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© 2019 MOELLER & POELLER ENGINEERING LTD

international power system consultants

power system simulation studies

MPE has extensive experience of modelling and simulation of all power system components for steady state, RMS, EMT, frequency domain / harmonic, or SSR studies. This includes individual power station or full power system studies for grid code compliance, G5/4, G5/5, P28, P29, or G74 requirements

 

load flow & contingency analysis

Our engineers have performed these studies for complete transmission systems, distribution networks, and individual sites, and for a range of purposes.  The results often feed into other studies that MPE can undertake such as protection coordination, arc flash and connection studies. The services that MPE offers in this area include:

  • collecting equipment data in the field

  • developing a network model

  • specifying continuous current ratings

  • assessing existing equipment ratings 

  • specifying transformer impedance & tap ranges

  • determining generator operating mode

  • determining generator reactive power requirements

  • evaluating maximum steady state line capacity

  • evaluating system reactive compensation requirements

  • identify required post-fault actions (manual or automatic)

  • PV and QV curves for assessing steady state voltage stability

 

Short circuit studies allow assessment of equipment rating (e.g. switchgear, cables, and generation), and provides input into other studies such as protection coordination or earthing design. MPE can perform these studies to any published standard (e.g. IEC 60909 (2016) or ER G74) using a range of software including DIgSILENT PowerFactory, PSS/E, ETAP, or MPE's in house short circuit calculation tool, which can be adjusted to any standard or non-standard fault current calculation method.  

Until recently fault current contribution from inverter based equipment (e.g. DFIG and full converter wind generation, PV generation, and HVDC) was neglected in the standards. Given the rise of this type of generation the latest IEC standard now caters for its controllable contribution to fault current. For similar reasons, the UK standard G74 has been recently updated. MPE was the lead technical consultant for this update, on behalf of the Energy Networks Association, to study and propose suitable options to the working group.

 

Power systems must remain stable for a variety of disturbances, considering a wide range of dynamic responses for different equipment and system configurations. MPE can perform dynamic studies to assess the stability of any network.  Our services include:

  • developing dynamic models for all types of equipment

  • creating network & controller models in DIgSILENT PowerFactory, PSS®E, PSCAD, ATP, RSCAD, and other software

  • simulations from 'single machine' to full power system 

  • determining appropriate scenarios to study and performing stability studies

  • designing mitigation measures to improve or maintain power system stability

  • performing grid code compliance or grid integration studies for any generator type

 

The results of the EMT studies can be used in insulation coordination procedures to define minimum insulation requirements for equipment, or to design mitigation measures such as surge arresters and sheath voltage limiters. These are designed in accordance with international standards such as IEC 60071 and IEEE C62.82.2.

 

We also specialise in circuit breaker transient recovery voltage (TRV) simulations to assess circuit breaker dielectric capabilities, and designing the most cost effective mitigation measures where required.

One area of particular expertise for MPE is with transient studies for HVAC connected offshore wind farms with long export cables (up to and in excess of 200 km and 275 kV), and array networks with voltages up to 66 kV. 

MPE has world-class experience in conducting electromagnetic transient (EMT) studies to calculate the maximum system overvoltages due to:
 

  • fault occurrence/clearing

  • switching transients

  • harmonic resonance & transformer energisation

  • ferroresonance

  • lightning strike

  • very fast transients (VFTO) in GIS SF6 substations

 

Harmonics in power systems can cause overvoltages, excessive heating of equipment, mal-operation of equipment, and poor power quality for end-users. Our comprehensive study approach considers different system configurations, equipment outages,  harmonic voltage gain factors / transfer coefficients, and harmonic impedance loci or full harmonic network models. MPE offers a suite of services including:

  • frequency domain harmonic studies to determine the likely impact of new or modified plant

  • compliance verification with national and international standards such as IEC 61000, IEEE 519 and UK ER G5/4 and G5/5

  • measurement for background harmonic assessment

  • incident investigation

  • development of harmonic standards

  • harmonic filter design to mitigate any issues

  • our speciality is harmonic studies for HVAC connected offshore wind farms (>200 km)

 

Electrical faults can release significant amounts of energy, endangering personnel.  Arc flash studies quantify the hazards posed by these faults, allowing suitable PPE and other mitigations to be put in place.

MPE can conduct complete arc flash studies in accordance with IEEE 1584.  Our services in this area include:

  • collecting equipment data and recording relay settings in the field

  • developing a network model 

  • calculating incident energy levels and arc flash boundaries

  • recommending mitigation strategies to reduce arc flash hazards

 

Our engineers are experienced with protection coordination studies for generators, transmission systems, distribution networks and industrial plants.

MPE offers a wide range of services related to protection systems including:

  • Developing protection philosophies and standards

  • Preparing concept and detailed designs for protection systems

  • Developing logic and setting files for protection relays

  • Carrying out relay coordination studies

  • Preparing settings for more complex elements such a distance, differential, restricted earth fault and more

  • Investigating protection trips and other events

  • Specifying ratings and accuracy classes for instrument transformers

 

Sub-synchronous resonance (SSR) studies are typically completed for transmission systems with series-compensated overhead lines near generating plant.  The series-connected capacitors can interact with generator mechanical systems, exciting torsional vibration modes and potentially causing severe damage to the turbine-generator shaft system.

If issues are identified, MPE's SSR specialists are able to design mitigation measures to prevent damage to equipment.

 

modelling of components and networks

MPE can develop customised plant and equipment simulation models, suitable for use with power system analysis software such as DIgSILENT Power Factory, PSCAD, EMTP-ATP, Siemens PSS/E, RSCAD and ETAP.

This service helps developers and manufacturers in fulfilling utility requirements for new generation sites.

We are also experienced in updating and debugging existing network models, as well as migrating models to different software platforms.

 

grid code compliance studies

We can provide all required grid and distribution code compliance studies for any international requirement (including ENTSO-E requirements) for synchronous or non-synchronous plant. In fact, MPE has developed many of the international requirements found in Grid Codes and Connection Conditions around the world. Therefore we understand the results the utilities are looking for. If non-compliance becomes apparent, then we can propose design modifications or recommend a course of action to resolve the issue, including supporting discussions with the utility / system operator. Examples of the studies we provide include; 

  • reactive capability

  • reactive power stability and voltage control 

  • PSS tuning & verification 

  • transient stability

  • fault ride through (FRT),

  • fast fault current injection,

  • frequency sensitive mode (frequency response),

  • LFSM-O & LFSM-U 

  • model verification with compliance tests. 

 

G5/4, P28, P29 studies

Grid owners may request power quality studies prior to allowing connection of new generation or loads to their network.  In the UK, these studies are known by the Engineering Recommendation standards G5/4 (harmonics), G5/5 (new harmonic standard) , P28 (rapid voltage change and flicker) and P29 (voltage unbalance).

MPE has substantial expertise in this area — we  have completed  numerous power quality studies, for sites that are only a few megawatts through to a 2 GW generating plant connected at 400 kV. Our services include:

  • harmonic studies as per G5/4, G5/5, IEC 61000 and IEEE 519 

  • assessment of flicker and rapid voltage changes in accordance to ER P28, IEC 61000 and IEEE 1789

  • assessment of voltage unbalance as per ER P29

 

let's talk

if you have a question about our services, or would like to talk about how we can help with one of our projects then please use the form below, where all offices will receive your message and the most appropriate person will reply as soon as possible