ABSTRACT This paper presents a novel control scheme of neutral point clamped (NPC) voltage source... more ABSTRACT This paper presents a novel control scheme of neutral point clamped (NPC) voltage source converter (VSC) based static synchronous compensator (STATCOM) to enhance the performance of wind farms. A novel control strategy for the STATCOM is presented by introducing a voltage equalizer for dc link capacitor voltages and decoupled current controllers to produce appropriate d-q currents. The controllers for the wind energy conversion system and STATCOM are implemented in Matlab/SimPower. The performance of the proposed control scheme is compared with the traditional vector control scheme and results show that the proposed scheme for the STATCOM shows better performance. The STATCOM is also used to enhance the system performance during loss of generation, load change, three phase fault, voltage sag and swell. The simulation results show that the STATCOM with the proposed controller can improve the steady state and dynamic responses, and enhance the system performance during various disturbances.
ABSTRACT In the proposed method, each loop in a network is represented as a circle, which is deri... more ABSTRACT In the proposed method, each loop in a network is represented as a circle, which is derived from the relationship between the change of load balancing due to the branch-exchange and the power-flows in the branches. If there is no change of load balancing in the system, then all the circles touch each other at the (0,0) coordinate. The circles with no load balancing are called zero load balancing change circles. The maximum load balancing loop in the network is identified by comparing the radii of all the modified zero load balancing change circles. The corresponding loop of the largest one gives the maximum improvement of load balancing in the network. Then the possible branch exchanges in the maximum load balancing loop are investigated by comparing the size of the circle for every branch-exchange. If the loads are balanced due to a branch exchange, the size of the circle diminishes and hence the smallest circle gives the maximum improvement in load balancing and the corresponding branch-exchange is considered to be the best candidate for maximum improvement in load balancing. To show the efficiency and performance of the proposed method for the solution of computationally complex and large dimensionality problems, a system with 69-bus and 7 laterals has been considered as the test system. Test results have shown that the proposed method can identify the most effective branch-exchange operations for load balancing with less computational effort and time. The number of load flow solutions has been reduced to a greater extent in the proposed method
ABSTRACT Network reconfiguration for maximizing voltage stability is the determination of switchi... more ABSTRACT Network reconfiguration for maximizing voltage stability is the determination of switching-options that maximize voltage stability the most for a particular set of loads on the distribution systems, and is performed by altering the topological structure of distribution feeders. Network reconfiguration for time-varying loads is a complex and extremely nonlinear optimization problem which can be effectively solved by Artificial Neural Networks (ANNs), as ANNs are capable of learning a tremendous variety of pattern mapping relationships without having a priori knowledge of a mathematical function. In this paper a generalized ANN model is proposed for on-line enhancement of voltage stability under varying load conditions. The training sets for the ANN are carefully selected to cover the entire range of input space. For the ANN model, the training data are generated from the Daily Load Curves (DLCs). A 16-bus test system is considered to demonstrate the performance of the developed ANN model. The proposed ANN is trained using Conjugate Gradient Descent Back-propagation Algorithm and tested by applying arbitrary input data generated from DLCs. The test results of the ANN model are found to be the same as that obtained by off-line simulation. The enhancement of voltage stability can be achieved by the proposed method without any additional cost involved for installation of capacitors, tap-changing transformers, and the related switching equipment in the distribution systems. The developed ANN model can be implemented in hardware using the neural chips currently available.
Network reconfiguration in distribution system is realized by changing the status of sectionalizi... more Network reconfiguration in distribution system is realized by changing the status of sectionalizing switches, and is usually done for the purpose of loss reduction. Loss reduction can result in substantial benefits for a utility. Other benefits from loss reduction include increased system capacity, and possible deferment or elimination of capital expenditures for system improvements and expansion. There is also improved
Network reconfiguration is an operation task, and consists in the determination of the switching ... more Network reconfiguration is an operation task, and consists in the determination of the switching operations such to reach the minimum loss conditions of the distribution networks. In this paper, a general formulation of the network reconfiguration for loss minimization is given for the optimization of distribution loss reduction and a solution approach is presented. The solution employs a search over
Distributed generation (DG) inclusion within the grid system potentially introduces problems rela... more Distributed generation (DG) inclusion within the grid system potentially introduces problems related to control, protection, harmonics, and network transients. This paper analyses one of the key issues: protection of the network, by ascertaining the impact of rotary DG inclusion on existing protection system of SWER (single wire earth return) lines and the DG sensitivity during faults. The analysis is carried out by estimating fault-sensitivity for the worst-case situation, determining the DG impact on the existing protection scheme, and comparing the network situation with and without DG during the fault. A model of arc voltage is used to represent a fault on a SWER scheme. The size of DG is selected based on the SWER capacity and SWER load. The study is conducted on an example SWER system by considering the SWER lines with and without DG and faults on the SWER backbone and laterals, and simulation results are reported. In every case studied, the fault current from the DG significantly exceeded the DG rating and the DG would have tripped. Thus the system reverts to the case with no DG. Even if DG did not trip, the fault current from the source would be largely independent of the DG, and thus the original feeder protection would continue to provide the same quality of performance. Hence, net sensitivity and existing protection system will not be adversely affected by DG inclusion in SWER lines. #
Inclusion of voltage support distributed generation (VSDG) can reinforce the feeder voltage of di... more Inclusion of voltage support distributed generation (VSDG) can reinforce the feeder voltage of distribution networks, especially in rural/remote areas where voltage dip and frequent blackouts are significant concerns for power utilities. However, installation of multiple distributed generators within a distribution grid system may introduce technical problems in network operation and control, including control interaction and/or voltage instability. This paper addresses the network issues that may occur during multiple VSDG inclusion in the network and presents analytical models and solutions to develop design criteria of VSDG installation in the networks. Voltage sensitivity of lines is investigated and the effect of DG real (P) and reactive (Q) power injections with Q priority is developed for optimal use of VSDG in correcting the network voltage. Interaction among VSDG controllers has been explored and a generalized model is presented to analyze this interaction between any number of VSDGs in the network. The model is tested on a sample VSDG system and test results are presented. The issue of which VSDG must be started recognizing the costs of starting is addressed using an inverse definite minimum time (IDMT) model. A prioritization and coordination scheme for start discrimination of multiple VSDGs is proposed which avoids hunting between multiple generators.
