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Glossary

Glossary of terms used in the National Electricity Market of Singapore (NEMS).

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

A

Ancillary Services

The additional services necessary to ensure the security and reliability of the power system. The ancillary services traded competitively on the wholesale market are regulation and the three classes of reserve (primary, secondary, contingency). The black-start ancillary service is contracted by Energy Market Company (EMC) on an annual basis.

B

Black-start Ancillary Service

A service to ensure that there is initial generation for system restoration following a complete blackout.

C

CCGT

Combined-cycle gas turbine.

Contestable Consumers

Consumers that have the right to choose to purchase electricity from a retail supplier, directly from the wholesale market or indirectly from the wholesale market through the Market Support Services Licensee (MSSL) SP Services. Consumers qualify to be contestable based on their level of electricity consumption.

Contingency Reserve

A reserve class that can be called upon within a 10-minute response time and sustained for at least 30 minutes.

Co-optimisation

The process used by the market clearing engine to ensure that the most inexpensive mix of energy reserve and regulation is purchased from the market to meet electricity demand in each dispatch period.

Counterfactual Uniform Singapore Energy Price (CUSEP)

The CUSEP (in $/MWh) is calculated by the market clearing engine (MCE) with the assumption that there is no dispatchable energy bids.

Curtailed Load (CL)

The Megawatt (MW) that is curtailed.

D

Degeneracy Issue

A mathematical degenerate state where a set of two or more solutions arise from the same objective function.

Demand Forecast

The demand forecast reports the forecasted electricity consumption in Singapore in each half-hour. This demand forecast excludes transmission losses, intertie flows and generation from exempted embedded generators.

Dispatch Schedule

A schedule produced by the market clearing engine every half-hour that is the basis for the supply of energy, reserve and regulation in the market.

DRC

Daily routine check. This is the price sanity check performed by Energy Market Company's (EMC) Market Operations team on a daily basis.

DRP

Disaster recovery plan.

E

Embedded Generators (EG)

Generation units that generate electricity to their onsite load principally for self consumption.

EMC and PSO Fees

These fees are the approved administrative costs for Energy Market Company (EMC) and the Power System Operator (PSO) to operate the NEMS in each fiscal year. These fees are recovered from both generators and retailers based on per MWh generated or consumed.

EMGrid

A visualisation tool used by Energy Market Company's (EMC) Market Operations team to view the connectivities of the physical network. This is based on the NWStat files as well as the outage files provided by the Power System Operator (PSO).

EMView

A tool developed by Energy Market Company's (EMC) Market Operations team to view the results of the market clearing engine.

Energy

The flow of electricity.

F

Full Retail Competition (FRC)

A situation in the retail market in which all consumers are contestable consumers i.e. have the right to choose to purchase electricity from a retail supplier, directly from the wholesale market or indirectly from the wholesale market through the Market Support Services Licensee (MSSL) SP Services.

G

Generation Registered Facility (GRF)

Generators that have been registered to provide one or more of the following: energy, reserve and/or regulation. These generators are 10MW or bigger in size, required to offer into the market and be centrally dispatched by the Power System Operator (PSO).

Generation Settlement Facility (GSF)

Generators that are less than 10MW in size and deliver only energy. These generators need not offer into the market and are not subject to dispatch by the Power System Operator (PSO). Embedded generators are usually classified as GSFs but not all GSFs are embedded generators.

Gigawatt (GW)

A measure of electrical power equal to one thousand megawatts. Gigawatt hour (GWh) represents the number of gigawatts produced or consumed in an hour.

GT

Open-cycle gas turbine.

H

HEUC

Hourly energy uplift charge.

HEUR

Hourly energy uplift rebate.

HLCU

Hourly load curtailment uplift.

HSFO

180-centistoke high sulphur fuel oil (180-CST HSFO). The relevant oil benchmark for Singapore's electricity industry.

I

Interruptible Load (IL)

A contestable consumer of electricity that participates in the wholesale market and allows its supply of electricity to be interrupted in the event of a system disturbance in exchange for reserve payment. The activation of interruptible loads is by the Power System Operator (PSO).

