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Item type:Item, Overlapping decompositions-based robust decentralized tabu search-optimized fixed structure H∞ frequency stabilizer design in interconnected power systems(2013-07-17)Ngamroo, IssarachaiAs interconnected power systems are subjected to load disturbances with changing frequency in the vicinity of the inter-area oscillation mode, the system frequency may severely oscillate. To stabilize frequency oscillation, the dynamic power flow control devices can be exploited. This paper focuses on a new robust decentralized fixed structure H<inf>∞</inf> frequency stabilizer design of power control devices based on overlapping decompositions. The tie-line between two interconnected systems can be treated as the overlapped variable so that the original system can be decomposed into two subsystems. The frequency stabilizer equipped with the power control device can be designed in each subsystem independently. The structure of frequency stabilizer is specified as the 2<sup>nd</sup>-order lead/lag compensator. To augment the system robust stability, the multiplicative uncertainty is employed to represent all unstructured system uncertainties. As a result, the multiplicative stability margin (MSM) can be used to guarantee the system robust stability. The control parameters of frequency stabilizer are optimized by a tabu search, so that the desired damping ratio of the target inter-area mode and the highest MSM are achieved. Two examples of power flow devices, i.e., high-voltage direct current transmission system and superconducting magnetic energy storage, are used to show the high performance and robustness against load disturbances and system parameters variation. © 2013 ICIC International. - Some of the metrics are blocked by yourconsent settings
Item type:Item, Wide area robust centralized PSO-based specified structure H∞ power system damping controller design considering uncertainties in time delay and system parameters(2013-02-15)Ngamroo, IssarachaiIt is well known that the time delay due to the wide area phasor measurement may cause a malfunction of wide area centralized control of power system damping controller (PSDC) and system instability eventually. Nevertheless, the uncertainties due to time delay and system parameters have never been considered in the previous researches of PSDC design. To tackle this problem, a wide area robust centralized particle swarm optimization (PSO)-based specified structure H<inf>∞</inf> PSDC design taking uncertainties due to communication delay and system parameters into account is proposed in this paper. Without explicit mathematic equations, the inverse input multiplicative model is applied to represent the unstructured uncertainties. The structure of PSDC is the practical 2nd order lead/lag compensator. To automatically tune the control parameters, the optimization based on an enhancement of damping effect and robust stability margin is achieved by PSO. To evaluate the proposed design technique, two examples of robust centralized PSDC, i.e., power system stabilizer and thyristor control series capacitor are demonstrated in a two-area four-machine interconnected power system,. Simulation study confirm that the proposed robust centralized PSDC is much superior to the conventional centralized PSDC in terms of stabilizing effect and robustness against uncertainties due to time delay and system parameters. © 2013 ICIC International. - Some of the metrics are blocked by yourconsent settings
Item type:Item, Specified structure mixed H2=H∞ control-based robust frequency stabilization in a smart grid by plug-in hybrid electric vehicles(2013-01-16)Ngamroo, IssarachaiIn the future smart grid, the penetration of wind power tends to increase significantly. This may cause the tie-line power and frequency fluctuations in the power grid. On the other hand, the plug-in hybrid electric vehicles (PHEV) are highly expected to be installed in the customer side. The bidirectional power control of PHEV can be applied to stabilize the power and frequency fluctuations. This paper proposes the specified structure mixed H<inf>2</inf>=H<inf>∞</inf> control design of bidirectional power controller of PHEV for robust frequency stabilization of the smart grid with large wind farms. System uncertainties are represented by the multiplicative perturbation model. The structure of power controller is specified as a proportional integral (PI) with single input. The PI parameters optimization problem is formulated based on the enhancement of control performance and robustness against system uncertainties. Without the difficulty of weighting functions selection as in a mixed H<inf>2</inf>=H<inf>∞</inf> control, the PI parameters are automatically tuned by particle swarm optimization. Simulation results confirm that the proposed robust controller is much superior to the conventional controller in terms of control performance and robustness against various uncertainties. © 2013 ICIC International. - Some of the metrics are blocked by yourconsent settings
Item type:Item, PSO-based specified structure mixed H2/H∞ multiple PHEV controllers for robust frequency control in interconnected power systems with large wind farms(2013-01-16) - Some of the metrics are blocked by yourconsent settings
Item type:Item, Robust coordinated control of electrolyzer and PSS for stabilization of microgrid based on PID-based mixed H 2/H ∞ control(2012-09-01)Ngamroo, IssarachaiIn the stand-alone microgrid with hybrid wind, fuel cell (FC) with electrolyzer (EZ) and diesel generations, the intermittent wind power may cause the serious power fluctuation. In addition to the hydrogen production for FC, the EZ can be used to alleviate power fluctuation by an appropriate control of the absorbed power. Nevertheless, the EZ may fail to suppress the power fluctuation due to large disturbances. To enhance the EZ control performance, a power system stabilizer (PSS) which is assumed to be equipped with a diesel generator can be used. This paper proposes the robust coordinated control of EZ and PSS for microgrid stabilization. The structure of power controller of EZ and PSS is a proportional-integral-derivative (PID). To improve the damping performance and robustness of EZ controller and PSS, the PID parameters of both EZ and PSS are simultaneously tuned based on the mixed H <inf>2</inf>/H <inf>∞</inf> control by bee colony optimization. Simulation studies show that the stabilizing performance and robustness of the proposed EZ and PSS are superior to those of the individual device under system uncertainties such as various wind patterns, loading conditions and severe faults. © 2012 Elsevier Ltd. - Some of the metrics are blocked by yourconsent settings
