As synchronous generators(SGs)are gradually displaced by renewable energy sources(RESs),the frequency stability of power systems deteriorates because RESs,represented by utility-scale solar and wind power sources,do n...As synchronous generators(SGs)are gradually displaced by renewable energy sources(RESs),the frequency stability of power systems deteriorates because RESs,represented by utility-scale solar and wind power sources,do not provide the inertial response,primary frequency response,secondary frequency response,and tertiary frequency regulation.As a result,the remaining SGs may not be sufficient to maintain the power balance and frequency stability.The concept and control strategies of virtual synchronous generators(VSGs)enable the inverter-based wind and solar power sources to emulate the outer characteristics of traditional SGs and participate in the active power and frequency control of power systems.This paper focuses on the automatic generation control(AGC)with virtual synchronous renewables(VSRs).First,the VSR strategy that enables the RESs to participate in AGC is introduced.Second,based on the interval representation of uncertainty,the output of RES is transformed into two portions,i.e.,the dispatchable portion and the stochastic portion.In the dispatchable portion,the RESs can participate in AGC jointly with SGs.Accordingly,a security-constrained economic dispatch(SCED)model is built considering the RESs operating in VSR mode.Third,the solution strategy that employs the slack variables to acquire deterministic constraints is introduced.Finally,the proposed SCED model is solved based on the 6-bus and 39-bus systems.The results show that,compared with the maximum power point tracking(MPPT)mode,VSRs can participate in the active power and frequency control jointly with SGs,increase the maximum penetration level of RESs,and decrease the operating cost.展开更多
Agile hardware design is gaining increasing momentum and bringing new chips in larger quantities to the market faster.However,it also takes new challenges for compiler developers to retarget existing compilers to thes...Agile hardware design is gaining increasing momentum and bringing new chips in larger quantities to the market faster.However,it also takes new challenges for compiler developers to retarget existing compilers to these new chips in shorter time than ever before.Currently,retargeting a compiler backend,e.g.,an LLVM backend to a new target,requires compiler developers to write manually a set of target description files(totalling 10300+lines of code(LOC)for RISC-V in LLVM),which is error-prone and time-consuming.In this paper,we introduce a new approach,Au-tomatic Target Description File Generation(ATG),which accelerates the generation of a compiler backend for a new tar-get by generating its target description files automatically.Given a new target,ATG proceeds in two stages.First,ATG synthesizes a small list of target-specific properties and a list of code-layout templates from the target description files of a set of existing targets with similar instruction set architectures(ISAs).Second,ATG requests compiler developers to fill in the information for each instruction in the new target in tabular form according to the list of target-specific properties syn-thesized and then generates its target description files automatically according to the list of code-layout templates synthe-sized.The first stage can often be reused by different new targets sharing similar ISAs.We evaluate ATG using nine RISC-V instruction sets drawn from a total of 1029 instructions in LLVM 12.0.ATG enables compiler developers to gen-erate compiler backends for these ISAs that emit the same assembly code as the existing compiler backends for RISC-V but with significantly less development effort(by specifying each instruction in terms of up to 61 target-specific properties only).展开更多
This paper investigates automatic generation control(AGC)of a realistic hybrid four-control area system with a dis-tinct arrangement of thermal units,gas units and additional power generation.A proportional-integral-d...This paper investigates automatic generation control(AGC)of a realistic hybrid four-control area system with a dis-tinct arrangement of thermal units,gas units and additional power generation.A proportional-integral-double deriva-tive cascaded with proportional-integral(PIDD-PI)controller is employed as secondary controller in each control area for robust restructured AGC considering bilateral transactions and contract violations.The Harris Hawks algorithm is used to determine the optimal controller gains and system parameters under several scenarios.Electric vehicle(EV)aggregators are employed in each area to participate fully along with thermal and gas units to compensate for the unscheduled system demand in the local area.A comparison of non-cascaded controllers such as PI-PD,PD-PID and the proposed PIDD-PI proves the superiority of the last.The effect of the decline in inertia is closely examined because of the sudden outage of a generating unit while at the same time considering the change in area frequency response characteristics and area control error.EV fleets make significant contributions to improving the system dynamics dur-ing system inertia loss.The use of EVs in the presence of a wind energy-supported grid can provide a stable efficacy to the power grid.Numerous simulations with higher load demands,stochastic communication delays in presence of the WTG plant,and violations in system loadings and changes in gas turbine time constants in the absence of WTG demonstrate the robustness of the proposed control approach.展开更多
