In order to address the issues that the magnetic coupled resonant wireless power transfer (MCR-WPT) system is sensitive to the resonant frequency and that transmission power is difficult to control with the non-resi...In order to address the issues that the magnetic coupled resonant wireless power transfer (MCR-WPT) system is sensitive to the resonant frequency and that transmission power is difficult to control with the non-resistive load in the MCR-WPT, a single-side regulation scheme for frequency and transmission power online is proposed, which is based on the inherent constraint relationships the among system parameters in the primary side. Thus, the communication between the primary side and the secondary side is avoided. First, the transfer models of resistance-capacitance load and resistance- inductance load are established, respectively. Next, the relationship between the input voltage phasor and the input current phasor is used to recognize the load property and value. Then, the coaxial rotation of the stepper motor and the rotating vacuum variable capacitor is conducted to unify resonant frequency both in the primary side and the secondary side. Finally, the regulations of both frequency and amplitude of input voltage are made to guarantee transmission power under a new resonant frequency point the same as the one when the only pure resistance part of load is accessed under the former resonant frequency point. Both simulation and experimental results indicate that the proposed regulation scheme can track remnant frequency and maintain transmission power constant.展开更多
This paper develops a flexible power regulation and limitation strategy of voltage source inverters(VSIs)under unbalanced grid faults.When the classical power theory is used under unbalanced grid faults,the power osci...This paper develops a flexible power regulation and limitation strategy of voltage source inverters(VSIs)under unbalanced grid faults.When the classical power theory is used under unbalanced grid faults,the power oscillations and current distortions are inevitable.In the proposed strategy,the extended power theory is introduced to compute the power feedbacks together with the classical power theory.Based on the combination of the classical and extended power theory,the proposed strategy can achieve the sinusoidal current provision and the flexible regulation between three common targets,i.e.,constant active power,balanced current,and constant reactive power.Meanwhile,the proposed strategy is associated with a power limiter,which is capable to keep the currents under the pre-defined threshold and to compute the maximum apparent power for better utilization of the inverter capacity.With this power limiter,the rated inverter capacity is fully used for both the active and reactive power provisions under unbalanced grid faults.Using the proposed power regulation and limitation,the VSI can avoid overcurrent tripping and flexibly regulate its power under unbalanced grid faults.All the conclusions are verified by the real-time hardware-in-loop tests.展开更多
To advance the field of science and technology,we need to revitalize the development of science and technology through innovation.The development of science and technology has many beneficial implications on the revit...To advance the field of science and technology,we need to revitalize the development of science and technology through innovation.The development of science and technology has many beneficial implications on the revitalization of the country.For this reason,universities in China should give full attention to their role as the main propeller of science and technology.“Streamlining administration,delegating powers,improving regulation,and strengthening services”is a policy issued by the Chinese government for the management of science and technology funds in colleges and universities.Based on the policy of“streamlining administration,delegating powers,improving regulation,and strengthening services,”colleges and universities must optimize the management of science and technology funds for their efficient use.In this paper,we analyzed the importance of the policy and put forward an effective management strategy,aiming to improve the management of science and technology funds in colleges and universities.展开更多
In China, according to the relative up-to-date regulations and standards, the maincontrol measure for NOX emission of coal-fired power plants is, in principle, low NOXcombustion. However, in recent years, more and mor...In China, according to the relative up-to-date regulations and standards, the maincontrol measure for NOX emission of coal-fired power plants is, in principle, low NOXcombustion. However, in recent years, more and more newlyapproved coal-fired plantswere required to install flue gas denitrification equipment. This article expounds if fluegas denitrification is necessary from several aspects, including constitution of NOX, itsimpact to environment, operation ofdeNOXequipment in USA, as wellas the differencein ambient air quality standard between China and World Health Organization. It setsforth themes in urgent need of study and areas where deNOX equipment is necessaryfor new projects, besides a recommendation that the emission standards for thermalpowerplants should be revised as soon as possible in China.展开更多