L

Load

The consumption of electricity.

Load Curtailment Price (LCP)

Price (in $/MWh) used to pay load registered facility (LRF) for its scheduled load curtailment quantity in each dispatch period.

Load Curtailment Quantity (LCQ)

Load curtailment quantity (in MWh) for a load registered facility (LRF) in each dispatch period.

M

Market Clearing Engine (MCE)

The linear computer programme used to calculate the spot market quantities and prices.

Market Energy Price (MEP)

This refers to the nodal energy price. (see 'nodal pricing')

Market Participant (MP)

A person who has an electricity licence issued by the Energy Market Authority (EMA) and has been registered with Energy Market Company (EMC) as a market participant.

Megawatt (MW)

A measure of electrical power equal to one million watts. Megawatt hour (MWh) represents the number of megawatts produced or consumed in an hour.

Metered Demand

The electricity consumption which is proxied by the withdrawal energy quantity (WEQ).

MEUC

Monthly energy uplift charge.

MNN Prices

Market network node or nodal energy prices are the prices received by generators. Nodal prices are determined according to the demand and supply characteristics of each of the injection nodes (market network nodes - MNNs), taking into consideration transmission losses and congestion on Singapore's electricity network. In the settlements reports, this is termed as the Market Energy Price (MEP).

N

NEMS

National Electricity Market of Singapore.

Net Treatment of Non-reserve Charges for Embedded Generators

With effect from June 2011, non-reserve charges (Energy Market Company fees, Power System Operator fees and monthly energy uplift charges) for embedded generation facilities will be administered based on their amount of net withdrawal (consumption) from or net injection (generation) into the grid. To qualify for this treatment, an embedded generation facility requires approval from the EMA and registration with EMC as an embedded generation facility.

Nodal Pricing

A market structure in which prices are calculated at specific locations or nodes in the power system to reflect the demand and supply characteristics of each location, taking into consideration transmission losses and congestion. Nodal pricing is also commonly referred to as locational marginal pricing. In the settlements reports, this is termed as the Market Energy Price (MEP).

Non-contestable Consumers

Consumers that are supplied by the Market Support Services Licensee (MSSL) SP Services at a regulated tariff. These consumers have not been given the right to choose to purchase electricity from either a retail supplier, directly from the wholesale market or indirectly from the wholesale market through the MSSL.

Non-regulatory withdrawal energy Quantity (NRQ)

Total non-regulatory withdrawal energy quantity (in MWh) for each settlement interval, being the amount of forecast load not covered by regulatory contracts (vesting and forward sales contracts).

O

Offered Implied Energy Consumption (OIEC)

The implied energy consumption quantity (in MWh) of each load registered facility in each period, based on each LRF's bids.

P

Period

Each half hour that the market clearing engine (MCE) runs. The MCE runs every half hour throughout the day, resulting in 48 trading periods each day.

Power System

The system comprising generation facilities and load facilities that are connected to the transmission system.

Price Separation

A large price deviation between two adjacent dispatch network nodes normally caused by transmission congestion.

Primary Reserve

A reserve class that can be called upon within a 8-second response time and sustained for at least 30 seconds.

Probability of Failure (POF)

Probability of failure is a measure of the reliability of a generation registered facility.

R

Reference Energy Withdrawal (REW)

Energy withdrawal target (in MW) calculated by the market clearing engine for each load registered facility (LRF) in each dispatch period, which includes both dispatchable and non-dispatchable portions of that LRF's consumption.

Regulation

A service provided by the generators to fine-tune the match between demand and supply. A frequency-following service.

Regulation Price

The market price determined for regulation. The cost of regulation is largely borne by the load.

Regulatory Load Quantity (RLQ)

Regulatory load quantity (in MWh) for each settlement interval which is the aggregate of vesting quantities and forward sales quantities across all settlement accounts received by the EMC from the Market Support Services Licensee (MSSL).

Reserve

Stand-by generation capacity or interruptible load that can be drawn upon when there is an unforeseen disruption of supply.

