Professional Certificate of Competency in Substation Design (Main Equipment)

Overview

Depending on the functions performed by a substation, the configuration and complexity can be quite varied. The skill of the designer is to anticipate the present and future needs that the substation will cater to, select appropriate design configuration and calculate the ratings of main equipment such as busbars, transformers and switchgear so as to ensure trouble free service over a number of decades. Sufficient thought should be given to the need for maintaining critical substation equipment and appropriate redundancies must be planned as well. This is essential as otherwise the consumers fed by the substation can suffer frequent supply outages, which is undesirable from service as well as financial point of view.

It is also necessary to ensure that the substation will work satisfactorily under various normal and not-so normal situations (such as short circuits and other types of abnormal events which can occur in a system) without any failures. This is done by means of various calculations which are performed to reflect a set of simulated conditions. These calculations are collectively called as system studies. The type of studies will depend upon the complexity and criticality of the substation and the loads connected to it. The simulations are carried out using specialised computer software. A designer should have clear understanding of the studies that need to be performed in a given case and should also be able to decide the conditions that are needed to be simulated for each study.

System studies can often bring out problem areas in the design. These need to be addressed by appropriate solutions involving equipment for voltage improvement, fault limiters and flicker compensation. Modern industries give rise to sizeable harmonic components which can result in premature equipment failures by heating and sometimes by harmonic resonance. Harmonic filters and other measures to inhibit resonance will have to be planned in such cases. These studies, when performed at the design stage, permit the designer to include the required corrective equipment proactively and integrate them with the rest of the system by providing proper space and switchgear as a part of the substation design, rather than as an afterthought.

These complex issues will be dealt in this program using a simple step-by-step approach through real life examples. At each step, the basic design approach and calculations will be performed by the students to clearly understand the concepts that are being taught.

Course Outline

MODULE 1: ROLE OF SUBSTATIONS IN AN ELECTRICAL NETWORK, TYPES AND CONFIGURATIONS OF SUBSTATIONS

• Networks-an introduction
• Substations as network nodes
• Substation types based on their position in the network
• Optimising the location of a substation
• 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
• Planning permit and zoning regulations

MODULE 2: EXAMPLES/CASE STUDIES OF SUBSTATION LOCATION AND SELECTION OF CONFIGURATION

Using a given set of data of loads and locations: perform the design of a typical HV substation and develop a suitable configuration, develop the single line diagram, calculate the current rating of busbars and feeders, perform busbar conductor sizing calculation

MODULE 3: 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
• Other calculations normally performed for substation design

MODULE 4: EXAMPLES/CASE STUDIES OF SYSTEM STUDIES REQUIRED AND SYSTEM STUDY SPECIFICATIONS

Develop the specification for a system study for the substation of the previous module including: studies to be made, points which should be studied, expected outcomes, impact on basic ratings, other issues such as handling excessive fault level and poor voltage conditions

MODULE 5: 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

MODULE 6: EXAMPLES/CASE STUDIES OF SUBSTATION EQUIPMENT RATINGS/ORDERING SPECIFICATIONS

Elaboration of example continued from modules 3 and 4: work out detailed ratings of equipment, update the single line diagram, layout of HV switchyard and sectional views, clearances, internal movements and enhanced clearances

MODULE 7: SUBSTATION EQUIPMENT FOR FAULT LIMITING, PF COMPENSATION

• Need for and application of: fault limiting reactors, power factor compensation equipment, static VAR compensators
• Principles of design and selection of ratings for fault limiting and pf compensation

MODULE 8: SUBSTATION EQUIPMENT FOR HARMONIC CONTROL

• What is meant by harmonics?
• The sources of harmonic generation
• The effect of harmonics on electrical equipment
• Applicable limits of harmonic distortion THD (V) and THD (I)
• Harmonic control measures: control at source, control by passive filters, control by active filters
• Rating of passive filters
• Integration of filters and PFC during design

MODULE 9: OVERVIEW OF MEDIUM VOLTAGE (MV) METAL ENCLOSED SUBSTATION EQUIPMENT

• Application of medium voltage in distribution networks
• Main equipment: metal-enclosed switchgear, isolators, circuit breakers, instrument transformers, distribution transformers
• Auxiliary systems
• Control, protection and auxiliary power
• Cabling in substations
• Ventilation and fire safety
• Typical SLD
• Layout options
• Work clearances
• Arc safety and fire safety in MV installations

MODULE 10: EXAMPLES/CASE STUDIES OF MV SUBSTATION EQUIPMENT DESIGN

Add an MV distribution requirement to the HV switchyard of module 6 with associated equipment for pfc and harmonic control. Based on the same: prepare a single line diagram for MV equipment, calculate ratings of pfc and harmonic control equipment

MODULE 11: MV SUBSTATION DESIGN AND SPECIFICATIONS

• Sizing of main equipment of MV substations
• Layout of typical MV indoor substation
• Facilities required
• Switchgear room planning
• Transformers-Indoor/outdoor options
• Space for auxiliary supply equipment
• Cabling as a part of building planning

MODULE 12: EXAMPLES/CASE STUDIES OF MV SUBSTATION EQUIPMENT LAYOUT

Based on the design details of module 11: work out space requirement for the switchgear, work out the space requirement for pfc and harmonic control equipment considering both indoor and outdoor options, prepare a layout in relation to the HV switchyard of module 6

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