The complexity and uncertainty in power systems cause great challenges to controlling power grids.As a popular data-driven technique,deep reinforcement learning(DRL)attracts attention in the control of power grids.How...The complexity and uncertainty in power systems cause great challenges to controlling power grids.As a popular data-driven technique,deep reinforcement learning(DRL)attracts attention in the control of power grids.However,DRL has some inherent drawbacks in terms of data efficiency and explainability.This paper presents a novel hierarchical task planning(HTP)approach,bridging planning and DRL,to the task of power line flow regulation.First,we introduce a threelevel task hierarchy to model the task and model the sequence of task units on each level as a task planning-Markov decision processes(TP-MDPs).Second,we model the task as a sequential decision-making problem and introduce a higher planner and a lower planner in HTP to handle different levels of task units.In addition,we introduce a two-layer knowledge graph that can update dynamically during the planning procedure to assist HTP.Experimental results conducted on the IEEE 118-bus and IEEE 300-bus systems demonstrate our HTP approach outperforms proximal policy optimization,a state-of-the-art deep reinforcement learning(DRL)approach,improving efficiency by 26.16%and 6.86%on both systems.展开更多
A DC regulated power supply with numerical control based on single chip microcomputer (SCM) is designed. SCM is the main controller and output voltage o{ DC power supply can be set by keyboard. The analog voltage ca...A DC regulated power supply with numerical control based on single chip microcomputer (SCM) is designed. SCM is the main controller and output voltage o{ DC power supply can be set by keyboard. The analog voltage can be obtained through D/A converter (DAC0832) so that different voltages can be provided by operational amplifier. The output voltage varies from 0 V to 12 V with the incremental value of 0. 1 V. The actual output voltage is shown in the nixietube. This DC regulated power supply is characterized by simple structure and easy operation.展开更多
Renewable energy sources(RESs)are rapidly devel-oping and their substitution for traditional power generation poses significant challenges to the frequency regulation in power systems.The load damping factor D charact...Renewable energy sources(RESs)are rapidly devel-oping and their substitution for traditional power generation poses significant challenges to the frequency regulation in power systems.The load damping factor D characterizes the active power of load that changes with power system frequency,which is an important factor influencing the frequency response.However,the value of D is small,resulting in the limitation in frequency regulation of the power system.This paper proposes a parallel-type load damping factor controller to enhance load damping factor by utilizing static var generators(SVGs)in substations.Additionally,it discusses the configuration method for the relevant parameters of the controller,evaluates its frequen-cy regulation capability,investigates the impact of large-scale application of the controller on static and dynamic loads,and conducts a comprehensive evaluation of the impact of the damping factor control process on the voltage stability of the main grid.The large-scale application of the proposed controller can significantly improve the frequency regulation capability,and almost have no influence on the working status of the load.It can also significantly improve the dynamic performance of system frequency.The proposed controller can provide technical support for the frequency regulation of new power systems with high proportion of RESs.展开更多
Half-wavelength transmission can transmit large-scale renewable energy over very long distances.This paper proposes an improved steady-state voltage-control method for half-wavelength transmission systems considering ...Half-wavelength transmission can transmit large-scale renewable energy over very long distances.This paper proposes an improved steady-state voltage-control method for half-wavelength transmission systems considering largescale wind-power transmission.First,the unique voltage characteristics of half-wavelength lines are deduced based on the distributed parameter model.In the secondary voltage-control level,reactive power-transmission limits of half-wavelength lines are introduced as another control objective except for tracing the pilot bus voltage reference.Considering the uncertainty and fluctuation of wind power,the overvoltage risk-assessment method of half-wavelength lines is presented to determine specific voltage-control strategies.Simulation results demonstrate that the proposed voltage-control method delivers superior tracking performance according to a voltage reference value and prevents the overvoltage risk of halfwavelength lines effectively in different wind-power penetrations.展开更多
Unpredictable power fluctuation and fault ridethrough capability attract increased attention as two uncertain major factors in doubly-fed induction generators(DFIGs)integrated DC power system.Present solutions usually...Unpredictable power fluctuation and fault ridethrough capability attract increased attention as two uncertain major factors in doubly-fed induction generators(DFIGs)integrated DC power system.Present solutions usually require complicated cooperation comprising multiple modules of energy storage,current control,and voltage stabilizer.To overcome the drawbacks of existing solutions,this paper proposes a superconducting magnetic energy storage(SMES)integrated currentsource DC/DC converter(CSDC).It is mainly composed of a current-source back-to-back converter,and the SMES is tactfully embedded in series with the intermediate DC link.The proposed SMES-CSDC is installed in front of the DC-DFIG to carry out its dual abilities of load voltage stabilization under multifarious transient disturbances and power regulation under wind speed variations.Compared with the existing DC protection devices,the SMES-CSDC is designed on the basis of unique current-type energy storage.It has the advantages of fast response,extensive compensation range,concise hardware structure,and straightforward control strategy.The feasibility of the SMESCSDC is implemented via a scaled-down experiment,and its effectiveness for DC-DFIG protection is verified by a large-scale DC power system simulation.展开更多
