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XYLENE POWER LTD.

SMART GRID

By Charles Rhodes, P.Eng., Ph.D.

DUMB GRID:
The present electricity grid in Ontario is a classic dumb grid in which central dispatch rather than distributed intelligence is used to match generation to load. The distributed intelligence on the grid is limited to substation transformer tap controllers which regulate feeder voltages and substation breaker controllers which clear, isolate and identify faults.

While the existing substation transformer tap controllers do a good job of feeder voltage regulation with no distributed generation, their proportional-integral (PI) voltage control algorithms are not compatible with other PI voltage controlled energy sources supplying the same feeder. As the system is presently configured distributed generators rely on the existing substation transformer tap controllers for voltage regulation. That arrangement is simple and reliable but the potential advantage of distributed generation assisting with black start and voltage regulation is lost.
 

LOAD FACTOR AND CAPACITY FACTOR:
A key issue facing electrical engineers is that for customers to substantially lower CO2 emissions the average power delivered to each customer via the electricity grid must greatly increase. In order to increase average power delivery without incurring huge capital expense for grid expansion the average customer load factor must increase. That increase in load factor can only be achieved if there is some form of power control and energy storage behind each electricity meter. Hence the first step toward achieving a future smart grid is adoption of an electricity rate that financially rewards load customers that achieve a high load factor and financially rewards distributed generators that achieve a high capacity factor.

The most effective way of incenting efficient utilization of the electricity grid is to provide a load factor and power factor based electricity rate for consumers and a capacity factor based compensation rate for generators. Then every load customer and every distributed generator would have a strong financial incentive to install automatic: power factor control, load control and energy storage equipment behind his/her electricity meter. This forest of load customer and distributed generator owned power control and energy storage systems would contain much of the distributed intelligence required by a Smart Grid.
 

SMART GRID:
A Smart Grid is an electricity grid that uses distributed control systems to achieve maximum efficiency, economy and reliability. Implementation of a Smart Grid involves modifying the concept of electricity dispatch. In a smart grid the electricity dispatched from central generation via transmission is the sum of the net requirements of the Local Distribution Companies and the transmission connected industries, each of which has distributed generation within its own service area. Each electricity substation should have its own local zone controller(s) which should act to maximize the load factor within its zone consistent with proper voltage regulation. If there is an electricity supply interruption the zone controller should have sufficient intelligence to obtain power from alternate sources.

Each zone controller on a smart grid must recognize circumstances when total functional generation capacity within a zone is insufficient to meet the electricity load in that zone, and must rapidly either import additional power and/or shed load to prevent a cascade system failure.
 

REDUNDANCY:
In order for local zone controllers to satisfactorily manage fault conditions there must be sufficient equipment redundancy that the electricity system can operate with any single major component out of service. A problem in Ontario at present is that there are numerous places, particularly around Toronto, where at peak load conditions there is insufficient equipment redundancy.
 

VOLTAGE CONTROL:
When there are numerous distributed generators supplying a feeder the issue of voltage control must be faced. All distributed generators should be programmed to output power on a precisely specified negative slope power versus voltage proportional control curve. The zone controllers must be designed for unconditional voltage stability. One of the implications of distributed voltage control is that all distributed generators should operate under partial power constraint, so that if one unit fails the remainer have sufficient reserve capacity to instantaneously meet the load. Under present circumstances of unconstrained distributed generation the Ontario electricity system is becoming unstable due to too much unconstrained renewable generation that relies on other generation for voltage control.
 

SMART AND SMARTER METERS:
Successful operation of a smart grid relies on an electricity rate that financially rewards both generators and load customers for provision of energy storage and power control. That electricity rate in turn relies on availability of directional interval kWh data from Smart Meters and Smarter Meters. A Smart Meter records cumulative net energy flow as a function of time. A Smarter Meter separately records cumulative energy flow in each direction as a function of time. A Smarter Meter allows use of energy flow direction dependent electricity rates and allows calculation of power factor as a function of time.
 

IMPLEMENTATION:
Implementation of a Smart Grid involves the following steps:
1. Upgrading the grid such that any single component can be taken out of service without impacting electricity service to end users;
2. Installation of Smart or Smarter kWh meters that record energy flows into or out of the grid as a function of time;
3. Installation of a communications system that gathers the metered data and that broadcasts common information needed by local controllers to optimize their control strategies;
4. Changes to the electricity rate structure so that all grid customers have a strong economic motivation to maximize generator capacity factor, maximize load factor and control their net generation/load in a manner which is consistent with stable and economic grid operation;
5. Implementation of the new electricity rate structure using the interval metered data;
6. Implementation of new local control systems at most substations and behind distributed generator and load customer electricity meters;
7. Implementation of energy storage behind distributed generator and load customer electricity meters;
8. Ongoing analysis of acquired data to identify electricity system components that need service or further upgrades.
 

IMPLEMENTATION PROBLEMS:
At the root of the smart grid implementation problem is the unwillingness of politicians to proceed with essential electricity rate changes and grid upgrades that have been clearly identified by engineers for many years. The best engineering solution in the world will not solve an electricity system problem if an elected politician blocks its physical implementation.
 

SMART METER PROBLEMS:
The Smart metering hardware installed by Hydro One Networks Inc. (HONI) in rural areas simply does not function as originally intended. This hardware relies on mesh communications between adjacent meters. The mesh communication concept works in dense urban areas but does not work in rural areas where adjacent customers are often hundreds of metres apart and are frequently further isolated by trees and hills. To make the Smart meter communication system work on long rural branch feeders HONI must supply and install much more communication equipment than was originally contemplated by the Ministry of Energy. The net result is that rural customers, who have the greatest potential to change their load profile in a manner beneficial to the grid, do not have functional Smart meters. Eight years after a "Smart meter" was installed at my home it is still only occasionally manually read. HONI is not able to give me any firm undertaking as to when if ever my Smart Meter will work.

The simple reality is that the presently non-communicating Smart meters should replaced by Smarter meters that can be read via the wireless Internet using the customers local area network (LAN) wireless router. Today most rural customers have either a wireless or a satellite internet service connected to a LAN wireless router. The electricity meter could be just another device served by that LAN router.
 

This web page last updated February 12, 2017.

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