Basic Substation Training

Basic Substation Training

By Kelvin Tang 4 June 2009

Basic Substation Training

•Basic substations

•Why do we need them?

•Different configurations

•Availability

•Design parameters

•Function of main components

•Cost drivers

Basic Substation Training

What is a Substation?

SUBSTATION - A facility that steps up or steps down the voltage in utility power lines. Voltage is stepped up where power is sent through long-distance transmission lines. It is stepped down where the power is to enter local distribution lines. - California Energy Commission Dictionary

An electricity substation is a place, which allows electricity to go from one part of the production system to another.

-Cambridge International Dictionary

Subsidiary station in which electric current is transformed. -Merriam Webster’s Dictionary

Basic Substation Training

What is a Substation?

Outdoor Substation is an open type of structure for supporting high-voltage air-insulated power equipment. – NEMA SG 6

Basic Substation Training

Why do we need a substation?

Substations are entities that integrate the power system (Generation, Transmission, and Distribution).

They provide: -Transformation -Switching -Tie Points -Sectionalizing -Protection -Compensation ABB

Basic Substation Training

Design Objective:

The substation design objective is to provide maximum

reliability, flexibility, and continuity of service and to meet these objectives with the lowest investment costs that satisfy system requirements. – Standard Handbook for Electrical Engineers

Basic Substation Training

Design Considerations:

•Load Capacity

•Environmental Considerations •Site Space Limitations

•Transmission Line right-of-way Requirements •Safety

•Maintenance and Operation •Expandability

•Cost

•Reliability

Basic Substation Training

Types of Substations:

•GIS – Gas Insulated Substation •Hybrid – SF₆ and Air

•Modular Substation •Standard Substation •Mobile Substation

•Distribution Substation (34-138 kV HV; 2.4-34.5 kV LV side) •Transmission Substation (230-745 kV HV; 34-230 kV LV side) •Switching Substation (Transmission SS without transformer)

Basic Substation Training

Types of Substations:

AIS

Advantages Disadvantages

Easy access to bus and equipment for inspection and repair

Equipment are subject to weather conditions, animals, vandalism, contamination

Lower cost Requires more real estate Design and material flexibility

Easy to expand

Easy to replace equipment

Basic Substation Training

Types of Substations:

AIS

Basic Substation Training

Types of Substations:

GIS

Advantages Disadvantages

Reduced space requirements Higher cost

Less exposure to contamination Requires clean work area for assembly HV Bus physically protected Expensive repair

Flexible layout and Expansion Requires special training for operators No concern about clearances to ground Spare parts are specialized

Can be installed indoors

Basic Substation Training

Types of Substations:

GIS

Basic Substation Training

Configurations of Substations:

•Segmented Single Bus (Single Bus with Sectionalizer) •Main and Transfer Bus

•Double Bus, Single Breaker •Double Bus, Double Breaker •Ring Bus

•Breaker and a Half

Basic Substation Training

Configurations of Substations:

Single Bus

Advantages Disadvantages

Least cost Bus fault causes a complete substation outage

Expandable Minimal flexibility for maintenance Simple protection scheme Expansion requires complete outage Simple operation

Less real estate requirements

Basic Substation Training

Configurations of Substations:

Segmented Single Bus

Advantages Disadvantages

Increased reliability Higher cost (more breaker / switches / relaying)

More operational flexibility (fault on the bus will de-energize only half of the SS)

More equipment to maintain Maintenance can be done in one bus while

the other is energized.

Outage can occur on several lines of the same bus

Basic Substation Training

Configurations of Substations:

MAIN AND TRANSFER BUS

Increased relaying complexity

Main and Transfer Bus

Advantages Disadvantages

Circuit breaker can be readily removed from service for maintenance

Extra circuit breaker

Relatively low cost for increased flexibility Requires a switching procedure for transferring a line to another breaker Failure on the main bus may cause a complete outage of the substation

Basic Substation Training

Configurations of Substations:

Complicated switch operation Each circuit can be connected to either bus

Complicated relaying

Tie breaker fault causes outage on the entire substation

Each bus can be isolated for maintenance

Double Bus, Single Breaker

Advantages Disadvantages

One breaker per line Extra breaker for coupling

Provide more flexibility Bus fault or breaker failure will disconnect all circuit connected to this bus

Requires additional switches

Basic Substation Training

Configurations of Substations:

