Steel plant powered by 4 generators without external grid connection.
Performance analysis of the Steel-plant.
Coordination of the main protection devices.
Optimized “Compensation System” performance requirements definition.
Harmonic performance analysis and design of the relevant AC filter banks.
Studies & technical support at suppliers premises.
Digital model and test cases for commissioning .
Verifications regarding motors starting in islanded operation with one or two generators.
Support the client regarding the compliance with the Grid Code.
Definition of the functional specification of a Fast Data Recorder (FDR).
Technical support to the customer in the negotiation with local electric authority regarding the so-called Power Purchase Agreement.

Verification of the rating of the SVC new components.
Review of the SVC Control and Protection System with participation at the Factory Acceptance Test of the same SVC Control and Protection System.
Technical support to the customer during the on-site commissioning of the refurbished SVC.

Solar Park on site measurements and transient network analysis.
On site measurements regarding fast transient voltages applied to MV/LV transformer by the switching of vacuum and SF6 breakers.
Network studies to add to measurements also a statistic analysis for the same events.
Harmonic measurements.

System studies to verify the behavior of a steel making plant based on AC or DC EAF in different operating conditions:

• Very weak supplying network
• Islanded operation of the factory

Supplying system conceived as a smart grid solution.
On site measurements on AC and DC Electric Arc Furnace (EAF) to characterize these loads from the electrical point of view.
Preparation in cooperation with the customer of a software with the relevant guide to define a preliminary technical selection of the main equipment for the specific configuration (generator types and rating, static compensation system type and rating, etc). In addition, the tool provides the CAPEX and OPEX of the selected solutions.

On-site measurements in the industrial factory plant to characterize the major fluctuating loads. Analysis of the events recorded and identification of preliminary solutions focused to avoid untimely generator trips.
Static studies (load flow and short-circuit currents).
Assessment of the preliminary rating of the SWC (Static Watt Compensator) and SVC (Static Var Compensator).

Design Reliability Assessment and Analysis of High Power Rectifier.
Definition and participation to laboratory tests for the root cause analysis of the diodes.
Electromagnetic simulations during different operating conditions. The scope was to reproduce different operating conditions of one rectifier group for the direct current and reverse voltage waveshapes assessment with the diode ratings and also in the event of loss of the reverse blocking capacity.
Electromagnetic transients during DC insulators switching. The scope was to reproduce the slow-front transient that was concurrently to the diodes failure.
Harmonics calculations and filters resistors design review. The converters were entirely modelled (regulating and rectifier transformers, filter banks, saturable reactors, rectifier and the electrolytic cells) in different significant configurations. A Montecarlo routine that consider deviations / asymmetries / tolerances of the equipment was applied.
Filters Resistors design review. In order to assess the rating of the resistors of the filters, decisive equipment stresses were applied.

Technical support in the design stage of the MONITA (Italy-Montenegro) HVDC Converter Stations mainly relevant to the following topics:
Interpretation of the network integration requirements stated by the TSOs

• Reactive Power Study: Reactive power size of the different AC filter banks; Strategy to switch-in and switch off the AC filter banks; Definition of a reactive power dead band to connect and disconnect AC filters.
• AC and DC Insulation Coordination Study: Selection of the proper arrester characteristics, considering several conditions or events that could generate transient overvoltages.
• AC Harmonic Performance Study: Assessment of the AC harmonic performance of the two converter stations with respect their connected HVAC system. Detailed rating of the AC filter banks in steady state and in transient conditions.
• HVAC network harmonic impedances: Assessment of the AC network harmonic impedances to be considered in the AC filter design.
• DC Harmonic Performance Study: Assessment of the DC harmonic performance of the two converter stations on the DC side of the link.
• Smoothing reactor basic design: Definition of the conditions to consider in the design of the smoothing reactors.
• Definition of the strategies for the control of the AC filter banks in case of contingencies (N-1, N-2). Assessment of harmonic performances and review of the rating.
• Reactive power and harmonic assessment during inverter high gamma operation.
• Verification of the AC filter banks performances and rating during network restoration.

In addition, regarding Valve hall and HVDC hall, coordination and supervision of the studies devoted to assess the fire load and to assess the relevant fire risk. AC and DC Insulation.
Coordination Study:
Assessment of the Fire load and relevant fire risk concerning valve halls and HVDC halls.
AC breakers requirements.

Electric and magnetic field of transmission lines and sub-stations.
Self-excitation phenomena.
Insulation coordination study in order to verify the following points:
Very Fast Front overvoltages, Lightning, Switching and Temporary overvoltages.
In addition, the Bus-transfer Current interruption duty analysis was analyzed

Technical support to an Italian Consultancy Firm for the execution of the detailed system studies. In particular:

• Analysis of the already performed studies.
• Definition of the methodologies, hypothesis and scenarios to be applied in the detailed studies following also customer requirements (with attention to AC and DC harmonic performances, AC/DC overhead lines interactions, harmonic modelling of the HVAC systems, valve arrangements, etc.)
• Participation to meetings with possible manufacturers.
• Technical support for the definition of the technical specifications for the actual tender. In particular:
• Technical Information (Lead role).
• Converter station losses (Lead role).
• Audible noise.
• General technical requirements.
• Standard Utility (SEC) technical specifications.
• Thyristor valves and associated equipment specifications (Lead role).
• Thyristor valve cooling system specification (Lead role).
• HVDC switchgear spec.
• AC harmonic filters and capacitor banks spec. (Lead role).
• DC harmonic filter spec. (Lead role).
• RI, TVI and PLC filter specifications.
• SOW and tech. Spec. For BAHRA HVDC station.
• SOW and tech. Spec. For PP11 HVDC station.
• Converter station single line diagram (Lead role).
• Converter stations layout (Lead role).

Technical support during bidder stage. In particular:

• Participation to meetings with possible manufacturers.
• Analysis of the different bids.

Comparative analysis between the equipment specified in the technical specifications, the design document at tender stage and the final design stage; Design review of the SVC, in terms of power, voltage and current:
Review of the TCR capability and relevant equipment ratings (i.e., reactors, thyristors);
Review of the filter banks (2nd, 3rd, 4th, 5th) rating.
Study of the behavior of the SVC in order to verify the SVC performance requirements and ratings.
Assessment of the suitability of the SVC system for the correct operation.
Recommendations in order to overcome the operational issues.