Structure Vulnerability Analysis: Evaluate critical equipment areas (e.g., PCS, MV transformers) for direct and indirect lightning threats
• Code-Based Risk Classification: Apply standard risk categories using construction type, equipment value, occupancy, and service continuity impact
• Lightning Protection Recommendations: Determine whether Lightning Protection Systems (LPS) are recommended based on risk level
• Design Coordination Support: Provide inputs to grounding, bonding, and surge protection strategy as part of the broader electrical design
• Documentation: Deliver a formal report summarizing risk assessment inputs, assumptions, results, and recommended mitigation actions

Renewable Interconnection & Generation Studies

Integrating renewable generation requires specialized studies to ensure grid stability and compliance. Our services include:

• Interconnection Modeling in PSCAD, PSS®E, PSLF, or ETAP to simulate impacts on the transmission and distribution systems.
• System Impact Studies (SIS) for PV, wind, and BESS projects to identify network modifications and protection adjustments.
• Voltage & Frequency Ride-Through Evaluations per IEEE 1547 and UL 1741 SA requirements.
• Reactive Power & Volt-Var Support Analysis for inverter-based resources to support grid voltage stability.
• Renewable Energy Curtailment & Dispatch Modeling for optimal utilization and economic operation.

Software Utilized

Our comprehensive toolkit ensures accurate and efficient analysis:

• ETAP: Load flow, short circuit, transient stability, protection coordination, Arc flash hazard analysis and safety compliance.
• PSSE & PSLF: Transmission planning, dynamic stability, and power flow simulations.
• PowerFactory DIgSILENT: Grid modeling, protection, and renewable integration studies.
• SCSC (CDEGS): Grounding, earthing, and electromagnetic analysis.
• SKM & EasyPower: Distribution system planning, arc flash, and protection coordination.
• PVSyst: Detailed solar PV performance modeling and shading analysis.
• CYME: Underground distribution and DER integration analysis.