With the specific characteristics of low-carbon intensity and economy,wind power has been widely promoted around the world.Due to the variable and intermittent nature of wind power production,the system has to frequen...With the specific characteristics of low-carbon intensity and economy,wind power has been widely promoted around the world.Due to the variable and intermittent nature of wind power production,the system has to frequently redispatch generators in order to ensure the effective use of wind power whilst maintaining system security.In this way,traditional generation costs are increased and the social benefit of wind power decreases indirectly.In this paper,a new regulation strategy based on power flow tracing was proposed,taking advantage of a comfort-constrained demand response strategy to follow the fluctuations of wind farm output,with the remaining imbalance of active power compensated by traditional generators.Examples showed that compared with conventional regulation,demand response could reduce the gross operating costs of the system,and the rapid response could help maintaining system stability in case of contingency.The strategy in this paper also applies to other large-scale integration problems associated with renewable energy resources which display short-term production variability.展开更多
The penetration rate of distributed generation is gradually increasing in the distribution system concerned.This is creating new problems and challenges in the planning and operation of the system.The intermittency an...The penetration rate of distributed generation is gradually increasing in the distribution system concerned.This is creating new problems and challenges in the planning and operation of the system.The intermittency and variability of power outputs from numerous distributed renewable generators could significantly jeopardize the secure operation of the distribution system.Therefore,it is necessary to assess the hosting capability for intermittent distributed generation by a distribution system considering operational constraints.This is the subject of this study.An assessment model considering the uncertainty of generation outputs from distributed generators is presented for this purpose.It involves different types of regulation or control functions using on-load tap-changers(OLTCs),reactive power compensation devices,energy storage systems,and the reactive power support of the distributed generators employed.A robust optimization model is then attained It is solved by Bertsimas robust counterpart through GUROBI solver.Finally,the feasibility and efficiency of the proposed method are demonstrated by a modified IEEE 33-bus distribution system.In addition,the effects of the aforementioned regulation or control functions on the enhancement of the hosting capability for intermittent distributed generation are examined.展开更多
This study focuses on the design and development of a simplified active power regulation scheme for a two-stage single-phase grid-connected solar-PV(SPV)system with maximum power point(MPP)estimation.It aims to formul...This study focuses on the design and development of a simplified active power regulation scheme for a two-stage single-phase grid-connected solar-PV(SPV)system with maximum power point(MPP)estimation.It aims to formulate and test an improvised new control scheme to estimate the real-time MPP of the PV panel and operate only at either the MPP or on the right-hand side(RHS)of the PV characteristics of the panel.A simple active power regulatory control scheme was formulated to provide frequency control services to a single-phase grid without using an energy storage device.The plant operator provides the reserve fraction as the input for the active power regulation controller.At any time,the reserve fraction is used to determine the magnitude of the reference power to be extracted from the PV panel for injection into the grid.A simple PI controller was used to track the calculated reference power.The different modes of operation of the regulatory scheme are presented in detail.All the above control schemes are integrated and implemented through appropriate switching of the DC-DC converter alone.The DC-AC converter maintains the DC link voltage and unity power factor at the single-phase grid terminals.The proposed control schemes were tested on a 250 Wp solar panel feeding power to a 230 V,50 Hz single-phase grid through a two-stage converter.The entire scheme was modeled using the Matlab/Simulink platform,and the same was validated by hardware experimentation using Chroma Solar Simulator and NI myRIO controller under varied irradiation,temperature,and reserve fractions.The simulation and hardware results are compared and reported.展开更多