Reserve Price

The market price determined for each of the three classes of reserve products traded (primary, secondary and contingency). The cost of reserve products is borne by the generators.

Retail Market

The transactions made between retail companies and end consumers.

S

Scheduled Implied Energy Consumption (SIEC)

The implied energy consumption quantity (in MWh) of each load registered facility (LRF) in each period based on each LRF's dispatch schedule.

Secondary Reserve

A reserve class that can be called upon within a 30-second response time and sustained for at least 10 minutes.

Short Term Load Forecast (STLF)

Forecast of the following 14 days' average system load for each half-hour period. It is sent to the market clearing engine once a day.

Singapore hub (SHUB)

Singapore hub or SHUB means the MNN at which all energy taken from the transmission system by load facilities is deemed to be withdrawn and all energy injected onto the transmission system by generation facilities referred to in section 5.1.3 of Chapter 2 is deemed to be injected.

ST

Steam turbine.

Supply Cushion

The supply cushion measures the percentage of total supply available after matching off demand.

T

Terawatt (TW)

A measure of electrical power equal to one million megawatts. Terawatt hour (TWh) represents the number of terawatts produced or consumed in an hour.

Total Curtailed Load (TCL)

Sum of the load scheduled to be curtailed (in MW) across all load registered facilities for each half-hour period.

Trading Date

Any calendar day since 1 January 2003 when electricity prices are traded in the National Electricity Market of Singapore (NEMS). One trading day consists of 48 trading periods.

Trading Month

Any calendar month since 1 January 2003 when electricity prices are traded in the National Electricity Market of Singapore (NEMS). One trading month may contain up to 31 trading days.

Trading Quarter

Each year consists of four quarters. Q1 is from January to March, Q2 is from April to June, Q3 is from July to September and Q4 is from October to December.

Trading Week

A trading week starts on a Sunday and ends on a Saturday. Typically, each trading week contains 7 days. However some trading weeks may contain less than 7 days e.g. in 2003 Week 1 and Week 53 had only 4 days each.

U

Uniform Singapore Energy Price (USEP)

The USEP is the weighted-average of the nodal prices at all off-take nodes.

V

Very Short Term Load Forecast (VSTLF)

Forecast of the following 7 hours' average system load for each half-hour period. It is sent to the market clearing engine every period.

Vesting Contract

A vesting contract is a regulatory instrument imposed on some generators by the Energy Market Authority (EMA) with the objective of mitigating the potential exercise of market power when the supply side of the industry is concentrated among a small number of generators. A vesting contract requires these generators to sell a specified quantity of electricity (vesting contract level) at a specified price (vesting contract hedge price).

Vesting Contract Hedge Price (VCHP)

The VCHP is calculated by the Market Support Services Licensee (MSSL) SP Services every three months. It is determined using the long run marginal cost of the most efficient generation technology in the Singapore power system i.e. the combined-cycle gas turbine (CCGT). Energy Market Company's (EMC) settlement system uses the VCHP to settle the vesting quantity between the MSSL and the generation companies.

Vesting Contract Hedge Quantity (VCHQ)

The VCHQ is the vesting contract hedge quantity allocated to some generators.

W

Wholesale Electricity Price (WEP)

Wholesale electricity price which is the net purchase price paid by retailers inclusive of all administrative costs and uplift charges incurred in the wholesale market. This price consists of the following cost components: USEP, AFP, HEUC, MEUC, Energy Market Company (EMC) fees and Power System Operator (PSO) fees.

Wholesale Market

The transactions made between generation companies and retail companies.

Withdrawal Contestable Quantity (WDQ)

Total withdrawal energy quantity of all contestable consumers (in MWh), determined for the purposes of recovering load curtailment uplift charges.

Withdrawal Energy Quantity (WEQ)

Withdrawal energy quantity (in MWh) refers to the amount of electricity withdrawn by load facilities. It is provided by the Market Support Services Licensee (MSSL), SP Services.

Withdrawal Energy Quantity by LRF (WLQ)

A load registered facility's (LRF) withdrawal energy quantity (in MWh). It is provided by the Market Support Services Licensee (MSSL), SP Services.