Advances in digital monitoring/control devices and networking technology have expanded the range of power monitoring equipment available, plus improved its functionality. The result is a significant new potential forincreasing power system reliability while decreasing system operating costs. These advances are causing a growing number of facilities to develop comprehensive energy management strategies that help them maximize their energy resources.
While most companies recognize the value of energy management, their success addressing the issue varies. Properly controlling a power system is often seen as too time consuming, inefficient, and expensive to be practical. Much of this perception stems from the past, when adequate monitoring equipment just wasn’t available:
- Monitoring devices were limited and analog based.
- The information they provided had to be gathered manually.
- These devices couldn’t be interconnected to collect and analyze pre- and post-fault system data, or to assess power factor.
As a result, power system management and maintenance functions were performed unnecessarily or not in time to prevent costly malfunctions.
Power Management Basics and Benefits
What is power management? Basically, it is “optimum continuity of power”—ensuring the highest quality power is available where needed, when needed, in the right amount, at the best cost, at all times. Effective power management is closely tied to an energy management program, or systematic approach to monitoring and controlling energy resources.
At the heart of the energy management program is the power monitoring system, also known as the power monitoring and control system (PMCS). A well-designed power monitoring system provides:
- Usage monitoring to track and analyze power consumption: kW, amps, Volts, etc.
- Power monitoring to protect the distribution system (via relays, power breakers, and other devices) against power outages, fault conditions, overloads, and downtime.
- Quality monitoring to track and analyze harmonics and disturbance data.
- Power factor status monitoring.
A well-planned, ongoing energy management program based on a modern power monitoring system offers these and other benefits:
- Correction of electrical equipment problems beforehand to prevent power outages and damage to distribution system components.
- Analysis of the power supply (source and quality) and demand patterns to develop appropriate
- load management strategies.
- Optimization of the distribution system to improve phase imbalances and maximize power availability.
- Automated billing for accurate cost allocations by area, process, etc.
Power Management System Components
At the heart of the power monitoring system and energy management program are the energy management system components, the hardware and software used for power monitoring and control.
Monitoring, control, and protection devices: The meters, trip units, relays, and other devices that control the source and flow of power, monitor power quality, protect the distribution system against overloads, etc.
Computer networks: Digital interconnects of various protocols that link the monitoring, control, and protection devices to a centralized computer(s) so system data can be collected and analyzed in real time.
Energy management software: Programs that collect data from the monitoring, control, and protection devices via the computer network and report this information in a graphical manner on the central computer display(s). Typically, such software can be customized to meet specific reporting needs.
In some cases, the energy management system components include programmable logic controllers (PLCs). These are often used as supervisory devices in control and gateway applications.
Implementing the Power Management Program
Getting a power management program off the ground involves planning and execution. The process begins by establishing program goals and strategies: What level of monitoring and control is needed? What analysis is to be performed (power quality, allocation usage reduction, etc.)? What are the desired system comparison-forecasting capabilities?
Goal setting is followed by reviewing and, if necessary, developing the distribution system’s single-line diagram. This drawing helps identify the best locations for placing the energy management components needed to accomplish program goals.
Next is the design and implementation (or upgrading) of an adequate power monitoring system. At this stage, all necessary monitoring, control, and protection devices are installed at predetermined locations.
The energy management system’s computer network links all devices together. Sometimes, a network suitable for energy management may already be in place (i.e., it was installed previously for purposes other than energy management). In such a case, network installation may not be a major task or expense.
Once the system hardware is in place, energy management software can be installed. This includes:
- Designing and setting up the power system monitoring “forms”: the computer screen displays used for data presentation and analysis.
- Defining monitoring, control, and protection devices within the software database.
- Establishing the communication link between all system hardware and software components.
At this point, the system can now be commissioned. Commissioning involves reviewing all energy management system hardware and software to ensure proper operation and coordination between components.
Finally, facility personnel are trained in energy management program operations. This includes such areas as using the system equipment, daily and weekly energy management procedures, data interpretation, preventive maintenance, and appropriate responses to specific situations.
Power Management Today and Tomorrow
A power management program to the level discussed here represents a significant investment to hire a consultant, plan the program, install equipment, and train personnel. Is the effort worth it? Naturally, results vary. But for most plants, the payback from cost savings, power system integrity, load monitoring/balancing, preventive maintenance, and allocations capability makes the answer a definite “yes.”
It’s important to remember that the most certain factor about the energy market is it will continue to change. And no one can predict exactly how these changes will shape tomorrow’s energy picture. An effective power management system can make dealing with these unknowns a whole lot easier.