Improving the Dynamic Performance of Distribution Electronic Power Transformers Using Sliding Mode Control

Hooshmand, Rahmat-Allah,Ataei, Mohammad,Rezaei, Mohammad Hosein The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1

These days, the application of electronic power transformers (EPTs) is expanding in place of ordinary power transformers. These transformers can transmit power via three or four wire converters. Their dynamic performance is extremely important, due to their complex structure. In this paper, a new method is proposed for improving the dynamic performance of distribution electronic power transformers (DEPT) by using sliding mode control (SMC). Hence, to express the dynamic characteristics of a system, different factors such as the voltage unbalance, voltage sag, voltage harmonics and voltage flicker in the system primary side are considered. The four controlling aims of the improvement in dynamic performance include: 1) maintaining the input currents so that they are in sinusoidal form and in phase with the input voltages so they have a unity power factor, 2) keeping the dc-link voltage within the reference amount, 3) keeping the output voltages at a fixed amount and 4) keeping the output voltages in sinusoidal and symmetrical forms. Simulation results indicate the potential and capability of the proposed method in improving DEPT behavior.

Fuzzy Logic Application in Fault Diagnosis of Transformers Using Dissolved Gases

Rahmat-Allah Hooshmand,Mahdi Banejad 대한전기학회 2008 Journal of Electrical Engineering & Technology Vol.3 No.3

One of the problems with the fault diagnosis of transformers based on dissolved gas is the inability to match the result of the different standards of fault diagnosis with real world standards. In this paper, the results of the different standards are analyzed using fuzzy logic and then compared with the empirical test. The proposed method is based on the standards and guidelines of the International Electrotechnical Commission (IEC), the Central Electric Generating Board (CEGB), and the American Society for Testing and Material (ASTM) and its main task is to assist the conventional gas ratio method. The comparison between the suggested method and existing methods indicates the capability of the suggested method in the on-line fault diagnosis of transformers, In addition, in some cases the existing standards are not able to diagnose the fault. For theses instances, the presented method has the potential of diagnosing the fault. In this paper, the information of three real transformers is used to show the capability of the suggested method in diagnosing the fault. The results validate the capability of the presented method in fault diagnosis of the transformer.

Real-Coded Genetic Algorithm Based Design and Analysis of an Auto-Tuning Fuzzy Logic PSS

Hooshmand, Rahmat-Allah,Ataei, Mohammad The Korean Institute of Electrical Engineers 2007 Journal of Electrical Engineering & Technology Vol.2 No.2

One important issue in power systems is dynamic instability due to loosing balance relation between electrical generation and a varying load demand that justifies the necessity of stabilization. Moreover, Power System Stabilizer (PSS) must have capability of producing appropriate stabilizing signals over a wide range of operating conditions and disturbances. To overcome these drawbacks, this paper proposes a new method for robust design of PSS by using an auto-tuning fuzzy control in combination with Real-Coded Genetic Algorithm (RCGA). This method includes two fuzzy controllers; internal fuzzy controller and supervisor fuzzy controller. The supervisor controller tunes the internal one by on-line applying of nonlinear scaling factors to inputs and outputs. The RCGA-based method is used for off-line training of this supervisor controller. The proposed PSS is tested in three operational conditions; nominal load, heavy load, and in the case of fault occurrence in transmission line. The simulation results are provided to compare the proposed PSS with conventional fuzzy PSS and conventional PSS. By evaluating the simulation results, it is shown that the performance and robustness of proposed PSS in different operating conditions is more acceptable

Fuzzy Logic Application in Fault Diagnosis of Transformers Using Dissolved Gases

Hooshmand, Rahmat-Allah,Banejad, Mahdi The Korean Institute of Electrical Engineers 2008 Journal of Electrical Engineering & Technology Vol.3 No.3

One of the problems with the fault diagnosis of transformers based on dissolved gas is the inability to match the result of the different standards of fault diagnosis with real world standards. In this paper, the results of the different standards are analyzed using fuzzy logic and then compared with the empirical test. The proposed method is based on the standards and guidelines of the International Electrotechnical Commission (IEC), the Central Electric Generating Board (CEGB), and the American Society for Testing and Material (ASTM) and its main task is to assist the conventional gas ratio method. The comparison between the suggested method and existing methods indicates the capability of the suggested method in the on-line fault diagnosis of transformers. In addition, in some cases the existing standards are not able to diagnose the fault. For theses instances, the presented method has the potential of diagnosing the fault. In this paper, the information of three real transformers is used to show the capability of the suggested method in diagnosing the fault. The results validate the capability of the presented method in fault diagnosis of the transformer.

