AuRA-NMS: A substation automation project for a ...

AuRA-NMS: A substation automation project for a potential smart grid Prof. Tim Green and many others

Achievements •  Demonstration of decentralised control •  MAS framework used to good effect •  Variety of algorithms designed and tested –  –  –  – 

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Line flow constraints under normal and fault conditions Voltage control in presence of DG Energy storage operation Restoration

Communications strategy Benefit case analysed Testing against real-time simulation complete Preparation for field trial advanced Final dissemination event on 24th June

AuRA-NMS

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“Active” because the objectives are: –  Enhanced utilisation of primary infrastructure –  Enhanced integration of distributed generation –  Incorporation of new control opportunities such as energy storage –  Creating flexibility for different future use

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“Autonomous and regional” because –  Decentralised and devolved from network control centre –  Operates across a region not just a feeder

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Decentralised because –  Exploits hierarchy of the underlying network –  Allows several small control problems to be solved quickly –  Allows data to be processed locally and summary data passed upwards

Specific Objectives •  Actively manage voltage and line-flow within limits using •  OLTC •  DG reactive power •  DG active power curtailment

•  Provide automated supply restoration for a wider range of situations •  Include storage as a network control option (not energy arbitrage) •  Minimise communications upgrade through control structure and state estimation

Testing Objectives • 

Establish a set of realistic test cases on network examples that show the issues of interest • 

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Test as a prelude to open-loop field trial •  •  • 

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Led to creation of the “case study documents” and IPSA models of the chosen networks. Led to hardware-in-the-loop testing of S/W on COM600 H/W against a real-time simulation of a network and its instrumentation. Led to setting up multiple COM600s (at different sites joined by a VPN) Guided to use OPC as the basis for exchanging data between algorithms and outside world, which is mirrored in real-time simulator

Independence in testing •  • 

Desirable for exposing over-looked issues in algorithm design and providing a high degree of assurance Led to test definition process and test base-cases plus unseen cases.

Prototype System and Lab Testing

Picture Source: ABB

•  Use hardware proven in a substation environment •  Use existing communications gateway software and IEC 61850 •  Test against realtime simulator for hardware-in-theloop verification

Restoration •  Scripting presently used to automated restoration of consumer supply post-fault •  Scripts are not always appropriate •  Real-time restoration algorithm must –  –  –  –  – 

Identify feeder sections off-supply Calculate real and reactive power to be restored Identify switching options Verify capacity exists Choose optimal solution

Voltage Control Using Case Based Reasoning with Optimal Power Flow Generators GSP Bus

Q Dispatch

Network

P Curtailment

Bus Voltages Line Flows Nodal load/gen

Bus Voltages Line Flows Nodal load/gen Generator P Requests Load Profiles GSP Bus Voltage

Tap Settings CBR

OPF

Tap Settings Q Dispatch P Curtailment

Sample Results from CBR testing EDF Reigate Network Under-voltage due to line switching

CBR algorithm adjusted the tap changer set points to correct the voltage level

Thermal Constraint Management •  Could use CBR •  Can also solve in real-time •  Reduce problem to a number of discrete choices of switching action, generator curtailment or load curtailment •  Use an “intelligent” algorithm to search all the possible actions •  This is the “Constraint Satisfaction Problem” •  Search in a tree structure and disregard unhelpful branches

Sample results from CSP testing – SP Mid - Wales Network Overvoltage due to generation changes

CSP algorithm constrains the output of DFIG3 at Cefn Croes to reduce the load on the affected line. The constraint is lifted when conditions allow.

Energy Storage • 

Based on ABB’s SVC Light system

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DC-link is supplemented with high voltage Lithium-Ion batteries

–  IGBT-based voltage source converter –  Fast and independent control of real and reactive powers –  Rated at 600 kW

–  Rated at 200 kWh (600 kW for 15mins)

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Being installed in EDF Energy Network –  11 kV distribution system in Hemsby, Norfolk chosen for proximity to wind farm –  At NOP between Ormesby and Martham

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Operating regime tested in Aura-NMS simulation –  Reactive power capability used for voltage control –  State-of-charge managed to be able to absorb energy when constraints would mean spilling of wind –  Stored energy released at times of low wind or high demand –  Could also support restoration

Picture Source: ABB

Communication Systems

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RTU

Base Station

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•  Two case studies, 11kV radial and 33kV meshed, assessed for testing and deployment of AURANMS •  Intention to make minimum changes •  Legacy in 11 kV case is “point-tocentre”

