Development of functional specifications for HVDC grid systems

Abstract

Several processes have been initiated for the development of technical concepts, guidelines and common requirements of HVDC Grid Systems. For implementing extended HVDC Grid Systems on a multi-vendor basis consolidated and agreed functional requirements for equipment and solutions are needed. Providing such requirements is the role of international standardisation bodies. With the primary focus on elaborating technical standards for HVDC Grid Systems, the CENELEC Technical Committee TC8X has started a new Working Group (WG06) "System Aspects of HVDC Grids". Considering that Grid Systems are an entirely new application of HVDC technology, the first goal of this working group is elaborating a document describing clear functional specifications of different aspects for HVDC Grid Systems and associated equipment. With view on the early stage of technology this paper discusses the need for standardisation and presents the scope and methodology of WG06. The approach chosen to develop functional specifications is explained using two examples. The main contribution of this paper is to present a methodology for and the challenges in developing standards in a new field of technology and to foster discussion.

An Architecture for a Multi-Vendor VSC-HVDC Station With Partially Open Control and Protection

“…For example, specific knowledge from the closed converter-internal protection ("MMC blocking characteristic", see Section III.B) may be needed to design the higher protection levels. Additionally, information from higher protection levels may be required to coordinate the MMC internal protection (e.g., fast de-blocking sequences or concepts that coordinate the timing of an MMC trip with a DCCB disconnecting a fault [56]- [58]). Also, backup protection and system-level coordination in partially or non-selective strategies are required.…”

Control-based fault current limiter for modular multilevel voltage-source converters

“…Given the number of inserted submodules and the sign of the arm current, the submodule balancing loop specifies which submodule will be inserted in order to balance the submodules voltages [1,7]. The lower the hierarchy, the faster the loop is and the shorter the time range, i.e., 20-500 ms for the outer loop and some µs for IGBT switching [27]. The control structure is depicted in Fig.…”

Alternate Arm Converters-Based HVDC Model Compatible With the CIGRE B4 DC Grid Test System

“…The top layer ("AC/DC Grid Control") defines the dispatch schedules for the overall power system [12]. The second layer ("Coordinated System Control") responds to the unscheduled events of the power system providing frequent set-points to the third layer with the timely coordination of all converter stations [19]. The third layer ("Converter Station Control") is the high-level control of the HVDC converter station which regulates active/reactive power, node voltages and frequency based on the set points.…”