Transmission Userguide

8/13/2019 Transmission Userguide

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ACCESS TO WESTERN POWERS TRANSMISSION

NETWORKS

A USERS GUIDE

Transmission Division

363 Wellington Street

PERTH WA 6000

GPO Box L921PERTH WA 6842

Telephone: (08) 9326 6687

Facsimile: (08) 9326 6550

Version 1 - April 1998


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Access To Western Powers Transmission Networks - A Users Guide


\Z\19098PC.DOC

TABLE OF CONTENTS

1. SUMMARY................................................................................................................................. 1

2. INTRODUCTION....................................................................................................................... 1

3. MARKET ARRANGEMENTS IN WESTERN AUSTRALIA.................................................. 1

4. ACCESS RULES......................................................................................................................... 2

5. TECHNICAL CODE .................................................................................................................. 2

6. APPLICATION PROCEDURE.................................................................................................. 3

7. ACCESS ENQUIRIES ................................................................................................................ 3

8. TREATMENT OF LOSSES & BALANCING........................................................................... 4

8.1 LOSSES ........................................................................................................................................ 4

8.2 BALANCING ................................................................................................................................. 4

9. DESCRIPTION OF NETWORK ASSETS ................................................................................ 4

10. TRANSMISSION NETWORK PRICING ............................................................................... 5

11. NETWORK CHARGES ........................................................................................................... 5

11.1 CHARGES TO A LOAD USER......................................................................................................... 5

11.2 CHARGES TO A GENERATOR........................................................................................................ 5

11.3 CHARGES TO A GENERATOR WITH ON-SITE LOADS ...................................................................... 6

11.4 CHARGES TO A USER WITH STANDBY USAGE............................................................................... 6

11.5 CATEGORIES OF CHARGES........................................................................................................... 6

12. ANCILLARY SERVICES......................................................................................................... 7

13. CAPITAL CONTRIBUTIONS................................................................................................. 7

14. FURTHER INFORMATION..................................................................................................... 8

BIBLIOGRAPHY............................................................................................................................ 8

FIGURE 1 - WESTERN POWERS TRANSMISSION NETWORKS.......................................... 9

FIGURE 2 - ACCESS APPLICATION PROCEDURE FLOW CHART..................................... 10

FIGURE 3 - TRANSMISSION NETWORK - ASSET DESCRIPTION ...................................... 11

APPENDIX 1 - ENERGY BALANCING EXAMPLE.................................................................. 12


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1. Summary

The Western Power transmission networks becameavailable for open access on 1 January 1997. This has

provided an opportunity for independent power

producers to compete with Western Power and other

generators in the supply of electrical energy using the

Western Power transmission networks. Access to the

Western Power transmission networks is managed by

the Transmission Division in the South West and

Pilbara Power Division in the North West, both of

which operate as ring-fenced business units. The

market arrangement currently supported is for

bilateral contract trading between generators and

loads. This is in contrast to the proposal for theNational Electricity Market (NEM) in Eastern

Australia where all electricity will be traded through a

pool. In the WA arrangement, independent

generators seeking access must do so in conjunction

with contracted associated loads.

The access regime has been developed through

extensive consultation with the Office of Energy and

industry representatives. The terms and conditions of

network access are defined by the Electricity

Transmission Regulations 1996 (Regulations), the

Electricity Transmission Access Technical Code

(Technical Code) and the Electricity TransmissionAccess Pricing and Charges paper (Pricing and

Charges Paper).

Both the technical requirements for access and the

transmission network pricing follow where practical

the proposals for the National Electricity Market. In

particular, the transmission Use of System prices vary

according to location to promote economic efficiency.

Ancillary services necessary for secure network

operation are provided by generators and the

transmission network operator and are charged for

according to usage by generators and loads.

The purpose of this brochure is to outline the open

access regime that has been set in place and provide

details on how to make an access application.

2. Introduction

Western Power has two separate transmission

networks: the South West Transmission Network and

the North West Transmission Network (refer to figure

1). A brief outline of each is given below. Reference

should be made to the Western Power publication

Transmission Networks for geographics and a more

detailed description of the transmission networks.

The South West Transmission Network extendsfrom Geraldton to Albany and across to the

Eastern Goldfields. It contains 140 substations,

some of which are privately owned, and over6000km of transmission/subtransmission lines

owned by Western Power. Other lines are

privately owned. The North West Transmission Network extends

from Dampier/Karratha to Roebourne/Cape

Lambert and across to Port Hedland. It contains

over 27 substations, some of which are privately

owned, and over 400km of

transmission/subtransmission lines owned by

Western Power. There is over 500km of privately

owned transmission lines.

