Guidance on the planning and design of dc links terminating at ac system locations having low Guidance on the planning and design of dc links terminating at ac system locations having lowshort-circuit capacities relative to the dc power infeed is provided in this guide. This guide is limited to the aspects of interactions between ac and dc systems that result from the fact that the ac system is weak compared to the power of the dc link (i.e., ac system appears as a high impedance at the ac/dc interface bus). This guide contains two parts: Part I, AC/DC Interaction Phenomena, classifies the strength of the ac/dc system, provides information about interactions...

Part I of the guide discusses the effects of various aspects of the ac/dc interactions on the design and performance of dc schemes where the ac system appears as a high impedance at the ac/dc interface bus; i.e., low and very low short-circuit (short-circuit ratio [SCR]) conditions. AC systems having zero or inadequate mechanical rotational inertia, such as island schemes with no or with limited local generation, are also considered. Environmental, siting, and construction issues are not addressed. General issues, such as steady-state reactive compensation and ac and dc filter requirements, are not in the scope of this guide, but would be included in a compl...

The purpose of Part I of this guide is to address factors required to be considered in the design of dc transmission schemes in the context of system interactions resulting from dc links terminating at ac system locations having low short-circuit capacities relative to dc power infeed and for cases where the inertia of the ac system is too low for satisfactory operation. The following ac/dc interactions are considered: power, voltage, and frequency instabilities; harmonic resonance-related instabilities; subsynchronous torsional interactions; temporary overvoltages; and recoveries from ac and dc faults.