Admittance space stability analysis of power electronic systems

Abstract

Power electronics based power distribution systems (PEDSs) are becoming increasingly common, particularly in marine and aerospace applications. Stability analysis of this class of systems is crucial due to the potential for negative impedance instability. Existing techniques of stability analysis introduce artificial conservativeness, are sensitive to component grouping, and at the same time do not explicitly address uncertainties and variations in operating point. A new stability criterion, which reduces artificial conservativeness and is also insensitive to component grouping is described. In addition, a means of readily establishing design specifications from an arbitrary stability criterion which specifically includes a provision to incorporate uncertainty, parameter variation, and nonlinearities is set forth. The method is presented in the context of a hardware test system and is experimentally validated.

Conformal mapping of impedance stability models for system-level dynamics assessments

“…The source impedance Z i (ω) is inductive at the low frequency range and capacitive in the high frequency range, and presents a wide and smooth magnitude peak at 5 Hz, which has been found to be highly dependent on the source converter controller. In the case of the load admittance, it should be noted that Y o (ω) is defined by a negative resistive behaviour in the low frequency range (∠Y o (ω) = 180 deg), as expected from a CPL [5], [6], [21], [22]. At the high frequency range, where the control action does not have an effect, Y o (ω) is inductive and has a low magnitude.…”

Dynamic Assessment of Source–Load Interactions in Marine MVDC Distribution

“…These stability-related problems and their possible solutions can also be found in [16]- [24]. DC-side modeling of power electronic systems as impedance is reported in [16]- [18] for dc applications. These works show that the small-signal analysis is a suitable method to linearize the power electronic systems.…”

“…1 can be scaled down to a simplified circuit like in Fig. 2 [17], [18], by assuming that both the sources and the loads are working with similar loading cycles, respectively. A key feature of Fig.…”

“…These works show that the small-signal analysis is a suitable method to linearize the power electronic systems. Furthermore, the impedance stability criteria can be applied to assess the relative stability by means of Nyquist or Bode diagrams [16]- [18]. This is further extended to multiterminal dc systems in [19].…”

“…This paper analyzes a possible MVDC electrical distribution system for a large marine vessel with power levels of several megawatts (MWs), considering the proven and available industrial technologies. Small-signal modeling and linear analysis at selected operation points is performed in order to identify the potential unstable conditions that may compromise the MVDC system design [1], [17], [18]. In order to analyze the source-load dynamic interactions, reasonable simplifications are made to the complex system.…”