Network reconfiguration for loss minimization is the determination of switching-options that mini... more Network reconfiguration for loss minimization is the determination of switching-options that minimizes the power losses for a particular set of loads on a distribution system. In this paper, a novel method is proposed by formulating an algorithm to reconfigure distribution networks for loss minimization. An efficient technique is used to determine the switching combinations, select the status of the switches, and find the best combination of switches for minimum loss. In the first stage of the proposed algorithm, a limited number of switching combinations is generated and the best switching combination is determined. In the second stage, an extensive search is employed to find out any other switching combination that may give rise to minimum loss compared to the loss obtained in the first stage.
International Journal of Innovations in Energy …, 2008
... 3, no. 1 (April 2008) Page 25 of 45 Page 8. Dr. Md. Enamul Haque graduated in electrical and ... more ... 3, no. 1 (April 2008) Page 25 of 45 Page 8. Dr. Md. Enamul Haque graduated in electrical and electronic engineering from Bangladesh Institute of Technology (BIT), Rajshahi, Bangladesh, in 1995. He received M.Eng.Sc. in electrical ...
ABSTRACT This paper presents a novel control scheme of neutral point clamped (NPC) voltage source... more ABSTRACT This paper presents a novel control scheme of neutral point clamped (NPC) voltage source converter (VSC) based static synchronous compensator (STATCOM) to enhance the performance of wind farms. A novel control strategy for the STATCOM is presented by introducing a voltage equalizer for dc link capacitor voltages and decoupled current controllers to produce appropriate d-q currents. The controllers for the wind energy conversion system and STATCOM are implemented in Matlab/SimPower. The performance of the proposed control scheme is compared with the traditional vector control scheme and results show that the proposed scheme for the STATCOM shows better performance. The STATCOM is also used to enhance the system performance during loss of generation, load change, three phase fault, voltage sag and swell. The simulation results show that the STATCOM with the proposed controller can improve the steady state and dynamic responses, and enhance the system performance during various disturbances.
ABSTRACT In the proposed method, each loop in a network is represented as a circle, which is deri... more ABSTRACT In the proposed method, each loop in a network is represented as a circle, which is derived from the relationship between the change of load balancing due to the branch-exchange and the power-flows in the branches. If there is no change of load balancing in the system, then all the circles touch each other at the (0,0) coordinate. The circles with no load balancing are called zero load balancing change circles. The maximum load balancing loop in the network is identified by comparing the radii of all the modified zero load balancing change circles. The corresponding loop of the largest one gives the maximum improvement of load balancing in the network. Then the possible branch exchanges in the maximum load balancing loop are investigated by comparing the size of the circle for every branch-exchange. If the loads are balanced due to a branch exchange, the size of the circle diminishes and hence the smallest circle gives the maximum improvement in load balancing and the corresponding branch-exchange is considered to be the best candidate for maximum improvement in load balancing. To show the efficiency and performance of the proposed method for the solution of computationally complex and large dimensionality problems, a system with 69-bus and 7 laterals has been considered as the test system. Test results have shown that the proposed method can identify the most effective branch-exchange operations for load balancing with less computational effort and time. The number of load flow solutions has been reduced to a greater extent in the proposed method
ABSTRACT Network reconfiguration for maximizing voltage stability is the determination of switchi... more ABSTRACT Network reconfiguration for maximizing voltage stability is the determination of switching-options that maximize voltage stability the most for a particular set of loads on the distribution systems, and is performed by altering the topological structure of distribution feeders. Network reconfiguration for time-varying loads is a complex and extremely nonlinear optimization problem which can be effectively solved by Artificial Neural Networks (ANNs), as ANNs are capable of learning a tremendous variety of pattern mapping relationships without having a priori knowledge of a mathematical function. In this paper a generalized ANN model is proposed for on-line enhancement of voltage stability under varying load conditions. The training sets for the ANN are carefully selected to cover the entire range of input space. For the ANN model, the training data are generated from the Daily Load Curves (DLCs). A 16-bus test system is considered to demonstrate the performance of the developed ANN model. The proposed ANN is trained using Conjugate Gradient Descent Back-propagation Algorithm and tested by applying arbitrary input data generated from DLCs. The test results of the ANN model are found to be the same as that obtained by off-line simulation. The enhancement of voltage stability can be achieved by the proposed method without any additional cost involved for installation of capacitors, tap-changing transformers, and the related switching equipment in the distribution systems. The developed ANN model can be implemented in hardware using the neural chips currently available.