The programme of implementation of access to

Western Powers transmission and distribution

networks, as determined by the Western Australian

State Government, is as follows:

Access to the transmission networks has beenavailable to all users regardless of load size since 1

January 1997. Access to the distribution networks has been

available to users with an average load of 10MWor above since 1 July 1997. Load levels for distribution network access will be

progressively reduced. The State Governments

current timetable for further deregulation is:

1 July 1998 - Average load of 5MW orabove;

1 January 2000 - Average load of 1MW orabove.

3. Market Arrangements in Western

Australia

The Western Australian transmission access regime is

currently based on physical bilateral contracts

between generators and loads. This is in contrast to

the proposed National Electricity Market which,

being much larger, will operate as a pool of

generators bidding into the market.

As a consequence of the (physical) bilateral contract

arrangements, users are required to ensure that the

energy imported at their load points is balanced with

the energy exported at their generation points


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(network losses are also taken into consideration).

Refer to section 8.2 of this brochure for more details.

Users must comply with the technical requirements

set out in the Technical Code to ensure that thereliability and integrity of the networks are

maintained.

Prices for access to the networks and related services

are set out in the Pricing and Charges Paper which is

published annually by Western Power.

A user is required to enter into an access agreement

with Western Power for the provision of access

services.

4. Access Rules

The requirements and regulations which form the

open access regime for the transmission networks in

Western Australia are set out in the following

documents:

Electricity Corporation Act 1994; Electricity Transmission Regulations 1996 (as

amended); Electricity Transmission Access - Pricing andCharges (published each financial year); Electricity Transmission Access - Technical Code

(Technical Code); and Electricity Referee and Dispute Resolution

Regulations 1997.

The Electricity Corporation Act 1994 requires

Western Power to provide access to its transmission

and distribution networks; the manner and timing

being prescribed by ministerial order. Section 100 ofthe Act provides for the Governor to make any

regulations necessary to give effect to the open access

regime, in accordance with the principles and

requirements set out in the Act.

The Electricity Transmission Regulations 1996 (as

amended) provide the framework for access to

Western Powers transmission networks. They set

out, among other things:

the application and access procedure; confidentiality requirements;

demand and energy balancing requirements; technical regulation provisions (contained in

the Technical Code); terms and conditions of an access agreement;

and transitional provisions.

Persons requiring access to Western Powers South

West network must submit an access application to

the Transmission Division of Western Power.

Persons requiring access to Western Powers North

West network must submit an access application to

the Pilbara Power Division of Western Power. Refer

to Section 6 of this brochure for more details.

The Pricing and Charges Paper sets out the prices tobe charged for access services (including ancillary

services). These charges are covered in more detail in

sections 11 and 12 of this brochure.

The Technical Code sets out the technical

requirements applying to the transmission networks

and users facilities, and the network planning criteria

to be used when planning reinforcements or

enhancements to the transmission networks. Further

detail is provided in Section 5 of this brochure.

The Electricity Referee and Dispute ResolutionRegulations 1997 establish the office of the Electricity

Referee for resolving disputes regarding transmission

and distribution access.

5. Technical Code

Regulations 26 and 27 of the Electricity Transmission

Regulations 1996 require Western Power to publish a

Technical Code and network planning criteria,

respectively. The Technical Code was first published

on 31 March 1997. It sets out, among other things:

transmission network performance criteria,including network planning criteria;

technical requirements of users facilities; inspection, testing, commissioning, disconnection

and reconnection requirements; power system security requirements; metering requirements; and schedules of technical details required to support

an application for connection.


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The Electricity Transmission Regulations 1996

require Western Power and all users to use all

reasonable endeavours to comply with the Technical

Code.

The requirements of the Technical Code are similar tothose set out in the National Electricity Code,

particularly those in Chapter 4 (Power System

Security) and Chapter 5 (Network Connection).

6. Application Procedure

Part 2, Access, of the Electricity Transmission

Regulations 1996 sets out the application procedure

for a person requiring access to Western Powers

transmission networks. Figure 2 shows the

application procedure (simplified) in flow chart form.