Item type:Item, Simultaneous optimization of SMES coil size and control parameters for robust power system stabilization(2011-06-01)Ngamroo, IssarachaiAs the coil size is the heart of superconducting magnetic energy storage (SMES), the simultaneous optimization of coil size and control parameters of SMES for robust power system stabilization is proposed. The structure of active and reactive power controllers of SMES is the practical first-order lead/lag compensator. To handle system uncertainties such as various generating and loading conditions, unpredictable network structures etc., the multiplicative uncertainty model is embedded in the system modeling. As a result, the optimization problem of SMES coil size and controller parameters based on the enhancement of system damping and robust stability margin against system uncertainties can be formulated. Solving the problem by a particle swarm optimization, both optimal coil size and controller parameters are obtained simultaneously and automatically. Simulation study in the West Japan six-area interconnected power system with two SMES units confirms the superior robustness and damping performance of the proposed SMES controller with an optimal coil size under various situations in comparison with the conventional SMES controller. © 2011 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Item, An optimization of robust SMES with specified structure H∞ controller for power system stabilization considering superconducting magnetic coil size(2011-01-01)Ngamroo, IssarachaiEven the superconducting magnetic energy storage (SMES) is the smart stabilizing device in electric power systems, the installation cost of SMES is very high. Especially, the superconducting magnetic coil size which is the critical part of SMES, must be well designed. On the contrary, various system operating conditions result in system uncertainties. The power controller of SMES designed without taking such uncertainties into account, may fail to stabilize the system. By considering both coil size and system uncertainties, this paper copes with the optimization of robust SMES controller. No need of exact mathematic equations, the normalized coprime factorization is applied to model system uncertainties. Based on the normalized integral square error index of inter-area rotor angle difference and specified structured H <inf>∞</inf> loop shaping optimization, the robust SMES controller with the smallest coil size, can be achieved by the genetic algorithm. The robustness of the proposed SMES with the smallest coil size can be confirmed by simulation study. © 2010 Elsevier Ltd. All rights reserved. - Some of the metrics are blocked by yourconsent settings
Item type:Item, Augmentation of electrolyzer control effect by PSS for microgrid stabilization using PID-based mixed H2/H∞ control(2011-01-01)Ngamroo, IssarachaiIn an isolated microgrid with hybrid wind, fuel cell (FC) with electrolyzer (EZ) and diesel generations, the intermittent wind power may cause the serious power fluctuation. In addition to the hydrogen production for FC, the EZ can be used to alleviate power fluctuation by control of the absorbed power. Nevertheless, the EZ may fail to suppress the power fluctuation due to the severe faults. To augment the EZ control performance, a power system stabilizer (PSS) which is assumed to be equipped with a diesel generator can be applied. This paper proposes the robust stabilization of isolated microgrid by EZ and PSS. The structure of power controller of EZ and PSS is a proportional-integral-derivative (PID) controller. To improve the damping performance and robustness of EZ controller and PSS, the PID parameters of both EZ and PSS are simultaneously tuned based on the mixed H<inf>2</inf>/H<inf>∞</inf> control by bee colony optimization. Simulation studies show that the stabilizing performance and robustness of the proposed EZ and PSS are superior to those of the individual device under system uncertainties such as various wind patterns, loading conditions and severe faults. © 2011 Praise Worthy Prize S.r.l. - All rights reserved. - Some of the metrics are blocked by yourconsent settings
Item type:Item, Robust SMES controller design based on inverse additive perturbation for stabilization of interconnected power systems with wind farms(2010-03-01)Ngamroo, IssarachaiThis paper proposes a robust controller design of Superconducting Magnetic Energy Storage (SMES) for stabilization of tie-line power oscillation in the interconnected power systems with wind farms. The inverse additive perturbation model is applied to represent system uncertainties such as several generating and loading conditions, variation of system parameters, wind power fluctuations, etc. The structure of active and reactive power controllers of SMES is the first-order lead-lag compensator. To tune the controller parameters, the optimization problem is formulated based on the enhancement of additive stability margin. The genetic algorithm is used to solve the problem and achieve the controller parameters. Simulation studies in the two-area four-machine interconnected power system with wind farms confirm the robustness of the proposed SMES under various operating conditions. © 2009 Elsevier Ltd. All rights reserved. - Some of the metrics are blocked by yourconsent settings
Item type:Item, Wide-area robust SMES controller design using synchronized PMUS for stabilization of interconnected power system with wind farms(2010-01-01)