2015-03 rocky mountain chapter 7x24 · the grid has always been smart; however, it is now smarter...

Smart Grid:

Characteristics, Opportunities and Challenges

Dr. Salman MohagheghiDepartment of Electrical Engineering and Computer ScienceColorado School of MinesGolden, CO [email protected]

2/38Dr. Salman Mohagheghi , All Rights ReservedMarch 3, 2015

� The grid has always been smart; however, it is now smarter

� The modern power grid is different from the traditional power grid in several aspects:

� More data captured from across the grid

� More opportunities for remote control

� Open non-proprietary designs

� Access to more computational power

� Abundance of structured data

� More reliable and efficient communication networks

� To Summarize:

� Smart Grid is more about Creation, Transmission and Utilization of Smart Data

Smart Grid – The Reality


Smart Grid – Requirements

Interoperability

Multi-Vendor

Plug & Play

Low Cost

Deployment

Maintenance

Energy

Scalability

Upgradability

Evolvability

System Growth

Big Data

Security

Cyber-Security

Confidentiality

Privacy

Sustainability

Low Carbon

Footprint

Asset Mgmt.

Energy

Conservation

Automation

Observability

Controllability

M2M

Availability

Redundancy

Fault Tolerance

Self-Healing

Data Quality

QoS

Validity

Accuracy

Integrity


� NIST has divided the smart grid into 7 domains

� Smart grid is a cyberphysical system that is achieved by overlaying communication infrastructure with the electric grid

Smart Grid Conceptual Model


Smart Grid Hierarchical View


� Abundance of Data: obtained from multitude of sensors, meters and Intelligent Electronic Devices (IEDs) from across the grid

� Automated Solutions: in theory, every device can be remotely monitored, configured and controlled

� Faster Dynamics: high penetration of non-dispatchable renewable resources across the grid

� Active Consumers: introduce a new set of dynamics

� Electric Vehicles: mobiles loads (and in the future: energy resources)

Smart Grid – What Has Changed?


� Dynamic Dispatch of Energy Resources

Smart Grid – What Is Needed?


Distributed Generation

� Historically:

� Embedded Generation/Dispersed Generation/Decentralized Generation

� Distributed Generation

� Distributed Energy Resources (DER); often meant to include both DG and Energy Storage (ES)

� No unique definition exists

� One definition: An electric power source connected directly to the distribution network or on the customer side of the meter

� According to this definition, a Combined Heat and Power (CHP) located on a large industrial site at the transmission level is still DG, whereas a medium-sized wind farm connected to the transmission system is not


DG Classification

� Dispatchable vs. Non-Dispatchable

� Rotory Based vs. Non-Rotory Based

� Based on size

� Physical interface and control methods

Primary Energy Source

Interface Power Flow Control

Conventional DG

Reciprocating EnginesSmall Hydro

SG AVR/Governor (+P, ±±±±Q)

Fixed-Speed Wind Turbine

IMStall/Pitch Control (+P, –

Q)

Nonconventional DG

Variable-Speed Wind Turbine

AC/DC/AC Converters

Turbine Speed, DC Link Control(+P, ±±±±Q)Microturbine

Solar PV, Fuel CellDC/DC/AC Converters

MPPT, DC Link Control(+P, ±±±±Q)


DG Sizes

� No general consensus

� In general, assumed to be connected to the distribution system (although some authors do not agree) < 10MW

� Size range examples:

� A few kW up to 50MW by EPRI

� Up to 25MW by Gas Research Institute

� Smaller than 50-100 MW by CIGRÉ

� A DER unit of 250 kVA or more should have means for monitoring its connection status, real power output, reactive power output and the voltage at the PCC


DG Grid Integration

� Smaller generators are not connected to the transmission network due to cost of HV transformers/switchgear, and also transmission network is often far from the renewable energy resource

� In different countries, if the power of the DG is higher than some percentage of transformer capacity (for example 40%), a dedicated feeder or a larger transformer is used

� Depending on the impedance of the system at the PCC, the appropriate size of DG is determined

Network Location Maximum Capacity of DGOut on 400V network 50kVAAt 400V busbars 200–250kVAOut on 11kV network 2–3MVAAt 11kV busbars 8MVAOn 15kV or 20kV network and at busbars

6.5–10MVA

On 63kV to 90kV network 10–40MVA


DG Interconnection Requirements

� General requirements according to IEEE 1547 v2003

� Disconnection due to voltage change

� Disconnection due to frequency change

� Maximum acceptable harmonic injection

Voltage Range (p.u) Time to Disconnect (sec)< 0.5 0.16

0.5 ~ 0.88 2.001.1 ~ 1.2 1.00

> 1.2 0.16

DER Size Frequency Range (Hz) Time to Disconnect (sec)

< 30 kW> 60.5 0.16< 59.3 0.16

> 30 kW> 60.5 0.16

< {59.8 – 57} Adjustable 0.16 to 300 Adjustable< 57 0.16

Harmonic h < 11 11 ~ 17 17 ~ 23 23 ~ 35 ≥≥≥≥ 35Total Current

Distortion% 4 2 1.5 0.6 0.3 5


DG Interconnection Requirements

� Requirements for connection to secondary networks (IEEE 1547.6 v2011)

� For a customer facility with DG:


Microgrid

� A local energy network, with distributed energy resources (DG, energy storage) and demand responsive loads, which can operate in parallel with the grid or in an intentional island mode to provide high reliability and resilience to grid disturbances

� Can provide continuous and high-quality supply of power in remote areas, or for protection of critical loads against power grid disturbances


Drivers for Microgrids

� Power grid operating closer to operational limits

� Latest advances in high efficiency DER

� Smart switches/smart meters

� Advanced automation techniques

� DER is becoming more “decentralized”

� Higher demand for uninterruptible power supply and higher quality of service

� Restructured electricity markets


No Unique Definition

Expert opinions from DTE Energy, CERTS, EPRI, European Research Project Cluster, Northern Power, PSERC, ENCORP, Sandia National Lab, NREL, LBNL, GE.