The large application of renewable energy generation(REG)has increased the risk of cascading failures in the power system.At the same time REG also provides the possibility of new approaches for the suppression of suc...The large application of renewable energy generation(REG)has increased the risk of cascading failures in the power system.At the same time REG also provides the possibility of new approaches for the suppression of such failures.However,the capacity and position of the synchronous generator(SG)involved in regulation limit the power regu-lation speed(PRS)of REG to the overload line which is the main cause of cascading failures,while the PRS of SG is related to the position and shedding power.REG and SGs have difficulty in achieving effective cooperation under constraints of system power balance.Particularly,the dynamic variation of line flow during power regulation causes new problems for the accurate evaluation of line thermal safety under overload.Therefore,a new strategy for quan-titatively coordinating shedding power and power regulation to block cascading failures in the dynamic security domain is proposed in this paper.The control capability and dynamic security domain of the overload line are mod-eled,and the coordination control method based on power regulation is then proposed to minimize shedding power.The algorithm for the optimal control scheme considers the constraints of load capacity,power source capacity and bus PRS.The correctness of the proposed method is verified using case studies.展开更多
DC regulated power has play a decisive role status in the modem enterprise production and family life. With the development of science and technology, all kinds of computer simulation technology is increasingly rising...DC regulated power has play a decisive role status in the modem enterprise production and family life. With the development of science and technology, all kinds of computer simulation technology is increasingly rising, the paper simulate and compare common DC regulated power with adjustable DC regulated power by Altium Designer software, intuitively demonstrates the stabilizing effect of the circuit, and introduces the characteristics of adjustable DC regulated power. Using AD13 software simulate and design DC stabilized power supply circuit, calculated the main parameters of the circuit, simulated and analyzed the circuit working simulation process and the working state of the circuit, it can visually verify the results of the theoretical analysis, and get relevant conclusions.展开更多
The electro-hydrostatic actuator (EHA) is a kind of power-by-wire (PBW) actuator that converts the electrical power into localized hydraulic power for flight control. By removing the central hydraulic power supply...The electro-hydrostatic actuator (EHA) is a kind of power-by-wire (PBW) actuator that converts the electrical power into localized hydraulic power for flight control. By removing the central hydraulic power supply together with hydraulic pipes, an EHA's reliability and efficiency are greatly improved but its frequency width and stiffness decreased. To overcome the drawback, this article proposes a novel structure of EHA associated with a power regulator. Composed of a high-pressure accumulator and a proportional valve, it can store and harness the hydraulic power flexibly according to the changing control requirements. The concept of transferred volume is put forward to estimate the capability of the power regulator. The actuator output position can be kept fixed with a hydraulic lock. The compounded control is specially developed to ensure the actuator system to operate in a correct manner. The simulation results indicate that the new-brand actuator results in efficient expanding of the system frequency width with an optimal power supply.展开更多
This paper proposes H∞controller design for platform position transfer and regulation of floating offshore wind turbines.The platform movability of floating wind turbines can be utilized in mitigating the wake effect...This paper proposes H∞controller design for platform position transfer and regulation of floating offshore wind turbines.The platform movability of floating wind turbines can be utilized in mitigating the wake effect in the wind farm,thereby maximizing the wind farm's total power capture and efficiency.The controller is designed so that aerodynamic force is adjusted to meet the three objectives simultaneously,that is,1)to generate the desired electrical power level,2)to achieve the desired platform position,and 3)to suppress the platform oscillation.To acquire sufficient aerodynamic force to move the heavy platform,the pitch-to-stall blade pitching strategy is taken instead of the commonly-used pitch-to-feather strategy.The desired power level is attained by the standard constant-power strategy for the generator torque,while Hstate-feedback control of blade pitch and nacelle yaw angles is adopted for the position regulation and platform oscillation suppression.Weighting constants for the H∞controller design are adjusted to take the trade-off between the position regulation accuracy and the platform motion reduction.To demonstrate the efficiency of the proposed controler,a virtual 5-MW semi-submersible wind turbine is considered.Simulation results show that the designed H∞controller successfully accomplishes the platform position transfer and regulation as well as the platform oscillation reduction against wind and wave disturbances,and that it outperforms a previously-proposed linear quadratic controller with an integrator.展开更多
