Novel Sub-Synchronous Oscillation Early Warning System for the GB Grid
Renewable energy supply is rapidly increasing in the Great Britain (GB) power system,leading to greater power transfer from high wind resource areas in Scotland to the load centres in the south.To relieve constraints to this southwards flow,series compensation is being installed in the transmission path,and a subsea High Voltage Direct Current (HVDC) link is being installed.This increases the boundary capability substantially,but introduces the risk of sub-synchronous resonances of various forms that need to be managed.Series compensation introduces new natural frequencies of oscillation that can in certain circumstances interact with thermal generation, HVDC links and renewable generation. In addition, there is potential for interaction of HVDC link & wind farm converter control systems with thermal generation. While studies, planning and design, filters and protection systems reduce the risk of occurrence and damage from this resonance effect, monitoring will also form a key element in overall risk mitigation strategy. A novel monitoring approach is taken to improve understanding of interactions that do not immediately lead to protection action or large-scale disturbances, and that enables a new risk management approach.This paper describes a system commissioned in 2015, under a partnership led by Scottish Power 1, the transmission owner in Central and Southern Scotland, for the detection and monitoring of sub-synchronous oscillations. The system will provide early warning of oscillations in real-time operational timescales, and facilitate off-line analysis of system behaviour related to interaction between the series compensation, HVDC systems and nearby generation units. The commissioning of this system coincides with the installation of series compensation at six locations on the Scotland-England transmission boundary, as well as the new, parallel, Western HVDC link from Scotland to North Wales. The sub-synchronous oscillation detection system is composed of data acquisition devices at several locations, and a central server that receives, collates, stores and processes the measurement data in real-time. This central server performs the sub-synchronous oscillation analysis, detects abnormal behaviour such as raised amplitude or poor damping of an SSO mode at one or more monitored locations, and raises alarms to the Grid Control Room. Operational actions can then be taken, such as bypassing of the series capacitors. A challenge in this project was the need for a standard data acquisition approach, with sufficient bandwidth to capture oscillations of up to 46Hz. Existing wide-area monitoring systems using Phasor Measurement Units (PMUs) reporting via the IEEE C37.118 protocol at 50 or 60 samples/second do not achieve this bandwidth, and it is not possible to achieve fast enough response with synchrophasors without degrading the accuracy. The solution uses a traditional PMU hardware, adapted to transmit a supplementary data stream of direct voltage & current waveform samples at 200 fps via the IEEE C37.118 protocol. The device has been termed a Waveform Measurement Unit (WMU). In addition, the system has the capability to record rotor speed signals synchronously with waveform data, in order to observe torsional oscillations together with network oscillations. This solution, using a measurement rate of 4 samples per cycle, provides sufficient bandwidth to capture SSO phenomena, whilst using a standard and widely-adopted transmission protocol. The approach could also be upgraded to higher sampling rates if needed.
Sub-Synchronous Resonance Sub-Synchronous Oscillations Torsional Interaction Control Interaction Series Compensation HVDC Waveform Measurement Unit WMU Oscillation monitoring VISOR Project
S. L. Zimath D. Wilson M. Agostini R. Giovanini S. Clark
Alstom Brazil Alstom UK
国际会议
国际大电网会议组织保护与自动化专业委员会年度会议暨学术研讨会
南京
英文
1-6
2015-09-20（万方平台首次上网日期，不代表论文的发表时间）