Power System Studies & Analysis

Load Flow Analysis:
To conduct a comprehensive evaluation of demand, power flow analysis, losses, power factor correction, and voltage drop calculations for AC and DC systems. Count on us to provide accurate analysis that enhances the effectiveness and productivity of your electrical systems.

Unbalanced Load Flow Analysis:
To accurately analyse radial and looped 3-phase and unbalanced 1-phase electrical systems. This analysis enables our engineers to identify and resolve issues pertaining to asymmetrical loads, unbalanced voltages, and potential equipment overloads in existing networks.

Unbalanced load flow analysis is crucial in the design of new installations to ensure efficient handling of uneven loads and asymmetrical conditions from the beginning.

Short Circuit Analysis:
Our comprehensive evaluation aims to detect fault currents, precisely locate potential problems within your system, and reduce risks by automatically comparing results with equipment ratings.   We have the capability to perform evaluations for electrical networks in both onshore (IEC 60909) and marine/offshore (IEC 61363) environments, guaranteeing the dependability and security of your electrical infrastructure.

DC Short Circuit Analysis:
Utilise our DC short circuit analysis services in accordance with the IEC 61660 standards.   We evaluate crucial variables such as the rate at which fault current increases, the maximum fault current, the time it takes for the system to reach its peak, and the conditions that remain constant over time.  In addition, we possess extensive knowledge in battery and charger modelling for Battery Energy Storage Systems (BESS), adhering to IEC standards, to guarantee a thorough assessment of the performance of your DC system.

The Importance of Load Flow Analysis for Renewable Energy Integration

Discover how Load Flow Analysis can help optimise grid efficiency, reduce operational challenges, and ensure grid code compliance. Explore how these studies support the adoption of renewable energy sources while maintaining grid stability.

Read the full article here.

Conducting an arc flash study for new and existing electrical power networks is crucial for ensuring the safety of personnel and protecting equipment. For existing networks, the study helps identify potential arc flash hazards, assess the level of risk, and implement appropriate safety measures.

By understanding the arc flash incident energy and associated hazards, operators can develop effective safety protocols, provide proper personal protective equipment (PPE), and minimise the risk of injury during maintenance or fault conditions. In the design phase of new electrical power networks, an arc flash study enables engineers to incorporate safety measures and equipment configurations that mitigate potential hazards from the outset. Overall, these studies contribute to a safer working environment, compliance with regulatory standards, and the protection of both personnel and critical electrical infrastructure from the dangers associated with arc flash events.

DC Arc Flash Energy Calculations
Conducting an arc flash study for a DC electrical system, especially in battery energy storage systems (BESS) and other DC networks, is essential for ensuring the safety of personnel and the integrity of equipment. These studies help identify potential arc flash hazards associated with DC systems, assess the incident energy levels, and implement appropriate safety measures.

Understanding the risks associated with arc flashes allows operators and engineers to establish effective safety protocols, choose proper personal protective equipment (PPE), and design systems that minimise the impact of potential faults.

With arc flash studies, we take a practical approach by carrying out the following steps:

• Arc flash Energy Calculations Study
• Arc Flash Mitigation Study (Minimising Protection Settings)
• Switchgear Risk Assessments
• Arc Flash Awareness Training

For battery energy storage systems and other DC networks, where high energy levels are involved, an arc flash study is instrumental in creating a safe working environment, preventing injuries, and protecting critical infrastructure. It enables the development of safety practices that are crucial for personnel working on or around DC systems, contributing to compliance with safety standards and regulations in the evolving landscape of renewable energy technologies.

5 Ways to Reduce the Risk of Arc Flash

Discover practical measures you can implement to ensure safety, compliance, and smooth running of your operations.

Explore key considerations for keeping your personnel safe here.

By obtaining existing Distributed Network Operator harmonic data and data that we can measure using data loggers we can accurately model the harmonics, resonance, and inter-harmonics around the power system network.

Harmonic modelling helps diagnose and fix voltage distortion and equipment compatibility issues in existing networks by analysing the harmonic profile. Engineers can predict and address harmonic resonance, reduce the risk of equipment failures, and optimise the overall performance of the power network.

Our proactive approach improves electrical infrastructure reliability, regulatory compliance, and load efficiency to standards such as IEEE 519-2014, IEC 61000-3-14, IEC 61000-3-6, and/or Engineering Recommendation ENA G5 Issue 5 (G5/5 Harmonics).

• Harmonic load flow
• Frequency scan analysis
• Filter sizing and verification reports
• Voltage flicker limitation studies
• Resonance condition identification
• Frequency-dependent modelling
• Harmonic filter design & sizing
• Automatic distortion evaluation
• Inter-harmonic simulation
• Distortion indices calculation
• Harmonics plots & report findings
• Calculation of K-Factors and Loss Factors for 2-winding transformers

Everything You Need to Know About Power System Harmonic Analysis

Uncover expert insights and learn how to address power quality issues caused by harmonics.

Read the full article here.

