Enhanced Power Capability of Generator Units for Increased Operational Security Using NMPC

Abstract

The ever-increasing penetration of intermittent energy sources introduces new demanding operating regimes for the bulk power generation in the power grid. During a worstcase power system disturbance scenario, the generator needs to operate beyond its limits to maintain stable operation. Therefore, a new online low-order thermal model of a hydrogenerator has been recently proposed, where the periodic extension of the long-forgotten capability diagram of the machine was in-depth investigated. An increased performance can be obtained if the total thermal capacity of the generator is exploited by applying optimal control theory in the Automatic Voltage Regulator (AVR). This paper proposes a Non-linear Model Predictive Controller (NMPC) combined with an Unscented Kalman Filter (UKF) with a modeling framework geared for use in a supervisory control structure for the conventional control system. The method provides maximum utilization of the machine's thermal capacity by providing the controller with an Enhanced Capability Diagram (ECD). Case studies on a single-machine system and a 16-bus multi-machine system were investigated. The results show that a satisfying controller action during different long-term voltage instability scenarios is realized.

High-Power Machines and Starter-Generator Topologies for More Electric Aircraft: A Technology Outlook

“…The main advantages are high power generation capacity over a broad speed range and fail-safe fault handling. In general, the rotor of the WFSM has high thermal inertia, which makes the machine less sensitive to short-term overloading [110], [111]. On the contrary, PMs are more vulnerable to thermal transients.…”

Future Operational Regimes of Bulk Power Generation in The Era of Global Energy Transition: Grid Codes, Challenges and Open Issues

“…An over-sized machine yields a significant cost impact. In addition to the nominal SCR, a dynamic SCR might be important in the cases where short-term reactive capabilities of the machine are utilized with more advanced control schemes [10].…”

“…However, if the approach of utilizing an extended capability diagram [10], [12] is used, as illustrated in Fig. 3, extreme points may be realized in a shorter period of time (dynamic rating).…”

“…This is mainly due to the large thermal inertia and the corresponding thermal time constants available in the machine. With new real-time monitoring and control technology [10], a dynamic envelop regime can be enforced on the generators. This approach would enhance the flexibility of the machine.…”

“…This approach would enhance the flexibility of the machine. In such a case, the OEL and SCL need to be replaced by this supervisory control structure [10]. The load cycle is depicted in Fig.…”