Conventional control systems used for regulated power supplies,including the proportional integral and derivation(PID)controller,have some serious disadvantages.The PID controller has a delayed feedback associated wit...Conventional control systems used for regulated power supplies,including the proportional integral and derivation(PID)controller,have some serious disadvantages.The PID controller has a delayed feedback associated with the control action and requires a lot of mathematical derivations.This paper presents a novel controlling system based on the artificial neural network(ANN),which can be used to regulate the output voltage of the DC power supply.Using MATLABTM,the designed control system was tested and analyzed with two types of back-propagation algorithms.This paper presents the results of the simulation that includes sum-squared error(SSE)and mean-squared error(MSE),and gives a detailed comparison of these values for the two algorithms.Hardware verification of the new system,using RS232 interface and Microsoft Visual Basic 6.0,was implemented,showing very good consistency with the simulation results.The proposed control system,compared to PID and other conventional controllers,requires less mathematical derivation in design and it is easier to implement.展开更多
基金The National Natural Science Youth Foundation of China(No.51507032)the Natural Science Foundation of Jiangsu Province(No.BK20150617)the Fundamental Research Funds for the Central Universities
文摘In order to address the issues that the magnetic coupled resonant wireless power transfer (MCR-WPT) system is sensitive to the resonant frequency and that transmission power is difficult to control with the non-resistive load in the MCR-WPT, a single-side regulation scheme for frequency and transmission power online is proposed, which is based on the inherent constraint relationships the among system parameters in the primary side. Thus, the communication between the primary side and the secondary side is avoided. First, the transfer models of resistance-capacitance load and resistance- inductance load are established, respectively. Next, the relationship between the input voltage phasor and the input current phasor is used to recognize the load property and value. Then, the coaxial rotation of the stepper motor and the rotating vacuum variable capacitor is conducted to unify resonant frequency both in the primary side and the secondary side. Finally, the regulations of both frequency and amplitude of input voltage are made to guarantee transmission power under a new resonant frequency point the same as the one when the only pure resistance part of load is accessed under the former resonant frequency point. Both simulation and experimental results indicate that the proposed regulation scheme can track remnant frequency and maintain transmission power constant.
基金This work is supported by the National Key Research and Development Program of China under Project 2021YFB2601600。
文摘This paper develops a flexible power regulation and limitation strategy of voltage source inverters(VSIs)under unbalanced grid faults.When the classical power theory is used under unbalanced grid faults,the power oscillations and current distortions are inevitable.In the proposed strategy,the extended power theory is introduced to compute the power feedbacks together with the classical power theory.Based on the combination of the classical and extended power theory,the proposed strategy can achieve the sinusoidal current provision and the flexible regulation between three common targets,i.e.,constant active power,balanced current,and constant reactive power.Meanwhile,the proposed strategy is associated with a power limiter,which is capable to keep the currents under the pre-defined threshold and to compute the maximum apparent power for better utilization of the inverter capacity.With this power limiter,the rated inverter capacity is fully used for both the active and reactive power provisions under unbalanced grid faults.Using the proposed power regulation and limitation,the VSI can avoid overcurrent tripping and flexibly regulate its power under unbalanced grid faults.All the conclusions are verified by the real-time hardware-in-loop tests.
文摘To advance the field of science and technology,we need to revitalize the development of science and technology through innovation.The development of science and technology has many beneficial implications on the revitalization of the country.For this reason,universities in China should give full attention to their role as the main propeller of science and technology.“Streamlining administration,delegating powers,improving regulation,and strengthening services”is a policy issued by the Chinese government for the management of science and technology funds in colleges and universities.Based on the policy of“streamlining administration,delegating powers,improving regulation,and strengthening services,”colleges and universities must optimize the management of science and technology funds for their efficient use.In this paper,we analyzed the importance of the policy and put forward an effective management strategy,aiming to improve the management of science and technology funds in colleges and universities.
文摘In China, according to the relative up-to-date regulations and standards, the maincontrol measure for NOX emission of coal-fired power plants is, in principle, low NOXcombustion. However, in recent years, more and more newlyapproved coal-fired plantswere required to install flue gas denitrification equipment. This article expounds if fluegas denitrification is necessary from several aspects, including constitution of NOX, itsimpact to environment, operation ofdeNOXequipment in USA, as wellas the differencein ambient air quality standard between China and World Health Organization. It setsforth themes in urgent need of study and areas where deNOX equipment is necessaryfor new projects, besides a recommendation that the emission standards for thermalpowerplants should be revised as soon as possible in China.
基金supported in part by the National Key R&D Program(2018AAA0101501)of Chinathe science and technology project of SGCC(State Grid Corporation of China).