P28/2, also known as voltage fluctuation studies, are relevant to a diverse range of facilities and serve as an important regulatory obligation for Distribution Network Operators (DNOs). These studies aim to prevent any negative impact on the public network caused by a private network, such as voltage flicker or voltage regulation issues.

The studies primarily focus on generation projects and battery storage projects to assess the Step Voltage Change (SVC) resulting from generation trips and the Rapid Voltage Change (RVC) resulting from transformer energisation and power swings in battery storage units.   Nevertheless, these principles can also be applied to sites that experience significant variations in their loads, such as those utilising large pumps and compressors, arc furnaces, winders, and similar equipment.

The most intriguing aspect arises in the context of battery energy storage projects.   These projects, which are new to Distribution Network Operators (DNOs), are causing significant unease among them.   Historically, BESS units were evaluated based on their ability to transition from maximum power import to maximum power export, and from maximum power export to maximum power import within a 1-second timeframe. However, it is now evident that this approach is overly simplistic.

P28 studies may involve a combination of Transient Motor Starting, Transient Stability and Transformer Energisation studies including:

• Step Voltage Change (SVC)
• Energy storage using batteries Power Ramps
• Energy storage using batteries Response from the DC/DR/DM
• Significant load increment and modification factors
• Flicker (Pst & Plt)

EPS can conduct a comprehensive P28/2 voltage fluctuation assessment for any site, utilising either DIgSILENT Power Factory or ETAP.

What is a P28 Study, and Why is it Important?

In this article, we explore the core aspects of P28 studies and how they help to identify and mitigate voltage fluctuation issues caused by new connections.

Uncover EPS’s expert insights here.

P29 studies are short for Electrical Networks Associate (ENA) standard P28, ‘Planning Limits for Voltage Unbalance’. In short, P29 studies focus on analysing unbalanced load flow (unbalanced phases).

It’s worth understanding that this is an uncommon study, which DNOs sometimes request. The study examines how new loads can unbalance the power system’s three phases. Basic power system theory states that all three phases of a power system should be equally balanced to optimise the system and prevent excessive heating and neutral currents. This is problematic for DNOs, hence why the P29 rules exist.

An unbalanced power system can cause G59 protection relays to trip due to a vector shift and phase unbalance.

Most loads connected at 11kV and above are three-phase (motors, generators, 3-phase inverters, etc.), which are balanced and will not cause system unbalance. DNOs usually accept a statement or brief report explaining this and do not require anything more formal.

A P29 study is more difficult when a system is connected at LV (rarely at HV) and contains many single-phase loads like domestic housing supplies, electrical trace heating, or industrial lighting systems. Single-phase loads can cause significant unbalance if the electrical designer is not careful. A computer model of the connected loads and an unbalanced load flow analysis to confirm the total unbalance are usually needed to demonstrate compliance with the standard.

It’s nearly impossible to get a balanced LV system, but the goal is to minimise unbalance.

Conducting a Transient Stability and Load Shedding study for both existing and new electrical power networks is essential for ensuring the resilience and stability of the system under dynamic conditions. For existing networks, this study helps identify vulnerabilities to transient disturbances, such as faults or sudden changes in load, and allows for the implementation of effective load shedding strategies.

By assessing the system’s transient stability, operators can enhance reliability and prevent cascading failures during disturbances. In the design phase of new electrical power networks, these studies enable engineers to optimise the system for transient stability from the outset, ensuring that it can withstand and recover from dynamic events. Overall, Transient Stability and Load Shedding studies contribute to a more robust power infrastructure, minimising the risk of widespread outages and enhancing the overall stability and reliability of the electrical network.

Electrical protection calculations diagnose vulnerabilities, improve system reliability, and identify areas for improvement in existing networks. To avoid issues in new installations, careful electrical protection calculations ensure that only the faulted part of the network trips. This proactive approach protects the network from faults and disruptions and optimises the electrical infrastructure from a reliability perspective. These calculations help organisations reduce risks, meet industry standards, and build a resilient power network that can meet current and future demands.

Time-Overcurrent Protection

• Overcurrent-time diagrams
• Cable and transformer damage curves
• Motor starting curves
• Steady-state response checks
• Steady-state short-circuit simulation with tracing of individual steps
• Steady-state tripping times for transient or sub-transient current/voltage values
• Transient response checks (requires Stability Analysis functions (RMS) or Electromagnetic Transient functions (EMT)

Distance Protection

• Time-Overcurrent Protection
• P-Q diagrams and R-X diagrams with support of the display of measured impedance trace
• Time-distance diagrams, with metric or calculation of zone, reach in forward and reverse direction

Case Study – Protection Coordination: North Sea Wind Farm

Optimised for safety and resilience – see how EPS enhanced system protection and compliance for our client’s offshore wind farm in the North Sea.

Read the full case study here.

EMT simulation can be utilised to address power system transient issues, including lightning, switching and temporary over-voltages, inrush currents, ferro-resonance effects, and sub-synchronous resonance problems. 

