The integration of large-scale new energy and high-capacity DC transmission leads to a reduction in system inertia.Grid-forming renewable energy sources(GF-RES)has a significant improvement effect on system inertia.Co...The integration of large-scale new energy and high-capacity DC transmission leads to a reduction in system inertia.Grid-forming renewable energy sources(GF-RES)has a significant improvement effect on system inertia.Commutation failure faults may cause a short-term reactive power surplus at the sending end and trigger transient overvoltage,threatening the safe and stable operation of the power grid.However,there is a lack of research on the calculation method of transient overvoltage caused by commutation failure in high-voltage DC transmission systems with grid-forming renewable energy sources integration.Based on the existing equivalent model of highvoltage DC transmission systems at the sending end,this paper proposes to construct a model of the high-voltage DC transmission system at the sending end with grid-forming renewable energy sources.The paper first clarifies the mechanism of overvoltage generation,then considers the reactive power droop control characteristics of GF-RES,and derives the transient voltage calculation model of theDC transmission system with GF-RES integration.It also proposes a calculation method for transient overvoltage at the sending-end converter bus with GF-RES integration.Based on the PSCAD/EMTDC simulation platform,this paper builds an experimental simulation model.By constructing three different experimental scenarios,the accuracy and effectiveness of the proposed transient overvoltage calculation method are verified,with a calculation error within 5%.At the same time,this paper quantitatively analyzes the impact of grid strength,new energy proportion,and rated transmission power on transient overvoltage from three different perspectives.展开更多
The bi-directional DC-DC converter(DDC)is commonly employed for a battery or supercapacitor(BA/SC)to accomplish power management flexibility.Current and voltage control for the DDC is crucial for power management.Focu...The bi-directional DC-DC converter(DDC)is commonly employed for a battery or supercapacitor(BA/SC)to accomplish power management flexibility.Current and voltage control for the DDC is crucial for power management.Focusing on control of the DDC,this paper first proposes a simple orderreduction control method for the first-order system,then applies the proposed control method to current and voltage control of the SC DDC.The effect of the inner current loop on the outer DC bus voltage loop is also analyzed.With the proposed simple order-reduction control method,the dynamic response of the SC DDC is obviously improved,and robustness to the SC voltage variation is achieved.The double-line-frequency ripple is also eliminated through the proposed simple and effective method.Finally,the effectiveness of the developed control algorithm is tested by the experiment.展开更多
As the penetration of renewable energy continues to increase,stochastic and intermittent generation resources gradually replace the conventional generators,bringing significant challenges in stabilizing power system f...As the penetration of renewable energy continues to increase,stochastic and intermittent generation resources gradually replace the conventional generators,bringing significant challenges in stabilizing power system frequency.Thus,aggregating demand-side resources for frequency regulation attracts attentions from both academia and industry.However,in practice,conventional aggregation approaches suffer from random and uncertain behaviors of the users such as opting out control signals.The risk-averse multi-armed bandit learning approach is adopted to learn the behaviors of the users and a novel aggregation strategy is developed for residential heating,ventilation,and air conditioning(HVAC)to provide reliable secondary frequency regulation.Compared with the conventional approach,the simulation results show that the risk-averse multiarmed bandit learning approach performs better in secondary frequency regulation with fewer users being selected and opting out of the control.Besides,the proposed approach is more robust to random and changing behaviors of the users.展开更多
This paper highlights the inefficiency of most dis-tributed controls in dealing with dynamic enhancement while coordinating distributed generators(DGs),leading to poor fre-quency dynamics.To address this concern,a two...This paper highlights the inefficiency of most dis-tributed controls in dealing with dynamic enhancement while coordinating distributed generators(DGs),leading to poor fre-quency dynamics.To address this concern,a two-level coupling-based frequency control strategy for microgrids is proposed in this paper.At the lower level,an adaptive dynamic compensa-tion algorithm is designed to tackle short-term and long-term frequency fluctuations caused by the uncertainties of renewable energy resources(RESs).At the upper level,an adaptive distrib-uted frequency consensus algorithm is developed to address fre-quency restoration and active power sharing.Furthermore,to account for the potential control interaction of the two designed levels,a nonlinear extended state observer(NESO)is intro-duced to couple their control dynamics.Simulation tests and hardware-in-the-loop(HIL)experiments confirm the improved frequencydynamics.展开更多
基金supported by Key Natural Science Research Projects of Colleges and Universities in Anhui Province(2022AH051831).