Application forms are available from, and should be

submitted to, the following contacts within Western

Power:

For access to the South West Network:

Manager Planning & Contracts

Transmission Division

Western Power Corporation

363 Wellington Street

PERTH WA 6000

GPO Box L921PERTH WA 6842

Telephone: (08) 9326 6687

For access to the North West Network:

Manager Pilbara Power

Pilbara Power Division

Western Power Corporation

18 Anderson Street

PORT HEDLAND WA 6721

PO Box 314

PORT HEDLAND WA 6721

Telephone: (08) 9173 8222

Following the receipt of an application, Western

Power must provide the applicant with an initial

response within 20 business days of receiving the

application. The initial response will set out

information such as:

whether it is likely that there is sufficient sparecapacity to provide access to the network or

whether the network will have to be augmented; whether it is likely that any connection will have

to be installed or upgraded;

whether a capital contribution will be required of

the user;

the period within which Western Power is able tomake a preliminary assessment; and

whether Western Power is able to make an accessoffer within 65 business days of receiving the

application, and, if not, an alternative period.

Following the initial response, Western Power

proceeds to performing a preliminary assessment of

the application and/or making an access offer.

A preliminary assessment is only performed ifrequested by the applicant. A preliminary assessment

is intended to provide an applicant with a good

assessment of their proposal in situations where the

making of an access offer may not be appropriate.

For instance, a number of generators may be

tendering to provide generation for a project. Not all

the generators will want Western Power to go as far

as making an access offer but will want to know the

feasibility of their proposal in terms of connecting to

the network.

Following an access offer being made by Western

Power, an applicant has 20 business days within

which to accept the offer. A longer period may be

given with Western Powers agreement.

Western Power charges for the assessment of an

access application. Details of the estimated charges

are provided to applicants in the initial response

provided by Western Power.

7. Access Enquiries

In the feasibility stage of a project, a person may notwish to make an application but would still like to

ascertain the likely feasibility of their project in terms

of being able to connect to the transmission network.

In this case, an access enquiry may be made.

Information regarding the proposal to be assessed

should be forwarded to the contacts mentioned in

Section 6. To assist people in providing relevant

information, it is often helpful if the information

requested in an application form is completed as far

as possible, however, it should be made clear that an

access enquiry is being made.


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Western Power charges for the assessment of an

access enquiry. Details of the estimated charges are

provided following the receipt of an access enquiry.

8. Treatment of Losses & Balancing

8.1 Losses

The calculation of system losses incurred in bilateral

access arrangements is based on network connection

point loss factors. Loss factors are used to determine

the half hourly energy to be sent out from generators

to meet the half hourly energy usages at the associated

load points plus system losses. Loss factors are

calculated in a similar way to that proposed for theNational Electricity Market (NEM). In the NEM, loss

factors are applied to pool prices. In WA, loss factors

are applied to quantities of power and energy.

Loss factors are based on marginal losses on the

system. They depend on the system operating

conditions and will vary with the load and generation

patterns. They are to be re-calculated annually and

based on past system operating conditions.

Loss factors are defined by the following equations:

For a lossless network with n nodes,i = n

Pi = o

i = 1

i.e. energy injected equals energy taken.

For actual networks where a proportion ofenergy is consumed (lost) in lines and

transformers, the energy balance is given by:

i = n

Li*Pi = o

i = 1

where Li is the loss factor for node i at which

incremental energy Pi is injected or taken.

8.2 Balancing

The principles of energy and demand balancing are

given in Part 4 of the Electricity Transmission

Regulations 1996. The prices and charges, including

practical examples, are provided in the Pricing andCharges Paper.

As stated earlier, the energy market arrangement

currently operating in the Western Australian

transmission open access regime is not based on a

generator pool system, but relies on bilateral contracts

between generators and loads.

Therefore, network users must use reasonable

endeavours to ensure that the energy imported at their

load (exit) points is balanced, after considering losses,

with the energy exported at their generation (entry)

points. It is likely that some form of load following

governor control would need to be installed to achieve

this.

Energy imbalances which occur within a permitted

tolerance of 3% of half the Contract Maximum

Demand, ie small load following errors, may be

settled on an energy basis. Where imbalances exceedthis tolerance, settlement will be on a financial basis

at published half hourly seasonal energy rates. An

energy balancing example is provided in Appendix 1

of this brochure.

However, to assure reliability of supply during periods

of generator maintenance or unplanned outages, users

are encouraged to contract for the provision of

standby power. This standby power, or standby

generation reservation, may be contracted from

Western Power or from any independent generator

user.

Where a users import power demand exceeds its

export power supply by more than its standby

generation reservation it will incur an excess standby

generation capacity charge for each kW in excess.