Possibility of losing half of the substation High availability and reliability

Double Bus, Double Breaker

Advantages Disadvantages

Each breaker can be serviced without disconnecting the circuit

Two breaker per circuit Either bus can be serviced without

interruption of power

Highest cost

Basic Substation Training

Configurations of Substations:

RING BUS

Difficult expansion No main bus

Requires a potential transformer in each circuit

One breaker per circuit

During fault only two breaker are tripped During breaker failure three breaker are tripped

All switches is done with breakers

Ring Bus

Advantages Disadvantages

Low cost Fault during a breaker maintenance causes a ring separation

Each breaker can be maintenance without outages

Automatic reclosing and protective relaying rather complex

Basic Substation Training

Configurations of Substations:

Either bus can be taken out of service Bus failure causes no outage

Complex reclosing and protection schemes Bus breaker failure removes only one

circuit

All switching done with breakers Simple operation

High availability

Breaker and a half

Advantages Disadvantages

Most flexible operation High cost

High reliability More breakers

Basic Substation Training

Availability of a Substation:

AVAILABILITY. Describes the reliability of power plants. It refers to the number of hours the Turbines are available to

produce power divided by the total hours in a year. - The Sun's Joules

Is the percent of the time that a unit is available to produce power whether needed by the system or not. It is a measure of overall unit reliability. It is equal to 100% less percentage of time of forced outage less percentage of time on scheduled outage. – Standard Handbook for Electrical Engineers

Basic Substation Training

Reliability of a Substation:

Reliability Engineering. The probability that a product will be operational after a period of usage or over a specified time

period, based on testing of the product under a prescribed operation and operating environment – Harcourt Dictionary

Basic Substation Training

Reliability of a Substation:

RELIABILITY - Electric system reliability has two

components: adequacy and security. Adequacy is the ability of the electric system to supply the aggregate electrical demand and energy requirements of the customers at all times, taking into account scheduled and unscheduled outages of system facilities. Security is the ability of the electric system to

withstand sudden disturbances such as electric short circuits or unanticipated loss of system facilities. Energy Terms

Dictionary

Basic Substation Training

Reliability of a Substation:

System reliability consists of two elements: dependability and security.

Dependability is the certainty of correct operation in response to system trouble, whereas security is the ability of the system to avoid misoperation with or without faults. Dependability can be checked relatively easily in the laboratory or during installation by simulated tests or a staged fault. Security, on the other hand, is much more difficult to check. A true test of system security would have to measure response to an almost infinite variety of potential transients and

counterfeit trouble indications in the power system and its environment. A secure system is usually the result of a good background in design, combined with

extensive model power system and can only be confirmed in the power system itself and its environment. – ABB Protective Relaying Theory and Applications

Basic Substation Training

Why High Voltage Product?

-High voltage products perform different important functions in the power system.

-Connect, Detect, Protect and Correct:

-connect the various parts in a substation.

-Detecting & monitor the operating levels of current and voltage for accurate energy measurement.

-protect the power system.

-correct the voltage and power factor.

Basic Substation Training

Components of a Substation:

Circuit breakers: Protects and isolates the power system from faulted lines and equipment. Has the ability of operate under load

Basic Substation Training

Components of a Substation:

Disconnect Switches: Provides a visual means of isolating a circuit. Usually operated without load

Basic Substation Training

Components of a Substation:

Grounding Switches: Provides a path from phase to ground

Basic Substation Training

Components of a Substation:

Current Transformers: Device used for measuring the primary current of the system

Basic Substation Training

Components of a Substation:

Potential Transformers: Device used for measuring the primary voltage of the system

Basic Substation Training

Components of a Substation:

Coupling Capacitors Voltage Transformer: Device used for measuring the primary voltage and sometimes also in conjunction with the Line Trap for telecommunication applications

Basic Substation Training

Components of a Substation:

Line Traps: Used in Power Line Carrier application for telecommunication between substations

Basic Substation Training

Components of a Substation:

Lightning Arresters and/or gaps: Device that provides a controlled point for diverting a surge or overvoltage, thereby protecting equipment

Basic Substation Training

Components of a Substation:

Power Transformers: Provides transformation of electric power from one voltage level to another at constant power

Basic Substation Training

Components of a Substation:

Shunt reactors: Used on long transmission line systems to limit the voltage during breaker operation

Basic Substation Training

Components of a Substation:

Current-limiting Reactors: Used to limit the short circuit level of a sub-transmission system

Basic Substation Training

Components of a Substation:

