Inside a demand-response system

Resources Powerit Solutions, Seattle, www.poweritsolutions.com

Many industrial users of energy think demand-response schemes made possible by smart grid technology are a great idea -- for somebody else. When you operate time-critical industrial processes like furnaces or conveyors, it is hard to envision a scenario in which you could shed such loads in the interest of reducing peak energy demand.

The latest energy management systems can put those concerns to rest. It has become a truism that businesses will almost certainly will leave money on the table — not only now but in the future — if they ignore utility programs coming online that offer opportunities for energy savings. Food processors, for example, count energy as their third largest operating expense, and it’s expected to grow.

It’s helpful to address a few common myths, then walk through how an advanced energy management system (EMS) works.

Myths vs. Reality

Myth one: To save on my energy bill, I’ll have to sacrifice production.

Not if you take the right approach. With an advanced EMS, built-in rules and constraints protect the production process and always supersede energy savings goals. You define the curtailment limits for each load, with the assistance of an energy engineer, so you can be assured the load is protected. The priorities that you set determine how loads will be selected for curtailment.

Myth two: The system will complicate the existing controls and make them impossible to maintain.

Not if you choose the right vendor and technology. You can integrate energy management technology in a way that causes neither harm nor unexpected disruptions to existing systems. An advanced EMS for industrial businesses will have several features that ease integration.

For example, wireless connectivity will let you monitor and direct plant or facility loads without adding cumbersome wiring. For hardwired systems, the strategy is to control points as “normally closed contacts.” If there is a performance problem with the EMS, other systems will return to normal operation.

Embedded control setpoints and rules are tailored for your facility and for each load. Once fine-tuned, the system should run with virtually no operator attention. We’ve seen customers forget they were managing their energy and unwittingly disconnect the technology — it can be that noninvasive and low maintenance.

Myth three: If advantages claimed were real, everyone would be using energy management technology.

The advantages claimed are indeed real. The problem isn’t the technology; it’s the fact that there are disincentives to use it, plus a general resistance to change and lack of knowledge about current technology. A plant engineer won’t get fired over a high energy bill. But heads can roll if the frozen french fries don’t get out on time. So engineers who think an EMS is a risk to production won’t consider it.

The balance of concerns is shifting, though: With shrinking margins and tight budgets forcing companies to cut operational expenses, energy is increasingly under scrutiny as a controllable cost.

An advanced EMS makes possible four ways of controlling energy use and costs: demand control, demand response, real-time pricing and energy efficiency. Technical personnel often think it’s impossible to save energy and money while maintaining production. But demand control allows almost all facilities to use energy more efficiently by reducing usage peaks. To show how this works, we’ll consider as an example Powerit’s Spara technology, a hardware and software system that integrates with a facility’s existing controls.

Spara software resides on its own Web-based embedded Linux server. The server has a number of networking and communication ports for connections to various controllers (PLCs, microcontrollers, VFDs, and so on). As is typical with EMS setups, there is no additional hardware required. The software normally uses existing control points to manage loads. If there are loads in the system that are unautomated, the usual approach is to add them using industrial 900-MHz wireless units to minimize the additional wiring involved.

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