This charge can only be applied once in every seven

day excess demand period to the maximum demand

imbalance occurring during that period.

Unlike energy imbalances, there is no permitted

tolerance for demand imbalances. This provides users

with a significant incentive to contract for the

provision of standby power.

To assist Western Power in the management of

transmission capacity, users are also given an

incentive to match their export supply and import

demand power to the generator declared sent out

capacity (DSOC) and load contract maximum

demand (CMD), respectively. Users which exceed

their DSOC or CMD will incur an excess network

usage charge.

9. Description of Network Assets


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The principal elements of the transmission networks

include transmission substations and zone substations,

interconnected by transmission and subtransmission

lines. The transmission networks enable the

transportation of electricity from power stations to

zone substations and high voltage customer loads.

The zone substations provide the interface betweenthe transmission networks and distribution networks.

For the purpose of transmission open access, the

transmission networks assets comprise Connection

assets, Shared Network assets and Ancillary Services

assets. These are described as follows:

Connection Assets: those assets at the point ofphysical interconnection with the transmission

networks which are dedicated to a user - that is, at

substations including transformers and

switchgear, but excluding the incoming lineswitchgear. Connection assets for generators are

referred to as entry assets and for loads they are

called exit assets.

Shared Network Assets: all other transmissionassets in the networks not dedicated to any

particular customer, but shared to some extent by

network users.

Ancillary Services Assets: network assetsperforming an Ancillary Services function

comprise:

Those providing a Control System Serviceeg system control centres, supervisory

control and communications facilities.

Those providing a Voltage Control servicein the networks eg a proportion of the costs

of capacitor and reactor banks in

substations.

Figure 3 shows in simplified form the principal

elements of the transmission networks and the

categorisation of the assets as described above.

10. Transmission Network Pricing

Transmission pricing for the Western Power

transmission network has been developed along

similar lines to other Australian states and as

proposed for the National Electricity Market. There

are two main aspects to determining prices: (i)

determination of the aggregate annual revenue

requirement (AARR), and (ii) the cost reflective

allocation of the revenue requirement to network

connection points. The methodology for the latter is

known as the cost reflective network pricing (CRNP)

method.

The AARR consists primarily of asset related charges

and operating costs, the largest component of which

is the asset charges reflecting the capital intensive

nature of transmission. Transmission assets areindependently valued using the Optimised Deprival

Value (ODV) methodology. The operating costs

component of revenue reflects good operating practice

and is scaled from year to year using an efficiency

factor to reflect expected improvements in operating

efficiency.

The CRNP method basically performs the function of

allocating network revenue requirements according to

usage of network assets. In principle the further the

load from generation sources, the higher will be the

usage of network assets and the higher the charges.The proportion of network AARR allocated using this

method (50%) is chosen to provide a pricing signal to

loads approximating the long run incremental cost of

network augmentation at each connection point. The

decision to base pricing on long run rather than short

run signals reflects the belief that most network users

invest for the long run and that short run signals for

the most part would not be effective.

11. Network Charges

11.1 Charges to a Load User

A load user will be required to pay the following

charges:

connection; exit use of system; common services; capital contribution in relation to any system

augmentation, connection assets or ancillary

service; and

excess standby generation capacity and excessnetwork usage charges.

11.2 Charges to a Generator

A generator will be required to pay the following

charges:

connection; entry use of system; ancillary service; capital contribution in relation to any system


service; and


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11.3 Charges to a Generator With On-site Loads

A generator with on-site loads which exports and

imports energy from the transmission network will be

required to pay the following charges:

connection; the higher of the entry use of system charge based

on the declared sent out capacity or the total of the

exit use of system and common services charges

based on the contract maximum demand (CMD);

ancillary service; capital contribution in relation to any system


service; and


11.4 Charges to a User With Standby Usage

A load user or a generator with on-site loads can

apply for network standby usage and receive a

discount on the common services charge if it satisfies

the following:

there is a feeder at the connection dedicated tostandby access or the total generation capacity of

on-site generators is more than 10MW; and the load factor of actual standby energy usage

during the standby terms is not more than 0.15.

Reference should be made to the Pricing and Charges

Paper for further details.

11.5 Categories of Charges

Connection charge: this charge is based on theconnection assets provided and includes the

control system service (CSS) charge which is one

of the ancillary services charges.

Transmission Use of System (TUOS) charge: this

charge provides locational signals to all network

users to encourage efficient network expansion.