文摘The complexity and uncertainty in power systems cause great challenges to controlling power grids.As a popular data-driven technique,deep reinforcement learning(DRL)attracts attention in the control of power grids.However,DRL has some inherent drawbacks in terms of data efficiency and explainability.This paper presents a novel hierarchical task planning(HTP)approach,bridging planning and DRL,to the task of power line flow regulation.First,we introduce a threelevel task hierarchy to model the task and model the sequence of task units on each level as a task planning-Markov decision processes(TP-MDPs).Second,we model the task as a sequential decision-making problem and introduce a higher planner and a lower planner in HTP to handle different levels of task units.In addition,we introduce a two-layer knowledge graph that can update dynamically during the planning procedure to assist HTP.Experimental results conducted on the IEEE 118-bus and IEEE 300-bus systems demonstrate our HTP approach outperforms proximal policy optimization,a state-of-the-art deep reinforcement learning(DRL)approach,improving efficiency by 26.16%and 6.86%on both systems.
文摘A DC regulated power supply with numerical control based on single chip microcomputer (SCM) is designed. SCM is the main controller and output voltage o{ DC power supply can be set by keyboard. The analog voltage can be obtained through D/A converter (DAC0832) so that different voltages can be provided by operational amplifier. The output voltage varies from 0 V to 12 V with the incremental value of 0. 1 V. The actual output voltage is shown in the nixietube. This DC regulated power supply is characterized by simple structure and easy operation.
基金funded by the State Grid Corporation of China(No.SGJSSZ00KJS2310831)"Research and application of key technologies for load flexibility resource mining and power grid regulation driven by industrial Internet".
文摘Renewable energy sources(RESs)are rapidly devel-oping and their substitution for traditional power generation poses significant challenges to the frequency regulation in power systems.The load damping factor D characterizes the active power of load that changes with power system frequency,which is an important factor influencing the frequency response.However,the value of D is small,resulting in the limitation in frequency regulation of the power system.This paper proposes a parallel-type load damping factor controller to enhance load damping factor by utilizing static var generators(SVGs)in substations.Additionally,it discusses the configuration method for the relevant parameters of the controller,evaluates its frequen-cy regulation capability,investigates the impact of large-scale application of the controller on static and dynamic loads,and conducts a comprehensive evaluation of the impact of the damping factor control process on the voltage stability of the main grid.The large-scale application of the proposed controller can significantly improve the frequency regulation capability,and almost have no influence on the working status of the load.It can also significantly improve the dynamic performance of system frequency.The proposed controller can provide technical support for the frequency regulation of new power systems with high proportion of RESs.
基金supported by State Grid Corporation of China,Projects under Grant 520626200031National Natural Science Foundation of China,No.51877200。
文摘Half-wavelength transmission can transmit large-scale renewable energy over very long distances.This paper proposes an improved steady-state voltage-control method for half-wavelength transmission systems considering largescale wind-power transmission.First,the unique voltage characteristics of half-wavelength lines are deduced based on the distributed parameter model.In the secondary voltage-control level,reactive power-transmission limits of half-wavelength lines are introduced as another control objective except for tracing the pilot bus voltage reference.Considering the uncertainty and fluctuation of wind power,the overvoltage risk-assessment method of half-wavelength lines is presented to determine specific voltage-control strategies.Simulation results demonstrate that the proposed voltage-control method delivers superior tracking performance according to a voltage reference value and prevents the overvoltage risk of halfwavelength lines effectively in different wind-power penetrations.
基金supported by the National Natural Science Foundation of China(No.51807128)。
文摘Unpredictable power fluctuation and fault ridethrough capability attract increased attention as two uncertain major factors in doubly-fed induction generators(DFIGs)integrated DC power system.Present solutions usually require complicated cooperation comprising multiple modules of energy storage,current control,and voltage stabilizer.To overcome the drawbacks of existing solutions,this paper proposes a superconducting magnetic energy storage(SMES)integrated currentsource DC/DC converter(CSDC).It is mainly composed of a current-source back-to-back converter,and the SMES is tactfully embedded in series with the intermediate DC link.The proposed SMES-CSDC is installed in front of the DC-DFIG to carry out its dual abilities of load voltage stabilization under multifarious transient disturbances and power regulation under wind speed variations.Compared with the existing DC protection devices,the SMES-CSDC is designed on the basis of unique current-type energy storage.It has the advantages of fast response,extensive compensation range,concise hardware structure,and straightforward control strategy.The feasibility of the SMESCSDC is implemented via a scaled-down experiment,and its effectiveness for DC-DFIG protection is verified by a large-scale DC power system simulation.
