Xiao-Ping Zhang

Presentations: 

Unlocking the Renewable Energy Integration by Flexible LCC HVDC

With the massive penetration of renewable energy into power systems, variations including fluctuations and intermittences of output powers of these renewable sources are of great concerns, which is considered to a grand challenge to renewable energy integration. It is evidenced that with the high penetration of renewable energy, variations of renewable energy have increased the costs of UK’s balancing markets very significantly. Therefore, there are needs to introduce new technical solutions to deal with the challenge. It has been recognised that wide area system integration becomes one of the attractive solutions.

For wide area system interconnection, traditional LCC (Line Commutated Converter) HVDC system is the key technology for long distance bulk power transmission. However, the LCC HVDC has two serious shortcomings (a) not being able to control its reactive power and terminal AC voltages; and (b) vulnerable to commutation failures.

This presentation will discuss the recent developments in LCC HVDC, which for the first time provides a new solution with a novel topology for Line-Commutated-Converter (LCC) HVDC, referred to as Flexible LCC HVDC, which can eliminate a very fundamental reliability problem, i.e. commutation failures of LCC HVDC, leading to blackouts, since its creation in 1950s.

We will show how in the next generation LCC HVDC – Flexible LCC HVDC, which has the ability to provide fast dynamic reactive power support for the AC systems and eliminate completely the commutation failures, will be able to support the wide area renewable energy integration and hence support energy transition towards net-zero.
Finally we will show the cost reduction of Flexible LCC HVDC in comparison to the traditional LCC HVDC by nearly 20%.

Future Energy Internet: Challenges and Solutions

With the massive penetration of renewable energy into power systems, variations including fluctuations and intermittences of output powers of these renewable sources are of great concerns, which is considered to a grand challenge to renewable energy integration. It is evidenced that with the high penetration of renewable energy, variations of renewable energy have increased the costs of UK’s balancing markets very significantly. Therefore, there are needs to introduce new technical solutions to deal with the challenge.

This presentation will review the technical challenges of future energy internet and then discuss the two possible solutions. One is about how to deal with the fluctuations and intermittences of output powers of these renewable sources where a new techno-economic framework in terms of energy quality will be introduced. Another one is about how to interconnect renewable energy sources using HVDC technologies in most efficient manner.

The Fundamental Challenge of of Renewable Energy Integration: Energy Quality

Variations and distortions, and interruptions of voltages (or voltage waveforms) and currents (or current waveforms) have been considered in the framework of power quality (or voltage quality). With the massive penetration of renewable energy into power systems, variations including fluctuations and intermittences of output powers of these renewable sources are of great concerns. It is evidenced that with the high penetration of renewable energy, variations of renewable energy have increased the costs of UK’s balancing markets very significantly. Therefore, there are needs to introduce a technical framework, namely, ‘energy quality’ to (a) define the quality of power waveforms; (b) propose measures/indices to characterize the variations (fluctuations and intermittences) of powers and power flows; (c) present methods to improve energy quality. Finally, examples will be given to show how the renewable energy variations can be mitigated via effective power aggregation/system interconnections.