A PRESENTATION ON LOAD SHEDDING

SUBMITTED BY BALURAM

NAIN 11EJCEE015

CONTENTS

IntroductionElectrical energy flow load shedding scheduleConventional load sheddingIntelligent load sheddingAffects of load sheddingBenefits of load sheddingDisadvantage of load sheddingElectricity saving v/s load sheddingConclusion

LOAD SHEDDING

Load shedding is a measure of last resort to prevent the collapse of the power system country-wide. When there is insufficient power station capacity to supply the demand (load) from all the customers, the electricity system becomes unbalanced, which can cause it to trip out country-wide (a blackout), and which could take days to restore.

As the difference between supply and demand becomes small, we refer to the system becoming “tight”.

This implies that action has to be taken to prevent the system from becoming unstable.

Power Generation(Thermal, Hydro-electric, Nuclear)

(Supply)Or

Non-conventional(Solar PV, Wind etc)

Consumers(Demand or Load)

e.g: Lighting-Computer/IT Equipment

-Industrial Processes

Ideally...Supply=Demand

(Power-generated=Power-consumed)

Transmission and DistributionNetwork(T & D)

DemandRapidly increasing

Supply

Load-sheddingDemand is more than supply (Basically a Power Shortage/Power Cut)

Increasing supply rapidly is very difficult

ELECTRICAL ENERGY FLOW

Optimize T&D infrastructure Deploy efficient substation automation Upgrade to smart metering solutions

Optimize quality and availability of supplied power Measure and improve delivered power quality Implement DG in frequently congested areas

Influence demand consumption Introduce new tariff structures and smart revenue metering Provide customers with accurate and relevant consumption data Establish DR programs

SUPPLY SIDE

Act on Users Educate people on efficient use of energy Act on business related procedures

Act on loads Replace, renovate aging loads (lighting, motors, HVAC, …) Implement intelligent load control (variable speed drives,

regulation systems, lighting control, ...)

Optimize quality and availability of on site power Measure and improve on site power quality Implement backup generation Exploit co-generation means

Optimize supply costs Use the right tariffs according to specific load profile Participate in DR programs Resell excess power

DEMAND SIDE

8

DEMAND RESPONSE

Demand Response

(DR)

Incentive-Basedoptions

Price-Basedoptions

Time-of-Use, TOU Real-Time Price, RTP Critical-Peak Pricing, CPP

Capacity Market Programs/Ancillary Services Market Programs

Demand Bidding/Buyback Emergency DR programs Direct Load Control Programs

Demand Response

(DR)

LOAD SHEDDING SCHEDULE

Load shedding schedules are drawn up in advance to describe the plan for switching off parts of the network in sequence during the days that load shedding is necessary.

On days when load shedding is required, the networks are switched off according to the predetermined plan, to ensure that, as far as possible, customers experience load shedding in accordance with the published load shedding schedules.

In exceptional circumstances, if scheduled load shedding is not achieving the required load reduction and/or unexpected emergencies or failures occur, then System Control Centres will shed load outside the published schedules by using emergency switching in order to protect the network.

PURPOSE OF LOAD SHEDDING SHEDULE

To make the schedules easier to understand and remember

To improve our ability to adhere to the planned schedules

To improve the stability and consistency of the schedules

To improve the predictability of being switched off To improve the communication of the schedules and

the status of the power system

INTELLIGENT LOAD SHEDDING

An effective load shedding approach requires a comprehensive understanding of power system Dynamics and process constraints, combined with knowledge of system disturbances.

Pre-disturbance operating conditions Total system load demand Generation of each on-site unit Spinning reserve for each on-site unit Control settings for each running unit

B. Post-disturbance operating conditions New system load demand Remaining generation from on-site generation Spinning reserve for each remaining unit Time duration to bring up the spinning reserve

C. Nature and duration of the disturbance: Electrical and/or Mechanical faults Complete or partial loss of power grid connection Complete or partial loss of on-site generation Location of disturbance Duration of disturbance and its termination (self

clearance, fault isolation, protection device tripping, etc.)

D. System transient response to a disturbance System frequency response (decay, rate of change,

final frequency) System voltage response Rotor angle stability of each remaining unit Operation of protective devices

A load shedding system, which can incorporate the above parameters into its calculation and decision making process, must possess certain intelligence.

In addition, power system modelling and simulation software tools have been significantly improved to perform various system analyses from a simple load flow study to more advanced studies such as transient stability analysis.