Network reconfiguration in distribution system is realized by changing the status of sectionalizi... more Network reconfiguration in distribution system is realized by changing the status of sectionalizing switches, and is usually done for the purpose of loss reduction. Loss reduction can result in substantial benefits for a utility. Other benefits from loss reduction include increased system capacity, and possible deferment or elimination of capital expenditures for system improvements and expansion. There is also improved
Network reconfiguration is an operation task, and consists in the determination of the switching ... more Network reconfiguration is an operation task, and consists in the determination of the switching operations such to reach the minimum loss conditions of the distribution networks. In this paper, a general formulation of the network reconfiguration for loss minimization is given for the optimization of distribution loss reduction and a solution approach is presented. The solution employs a search over
Distributed generation (DG) inclusion within the grid system potentially introduces problems rela... more Distributed generation (DG) inclusion within the grid system potentially introduces problems related to control, protection, harmonics, and network transients. This paper analyses one of the key issues: protection of the network, by ascertaining the impact of rotary DG inclusion on existing protection system of SWER (single wire earth return) lines and the DG sensitivity during faults. The analysis is carried out by estimating fault-sensitivity for the worst-case situation, determining the DG impact on the existing protection scheme, and comparing the network situation with and without DG during the fault. A model of arc voltage is used to represent a fault on a SWER scheme. The size of DG is selected based on the SWER capacity and SWER load. The study is conducted on an example SWER system by considering the SWER lines with and without DG and faults on the SWER backbone and laterals, and simulation results are reported. In every case studied, the fault current from the DG significantly exceeded the DG rating and the DG would have tripped. Thus the system reverts to the case with no DG. Even if DG did not trip, the fault current from the source would be largely independent of the DG, and thus the original feeder protection would continue to provide the same quality of performance. Hence, net sensitivity and existing protection system will not be adversely affected by DG inclusion in SWER lines. #
Inclusion of voltage support distributed generation (VSDG) can reinforce the feeder voltage of di... more Inclusion of voltage support distributed generation (VSDG) can reinforce the feeder voltage of distribution networks, especially in rural/remote areas where voltage dip and frequent blackouts are significant concerns for power utilities. However, installation of multiple distributed generators within a distribution grid system may introduce technical problems in network operation and control, including control interaction and/or voltage instability. This paper addresses the network issues that may occur during multiple VSDG inclusion in the network and presents analytical models and solutions to develop design criteria of VSDG installation in the networks. Voltage sensitivity of lines is investigated and the effect of DG real (P) and reactive (Q) power injections with Q priority is developed for optimal use of VSDG in correcting the network voltage. Interaction among VSDG controllers has been explored and a generalized model is presented to analyze this interaction between any number of VSDGs in the network. The model is tested on a sample VSDG system and test results are presented. The issue of which VSDG must be started recognizing the costs of starting is addressed using an inverse definite minimum time (IDMT) model. A prioritization and coordination scheme for start discrimination of multiple VSDGs is proposed which avoids hunting between multiple generators.
Network reconfiguration for loss minimization is the determination of switching-options that mini... more Network reconfiguration for loss minimization is the determination of switching-options that minimizes the power losses for a particular set of loads on a distribution system. In this paper, a novel method is proposed by formulating an algorithm to reconfigure distribution networks for loss minimization. An efficient technique is used to determine the switching combinations, select the status of the switches, and find the best combination of switches for minimum loss. In the first stage of the proposed algorithm, a limited number of switching combinations is generated and the best switching combination is determined. In the second stage, an extensive search is employed to find out any other switching combination that may give rise to minimum loss compared to the loss obtained in the first stage.
International Journal of Innovations in Energy …, 2008
... 3, no. 1 (April 2008) Page 25 of 45 Page 8. Dr. Md. Enamul Haque graduated in electrical and ... more ... 3, no. 1 (April 2008) Page 25 of 45 Page 8. Dr. Md. Enamul Haque graduated in electrical and electronic engineering from Bangladesh Institute of Technology (BIT), Rajshahi, Bangladesh, in 1995. He received M.Eng.Sc. in electrical ...
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