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Intelligent Control for Reliable Electric Energy

by Professor Dan Trudnowski

 

An efficient, reliable, and affordable electric-power grid continues to be critical to the economic and social health of the United States. Growing demand, lack of investment, and new national security requirements point to the need for significant investment in upgrading the US power grid. Recent indicators of this include the significant increase in power outages over the last decade; these include the massive outages experienced by the western North American power system in August and July 1996, and the August 2003 east-coast power outage.  These are the first massive outages since the northeast coast outage in 1965.  Advanced control and new operating paradigms offer considerable benefits in terms of cost savings, reliability, and national security for the grid of the future. 

 

Recognizing this potential, the USDOE has provided funding to Montana Tech to develop key technologies for applying real-time advanced control to improve grid reliability and efficiency. Our program is developing advanced control technologies for improving grid reliability and efficiency, facilitating deployment of these technologies to the industry, and educating the next generation of engineers in intelligent utilization and operation of electrical energy systems.

 

Modern electric grids tend to fail due to unstable operation often encountered under heavy loading conditions resulting in wide-spread blackouts. Unstable operation can be avoided using two basic approaches: 1) increase and upgrade the T&D system (e.g., add more transmission lines); or 2) use advanced technologies to control potentially unstable conditions allowing reliable transfer of higher power levels in the existing infrastructure. The control approach has many cost-saving advantages but requires significant investment in research and development. Our research efforts focus on two key technologies. The first technology uses advanced signal processing and time-synchronized measurements to detect oncoming unstable operation which can be used to pre-warn grid operators of a potentially unstable condition. The second technology uses advanced control algorithms, which can be applied to actuators to stabilize a grid during a major disruption. 

 

Detecting and Avoiding Grid Instability

 

In a typical grid failure, an unstable condition takes many minutes or even hours to build up.  For example, the grid loading slowly increases over the course of a day as more and more consumers increase demand. Then, certain contingencies cause the system to approach instability. Unfortunately, because the US grid is the world’s largest engineering machine, detecting the approaching instability is often very difficult, if not impossible. In the grid of the future, unstable operation will be detected prior to the onset of the instability and intelligent control systems will provide critical information to system operators to avoid the oncoming unstable operation. The critical technology in this scenario is the ability to quickly detect the on-coming instability. A principal goal of the proposed research is to develop real-time methods to reliably detect the approaching instabilities using phasor measurement technology and related real-time signal-processing algorithms. Figure 1 shows a version of a Real-Time Dynamic Monitoring System that is being developed for this project.

 

Real Time Dynamic Monitor System (RTDMS)

 

 

Advanced Control

 

Recent advancements in power-system actuators and phasor measurement technology make real-time control of the grid feasible.  Actuators include controllable consumer loads and power-electronic controllable devices such as variable capacitors and fly wheels. One example of a controllable consumer load is DOE’s GridFriendly appliance (see Figure 2). As a power system enters an unstable condition, these actuators can be modulated to stabilize the grid during a major disruption. Currently, modern grids are primarily controlled through the generation. Control of the load and special actuators provides significantly more leverage to impact the system. The resulting influence on grid reliability is significant.    

 

Pacific Northwest National Laboratory engineers are designing smart chips that can be applied into household appliances and would continually monitor fluctuations in the power grid. When the grid is under high periods of stress, a grid-friendly appliance would identify these fluctuations and, within milliseconds, automatically shut down for a short period of time to give the grid operators time to stabilize the system. It could even turn on momentarily to absorb excess power from fluctuations during a crisis.

 

As a power system enters an unstable condition, these actuators can be modulated to stabilize the grid during a major disruption. Currently, modern grids are primarily controlled through the generation. Control of the load and special actuators provides significantly more leverage to impact the system. The resulting influence on grid reliability is significant.    

 

Additional information is available on the Project Fact Sheet (PDF 4 MB).