There are exit TUOS charges and entry TUOS

charges. The exit TUOS charge applies to a user

who imports electricity from the transmission

network (load user). 50% of the cost of the

transmission shared network is allocated to the

exit TUOS cost pool. This cost pool is allocated to

individual load users using the Cost Reflective

Network Pricing (CRNP) method. The exit TUOS

prices are based on the CMDs.

The entry TUOS cost pool represents 20% of the

cost of the transmission shared network assets and

is allocated to generators. This cost pool is

allocated to individual generators using the CRNP

method. The entry TUOS prices are based on the

declared sent out capacities.

Common service charge: the remaining 30% ofthe cost of the transmission share network plus

two-thirds of the voltage control cost is postage

stamped to all load users. Ancillary services charges: these are to recover the

cost of providing the following services:

voltage control control system services (CSS) spinning reservepost trip management energy balancingVoltage control charge: one third of the voltage

control cost is allocated to the connection charge

and the remaining is included in the common

services charge.

CSS charge: this is allocated to all connection

points based on the equivalent number of remote

terminal units (RTU) installed on site. This

charge is included in the connection charge for

simplicity.

Spinning reserve charge: at present,

approximately 20% of the spinning reserve cost is

allocated to load users and the remaining to

generators with a generation capacity of 10MW

and higher. Refer to the Pricing and Charges

Paper for details of the allocation.

Post trip management charge: this is allocated to

generators based on the number of times the unit

is tripped and its MW losses. Refer to the Pricing

and Charges Paper for details of the charge

calculation.

Energy balancing charge: this consists of the

balancing service charge and the out of balancing

and half hourly out of balancing charges. The

balancing service charge depends on the number

of connections involved in the access

arrangement. The out of balancing and half

hourly out of balancing charges depend on usage.

Loss factors are used to determine the system

losses. Refer to regulation 22 in the Electricity

Transmission Regulations 1996 for details.


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Refer to section 12 of this brochure for further

details on ancillary services, including definitions

of the services listed above.

Capital contribution charge: refer to Section 13,Capital Contributions, below.

Excess standby generation charge: refer to section8.2 of this brochure for details.

Excess network usage charge: refer to section 8.2of this brochure for details.

12. Ancillary Services

Western Power in its role of system operator is

responsible for maintaining the quality of supply, and

ensuring the safe, secure and reliable operation of the

power system. To satisfy these responsibilities, a

system operator must be able to monitor and correct

where necessary the system frequency and voltage,

transmission network loading, generation dispatch,

communication and SCADA facilities.

To this end, Western Power has defined a number of

categories of ancillary services which are provided bygeneration, transmission, and system operations

communication and control equipment.

These categories are:

Voltage Control; Spinning Reserve; Post Trip Management;

Control System Services; and Energy Balancing.

Voltage Control is required to maintain the system

voltage within operational limits during steady state

operation and in the aftermath of trips. It is achieved

by regulating generator MVAr output and

transmission voltage control equipment, such as

capacitors, reactors and transformer on-line tap

changers.

Spinning Reserve is the additional generation

capacity and interruptible load schemes necessary to

maintain the system frequency during load

fluctuations and generator tripping.

Post Trip Management is the maintenance of system

stability in the aftermath of generator trips. It is

provided by spinning and standing reserves.

Control System Services is the 24 hour monitoring

and control of the power system, including data

acquisition, switching and generator dispatch. It is

provided by control centres and SCADA and

communication assets.

Energy Balancing refers to the marginal energy

trades that will occur between Western Power and

independent generation. The energy balancing

ancillary service is required to monitor and record

energy supply and usage in order to facilitate energy

balancing and settlement.

13. Capital Contributions

A new user who requires Western Power to make a

capital investment to provide the access services, the

connection services or the ancillary service to it will

be required to make a capital contribution to make the

investment commercially viable to Western Power.

The investment is commercially viable to Western

Power if:

Western Power can recover within a reasonabletime the costs, the capital investment and a

reasonable rate of return without increasing the

charges payable by the existing users to contribute

to the new investment; and Western Power has sufficient allocated capital

funds to undertake the augmentation.

The reasonable time, which is limited to 15 years, is

determined based on:

the expected commercial life of the augmentation; the potential future use of the augmentation by

existing and potential users; the financial viability of the applicant and the

applicants business; and Western Powers performance targets.Reference should be made to the Electricity

Transmission Regulations 1996 (as amended) for

details.


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14. Further Information

Further information on all aspects of access to

Western Powers transmission networks (including

obtaining various documents and application forms -

see Bibliography below) may be obtained from thecontacts given in Section 6 of this brochure.

