TSO-DSO Interactions

College of Engineering and Architecture

TSO-DSO Interactions: EMS-DMS Data Exchange

Anjan BoseWashington State UniversityPullman, Washington, USA

Electric Power Control CentersReykjavik, IcelandMay 12-15, 2019


Energy Management System (EMS)• Multiple EMS in one Interconnection§ Horizontal – each covering a portion of the grid§ Vertical – each covering a function (transmission,

balancing)

• Data in EMS§ Static data – system information§ Dynamic data – streaming measurements§ Historic data – stored measurementsWhat about PMU data?

Interconnection Control/Monitoring Center

RC1

Sub1Sub10

0

RCi RC10

Act1-10 Sen1-100

Subk

… …… …

BA1

BAj

BAn

……

… …


SCADA-AGC (1960s)The digital control center (SCADA-AGC)• The RTU to gather digital data at substation• Comm. channel from sub to control center (CC)• The SCADA§ The Data Acquisition from RTU to CC§ The Supervisory Control signal from CC to RTU

• The screen based operator display• Automatic Generation Control (AGC)§ The digital algorithm for ED§ The digital version of LFC


EMS (1970s)The Energy Management System (EMS)• State Estimation (SE)• Static Security Analysis (n-1)• Dynamic Security Analysis (stability)§ Transient, Oscillatory, Voltage

• Optimal Power Flow based analysis§ Preventive Action calculation§ Corrective Action calculation


Distribution Management System (DMS)• Widespread deployment last decade• Coincides with growth in DG, DR - cheaper ICT• Applications§ SCADA – increasing observability and control§ Remote or automatic sectionalizing§ Voltage control (VVO, CVR)

• Combining functions§ GIS§ OMS§ Crew Dispatch§ AMI


Drivers Changing EMS-DMS Interactions• Distributed Generation (DG) Increasing in

Distribution System§ Will need monitoring (observability)§ Will need control (controllability)

• Demand Response (DR) Requiring Control of Loads§ Controllable loads require monitoring

• Storage can be generation and load• Aggregators will require communication paths in

addition the EMS-DMS communications


What EMS Applications require DMS Data?• Balancing (frequency control)§ AGC is centralized at each BA§ Most generation must be observable, some

controllable§ All controllable loads must be observable

• Voltage Control§ This is more regional, less central§ Distributed control possible§ T and D can be controlled separately with some

coordination


Customer Side Observability• Smart Meters§ Gateway between utility and customer§ Utility can send price signals or control signals§ Change rates (in real time?)§ Control appliances (especially heating/cooling)

• Customer Applications§ Optimize energy efficiency and energy cost§ Demand response§ Can integrate generation (roof PV), storage (EV)

• Microgrids


Role of Aggregator• Aggregator has the dual function of§ Selling services§ Controlling devices

• Aggregator has to communicate with§ Market to sell services§ With EMS to control for balancing services§ With DMS to stay within safe distribution limits

• These multiple communications can be set up several different communication architectures

• These add complexity to the EMS-DMS data exchange


During Abnormal Operations• During Limit Violations§ Corrective actions have to be taken§ Could be automatic or manual§ Special/more data exchange may not be needed§ Voice communication will increase

• During restorative state§ If equipment is damaged, communications may

also be damaged§ Manual actions will increase many-fold§ Voice communication will also increase§ After natural disasters, more action is at the DSO


Static System Data• Most applications require system data• Real-time data from outside the control center

jurisdiction require system data from outside• This applies to interconnected neighbors as well

as connected distribution systems• Static system data can be exchanged less often,

say weekly, monthly• System data must be updated by owner, then

shared, so all databases can be updated


Data Base Issues• At present all applications (XMS) have separate

data bases and cannot exchange data• All data must be coordinated across the whole

system from consumers to generation• Standards will be key• Real time data is geographically dispersed and

require a distributed data base• Data has to be moved timely to where it is needed

which requires a flexible communication system• All data bases in the same interconnection will

have to be coordinated


Conclusions/Challenges• Control Center Functions§ EMS mature§ DMS evolving (DERMS, Aggregator, IPP)

• Control Center Jurisdictions§ Observability (Customer, IPP, Aggregator)§ Controllability (Customer, IPP, Aggregator)§ AGC requires direct central control

• Markets§ Coordination with EMS (same system models)§ Coordination with DMS (???)

• Regulations and Standards

Documents

TSO-DSO Interactions