Topic
Output impedance
About: Output impedance is a research topic. Over the lifetime, 11185 publications have been published within this topic receiving 134949 citations.
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01 Dec 2005
TL;DR: In this paper, a novel wireless load sharing controller for islanding parallel inverters in an ac distributed system is proposed, where the resistive output impedance of the parallel-connected inverters is explored.
Abstract: In this paper, a novel wireless load-sharing controller for islanding parallel inverters in an ac distributed system is proposed. The paper explorers the resistive output impedance of the parallel-connected inverters in an island microgrid
718 citations
TL;DR: Adapt virtual output impedance is proposed in order to achieve a proper reactive power sharing regardless of the line impedance unbalances and can be properly shared due to the addition of a current harmonic loop in the control strategy.
Abstract: In this paper, a method for the parallel operation of inverters in an ac-distributed system is proposed. This paper explores the control of active and reactive power flow through the analysis of the output impedance of the inverters and its impact on the power sharing. As a result, adaptive virtual output impedance is proposed in order to achieve a proper reactive power sharing, regardless of the line-impedance unbalances. A soft-start operation is also included, avoiding the initial current peak, which results in a seamless hot-swap operation. Active power sharing is achieved by adjusting the frequency in load transient situations only, owing to which the proposed method obtains a constant steady-state frequency and amplitude. As opposed to the conventional droop method, the transient response can be modified by acting on the main control parameters. Linear and nonlinear loads can be properly shared due to the addition of a current harmonic loop in the control strategy. Experimental results are presented from a two-6-kVA parallel-connected inverter system, showing the feasibility of the proposed approach
676 citations
Patent•
09 Feb 2000
TL;DR: In this paper, an electricity storage device and a portable electric-powered tool is described. But the connection of the battery and the super capacitor does not need any converters or current-limiting resistors.
Abstract: An electricity storage device and a portable electric-powered tool. The device comprises at least a battery; at least a super capacitor, which has lower internal impedance, when fully charged, than that of the battery and connects the battery in parallel; and an output end for supplying the electricity. The super capacitor is the major power supply for the pulse current output; the battery is used for generating electricity to the super capacitor and is the secondary power supply for the pulse current output. The connection of the battery and the super capacitor does not need any converters or current-limiting resistors.
652 citations
TL;DR: In this article, a new forbidden region for impedance ratio Z/sub o/Z/sub i/ on the S-plane is proposed as the system stability margin requirement, based on which the impedance specifications of individual loads are established.
Abstract: In a DC distributed power system, the interaction between individually designed power modules/subsystems may cause the instability of the whole system. In a small-signal sense, system level stability is determined by the impedance ratio Z/sub o//Z/sub i/. Here, Z/sub o/ is the output impedance of the source module/subsystem, and Z/sub i/ is the input impedance of the load module/subsystem. As a result, an effective way to prevent system instability is defining impedance specifications for modules/subsystems. This paper briefly summarizes existing works and introduces the authors' contribution in defining impedance specifications. A new forbidden region for impedance ratio Z/sub o//Z/sub i/ on the S-plane is proposed as the system stability margin requirement. Based on this proposed forbidden region, the impedance specifications of individual loads are established. Further, a very practical measurement approach is developed to examine whether or not the system stability margin requirement of the forbidden region is satisfied.
538 citations
20 Jun 1993
TL;DR: In this paper, a forbidden region for the polar plot of the ratio of impedances at the interface between two cascaded power subsystems is determined, and a method of transforming the forbidden region into a load impedance specification for a given source impedance is developed.
Abstract: By applying the loop gain analysis technique, a forbidden region for the polar plot of the ratio of impedances at the interface between two cascaded power subsystems is determined. A method of transforming the forbidden region into a load impedance specification for a given source impedance is developed. The method assures system stability and minimal performance degradation of the distributed power system, while allowing impedance overlap at the interface. >
504 citations