“Complex systems are counterintuitive. That is, they give indications that suggest corrective action which will often be ineffective or even adverse in its results,”says Jay Wright, Forrester.
Power Industry is facing revolutionary changes. The direction of the US Government to low carbon footprint and, as a consequence, high penetration of Renewable Energy Resources and Smart Grid Technologies are completely transforming planning and operational patterns for electric grid. As more and more variable and demand response resources being integrated in the electric grid, the grid operation is experiencing increasing level of uncertainties. The decision making process under such environment becomes more challenging. The grid architecture and control also becomes more and more decentralized requiring new control paradigms and reliability metrics to be investigated in order to achieve much higher level of flexibility and resilience. These changes are disruptive enough to cause even transformations in utility business dealing with completely unknown situations.
On the other hand, the evolution in computing; generation, transmission and distribution technologies and mathematical methods creates opportunities for innovation in power system design and control. New mathematical models for power system analysis and operation are being developed to address above challenges.
We will discuss the need for new power system control and electricity market design directions while managing grid complexity.
“The grid architecture and control also becomes more and more decentralized requiring new control paradigms and reliability metrics to be investigated”
Electric Grid Architecture Evolution
Modern power systems are going through different stages of evolution driven by technical, economic, and regulatory events. They went from decentralized, very loosely coupled grid to highly interconnected centrally controlled systems. The increased complexity and lack of ability to manage it led to major blackouts forcing significant changes in system planning and operation. The Great Northeast Blackout of 1965 led to creation of the power pools with control centers running Energy Management Systems (EMS), centralized regional planning and control. Each pool linked together multiple neighboring transmission companies with much stronger ties among them (Fig. 1). Besides local control centers, power pools created pool control center. Not only did this help increasing reliability and resilience by the ability to provide balancing assistance, but also created saving for the member companies by using less expensive generation to meet the regional load. With the inception of the electricity markets in late 90-s and creation of ISOs/RTOs, market players started placing economic transactions across the pool boundaries increasing the complexity of the grid operation. This led to reinforcement of the transmission and tighter integration of the interconnected systems. The complexity of such an architecture required new ways of the system control. The Economic Dispatch (ED) being done in each market area independently created so-called “seams” issues – inefficient utilization of the interties. This, in turn, required additional information technology and communication infrastructure to coordinate market operation across large geographic areas.
Currently, the power industry is facing another revolutionary change. Government directives to lower the carbon footprint and, as a consequence, high penetration of Renewable Energy Resources and Smart Grid technologies are completely transforming planning and operational patterns for the electric grid again. Traditionally, electric grid upgrades have been done centrally during transmission planning process. The process follows very strict reliability standards and large number of system studies, both in the steady state and dynamical. Today, numerous changes to the grid are made ad hoc: distributed generation, microgrids, storage, etc. System operators lose control of the network perimeter. Significant part of the generation resources is unobservable for the system operators. The unprecedented level of uncertainty is introduced not only in the location of the distributed resources, but their intermittent nature as well. The output of wind and PV generation can swing significantly in time. The tribal knowledge of system operators is failing in dealing with completely different patterns of the system behavior. Even the concept of contingency is changing from being binary (the element of the grid is on or off) to a continuous in time change. The system load or generation can change by several thousand MW in comparatively short period of time. This behavior, considered as abnormal or emergency, becomes part of normal operation. This creates tremendous complexity in power system control.