Migration of electric power generation to the periphery of the grid is presenting new challenges for load balancing and synchronisation. The continuing need for greater efficiency in electric power utilisation and control also means that control systems are in the process of migrating towards individual loads. As a result, greater intelligence is required throughout the grid, from point of power generation to point of power consumption. And the combination of power and intelligence is presenting both challenges and opportunities to the electronics designer: challenges because small, cost-effective intelligent power management modules need to combine digital logic with mains power, and opportunity because new and innovative board level technologies exist to match this challenge.
The "Smart Grid" concept is driven by the transformation of the electric utility industry from a commodity business, where power flows in one direction, toward a services-oriented business in which customers are both producers and consumers. In addition, ageing infrastructure, legislation and economic imperatives demand improvements in efficiency, as centralised load balancing in the current grid requires standby capacity which costs money and burns fuel. This new business model involves active demand-side management in addition to the supply-side management formerly done through passive metering systems. Consumers will be making choices as to how, when, and from whom they purchase electricity or provide demand reductions, and whether to become producers themselves.
Figure 1. The basic Smart Grid concept (source: SmartGrids)
While much of the discussion surrounding Smart Grid is concerned with integration of distributed power generation into the grid and load balancing through the introduction of parallel IT infrastructure as shown in Figure 1, the concept basically involves the creation of active crosspoints capable of controlling power either in the form of supply or demand thereby stabilising the network from the periphery inward. For example, a point-of-use Power Management System has to communicate with other crosspoints, sense the local load, and provide additional demand-side management through direct load control of devices such as hot water heaters, air conditioners, thermostats, and other appliances, as well as to lower the overheads involved in switching Electrical Service Providers (ESPs), where retail choice exists. Distributed intelligence in the form of "Smart Meters" (aka Remote Terminal Units or RTU) also enable ESPs to reduce operating costs and enhance their responsiveness with such capabilities as outage detection and remote connect/disconnect functionality. Smart Meters make it easier for ESPs to offer net metering and feed-in tariffs for customers who own generation such as rooftop solar, where policies exist to promote the adoption of such systems.
Therefore, at the edges of the grid demand side management will be in the form of a “power control computer” with autonomous communication capabilities either via wireless or broadband-over-powerline. This means that control logic will meet mains voltages through metering/consumption monitoring and load regulation. These applications confront the designer with problems which usually are partitioned into separate subsystems: digital logic, communications, and mains voltage (240 VAC)/medium current (20 - 90A) sensing/switching.
To be effective, the Smart Grid needs to involve every point of generation / load. And on the load side it has to approach consumer electronics pricepoints to bring it within reach of the greatest number of users. Although timing of the rollout of Smart Grid infrastructure will vary from region to region depending on saturation and the regulatory environment, market analysts BPA Consulting (UK) expect worldwide shipments of smart meters will peak in 2018 at some 140 million units annually, declining to “only” 115 million by 2022. Figure 2 shows the growth in value for RTUs broken down between data processing/communications and metering for the German market, and every major regional market is closely concerned with these issues.
Figure 2. RTU Functional Value, Germany (source: BPA Consulting, trend:research)
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