Command governor–based adaptive control(CGAC)is a recent control strategy that has been explored as a possible candidate for the challenging task of precise maneuvering of unmanned underwater vehicles(UUVs)with param...Command governor–based adaptive control(CGAC)is a recent control strategy that has been explored as a possible candidate for the challenging task of precise maneuvering of unmanned underwater vehicles(UUVs)with parameter variations.CGAC is derived from standard model reference adaptive control(MRAC)by adding a command governor that guarantees acceptable transient performance without compromising stability and a command filter that improves the robustness against noise and time delay.Although simulation and experimental studies have shown substantial overall performance improvements of CGAC over MRAC for UUVs,it has also shown that the command filter leads to a marked reduction in initial tracking performance of CGAC.As a solution,this paper proposes the replacement of the command filter by a weight filter to improve the initial tracking performance without compromising robustness and the addition of a closed-loop state predictor to further improve the overall tracking performance.The new modified CGAC(M-CGAC)has been experimentally validated and the results indicate that it successfully mitigates the initial tracking performance reduction,significantly improves the overall tracking performance,uses less control force,and increases the robustness to noise and time delay.Thus,M-CGAC is a viable adaptive control algorithm for current and future UUV applications.展开更多
The control parameters of electronic governor that influence the transient characteristics of the engine are analyzed.An electric control unit was developed and the control parameters were calibrated on the test bench...The control parameters of electronic governor that influence the transient characteristics of the engine are analyzed.An electric control unit was developed and the control parameters were calibrated on the test bench.The initial value of integral term and the maximum output of rack position proportion,integration and derivation（PID）controller affect the step and triangle response drastically.Through correcting the proportional term and integral term of speed PID controller,the dynamic speed drop and speed overshoot are improved.A property control strategy for cold starting an engine is set,and the calibration process indicates that the fuel injected into the cylinder per cycle and the desired speed ascend rate drastically affect the start transient process.展开更多
Technical and economical impacts of distributed resources have encouraged big industry managers and distribution systems’ owners to utilize small type of electric generations. One important preventive issue to develo...Technical and economical impacts of distributed resources have encouraged big industry managers and distribution systems’ owners to utilize small type of electric generations. One important preventive issue to develop these units is islanding situation. Expert diagnosis system is needed to distinguish network cut off from normal occurrences. It should detect islanding in time to disconnect the unit and prevent any additional failures in equipment. An important part of synchronous generator is automatic load-frequency controller (ALFC). This controller is designed properly to respond to load variations and to fix frequency at constant value when working alone as an islanding system and to control output power when operating in parallel with the main. In this paper, a new approach based on monitoring ALFC re-sponse with regard to input signal to governor is introduced. Numbers of initial crossing value are introduced as an index for islanding detection. Simulation results show that input signal to governor has different characteristics in common disturbances.展开更多
The distributed generator over the last 30years has posed several challenges when they are connected to a distributed network.The most immediate problem is to change the voltage at the connection point depending on th...The distributed generator over the last 30years has posed several challenges when they are connected to a distributed network.The most immediate problem is to change the voltage at the connection point depending on the power supplied to the network and may cause it to exceed statutory limits.This paper describes a new control scheme for a distributed generator for supporting the voltage control in the network,thus ensuring the distributed generator to contribute to network voltage management.The scheme performance is demonstrated by a model for a distributed generator connected to a distribution network.The result shows that using the new control scheme,the distribution network voltage constraints are maintained while maximizing the active power delivered by distributed generators.展开更多
文摘Command governor–based adaptive control(CGAC)is a recent control strategy that has been explored as a possible candidate for the challenging task of precise maneuvering of unmanned underwater vehicles(UUVs)with parameter variations.CGAC is derived from standard model reference adaptive control(MRAC)by adding a command governor that guarantees acceptable transient performance without compromising stability and a command filter that improves the robustness against noise and time delay.Although simulation and experimental studies have shown substantial overall performance improvements of CGAC over MRAC for UUVs,it has also shown that the command filter leads to a marked reduction in initial tracking performance of CGAC.As a solution,this paper proposes the replacement of the command filter by a weight filter to improve the initial tracking performance without compromising robustness and the addition of a closed-loop state predictor to further improve the overall tracking performance.The new modified CGAC(M-CGAC)has been experimentally validated and the results indicate that it successfully mitigates the initial tracking performance reduction,significantly improves the overall tracking performance,uses less control force,and increases the robustness to noise and time delay.Thus,M-CGAC is a viable adaptive control algorithm for current and future UUV applications.
文摘The control parameters of electronic governor that influence the transient characteristics of the engine are analyzed.An electric control unit was developed and the control parameters were calibrated on the test bench.The initial value of integral term and the maximum output of rack position proportion,integration and derivation（PID）controller affect the step and triangle response drastically.Through correcting the proportional term and integral term of speed PID controller,the dynamic speed drop and speed overshoot are improved.A property control strategy for cold starting an engine is set,and the calibration process indicates that the fuel injected into the cylinder per cycle and the desired speed ascend rate drastically affect the start transient process.
文摘Technical and economical impacts of distributed resources have encouraged big industry managers and distribution systems’ owners to utilize small type of electric generations. One important preventive issue to develop these units is islanding situation. Expert diagnosis system is needed to distinguish network cut off from normal occurrences. It should detect islanding in time to disconnect the unit and prevent any additional failures in equipment. An important part of synchronous generator is automatic load-frequency controller (ALFC). This controller is designed properly to respond to load variations and to fix frequency at constant value when working alone as an islanding system and to control output power when operating in parallel with the main. In this paper, a new approach based on monitoring ALFC re-sponse with regard to input signal to governor is introduced. Numbers of initial crossing value are introduced as an index for islanding detection. Simulation results show that input signal to governor has different characteristics in common disturbances.
基金supported by EPSRC SUPERGEN 1 Renewal Core-FlexNet:Renewal of the Supergen Consortium on Future Network Technologies.EPSRC GRANT Reference EP/E4011X/1
文摘The distributed generator over the last 30years has posed several challenges when they are connected to a distributed network.The most immediate problem is to change the voltage at the connection point depending on the power supplied to the network and may cause it to exceed statutory limits.This paper describes a new control scheme for a distributed generator for supporting the voltage control in the network,thus ensuring the distributed generator to contribute to network voltage management.The scheme performance is demonstrated by a model for a distributed generator connected to a distribution network.The result shows that using the new control scheme,the distribution network voltage constraints are maintained while maximizing the active power delivered by distributed generators.
