Basics of Load Allocation

Jennifer Taylor,Chris Hammond

What we’ll cover today

• Basic overview• Beyond the basics

– “tricks of the trade” to simplify complex ways to load allocate

Load allocation

• What is it?– The process of distributing kW or Amps per

phase load at a given point to the individual circuit elements downline from that point.

– Somewhat of an art form, isn’t concrete– Close approximation of actual loading

• Isn’t real time

What type of study?• What you are planning to do with the model will

determine how you want to approach load allocation:– Planning study = worst case

• NCP data for all areas of the study

– Specific snapshot in time• Example: planned substation outage

– Coincident Data corresponding to the conditions youare examining

Getting started – Gathering Data

• First look at what type of data is available– At the “source” (Load Control Point)

• Substation: kW or Amp data• Feeders: Amps• Downline LCP

– Downline elements• What type of load bearing elements do I have?

– Consumers– Line sections

Getting Started – Gathering Data

• Decide how to distribute the load– Billing data– AMR data– Distribution transformers– Geographic model

Choose the load allocation method• Length – no billing data required• REA –1950s standard, needs kWh• Seasonal – uses kWh but allows for a % CF (coincidence

factor)• Transformer kVA – must have kVA rating for all distribution

transformers• kWh – requires kWh from billing file• Diversity – requires kW and maybe kWh

or trkVA

Set up Load Groups

• Load Groups are used to define “types of consumers.”

• Examples of typical load groups:– Residential– kW Demand

• Each load group can be assigned a different load allocation method.

Set up Load Groups

Methods and Groups

• Deciding on (a) how many load groups and (b) what type of load allocation methods to use go hand in hand.

• Understanding how the fixed and allocated methods work together is important in making your decision.

• Let’s take a closer look at the Diversity allocation methods.

Diversity: Fixed vs. Allocated

• Fixed– Fixed amount of kW for a given load group

• Coincidence Factor - % of this fixed amount that will be allocated– Ex. LCP = 10,000kW, Dmd load group total kW =1000kW

80% CF = 800 kW allocated to Dmd load group

– Tip: Choose a % CF for your fixed group that will yield the Load Factor that you want for the allocated group.

Diversity: Fixed vs. Allocated

Diversity: Fixed vs. Allocated

• Allocated– Allows a load factor to be applied if more than

one load group is using an “allocated” method• Ex. Residential users = Residential group

Large Power users = kW Demand group

Load factor (LF) Residential = 45%Large Powers = 55%

Diversity: Fixed vs. Allocated

More than one group allocated

• How does this work?– Step 1: XRESI= Σ kWhRESI / %LFRESI

XDMD= Σ kWhDMD / %LFDMD

– Step 2: %LCPRESI=LCPTOT* XRESI/(XRESI+ XDMD)%LCPDMD=LCPTOT* XDMD/(XRESI+ XDMD)

– Step 3: Allocate kWh group based on kWh.Allocation continues with fixed kWwith 100% CF.

What’s Next?

• Now that we’ve…– Decided on type of study– Gathered data– Set up load groups– Chosen load allocation methods

• Start applying data and allocating load

Billing Download

• If you’re using billing information or AMI, you must get that information into the model.

Billing Download

• Billing data can be viewed under the Billing Load tab.

Define Load Control Points

Define Load Allocation Settings

Run it!

Verify Results

Load Groups

Q: Why would you want more—or different—load groups?

A: To try and make load allocation better and easier, based on particular characteristics of the load.

Load Groups

Available Load Groups

Load Allocation Preferences

Set Up Load GroupsNumber of Groups – Up to

four (4)Names of Groups

Load Information

What type of load information do you have available?

kWh kWkVAr kVAPower Factor Rate CodeLoad Factor Time of Use

Load Information

You see your available load information…

Now – What do you want to do with it?

Billing Load Setup

• Here is the billing load table. Notice the Group Names are down the left side and the load values used are listed across the top.

Billing Load Setup

Now you see what is actually used in the load table for allocating load.

kWkVArkWhkVA – Transformer kVACons – Number of consumers

Billing Load SetupThis is where the rules

are set up to place the load into the correct load group. You can even create rules based on data irrelevant to load allocation.

Billing Load Setup

These rules allow you to put the load into the correct load groups. Anything in the load file can be used to help filter the load and get sorted into the desired group. In this example, the rate code was used to put load into the Horsepower Load Group. And the “kW > 0” puts the demand loads into the kW Demand Load Group.

Billing Load Setup

When setting up Load Rules, if the load fits the rules for one, it will go into it. If there need to be more restrictions, then add the condition in the rules.

Example:

Billing Load Setup

(1) You know the information that WindMil needs to apply load.

(2) Now you need to look at your load file and see what you have.

(3) Then you have to figure out how you can use the rules and get the information where you need it.

Billing Load Setup

The load file may be either:Space Delimited

orComma Delimited

The load file may include the information you want to use. You may have to modify it in another program to get your desired information.

Billing Load File

I prefer comma delimited files. They import into Excel very easily for manipulation and checking.

In the spreadsheet, the load can be checked for errors. Needed calculations can be performed, such as load factor or power factor.

Load Allocation

Now the load can be applied to the groups that you desire.

Load Allocation can now be performed.

Why Go Through the Trouble?

Separating the load into groups allows you to adjust your load allocation settings to model your circuit best.

Diversity Factors, Power Factors, Load Factors

Why Go Through the Trouble?Examples of types of loads that may help load allocation

improve your system.Demand loads with poor load factors – actual

contribution to peak – coincident factorPump loads – poor power factor associated with

lightly loaded motor conditionsCyclic loads – chicken houses

Why Go Through the Trouble?

• To improve system allocated power factor• Having load separated allows the user to adjust

the power factor of the residential group and allows the power factor to swing and adjust accordingly for these loads.

• Improve existing system model• Improve capacitor recommendations

Why Go Through the Trouble?

• For cyclic loads (such as chicken houses). The load may be on only half of month, but the entire demand is on during peak.

• For time of use, the load can be allocated for peak condition and for non-peak times to find loading problems with only one load file.

Load Allocation

Depending on your available load information, there are ways to improve your system loading to make your model as useful as possible. And all good system models start with good load.