EHV, HV, and MV Power System Studies

A power distribution system forms the backbone of reliable electrical delivery, channeling power from sources like generators or utility feeds to the end users within a facility or plant. Think of it as the essential highway network that ensures electricity reaches motors, heaters, and various industrial loads safely and efficiently.

These systems are comprised of several critical components:

• Transformers: Step voltage up or down to match system requirements.
• Switchgear: Controls, protects, and isolates electrical equipment, enhancing safety and reliability.
• Motor Control Centers (MCCs): Centralized platforms for managing motor-driven equipment.
• Distribution Panels: Allocate and distribute power to various circuits.
• Loads: End-use devices such as motors, heaters, and other process equipment.

All these elements are interconnected—primarily via cables, but for high-capacity or short-distance links (like between transformer secondaries and switchgear), bus ducts or cable bus systems are also commonly used.

With this robust foundation, we move into the core analysis of load flow, short circuit conditions, and dynamic stability to ensure your system performs under real-world demands.

For grounding system design, our studies follow widely recognized industry standards, including IEEE 80 and IEEE 665. These guidelines ensure safe system operation, effective fault current dissipation, and protection for personnel and equipment.

• IEEE 80: Guide for Safety in AC Substation Grounding
• IEEE 665: Guide for Generating Station Grounding

By adhering to these standards, we deliver grounding designs that meet rigorous utility and industrial requirements.

A robust grounding grid lays the foundation for both personnel safety and equipment protection. Our approach focuses on engineering a low-impedance connection to earth, efficiently dissipating fault currents and minimizing dangerous voltage gradients.

Designing an effective grounding grid begins with a thorough site assessment:

• Soil Resistivity Testing: Understanding local soil conditions is crucial, as soil resistivity determines the grid’s performance.
• Fault Level Evaluation: Grid conductor sizes and layouts are tailored to handle expected fault currents safely.
• Standards Compliance: We base our designs on global industry benchmarks such as IEEE 80 and IEEE 665.

Specialized software tools, including ETAP and SKM Power Tools, support our analysis by optimizing conductor placement, the number and depth of ground rods, and grid configuration. This ensures both step and touch voltages remain well within safety thresholds for workers and the public.

Advanced simulations also aid in coordinating grounding with overall site shielding, helping address complex cases—like achieving adequate protection in high-resistivity soils or congested industrial sites.

Motor starting studies are essential for evaluating how motors will perform under real-world conditions, particularly during voltage dips and initial energization. There are two main approaches:

• Static motor starting studies focus on the worst-case scenario, assuming the motor behaves like a locked rotor throughout acceleration. This method provides a conservative assessment using simplified parameters, making it a practical first step when detailed load information is unavailable.
   
• Dynamic motor starting studies take a deeper dive. They leverage more granular data—such as load torque curves and detailed equipment characteristics—to model the entire acceleration process over time. This approach yields greater accuracy but requires high-quality, comprehensive input data.
   

Both methods help ensure reliable motor operation, with the appropriate choice depending on the available information and the level of detail required for your project.

Large motor startups don’t just flip a switch—they momentarily become the grid’s hungriest guests, pulling several times their normal current. This hefty inrush can cause significant voltage dips at upstream buses. The impacts don’t stop there: if left unchecked, you risk nuisance tripping of protective devices, transformer overloads, or disruptions to neighboring sensitive equipment.

That's why motor starting studies are critical. Using PSCAD and PSS®E, we meticulously analyze both static and dynamic motor starts:

• Static studies examine the worst-case scenario, considering the locked-rotor condition to check for excessive voltage drops and validate transformer sizing.
• Dynamic studies dig deeper, factoring in motor torque and load profiles for more nuanced insights—essential when detailed operating data is available.

Whether planning a single large compressor or coordinating multiple process motors, our motor starting analyses ensure:

• Acceptable voltage dips across buses
• Optimal transformer and tap changer selection
• Proper protection relay settings

By predicting and mitigating these challenges early in design, our studies keep your system resilient—so your grid doesn't flinch, no matter the machinery coming online.

When large motors are switched on, they draw a surge of current—often up to six times their standard running current. This “inrush” can trigger significant voltage dips on upstream buses, potentially leading to nuisance trips of circuit breakers or unwanted equipment malfunctions.

Motor starting studies using PSCAD and PSS®E are essential for:

• Ensuring voltage stability during motor energization
• Verifying transformer sizing and appropriate tap selection
• Optimizing relay settings for effective motor protection

These analyses generally come in two flavors:

• Static motor starting: Focuses on evaluating the worst-case voltage drop and system impact based on a locked-rotor scenario.
• Dynamic motor starting: Offers a deeper dive, accounting for motor load characteristics and the system’s transient response, providing more accurate results when detailed data is available.

Evaluating motor starts in this way keeps the broader power system reliable and safeguards critical equipment throughout your plant or facility.