Defence Plan of Power System of Macedonia

Taking into account that well-connected interconnection systems run closer and closer to their operation limits and that the stability and reliability of the individual national electric power systems have become very dependent on each other, each TSO should pay special attention on emergency procedures and develop a forehand activities in order to prevent the occurrence and mitigate the consequences of incidents in the network. In accordance with the stringent rules set out in the ENTSO-E Policy 5 (Emergency procedures), the main task of this Study is creation of the defence plan of the Macedonian power system that would provide solutions and recommendations to minimize the consequences of some less probable disturbances or widespread disturbances, which may cause blackout and also to define detailed restoration procedures in case that partial or total blackout occurs.

The main activities within this Study are the following:

• Update of dynamic model – reviewing of current dynamic model, preparing of input data questionnaires, gathering necessary information about dynamic parameters from power plant sites, dynamic model update in PSS/E format and report about dynamic model update

• Defence plan - overview of present state related to defence plan development, OTDF analyses and determination of observability area, Steady state security assessment, Voltage stability assessment (voltage profiles, PV and QV analyses), determination of preventive and remedial actions, frequency stability assessment, under frequency load shedding plan, Transient stability assessment (transient stability margin, critical clearing time), small-signal stability assessment (modal analyses, small-signal stability margin, damping ratio)

• Restoration plan – Restoration without external voltage source (bottom-up), restoration with external voltage source (top-down), restoration strategies, criteria for the selection of black start generator units, initial loading of black start generator, operational procedure, verification of operational procedure throughout dynamic simulations.

The following activities have been performed:

• Dynamic modelling

• Present state analyses (compatibility of existing defence plan with ENTSO-E Policy, relay protection settings, generator, turbine governor and excitation system models, functionality of existing under frequency load shedding plan, load shedding procedures, description of critical network conditions from the past)

• Load flow analyses

• Voltage profile analyses

• Steady-state security assessment

• Voltage stability assessment

• Frequency stability assessment

• Transient stability assessment

• Small signal stability assessment

• Black start capability assessment

• Restoration plan development

• Verification of restoration plans.