基金supported by the Research and Application of Key Technologies of Flexible Power Supply System Under Various Emergency Scenarios(No.5442PD210001)。
文摘As synchronous generators(SGs)are gradually displaced by renewable energy sources(RESs),the frequency stability of power systems deteriorates because RESs,represented by utility-scale solar and wind power sources,do not provide the inertial response,primary frequency response,secondary frequency response,and tertiary frequency regulation.As a result,the remaining SGs may not be sufficient to maintain the power balance and frequency stability.The concept and control strategies of virtual synchronous generators(VSGs)enable the inverter-based wind and solar power sources to emulate the outer characteristics of traditional SGs and participate in the active power and frequency control of power systems.This paper focuses on the automatic generation control(AGC)with virtual synchronous renewables(VSRs).First,the VSR strategy that enables the RESs to participate in AGC is introduced.Second,based on the interval representation of uncertainty,the output of RES is transformed into two portions,i.e.,the dispatchable portion and the stochastic portion.In the dispatchable portion,the RESs can participate in AGC jointly with SGs.Accordingly,a security-constrained economic dispatch(SCED)model is built considering the RESs operating in VSR mode.Third,the solution strategy that employs the slack variables to acquire deterministic constraints is introduced.Finally,the proposed SCED model is solved based on the 6-bus and 39-bus systems.The results show that,compared with the maximum power point tracking(MPPT)mode,VSRs can participate in the active power and frequency control jointly with SGs,increase the maximum penetration level of RESs,and decrease the operating cost.
基金supported by the Strategic Pilot Science and Technology Project of Chinese Academy of Sciences(Category C)under Grant No.XDC05000000the Youth Program of National Natural Science Foundation of China under Grant No.61802368.
文摘Agile hardware design is gaining increasing momentum and bringing new chips in larger quantities to the market faster.However,it also takes new challenges for compiler developers to retarget existing compilers to these new chips in shorter time than ever before.Currently,retargeting a compiler backend,e.g.,an LLVM backend to a new target,requires compiler developers to write manually a set of target description files(totalling 10300+lines of code(LOC)for RISC-V in LLVM),which is error-prone and time-consuming.In this paper,we introduce a new approach,Au-tomatic Target Description File Generation(ATG),which accelerates the generation of a compiler backend for a new tar-get by generating its target description files automatically.Given a new target,ATG proceeds in two stages.First,ATG synthesizes a small list of target-specific properties and a list of code-layout templates from the target description files of a set of existing targets with similar instruction set architectures(ISAs).Second,ATG requests compiler developers to fill in the information for each instruction in the new target in tabular form according to the list of target-specific properties syn-thesized and then generates its target description files automatically according to the list of code-layout templates synthe-sized.The first stage can often be reused by different new targets sharing similar ISAs.We evaluate ATG using nine RISC-V instruction sets drawn from a total of 1029 instructions in LLVM 12.0.ATG enables compiler developers to gen-erate compiler backends for these ISAs that emit the same assembly code as the existing compiler backends for RISC-V but with significantly less development effort(by specifying each instruction in terms of up to 61 target-specific properties only).
文摘This paper investigates automatic generation control(AGC)of a realistic hybrid four-control area system with a dis-tinct arrangement of thermal units,gas units and additional power generation.A proportional-integral-double deriva-tive cascaded with proportional-integral(PIDD-PI)controller is employed as secondary controller in each control area for robust restructured AGC considering bilateral transactions and contract violations.The Harris Hawks algorithm is used to determine the optimal controller gains and system parameters under several scenarios.Electric vehicle(EV)aggregators are employed in each area to participate fully along with thermal and gas units to compensate for the unscheduled system demand in the local area.A comparison of non-cascaded controllers such as PI-PD,PD-PID and the proposed PIDD-PI proves the superiority of the last.The effect of the decline in inertia is closely examined because of the sudden outage of a generating unit while at the same time considering the change in area frequency response characteristics and area control error.EV fleets make significant contributions to improving the system dynamics dur-ing system inertia loss.The use of EVs in the presence of a wind energy-supported grid can provide a stable efficacy to the power grid.Numerous simulations with higher load demands,stochastic communication delays in presence of the WTG plant,and violations in system loadings and changes in gas turbine time constants in the absence of WTG demonstrate the robustness of the proposed control approach.