文摘The integration of large-scale new energy and high-capacity DC transmission leads to a reduction in system inertia.Grid-forming renewable energy sources(GF-RES)has a significant improvement effect on system inertia.Commutation failure faults may cause a short-term reactive power surplus at the sending end and trigger transient overvoltage,threatening the safe and stable operation of the power grid.However,there is a lack of research on the calculation method of transient overvoltage caused by commutation failure in high-voltage DC transmission systems with grid-forming renewable energy sources integration.Based on the existing equivalent model of highvoltage DC transmission systems at the sending end,this paper proposes to construct a model of the high-voltage DC transmission system at the sending end with grid-forming renewable energy sources.The paper first clarifies the mechanism of overvoltage generation,then considers the reactive power droop control characteristics of GF-RES,and derives the transient voltage calculation model of theDC transmission system with GF-RES integration.It also proposes a calculation method for transient overvoltage at the sending-end converter bus with GF-RES integration.Based on the PSCAD/EMTDC simulation platform,this paper builds an experimental simulation model.By constructing three different experimental scenarios,the accuracy and effectiveness of the proposed transient overvoltage calculation method are verified,with a calculation error within 5%.At the same time,this paper quantitatively analyzes the impact of grid strength,new energy proportion,and rated transmission power on transient overvoltage from three different perspectives.
基金supported in part by the National Natural Science Foundation of China under Grant 52007034.
文摘The bi-directional DC-DC converter(DDC)is commonly employed for a battery or supercapacitor(BA/SC)to accomplish power management flexibility.Current and voltage control for the DDC is crucial for power management.Focusing on control of the DDC,this paper first proposes a simple orderreduction control method for the first-order system,then applies the proposed control method to current and voltage control of the SC DDC.The effect of the inner current loop on the outer DC bus voltage loop is also analyzed.With the proposed simple order-reduction control method,the dynamic response of the SC DDC is obviously improved,and robustness to the SC voltage variation is achieved.The double-line-frequency ripple is also eliminated through the proposed simple and effective method.Finally,the effectiveness of the developed control algorithm is tested by the experiment.
基金supported by the National Natural Science Foundation of China(No.51907026)Natural Science Foundation of Jiangsu(No.BK20190361)+1 种基金Jiangsu Provincial Key Laboratory of Smart Grid Technology and EquipmentGlobal Energy Interconnection Research Institute(No.SGGR0000WLJS1900107)
文摘As the penetration of renewable energy continues to increase,stochastic and intermittent generation resources gradually replace the conventional generators,bringing significant challenges in stabilizing power system frequency.Thus,aggregating demand-side resources for frequency regulation attracts attentions from both academia and industry.However,in practice,conventional aggregation approaches suffer from random and uncertain behaviors of the users such as opting out control signals.The risk-averse multi-armed bandit learning approach is adopted to learn the behaviors of the users and a novel aggregation strategy is developed for residential heating,ventilation,and air conditioning(HVAC)to provide reliable secondary frequency regulation.Compared with the conventional approach,the simulation results show that the risk-averse multiarmed bandit learning approach performs better in secondary frequency regulation with fewer users being selected and opting out of the control.Besides,the proposed approach is more robust to random and changing behaviors of the users.
基金This work was supported in part by the Jiangsu Funding Program for Excellent Postdoctoral Talent(No.2023ZB391)in part by the China Postdoctoral Science Foundation(No.2023M740588)in part by the National Natural Science Foundation of China(No.52077036).
文摘This paper highlights the inefficiency of most dis-tributed controls in dealing with dynamic enhancement while coordinating distributed generators(DGs),leading to poor fre-quency dynamics.To address this concern,a two-level coupling-based frequency control strategy for microgrids is proposed in this paper.At the lower level,an adaptive dynamic compensa-tion algorithm is designed to tackle short-term and long-term frequency fluctuations caused by the uncertainties of renewable energy resources(RESs).At the upper level,an adaptive distrib-uted frequency consensus algorithm is developed to address fre-quency restoration and active power sharing.Furthermore,to account for the potential control interaction of the two designed levels,a nonlinear extended state observer(NESO)is intro-duced to couple their control dynamics.Simulation tests and hardware-in-the-loop(HIL)experiments confirm the improved frequencydynamics.