Bibliography

1. Electricity Corporation Act 1994.2. Electricity Transmission Regulations 1996 (as

amended).3. Electricity Referee and Dispute Resolution

Regulations 1997.4. Western Power Corporation, Electricity

Transmission Access - Pricing and Charges - 1

July 1997 to 30 June 1998.5. Western Power Corporation, Electricity

Transmission Access - Technical Code.6. Western Power Corporation, Transmission

Networks.

Documents 1, 2 and 3 are available from:

State Law Publisher10 William Street

PERTH WA 6000

Telephone: (08) 9321 7688

Facsimile: (08) 9321 7536

Documents 4, 5 and 6 are available from the Western

Power contacts listed in Section 6 of this brochure.


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FIGURE 1 - WESTERN POWERS TRANSMISSION NETWORKS


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APPLICANT

1. Formulate proposal.

2. Submit access application with

optional request for preliminary

assessment.

6. Accept access offer within 20

business days or such longer

period as is agreed.

WESTERN POWER

3. Prepare written response to access

application within 20 business days

(unless further information

requested by Western Power).

Response to include:

. time for preliminary assessment;

. time to make access offer.

4. If a preliminary assessment isrequired, prepare report within

time specified in response,

otherwise prepare access offer

within period specified in response

(unless further information

requested by Western Power).

5. Prepare access offer within time

specified in response (unlessfurther information requested by

Western Power).

7. Finalise access agreement.

NOTE: The application procedure shown in this chart is in simplified form. The

procedure and times for performing activities are subject to conditions

and variations set out in Part 2 of the Electricity Transmission

Regulations 1996.

FIGURE 2 - ACCESS APPLICATION PROCEDURE FLOW CHART


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FIGURE 3 - TRANSMISSION NETWORK - ASSET DESCRIPTION

Generator

Transformer

330,220 & 132 kV

Lines

132 & 66 kV

Lines

POWER

STATION

TRANSMISSION

SUBSTATION

TRANSMISSION

NETWORK

TRANSMISSION

SUBSTATION

SUBTRANSMISSION

NETWORK

ZONE/CUSTOMER

SUBSTATION

SHARED

NETWORK

ASSETS

CONNECTION

(ENTRY)

ASSETS

CONNECTION

(EXIT)

ASSETS

TRANSMISSION

NETWORK


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Appendix 1 - Energy Balancing Example

The following energy balancing example assumes a transmission access agreement consisting of two

generators in the users group of entry connections and three loads in the users group of exit

connections.

The entry and exit point energy amounts are based on a single half hour energy reading.

Gen 1 Gen 2 Load 1 Load 2 Load 3

Entry Loss Factor (LFEntry) 1.025 1.020

Entry Energy Reading, kWh ( ETEntry) 4763.5 3239.0

Contract Max Demand, kW ( CMD) 11000 16000 8000

Exit Loss Factor (LFExit) 1.040 1.030 1.035

Exit Energy Reading, kWh (ETExit) 2705.5 3964.0 1989.5

Energy Imbalance (EIMB) = Energy Entry Amount (EEA) - Energy Exit Amount (EEXA)

EEA = (ETEntry * LFEntry)

= (4763.5 * 1.025) + (3239.0 * 1.020)

= 8186.37 kWh

EEXA = (ETExit * LFExit)

= (2705.5 * 1.04) + (3964.0 * 1.03) + (1989.5 * 1.035)

= 8955.77 kWh

EIMB = 8186.37 - 8955.77

= -769.40 kWh

Permitted Tolerance (TOL) = 3% * CMD/2

= 0.03 * (11000 + 16000 + 8000)/2

= +/-525 kWh

Energy Settlement

The energy imbalance amount to be settled on an energy basis by the end of the month, called the

Adjusted Net Amount (ANA), is equal to the negative of the Permitted Tolerance = -525 kWh.

The aggregate of this amount and all other ANAs for the month would be multiplied by the

appropriate out of balance price to calculate the energy out of balance charge for the month.

Financial Settlement

The energy imbalance amount to be settled on a financial basis at half hourly seasonal energy rates,

called the Revised Net Amount (RNA), is equal to the amount in excess of the Permitted Tolerance =

-769.40 - (-525) = -244.40 kWh

This amount would be multiplied by the applicable half hour seasonal energy price to calculate the

energy imbalance charge.

In both cases the energy imbalance is negative. The user would, therefore, be in debt to Western

Power for the energy deficit.

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