Constant-Power Load System Stabilization by Passive Damping

Abstract

This paper addresses stability problems in power systems with loads that exhibit constant-power behavior. Instability may occur in such systems due to the negative incremental impedance of constant-power loads (CPLs). Existing approaches to stabilizing such systems require modification of the source and/or the load control characteristics, or isolating the CPL from the rest of the system by additional active devices, which are difficult to implement and often conflict with other system requirements such as control bandwidth, size, weight, and cost. In this paper, we investigate passive damping as a general method to stabilize power systems with CPL. Using a representative system model consisting of a voltage source, an LC filter, and an ideal CPL, we demonstrate that a CPL system can be stabilized by a simple passive damping circuit added to one of the filter elements. Three different damping methods are considered and analytical models are developed for each method to define damping parameters required for stabilizing the system. Time-and frequency-domain measurements from an experimental system are presented to validate the methods.

A systematic approach to constant power load stabilization by passive damping

“…[1]). In our methodology we do not restrict the class of load models; for example we admit frequency-domain models of as differences of squares (P (−s) P (s) − N (−s) N (s)).…”

“…Other methods propose stabilization by passive damping (see e.g. [1]), where a passive load (filter) is interconnected to the system in order to guarantee stability. In such approach the main issue is how to design the stabilizing filter impedance, while also satisfying additional specifications, e.g.…”

“…This framework offers several advantages over the classical one based on state space descriptions sharing the same state space (see [9], [11]). Moreover, in our framework it is straightforward to accommodate more general descriptions of the instabilitygenerating mechanism than the traditional negative resistance one (see [1]), e.g. frequency-dependent negative impedances.…”

Passivity-Based Control of Switched Reluctance-Based Wind System Supplying Constant Power Load

“…In [5], a passive stabilization method is used using passive components such as RC and RL parallel dampers, which is plagued by reduced system efficiency. To avoid reduced efficiency, an active damping approach is proposed in [6] by injecting a compensating current using an auxiliary line regulating circuit (LRC), which makes the system complicated.…”

Analysis and Design of an Active Stabilizer for a Boost Power Converter System

“…In order to meet the cascaded system (LC filter and DC/DC converter) stability requirements, one solution is to damp the input filter using an impedance criterion (Middlebrook criterion) [10][11][12].…”