RTU

RTU

Paknet protocol If collision, the terminal backs off for 26ms The terminal retries with a probability P Probability P set by the network operator

•  Better bandwidth and better multiple access control required

Collision Probability

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How much asset replacement is needed to accommodate DG under “Fit and Forget” and “Active Management” scenarios? Analysis Performed on UKGDS and extrapolated to GB as a whole –  DG connected over 50% of GSPs and 2/3 of the 11kV feeders (L) –  DG connected over 50% of GSPs and 1/3 of the 11kV feeders (LM) –  DG connected over 25% of GSPs and 2/3 of the 11kV feeders (HM) –  DG connected over 25% of GSPs and 1/3 of the 11kV feeders (H)

Percentage of scheme to be replaced (%)

How Effective is Active Management? 18 16 14 12 10 8 6 4 2 0 L (F&F)

L (AM)

LM (F&F)

LM (AM)

HM (F&F)

HM (AM)

H (F&F) H (AM)

Penetration scenario (Management policy) 11kV lines

33/11kV transformers

33kV lines

Percentage of lines and substations to be upgraded in the UK for a DG penetration of 10GW and for different penetration scenarios

Field Installation •  Reigate, Horley & Nutfield hardware deployed –  (excluding ABB RTU)

•  Installation of ADSL communications (between three substations) to be complete by middle of June •  6 secondary substations per primary substation selected for data gathering –  ABB REF615 used to gather and relay measurements via GPRS –  Pre-site test being set-up at EDF energy location

•  Secondary substations hardware being installed from late May •  Software integration proceeding and hoping to be complete at end of May (dependent on feedback from EDF Energy) •  Hardware and software integration, in-house, to be complete by end of June •  System deployed by end of July

Energy Storage Installation •  Energy storage land issues that delayed the project are now resolved •  Main Energy Storage equipment now being progressed with installation planned for the summer. •  Martham and Ormesby network hardware is on order •  Preliminary surveys have been carried out •  Project timings follow on about 3-4 months behind the Regional Autonomous Network Project.

Papers 1.  2.  3.  4.  5.  6.  7. 

N Wade, P Taylor, P Lang, & J Svensson, Energy storage for power flow management and voltage control on an 11kV UK distribution network. 20th International Conference on Electricity Distribution, June 2009 T Xu, P Taylor, S McArthur, G Ault, E Davidson, M Dolan, C Yuen, M Larsson, D Roberts, P Lang, & D Botting, Integrating voltage control and power flow management in AuRA-NMS. CIRED SmartGrid Seminar, June 2008 T Xu & P Taylor, Voltage control techniques for electrical distribution networks including distributed generation. 17th IFAC World Congress, July 2008 T Xu & P Taylor, An intelligent voltage control approach for distribution network. China international conference on electricity distribution, December 2008 T Xu, M Prodanovic, E Davidson, P Taylor, T Green, & S McArthur, Case based reasoning techniques for distributed voltage control. CIRED annual conference, June 2009 A Ahmadi & T Green, Optimal power flow for autonomous regional active network management systems. IEEE Power Engineering Society General Meeting, July 2009 A Ahmadi, D Roberts, & T Green, Optimal power flow as a tool for examining losses and DG penetration in distribution networks. Cigré annual conference, August 2008

Papers 8.  9.  10. 

11.  12.  13.  14. 

E Davidson, M Dolan, S McArthur, & G Ault, The use of constrain programming for the autonomous management of power flows. Proceedings of the 15th International Conference on Intelligent Systems Applications to Power Systems, November 2009 M Dolan, E Davidson, F Coffele, G Ault, I Kockar, & J McDonald, Using optimal power flow management of power flows with active distribution networks within thermal constraints. University Power Engineering Conference, September 2009 E Davidson, S McArthur, M Dolan, & J McDonald, Exploiting intelligent system techniques within an autonomous regional active network management system. IEEE PES General Meeting, July 2009 M Dolan, E Davidson, G Ault, & J McDonald, Techniques for managing power flows in active distribution network within thermal constraints. CIRED annual conference, June 2009 E Davidson, S McArthur, J McDonald, & P Taylor, An architecture for flexible and autonomous network management systems. CIRED annual conference, June 2009 E Davidson, S McArthur, C Yuen, & M Larsson, Towards the delivery of smarter distribution networks through the application of multi-agent systems technology. IEEE Power Engineering Society General Meeting, July 2008 E Davidson & S McArthur, Exploiting multi-agent system technology within an autonomous regional active network management system. Proceedings of the 14th Annual Conference on Intelligent Systems Applications to Power Systems, November 2007