OBJECTIVE OF INTELLIGENT LOAD SHEDDING

Automatic recall of system configuration, operating condition, and system response to disturbances

Pattern recognition capability to predict system response to disturbances

Systems knowledgebase trainable by user defined cases

Self-learning capability to new system changes Shed the minimum amount of load to maintain

system stability

BENEFIT OF INTELLIGENT LOAD SHEDDING

Optimize load preservation Eliminate unnecessary load shedding Reduction of spinning reserve requirements Reliable load preservation system

AFFECT OF LOAD SHEDDING

The following will not be available when the electricity supply to your home is switched off:

Electric geyser and electrically heated water supplies Electric stoves, electric kettles, microwave ovens and

refrigerators Lights TV and hi-fi equipment Electrically motorised security gates and garage

doors Pool pumps Personal computers

Electric air conditioning Electric alarm clocks Household electric pumps for irrigation or

plumbing systems Electrically operated ignition systems on

certain gas appliances

CONSIDERATION DURING LOAD SHEDDING

Remember to reset the time control clocks on cooking ovens, pool pumps, geysers and other automatically controlled appliances, unless these are battery operated.

remember that householders are responsible for all electricity usage and appliances in their homes.

Ensure that your cell phone is always fully charged when power is available.

Think about transport and communication

Ensure that your vehicle (car, motorcycle, etc.) always has fuel in the tank because petrol stations cannot pump fuel during power outages.

Ensure that you have enough cash because ATMs cannot operate without electricity.

Think about access, security and safety and release automatic electric garage door mechanisms so that you can gain access to your property during a power outage.

Release electric security gates and switch to manual operation to avoid being either locked out of or into your home.

Keep temporary lighting readily available, e.g. battery powered torches and candles and make sure you put these items in places where they will be easy to find in the dark.  

BENEFIT OF LOAD SHEDDING

Demand control Demand control involves making precisely timed load

reductions to prevent energy spikes. Savings come from lower peak demand charges. 

Time-of-use management With this approach, often called “load shifting,”

savings come from managing operations to shift power use to nonpeak times.

Real-time pricing (RTP) optimization Utilities that use this pricing method change their

rates frequently based on the market price of electricity.

Participating in an RTP program means that much of the time rates are 20 to 40 percent lower, but peak rates can be astronomical even as high as 100 times the usual rate for short periods.

Saving money involves shifting your facility’s energy use as much as possible to lower-priced periods and away from super-peak periods.

Demand response  Demand response programs, which let you earn

money for reducing electricity use on demand, come in two main favours.

standby/reliability With standby/reliability programs, you commit to

specific load reductions when the grid is under stress. These events are infrequent and typically last two to four hours.

reserves/market-based With reserves/market-based programs, participation is

usually voluntary. Instead of committing in advance to cutting a certain number of kilowatts, you agree to cut usage for a quoted price. Participants can decide on a daily basis or with even shorter notice whether they want to participate and for what amount.

DISADVANTAGE OF LOAD SHEDDING

Even though people are trying to cope with this situation with the help of alternate energy resources there are lots of drawbacks and disadvantages.

Industries having to consume huge amounts of power to run their machinery for bulk production of materials cannot depend upon the alternate resources.

We can look at the examples of factories being closed down or shut down in the past due to electrical supply not being able to meet the demand that is created.

One another major problem in our society created by load shedding is safety.

People in our society not only work at day but have night shifts as well.

These people face serious threat from attackers at night specially walking down dark narrow lanes with no light.

ELECTRICITY SAVING

Load shedding is therefore done to protect the national power system from collapsing.

Saving electricity (by using energy-efficient appliances, switching off equipment when not in use, using alternative sources of energy such as solar geysers) has benefits such as reduced cost, less pollution, the better use of natural resources (coal, water and fuel) and less wear and tear on the power stations, transmission and distribution systems and it saves customers money.

In these times of capacity constraints, saving electricity also means that the load on the national power system is reduced.

This helps to stabilise the balance between the available generation and the demand, in this way reducing the risk of load shedding.

This is why saving electricity can help to prevent the need for load shedding, especially if customers switch off unnecessary appliances and loads during peak periods, and also at other times when the risk of load shedding is high (when the Power Alert goes into Orange, Red or Brown).

FAULT VS LOAD SHEDDING

When the power goes off, it is not possible to know if it is a fault, emergency load shedding or a scheduled load shedding except by looking at the published schedules.

If an outage occurs at a different time to the published schedule, or goes on for longer than the published time, and emergency load shedding is not being publicised in the media, it should be treated as a fault.

Customers must always check the load shedding schedules, and any outage that does not coincide with these must be reported as a fault.

CONCLUSION

Automatic load shedding is basically a last resort backup measure. As such, it will be called on to operate only when a highly improbable, potentially catastrophic disturbance occurs.

Our method is based on extracting a set of features from the traffic streams to build an on-line prediction model of the query resource requirements, which is used to anticipate overload situations and effectively control the overall system CPU usage, with minimum impact on the accuracy of the results.

We also intend to develop smarter load shedding strategies that allow the system to maximize its overall utility according to utility functions defined by each query.

Just switch off the lights and electrical appliances when they are not required.

THANK YOU

ANY QUERY??