Our Electrical Power System Consultants use PSCAD, to allow us to conduct the following EMT (Electro-Magnetic Transient) studies: 

• Cable, transmission line and substation insulation coordination 
• Wind and solar PV integration studies, wind/ PV dynamic response, transient & voltage stability, fault ride through (LVRT) 
• Harmonics and power quality analysis, harmonics impacts of static generators and loads 
• Protection system modelling and relay testing via Comtrade files 
• Modelling fast power electronic devices such as HVDC, FACTS, SVC, STATCOM systems 
• Modelling inverter-based generation systems (solar, energy storage and wind) for transient simulation 
• Modelling steam turbine, gas turbine and reciprocating engine governors, generator exciters / AVR, PSS, and other associated control systems 

 Additional studies: 

• Simulation of the overvoltages in switching and lightning, especially for EHV networks 
• Sub-Synchronous Resonance, series capacitors, and Sub-synchronous Torsional Interactions (SSTI) 
• Transformer energisation, ferro-resonance, motor starting 
• Transient Recovery Voltage (TRV), capacitor switching and temporary overvoltage’s 
• Power oscillations 
• Saturation and surge arrester modelling
   

Understanding EMT vs. RMS Simulations in Electrical Power Systems

Explore the key differences between EMT and RMS simulations here.

Transient motor starting analysis is essential for both new and existing electrical power networks to understand motor dynamics during start-up. This analysis identifies voltage dips and mechanical stresses that can affect motor performance in existing or new networks.

Operators can improve system reliability and prevent motor starting failures by understanding and mitigating these transient conditions. Transient motor starting analysis ensures that new electrical power networks are designed to meet motor initiation requirements, minimising voltage dips and determining the optimal motor starting sequence depending on the process. This proactive approach optimises motor starting procedures to protect equipment and extend the life and efficiency of the power network, ensuring smooth and reliable operations for a variety of industrial processes.

TMS studies are also used to assist with calculating the motor protection settings for motor protection relays. We generally carry out one or several of the following activities for Transient Motor Starting analysis:

• Single, multiple or sequential motor starting
• Transient motor starting (synchr./asynchr. motors)
• Steady-state motor starting
• Various motor starting methods (reactor, auto-transformer, variable rotor resistance, star delta, etc.)
• Thermal limit check of cables and transformers
• Typical & common disturbances & operations actions
• Transient simulation action for various fault types
• Simulate split system & combine multiple subsystems
• Automatic relay actions per settings & system dynamics

What is a Transient Motor Starting Study?

Discover the crucial role Transient Motor Starting studies play in ensuring smooth and reliable operations.

Explore our expert insights here.

Performing Transformer Energisation Studies is essential for ensuring the dependable and secure operation of transformers during start-up, whether for existing or new electrical power networks. These studies are essential for identifying potential problems such as inrush currents, overvoltages, and other transient phenomena that may occur when transformers are energised in existing networks.

Operators can enhance overall system reliability by understanding and mitigating these temporary effects, optimising the energisation and minimising stress on the transformer. Transformer Energisation Studies are crucial in the context of new installations as they enable the design of protective measures and control strategies to prevent excessive stresses on the transformer and its associated equipment. By adopting a proactive approach, the energisation process is carefully synchronised with the transformer’s specifications, thereby improving the lifespan and efficiency of the electrical power network.

Delving Into Transformer Inrush Current and Energisation Studies

Avoid costly system downtime with our transformer energisation expertise. Explore the impact inrush currents can have on your electrical assets and uncover key risk mitigation strategies.

Read the full article here

Quasi-dynamic simulation aims to accurately represent an electrical system’s temporary effects and changing behaviour. This makes it especially valuable for analysing situations involving sporadic or time-based energy sources.  It aids engineers in evaluating the dynamic reaction of the system in response to varying conditions.

For example, consider a microgrid comprising a combination of photovoltaic (PV) solar panels and a battery storage system.  The objective is to assess the system’s efficiency in response to different levels of solar irradiance and electricity demand fluctuations throughout the day.

Quasi-dynamic simulation provides a comprehensive comprehension of the PV and battery storage system’s interaction with diverse conditions over the course of the day.

Engineers can evaluate the system’s performance, including the battery’s efficiency in mitigating power fluctuations and meeting load requirements during times of limited solar energy production.

Quasi-dynamic simulation is a useful tool for understanding the dynamic characteristics of renewable energy and storage systems. It can assist in designing, optimising, and evaluating the performance of these systems over time.

We provide an efficient and effective reliability assessment of the availability and quality of power throughout your power network. This study calculates expected interruption frequencies and annual interruption costs using network reliability assessment. The importance of each outage is determined by statistical data on outage frequency and duration, protection systems, and network operator resupply efforts. This optimal power restoration process can be analysed and implemented for specific situations.

The total electric interruptions for loads in a power system during an operating period are calculated using statistical methods for the reliability study. The simulation calculates several indices to describe interruptions and their effects. With the reliability analysis, an optimal way to place remote controlled switches (RCS) can be determined to resupply as much demand as possible in the shortest time with a given number.

Generation Adequacy Analysis uses stochastic methods to assess system supply capabilities.

• Unbalanced system reliability calculation
• Customer-oriented indices
• Energy (cost) indices
• Sensitivity analysis
• Single & double contingency
• Looped & radial systems