基金supported by Special Fund of the National Basic Research Program of China ("973" Program),Grant Nos. 2009CB219701,2010CB234608)Tianjin Municipal Science and Technology Development Program of China (Grant No. 09JCZDJC25000)+1 种基金Research Fund for the Doctoral Program of Higher Education of China (Grant No.20090032110064)Pacific Institute for Climate Solutions (PICS)
文摘With the specific characteristics of low-carbon intensity and economy,wind power has been widely promoted around the world.Due to the variable and intermittent nature of wind power production,the system has to frequently redispatch generators in order to ensure the effective use of wind power whilst maintaining system security.In this way,traditional generation costs are increased and the social benefit of wind power decreases indirectly.In this paper,a new regulation strategy based on power flow tracing was proposed,taking advantage of a comfort-constrained demand response strategy to follow the fluctuations of wind farm output,with the remaining imbalance of active power compensated by traditional generators.Examples showed that compared with conventional regulation,demand response could reduce the gross operating costs of the system,and the rapid response could help maintaining system stability in case of contingency.The strategy in this paper also applies to other large-scale integration problems associated with renewable energy resources which display short-term production variability.
基金the Scientific and Technological Project of SGCC Headquarters entitled“Smart Distribution Network and Ubiquitous Power Internet of Things Integrated Development Collaborative Planning Technology Research”(5400-201956447A-0-0-00).
文摘The penetration rate of distributed generation is gradually increasing in the distribution system concerned.This is creating new problems and challenges in the planning and operation of the system.The intermittency and variability of power outputs from numerous distributed renewable generators could significantly jeopardize the secure operation of the distribution system.Therefore,it is necessary to assess the hosting capability for intermittent distributed generation by a distribution system considering operational constraints.This is the subject of this study.An assessment model considering the uncertainty of generation outputs from distributed generators is presented for this purpose.It involves different types of regulation or control functions using on-load tap-changers(OLTCs),reactive power compensation devices,energy storage systems,and the reactive power support of the distributed generators employed.A robust optimization model is then attained It is solved by Bertsimas robust counterpart through GUROBI solver.Finally,the feasibility and efficiency of the proposed method are demonstrated by a modified IEEE 33-bus distribution system.In addition,the effects of the aforementioned regulation or control functions on the enhancement of the hosting capability for intermittent distributed generation are examined.
文摘This study focuses on the design and development of a simplified active power regulation scheme for a two-stage single-phase grid-connected solar-PV(SPV)system with maximum power point(MPP)estimation.It aims to formulate and test an improvised new control scheme to estimate the real-time MPP of the PV panel and operate only at either the MPP or on the right-hand side(RHS)of the PV characteristics of the panel.A simple active power regulatory control scheme was formulated to provide frequency control services to a single-phase grid without using an energy storage device.The plant operator provides the reserve fraction as the input for the active power regulation controller.At any time,the reserve fraction is used to determine the magnitude of the reference power to be extracted from the PV panel for injection into the grid.A simple PI controller was used to track the calculated reference power.The different modes of operation of the regulatory scheme are presented in detail.All the above control schemes are integrated and implemented through appropriate switching of the DC-DC converter alone.The DC-AC converter maintains the DC link voltage and unity power factor at the single-phase grid terminals.The proposed control schemes were tested on a 250 Wp solar panel feeding power to a 230 V,50 Hz single-phase grid through a two-stage converter.The entire scheme was modeled using the Matlab/Simulink platform,and the same was validated by hardware experimentation using Chroma Solar Simulator and NI myRIO controller under varied irradiation,temperature,and reserve fractions.The simulation and hardware results are compared and reported.
基金supported in part by the National Natural Science Foundation of China under Grant 51877018in part by the Natural Science Foundation of Chongqing under Grant cstc2019jcyj-msxmX0321in part by the Graduate Research and Innovation Foundation of Chongqing,China under Grant CYB22019.
