Power Systems Analysis

We will determine fault levels throughout the power systems. The short circuit study will be used to:

• Calculate minimum and maximum fault levels throughout the power system
• Confirm the adequacy of your existing switchgear to cope with short circuits
• Ensure switchgear is adequately rated throughout the power system
• Select the correct rating of your switchgear before purchase
• Investigate short circuits related incidents at site
• Identify underrated equipment before extensive system damage can occur
• Increase facility reliability, equipment protection and personnel safety
• Aid in future expansion plans by providing accurate fault current calculations at each location in the system, thereby allowing properly rated equipment to be specified.

Depending on your needs, we will evaluate and confirm the rating of your components such as cables and transformers to ensure that they are adequately rated for load current. The load flow study will:

• Calculate maximum demand & voltage drops
• Select appropriate cable sizes
• Evaluate power factor correction, calculate real and reactive power loses
• Confirm motor start-up and its impact on the rest of the system
• Reduce your electric bill by determining the location and size of power factor correction capacitors
• Aid in future planning and present day operation by demonstrating how the electrical system will perform during normal and emergency operating conditions
• Determine the proper transformer tap settings so that the correct voltage will be present at motors and other loads during full load and no load conditions
• Identify under-utilised equipment to which will allow for future load growth
• Identify overloaded equipment
• Increase the distribution system operating efficiency and determine the most optimum operating configuration
• Evaluate and compare network expansion & alternatives to support capital projects operation & expenditures(OPEX and CAPEX).

Depending on your needs, we will evaluate and confirm the rating of your components such as cables and transformers to ensure that they are adequately rated for load current. The load flow study will:

• Flash hazard boundary
• Amount of incident energy
• Shock hazard
• Limited approach
• Restricted approach
• Prohibited approach
• Adjust protection settings to reduce the PPE requirements
• Increase facility reliability, equipment protection, and personnel safety
• Determine the level of Personal Protective Equipment (PPE) to be worn
• Investigate alternative options (modern engineering controls) to ensure adequate safety on site, and evaluate cost effective arc flash hazard control measures
• Provide the required PPE labels throughout your site.

We will identify, analyse harmonics generated by non-linear equipment. The study will determine if your facility exceeds the power supply authority limits. We will then determine harmonic mitigation techniques to reduce the harmonics including phase shifting, zig-zag transformers and harmonic filter installation. A Harmonic study complying with methodologies outlined in IEC 61000 & IEE519 standards will be used to:

• Identify the source of harmonics (internal or external to your facility)
• Evaluate the impact of non-linear loads (harmonic sources) on facility distribution systems
• Evaluate compliance with power supply authority
• Verify the proper size and placement of capacitors when harmonic sources are present
• Verify the proper size, configuration and placement of filters, if necessary
• Size harmonic filters based on present harmonics in your system
• Determine the economic benefits of PFC filter banks based on current tariff structure and your actual bills.
• Determine the impact of PFC filter banks switching on the rest of the power systems.

We will determine the impact of motor starting throughout the power systems. The motor acceleration study will:

• Determine voltage drops during motor-starting
• Confirm motor start-up using static modelling
• Confirm motor start-up using dynamic modelling
• Investigate multi-sequence motor starting
• Evaluate soft-staring & VFD frequency control motor starting
• Evaluate load & generation transitioning.

We will model all protective devices in your system including Fuses, MCBs, MCCBs, ACBs and modem digital protection relays. The protection coordination study will:

• Ensure all electrical equipment is adequately protected against overloads, fault currents & earth fault, evaluate and confirm adequacy and performance of protection CTs
• Confirm coordination between upstream and downstream devices using graphical Time Current Curves (TCCs) and sequence of operation analyser to avoid and totally eliminate costly spurious trips in the power system
• Determine optimal settings of all protective equipment
• Evaluate impacts of motor starting on protection settings
• Calculate relays settings to cater for impacts of infeeds and mutual couplings in parallel and T’d-feeders for HV & EHV systems.

We will undertake advanced power system studies to determine the feasibility of generator connection to the distribution network. The modelling process will include several types of simulation. Each simulation will be used to test the generator performance against a different group of requirements as outlined in the Technical Rules (NER). Depending on the size of the generator we will undertake the following studies:

• Load flow study to assess over/under voltage, overloading, adequate active and reactive power reserves, operational constraints and precautions required;
• Short circuit study to confirm fault rating of connected equipment and determine if the rating will be adequate or exceeded;
• Stability study to determine how the power system operates during different disturbances, in particular how fast the protective devices will clear the fault before the generator and surrounding power system become unstable;
• Power quality study to ensure that distorting loads do not cause unacceptable power quality in the power system.
• Network black start study to ensure that the plant can be reinstated from system black out and demonstrating if it’s capable of doing this automatically without the grid or diesel generator supply.
• Under-voltage ride through study to demonstrate that the renewable plant, when supplying the normal load, can ride through a 3-Phase fault at specific terminals on the reticulation network, such as at MV/LV main board terminals of step down transformer.
• Generator reactive capability study to confirm that the reactive power requirements of the generator are not excessive or if switched capacitor banks need to be provided at the generator terminals.
• Frequency control study to conform that the power plant governor droop settings are coordinated with existing generator governor droop settings and demonstrate that the plant block load acceptances and rejections occur in a stable manner. This study investigates frequency stability issues that may arise with different generator combination: Wind, Solar, Diesel generator and Battery systems.

We will determine if your substation grounding grid design is safe. We will limit touch and step potential to values below recommended limits for safe operation and protection of personnel. Using IEEE 80-2000 & IEC 60479 standards, we will:

• Analyse earth grid model from field measurements
• Analyse grid and earth potential
• Analyse multiple ground systems
• Analyse the potential rise for each grounding system including neighbouring passive grids or rods
• Calculate maximum permissible touch and step voltages
• Evaluate danger points in the substation and outside the substation
• Calculate voltage, step voltage ad earth potential rise
• Determine the size of earthing conductors.