XYLENE POWER LTD.

SMART GRID

By C. Rhodes

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 reasonable job of feeder voltage regulation with no distributed generation, their proportional-integral (PI) voltage control algorithms are not designed to be compatible with other voltage controlled energy sources supplying the same feeder. The control system still functions if the distributed generators rely on the existing substation transformer tap controllers for voltage regulation, but then much of 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 by the electricity grid has to greatly increase. In order to increase average power delivery without incurring huge capital expense for grid expansion the average customer load factor and the average distributed generator capacity factor must both substantially increase. That increase in load factor and capacity factor can only be achieved if there is some form of energy storage and power control behind each electricity meter. Thus the very first step toward achieving a future smart grid is an electricity rate structure that financially rewards grid load customers that achieve a high daily load factor and financially rewards distributed generators that achieve a high daily capacity factor.

Time of use electricity rates are a very crude way of attempting to increase average customer daily load factor. Once smart meters are in place and fully operational a much more effective way of improving load factor is to offer a daily load factor or daily generator capacity factor dependent electricity rate. If this rate is properly set every load customer and every distributed generator has a strong financial incentive to install energy storage and automatic load control behind his electricity meter. This forest of customer owned load control systems contains 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 abandonment of the concept of central control of all electricity dispatch. Instead each part of the electricity system should have its own local zone controller which should act to maximize the daily load factor or daily generator capacity factor within that zone consistent with proper voltage regulation. Ideally, if there is an electricity supply interruption the zone controller should have sufficient intelligence to obtain power from alternate sources. A local control zone may be as small as a single building.

Each zone controller on a smart grid must recognize circumstances when total electricity supply to that zone is not sufficient to meet the total electricity demand in that zone, and must rapidly shed load to prevent a cascade power 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 transmission/distribution redundancy simply does not exist at peak load conditions.

VOLTAGE CONTROL:
When there are numerous distributed generators supplying a feeder the issue of voltage control must be faced. Distributed generators must be programmed to net output on a negative slope power versus voltage proportional control curve. The zone controllers must be designed for unconditional power stability except when there is sudden loss of electricity supply. One of the implications of distributed voltage control is that distributed generators operate under power constraint. As the electricity system becomes less dependent on fossil fuels at the margin, distributed generator power constraint becomes a fact of life.

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.

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 directional interval kWh meters that record all 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 metered data to identify grid segments that need service or further upgrades.

PROGRESS:
In mid 2010 Ontario is still in the midst of steps #1,#2 and #3. The Ontario government, the Ontario Power Authority (OPA) and the Ontario Energy Board (OEB) have made little or no progress on step #4 and #5. The technology necessary to implement step #6 exists, but end users have little motivation to apply it because there is insufficient economic incentive in the electricity rate structure. There has been no progress on steps #7 and #8.

PROBLEMS:
At the root of the smart grid implementation is the unwillingness of politicians to proceed with essential 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 a local politician with NIMBY supporters blocks its physical implementation.

Ontario has a fundamental problem that both the province and local municipalites have not made adequate planning provisions for electricity transmission corridors. Until provincial politicians address this problem this issue will constrain the potential smart grid benefits. At the present the OPA is attempting to resolve transmission bottlenecks through the use of local natural gas fired generation. However, use of this generation is contrary to necessary CO2 emission reductions and needs dedicated energy transmission corridors through urban areas for supplying the natural gas to the generators. The intelligent solution is to face the energy transmission corridor planning issue head on and to reserve energy transmission corridors where they are reasonably required.

ENERGY TRANSMISSION CORRIDORS:
Proper long term grid planning requires restricting use of real estate along future energy transmission corridors. The energy transmission corridor land acquisition process takes many years. Successive Ontario governments have procrastinated about this issue for the last four decades.

This web page last updated September 12, 2010.