Mitigating the effect of low inertia and low short-circuit level in HVDC-rich AC grids

减轻富含 HVDC 的交流电网中低惯量和低短路水平的影响

• 批准号: EP/L021455/1
• 负责人: Jun Liang
• 金额: $ 37.67万
• 依托单位: CARDIFF UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FL021455%2F1
• 关键词: Mitigating; effect; low; inertia; short

Renewable power, particularly offshore wind power, will be a major element of the UK's transition to meet its energy demands while reducing carbon emissions. HVDC will be the key technology for integrating offshore wind power into the UK AC grid and for interconnecting other AC grids in Europe. Line commutated converter (LCC) HVDC is particularly suitable for bulk power transfer while voltage source converter (VSC) HVDC is particularly suitable for connecting offshore power into AC grids with low inertia and low short-circuit level. Multi-terminal HVDC networks and DC grids based on VSC technology will be developed across the North Sea to form a future SuperGrid to increase the flexibility, redundancy and economic viability of offshore wind power transmission.Conventional synchronous generators will be replaced increasingly by renewable generation with power electronic converters and HVDC transmission. This causes significant reduction of system inertia and short-circuit level. Particularly in the UK, large scale offshore wind power and interconnection with grids in other European countries will lead to an HVDC-rich AC grid. This will result in AC grids with low fault-circuit and low inertia which will present a series of challenges for AC system operation such as the potential impact on existing relaying protection; frequency instability and commutation failure of LCC HVDC.This proposed project will look at the behaviour of low-inertia and low short-circuit level in HVDC-rich AC grids supplied through power electronic converters. The challenges will be that the capability of HVDC links to provide the system support could be (at the same time) adversely affected by these effects on the grids. LCC HVDC can provide artificial inertia but requires high short-circuit ratio of the grid to work properly. During AC fault and post-fault restoration, the inertia support capability of the LCC would be limited at the very time it is most needed. VSC HVDC control is less dependent to AC grids. However a DC fault can be easily propagated across whole HVDC grid due to the very low resistance of DC lines, which in turn affects the AC sides of all terminals. During the DC fault, the real power injected into AC grids as well as the inertia support from VSC HVDC grids would be lost at the very moment it is much needed to maintain the system frequency. At the same time, reactive power support to AC grids from VSC HVDC grids would also be lost completely or partially depending on converter topologies. Investigations will be undertaken of the inertia support from HVDC converters, on the capabilities of the different types of converters to mitigate low-inertia effects and on their coordination through the AC side (for point-to-point HVDC links) or through the DC side (for converters within the same DC grid).The hardware-in-loop (HIL) platform at Cardiff University, which consists of a HVDC grid test rig, a real time digital simulator (RTDS) and a power amplifier, will play a key role in the modelling and testing of HVDC-rich grids and HVDC converter control for mitigating low-inertia and low short-circuit level effects.Through this project, in-depth understanding of operation characteristics of AC grids which are rich in HVDC links will be achieved. Solutions will be founded to enhance the system inertia and short-circuit level. More renewable power through HVDC can be integrated into AC grids without deteriorate the system performance. The research outputs of this project will be disseminated through industrial partners, international academic associations, conferences and journal publications.

可再生能源，特别是海上风力发电，将成为英国在满足能源需求的同时减少碳排放的主要因素。高压直流输电将是将海上风电整合到英国交流电网以及连接欧洲其他交流电网的关键技术。线路换向换流器（LCC）HVDC特别适合于大容量电力传输，而电压源换流器（VSC）HVDC特别适合于将海上电力连接到具有低惯性和低短路水平的AC电网。基于VSC技术的多端高压直流输电网络和直流电网将在北海开发，以形成未来的超级电网，从而提高海上风电传输的灵活性、冗余性和经济可行性。传统的同步发电机将越来越多地被具有电力电子转换器和高压直流输电的可再生发电所取代。这导致系统惯性和短路水平的显著降低。特别是在英国，大规模海上风电和与其他欧洲国家电网的互联将导致高压直流丰富的交流电网。这将导致交流电网具有低故障电路和低惯性，这将对交流系统运行提出一系列挑战，例如对现有继电保护的潜在影响; LCC HVDC的频率不稳定和换相失败。本拟议项目将研究通过电力电子转换器提供的高压直流丰富的交流电网中的低惯性和低短路水平的行为。挑战将是HVDC链路提供系统支持的能力可能（同时）受到这些对电网的影响的不利影响。LCC HVDC可以提供人工惯性，但需要电网的高短路比才能正常工作。在交流故障和故障后恢复期间，LCC的惯性支持能力将在最需要的时候受到限制。VSC HVDC控制较少依赖于AC电网。然而，由于直流线路的电阻非常低，直流故障很容易在整个HVDC电网中传播，这反过来又会影响所有终端的交流侧。在直流故障期间，注入交流电网的真实的功率以及来自VSC HVDC电网的惯性支持将在非常需要维持系统频率的时刻丢失。与此同时，从VSC HVDC电网到AC电网的无功功率支持也将完全或部分地丧失，这取决于转换器拓扑。将对高压直流换流器的惯性支持、不同类型换流器减轻低惯性影响的能力及其通过交流侧的协调进行调查（对于点对点HVDC链路）或通过DC侧（用于同一直流电网内的换流器）。卡迪夫大学的硬件在环（HIL）平台由高压直流电网测试装置组成，一个真实的时间数字仿真器（RTDS）和一个功率放大器，将在高压直流输电丰富的电网和高压直流输电换流器控制的建模和测试中发挥关键作用，以减轻低惯性和低短路水平的影响。通过这个项目，将深入了解交流电网的运行特性，丰富的高压直流输电链路。提出了提高系统惯性和短路水平的解决方案。通过高压直流输电可以将更多的可再生能源并入交流电网，而不会恶化系统性能。该项目的研究成果将通过工业伙伴、国际学术协会、会议和期刊出版物传播。

项目成果

Coordination of Fast Frequency Support from Multi-Terminal HVDC Grids

多终端 HVDC 电网快速频率支持的协调

• 发表时间: 2018
• 作者: Jose K.F.

Inertial Contribution from Large Scale Variable-Speed Wind Turbines Connected to the GB Grid

连接到英国电网的大型变速风力发电机的惯性贡献

• DOI: 10.1049/cp.2017.0064
• 发表时间: 2017
• 作者: Jose K

Power Flow Management in MTdc Grids Using Series Current Flow Controllers

使用串联电流控制器的 MTdc 电网中的潮流管理

• DOI: 10.1109/tie.2018.2890495
• 发表时间: 2019
• 期刊: IEEE Transactions on Industrial Electronics
• 影响因子: 7.7
• 作者: Balasubramaniam S

Fast Frequency Response From Offshore Multiterminal VSC-HVDC Schemes

• DOI: 10.1109/tpwrd.2016.2632860
• 发表时间: 2017-12-01
• 期刊: IEEE TRANSACTIONS ON POWER DELIVERY
• 影响因子: 4.4
• 作者: Adeuyi, Oluwole Daniel;Cheah-Mane, Marc;Jenkins, Nick
• 通讯作者: Jenkins, Nick

Enhanced Fast Frequency Support Schemes

增强的快速频率支持方案

• DOI: 10.1109/pesgm41954.2020.9281764
• 发表时间: 2020
• 作者: Balasubramaniam S