Raw data extracted from the presentation “Microgrid Business Cases” by Public Interest Energy Research Program, California Energy Commission, December 2004


Microgrid Classification based on Application

� Campus Environment/Institutional Microgrids

� Single owner of both generation and loads; from 4MW to 40+ MW

� Remote “Off-grid” Microgrids

� In island mode at all times; ideal for remote villages, islands

� Military Base Microgrids

� Focus on both physical and cyber security for military facilities

� Commercial and Industrial (C&I) Microgrids

� Maturing quickly in North America and Asia Pacific

� Community/Utility Microgrids

� Europe leads this segment; usually do not “island”

� Disaster-Relief Microgrids

� When grid is down and power is needed for post-disaster recovery

Source: Asmus and Stimmel, Utility Distribution Microgrids 2012


Predictions

Source: Jim Riley, Challenges for Microgrid Deployment Interoperability and Technological Readiness, 2013.

� Likely industries to deploy over the next 5 years:


Microgrid Classification based on Topology

According to IEEE 1547.4-2011


Microgrid Classification based on Size

� Single Facility Microgrid (< 2MW)

� Industrial and commercial buildings, residential buildings and hospitals

� Multiple Facility Microgrid (2-5MW)

� Spans multiple buildings or structures with a typical load of 2-5 MW

� Examples include campuses, military bases, industrial and commercial complexes and building residential developments

� Feeder Microgrid (5-10MW)

� May include smaller single or multiple facility Microgrids

� Manages the whole distribution feeder

� Substation Microgrid (10+ MW)

� Manages the whole distribution substation

� Likely to include some generation directly at the substation


Micro-Generators

� Grid Forming Units

� Diesel generator or a battery inverter

� One master controls the frequency and voltage by balancing the power

� Grid Supporting Unit

� Active and reactive power are determined by the voltage and frequency

� Grid Parallel Units

� Uncontrolled generators such as wind energy converters or PV-inverters without control


Microgrid Control

� Grid Forming Control

� During island mode

� Need to set voltage and frequency

� For multiple-unit case, we can have Master-Slave or Multi-Master control mode


Demand Response


� Reliability-Based Programs

� Direct Load Control

� Shutting down the directly controllable loads of the customers

� For residential and commercial customers; short notice; often uses a one-way remote switch

� Interruptible and Curtailable (I&C) DR

� Sending curtailment request signals to the customers

� For commercial and industrial customers; larger amounts of power ~ several kW; 30-minutes to a few hours of advance notice

� Emergency GR: for large commercial and industrial customers

� DR Bids

� Receiving and (if economically viable) accepting Curtailment Bids from customers

Demand Response


Demand Response

� Price-Based Programs

� Critical Peak Pricing (CPP)

� Time-of-Use Pricing (TOU)

� Real-Time Pricing (RTP)


Demand Response


Demand Response Chronological Steps


Industrial Sector and DR

� Opportunity: 2-8% of total customers, up to 80% of electricity usage

� During peak load can assist the utility through

� On-site generation

� Demand Shifting

� Curtailment of Noncritical Loads

� Temporary Shutdown

Challenges:

� Loss of load leads to loss of revenue, not just inconvenience

� More difficult to determine critical loads versus non-critical loads

� Scheduled maintenance, crew management, inventory management, workstation characteristics (capacity, configuration)


Dynamic DR for Industrial Systems

Source: S. Mohagheghi and N. Raji, “Dynamic Demand Response,” IEEE Industry Applications Magazine, March/April 2015.


Supplying Critical Loads during an Outage

Transfer Switch UPS

Flywheel


� Objective: Use alternate sources and alternative routes to provide power to the outage area

� Select N/O tie-switches that now have to be closed

� Algorithm needs to:

� Estimate the free capacity of the alternate source

� Estimate the free capacity of the alternate route

� Estimate the total load requirements of the outage area

� Suggest a plan if load balance adds up

� Benefits: faster restoration reduces the stress on UPS and emergency backup power

Service Restoration


Service Restoration


� Challenges:

� Installation and maintenance cost of advanced components

� Need for implementing a scalable and flexible communication infrastructure

� Need for implementing communication resources (bandwidth, spectrum, memory)

� Incorporating less-economical renewable resources into grid operation and dispatch

� Sophisticated platforms for data management (access, privacy, security)

� No short term ROI

Smart Grid Deployment


� Opportunities:

� Promising advances in energy-aware and resource-aware sensors and actuators

� More energy efficient interfaces for DER

� Decrease in the cost of communication devices and networks

� Increase in the number of success stories

Smart Grid Deployment


� Smart Grid paradigm can help customers in various ways:

� DER/Microgrid: Offer flexibility and a certain level of autonomy

� Distribution and Feeder Automation: Can improve reliability and reduce the frequency/duration of outages

� Demand Response: Leads to a less volatile electricity market and more transparency

� Asset management: Helps optimize the utilization of assets, and reduces the need for repair and replacement. This reduces the overall operational cost of the grid.

Concluding Remarks


� However:

� Solutions can be expensive

� Cost of electricity “could” increase temporarily

� ROI is not immediate

� Need to value benefits in the context of risk

� Need to promote the culture of sustainability

Concluding Remarks

2015-03 rocky mountain chapter 7x24 · the grid has always been smart; however, it is now smarter...

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