文摘The large application of renewable energy generation(REG)has increased the risk of cascading failures in the power system.At the same time REG also provides the possibility of new approaches for the suppression of such failures.However,the capacity and position of the synchronous generator(SG)involved in regulation limit the power regu-lation speed(PRS)of REG to the overload line which is the main cause of cascading failures,while the PRS of SG is related to the position and shedding power.REG and SGs have difficulty in achieving effective cooperation under constraints of system power balance.Particularly,the dynamic variation of line flow during power regulation causes new problems for the accurate evaluation of line thermal safety under overload.Therefore,a new strategy for quan-titatively coordinating shedding power and power regulation to block cascading failures in the dynamic security domain is proposed in this paper.The control capability and dynamic security domain of the overload line are mod-eled,and the coordination control method based on power regulation is then proposed to minimize shedding power.The algorithm for the optimal control scheme considers the constraints of load capacity,power source capacity and bus PRS.The correctness of the proposed method is verified using case studies.
文摘DC regulated power has play a decisive role status in the modem enterprise production and family life. With the development of science and technology, all kinds of computer simulation technology is increasingly rising, the paper simulate and compare common DC regulated power with adjustable DC regulated power by Altium Designer software, intuitively demonstrates the stabilizing effect of the circuit, and introduces the characteristics of adjustable DC regulated power. Using AD13 software simulate and design DC stabilized power supply circuit, calculated the main parameters of the circuit, simulated and analyzed the circuit working simulation process and the working state of the circuit, it can visually verify the results of the theoretical analysis, and get relevant conclusions.
基金National Natural Science Foundation for Distinguished Young Scholars of China (50825502)
文摘The electro-hydrostatic actuator (EHA) is a kind of power-by-wire (PBW) actuator that converts the electrical power into localized hydraulic power for flight control. By removing the central hydraulic power supply together with hydraulic pipes, an EHA's reliability and efficiency are greatly improved but its frequency width and stiffness decreased. To overcome the drawback, this article proposes a novel structure of EHA associated with a power regulator. Composed of a high-pressure accumulator and a proportional valve, it can store and harness the hydraulic power flexibly according to the changing control requirements. The concept of transferred volume is put forward to estimate the capability of the power regulator. The actuator output position can be kept fixed with a hydraulic lock. The compounded control is specially developed to ensure the actuator system to operate in a correct manner. The simulation results indicate that the new-brand actuator results in efficient expanding of the system frequency width with an optimal power supply.
基金This work was supported by the Natural Sciences and Engineering Research of Council of Canada(NSERC)(No.11R82911)the National Council of Science and Technology of Mexico(CONACYT).
文摘This paper proposes H∞controller design for platform position transfer and regulation of floating offshore wind turbines.The platform movability of floating wind turbines can be utilized in mitigating the wake effect in the wind farm,thereby maximizing the wind farm's total power capture and efficiency.The controller is designed so that aerodynamic force is adjusted to meet the three objectives simultaneously,that is,1)to generate the desired electrical power level,2)to achieve the desired platform position,and 3)to suppress the platform oscillation.To acquire sufficient aerodynamic force to move the heavy platform,the pitch-to-stall blade pitching strategy is taken instead of the commonly-used pitch-to-feather strategy.The desired power level is attained by the standard constant-power strategy for the generator torque,while Hstate-feedback control of blade pitch and nacelle yaw angles is adopted for the position regulation and platform oscillation suppression.Weighting constants for the H∞controller design are adjusted to take the trade-off between the position regulation accuracy and the platform motion reduction.To demonstrate the efficiency of the proposed controler,a virtual 5-MW semi-submersible wind turbine is considered.Simulation results show that the designed H∞controller successfully accomplishes the platform position transfer and regulation as well as the platform oscillation reduction against wind and wave disturbances,and that it outperforms a previously-proposed linear quadratic controller with an integrator.
文摘Conventional control systems used for regulated power supplies,including the proportional integral and derivation(PID)controller,have some serious disadvantages.The PID controller has a delayed feedback associated with the control action and requires a lot of mathematical derivations.This paper presents a novel controlling system based on the artificial neural network(ANN),which can be used to regulate the output voltage of the DC power supply.Using MATLABTM,the designed control system was tested and analyzed with two types of back-propagation algorithms.This paper presents the results of the simulation that includes sum-squared error(SSE)and mean-squared error(MSE),and gives a detailed comparison of these values for the two algorithms.Hardware verification of the new system,using RS232 interface and Microsoft Visual Basic 6.0,was implemented,showing very good consistency with the simulation results.The proposed control system,compared to PID and other conventional controllers,requires less mathematical derivation in design and it is easier to implement.