Station buses and insulators: Used to route the electrical energy within the SS

Basic Substation Training

Components of a Substation:

equipment during normal or fault situation, and provides a solid voltage reference point

Basic Substation Training

Components of a Substation:

Series Capacitors: Used in EHV systems to increase power flow capacity and system stability

Basic Substation Training

Components of a Substation:

Shunt Capacitors: Used for compensating a reactive load and for regulating the voltage

Basic Substation Training

Components of a Substation:

Auxiliary Power System: Provides the electricity needed to insure the proper operation of the substation. (Ex.: Auxiliary Transformer, Load Center, Motor Control Center, AC

Distribution Panel, DC Distribution Panel, Battery Bank, Battery Charger, etc.)

Basic Substation Training

Components of a Substation:

Control and Protection System: Provides means to

electrically operate the equipment of a substation from a remote location and also protects the HV equipment in the event of a fault. (Ex.: Protection Relays, Control Panel, Control Panel Accessories e.g., control switches, test switches, indicating lights, etc.)

Basic Substation Training

Design Parameters:

Voltage:

(V) Term used to designate electrical pressure or force that causes current to flow. – Dictionary of Electronics VOLTAGE. The difference in electrical potential

between any two Conductors or between a conductor and ground. It is a measure of the electric energy per electron that electrons can acquire and/or give up as they move between the two conductors. – The Sun’s Joule

Basic Substation Training

Design Parameters:

Current:

Current - The flow of electrons through a complete circuit. – Smart.com

Measured in amperes, it is the flow of electrons through a

conductor. Also know as electron flow. – Dictionary of Electronics

Basic Substation Training

Design Parameters: Power:

Amount of energy converted by a circuit or component in a unit of time, normally seconds. Measured in units of

watts. (joules/second). – Dictionary of electronics

Basic Substation Training

Design Parameters: Power:

POWER The rate at which energy is consumed or produced. It is expressed in Watts (W). A 1-watt source supplies energy at the rate of 1 Joule per second. (A 100-watt lamp consumes energy at the rate of 100 joules per second; the human body

involved in normal activity is rated at about 100W, a significant proportion being used to drive the brain). The Sun radiates

energy at the rate of about 70 million watts per square meter of its surface; at the equator the Earth receives a mean annual

solar energy flux of around 1,400 watts per square meter. - The Sun’s Joule

Basic Substation Training

Civil Design Parameters: Codes:

SBC – Standard Building Code

BOCA – Building Officials Code Administrators IBC – International Building Code

ASCE – American Society of Civil Engineers NESC – National Electrical Safety Code

NEMA SG6 – National Electrical Manufacturer Association IEEE – International Electrical and Electronic Engineers Code

Basic Substation Training

Civil Design Parameters: Seismic

Zone:

Can be measured on:

Zone 1, Zone 2, Zone 3, Zone 4 0.1G, 0.2G, 0.3G m/s2

From the “No Seismic” to the “Max Seismic” Zone there may be up to 50% (Breakers and Transformers) difference in the

foundation and structural design

Basic Substation Training

Civil Design Parameters: Wind:

Wind Load = 0.0256 x V2 _{x factor x S}

It is the biggest load in a substation structure (except for breakers and transformers)

Basic Substation Training

Civil Design Parameters: Ice:

This load can double the normal weight of Conductors and Rigid Buses

Basic Substation Training

Civil Design Parameters: Soil

Properties:

Soil can vary from a swamp to rocky.

The volume of the foundations can vary up to 100% and the cost up to 200% due to these properties

Basic Substation Training

Civil Design Parameters: Water

Table:

Water must be pumped out of the foundation before pouring concrete on it

Basic Substation Training

A substation may cost from < 1 million dollars up to tens of millions

Basic Substation Training

Acknowledgements:

For the support and information sharing, thanks to:

• Juliano Braz

• Sylvester Phang • Wong Weng Woi • Sankaran-T Arasu

Basic Substation Training

Bibliography:

1. G. Balzer, B. Boehle, K. Haneke, H. G. Kaiser, R. Pohlmann, W. Tettenborn, G. Voss, ABB Switchgear Manual, Tenth Edition

2. W. A. Elmore, ABB Protective Relaying Theory and Applications

3. D. Fink, H. Beaty, Standard Handbook for Electrical Engineers, Thirteenth Edition, McGraw Hill, 1993

4. ABB Power Technologies, High 5, http://www49.de.abb.com/

ABB