COURSE OUTLINE

ROLE OF SUBSTATIONS IN AN ELECTRICAL NETWORK, TYPES AND CONFIGURATIONS OF SUBSTATIONS

• Networks – an introduction
• Different voltages in a network
• Substations as network nodes
• Substation types based on their position in the network
• Optimising the location of a substation
• Substation options: Outdoor air insulated, GIS, Indoor air insulated
• Configurations of HV substations based on their bus arrangement (typical SLD)
• Data on the industrial loads required for the design of the electrical supply substation
• Load assumptions for residential and commercial consumers
• Environmental issues in the location of a switchyard and mitigation measures

SYSTEM STUDIES REQUIRED FOR FINALISING EQUIPMENT RATINGS

• Load flow study (active/reactive loads)
• Short circuit study
• Harmonic flow
• Voltage profile and reactive power compensation
• Stability study
• Note: The objective/relevance of each of these studies to the substation equipment selection and specifications, the inputs required and outputs expected will be covered in this section. A broad overview of the studies will be provided without going into the actual calculations involved.

OVERVIEW OF SWITCHYARD EQUIPMENT AND THEIR ORDERING SPECIFICATIONS

• Main (primary) equipment
• Busbars
• Disconnectors
• Circuit breakers
• Instrument transformers
• Lightning arrestors
• Power transformers
• Structures
• Layout options
• Sectional and Safety clearances and their influence on the layout
• Design of busbars (strung/tubular) and interconnections between equipment
• Interconnecting cables and use of marshalling kiosks

PROTECTION DESIGN FOR SUBSTATION

• Brief overview of protection
• Over current protection
• Protection coordination
• Protection of transformers
• Busbar protection
• Feeder protection
• Current transformers requirements for protection
• Equipment requirements for substation automation
• PLCC applications in protection and communication
• PLCC hardware and integrating them with the switchyard equipment

SUBSTATION EQUIPMENT FOR FAULT LIMITING, PFC AND HARMONIC CONTROL

• Need for and application of:
  • Fault limiting reactors
  • Power factor compensation equipment
  • Static VAR compensators
  • Harmonic filters
  • Equipment design and selection of ratings
  • Layout of these equipment in a switchyard

EARTHING SYSTEM AND LIGHTNING PROTECTION OF SWITCHYARDS

• Basics of functional and protective earthing
• Touch and step voltages in substations
• Earth grid and its role in safety
• Switchyard fence-why it should be a part of the earth grid
• Design of earth grid-basic considerations in conductor sizing and mesh spacing
• Pros and cons of including the control building within the  switchyard earth grid
• Earth mat laying and welding
• Safety mesh at operating points
• Role of gravel layer in safety
• Transferred voltage hazards
• Planning isolation of outgoing services to avoid transfer voltage
• Basics of lightning and hazards
• Role of shield wire and lightning masts
• Typical configurations of lightning protection of switchyards
• Analysis of hazard using cone of protection and rolling sphere methods
• Selection of lightning arrestors-Types, class and ratings

SWITCHYARD CONTROL AND INTERLOCKING

• Dc power requirements for switchyard equipment
• Dc equipment configuration and specifications
• Dc distribution for switchyard equipment
• Battery calculations basis
• Space planning and related facilities for a battery installation
• Ac auxiliary power for switchyard systems-loads which require ac power
• Possible source options
• Ac auxiliary distribution for switchyard equipment and support systems
• Control scheme of disconnectors and circuit breakers
• Control interconnection approach
• Use of optical fibre-based control scheme
• Role and location of marshalling kiosks in different bays

SWITCHYARD-FACILITY PLANNING

• Site preparation, levelling
• Earth resistivity measurement and its role in design verification
• Civil works such as equipment foundations, cable trenches, control building, storm drains, transformer oil collection pit
• Structures and their design requirements
• Substation fence and physical security
• Surveillance
• Planning water requirements and supply arrangement
• Fire protection, lighting and ventilation of control room and other equipment