Improving the Dynamic Performance of Distribution Electronic Power Transformers Using Sliding Mode Control

Rahmat-Allah Hooshmand,Mohammad Ataei,Mohammad Hosein Rezaei 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1

These days, the application of electronic power transformers (EPTs) is expanding in place of ordinary power transformers. These transformers can transmit power via three or four wire converters. Their dynamic performance is extremely important, due to their complex structure. In this paper, a new method is proposed for improving the dynamic performance of distribution electronic power transformers (DEPT) by using sliding mode control (SMC). Hence, to express the dynamic characteristics of a system, different factors such as the voltage unbalance, voltage sag, voltage harmonics and voltage flicker in the system primary side are considered. The four controlling aims of the improvement in dynamic performance include: 1) maintaining the input currents so that they are in sinusoidal form and in phase with the input voltages so they have a unity power factor, 2) keeping the dc-link voltage within the reference amount, 3) keeping the output voltages at a fixed amount and 4) keeping the output voltages in sinusoidal and symmetrical forms. Simulation results indicate the potential and capability of the proposed method in improving DEPT behavior.

New Optimal design of D-STATCOM Compensation to Improve Power Quality Indices in Distribution Systems

Rahmat Allah Hooshmand,Amin Khodabakhshian,Mehdi Torabian Esfahani 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

In this paper the power quality phenomena regarding universal valid standards is first studied and analyzed. Then, in order to improve these phenomena in the distribution systems, the optimization design of compensating D-STATCOM by presenting a new method based on PSO (Particle Swarm Optimization) will be presented. This method not only improves the power quality indices and reduces distribution network harmonics, but also reduces active and reactive power oscillations of the system within reasonable limits. The voltage of the compensating DC capacitor is also satisfactorily stabilized within a reasonable limit.

Real-Coded Genetic Algorithm Based Design and Analysis of an Auto-Tuning Fuzzy Logic PSS

Rahmat-Allah Hooshmand,Mohammad Ataei 대한전기학회 2007 Journal of Electrical Engineering & Technology Vol.2 No.2

One important issue in power systems is dynamic instability due to loosing balance relation between electrical generation and a varying load demand that justifies the necessity of stabilization. Moreover, Power System Stabilizer (PSS) must have capability of producing appropriate stabilizing signals over a wide range of operating conditions and disturbances. To overcome these drawbacks, this paper proposes a new method for robust design of PSS by using an auto-tuning fuzzy control in combination with Real-Coded Genetic Algorithm (RCGA). This method includes two fuzzy controllers; internal fuzzy controller and supervisor fuzzy controller. The supervisor controller tunes the internal one by on-line applying of nonlinear scaling factors to inputs and outputs. The RCGA￢based method is used for off-line training of this supervisor controller. The proposed PSS is tested in three operational conditions; nominal load, heavy load, and in the case of fault occurrence in transmission line. The simulation results are provided to compare the proposed PSS with conventional fuzzy PSS and conventional PSS. By evaluating the simulation results, it is shown that the performance and robustness of proposed PSS in different operating conditions is more acceptable.

Power Quality Enhancement in Power System with Electric Arc Furnaces by Shunt Active Power Filter Optimum Design

Rahmat Allah Hooshmand,Amin Khodabakhshian,Mehdi Torabian Esfahani 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

In this paper the design of optimum shunt active power filter in order to improve the power quality indices in power systems with electric arc furnaces will be discussed. The selected model for the arc is based on a combination of Cassie-Mayer equations. The conventional controllers are not capable of improving the power quality for these types of systems. Therefore, for improving the power quality indices a new method based on fuzzy controller is employed to design an optimum shunt active power filter. The simulation results show the advantages of using fuzzy control.

Electric Arc Furnace Voltage Flicker Mitigation by Applying a Predictive Method with Closed Loop Control of the TCR/FC Compensator

Kiyoumarsi, Arash,Ataei, Mohhamad,Hooshmand, Rahmat-Allah,Kolagar, Arash Dehestani The Korean Institute of Electrical Engineers 2010 Journal of Electrical Engineering & Technology Vol.5 No.1

Modeling of the three phase electric arc furnace and its voltage flicker mitigation are the purposes of this paper. For modeling of the electric arc furnace, at first, the arc is modeled by using current-voltage characteristic of a real arc. Then, the arc random characteristic has been taken into account by modulating the ac voltage via a band limited white noise. The electric arc furnace compensation with static VAr compensator, Thyristor Controlled Reactor combined with a Fixed Capacitor bank (TCR/FC), is discussed for closed loop control of the compensator. Instantaneous flicker sensation curves, before and after accomplishing compensation, are measured based on IEC standard. A new method for controlling TCR/FC compensator is proposed. This method is based on applying a predictive approach with closed loop control of the TCR/FC. In this method, by using the previous samples of the load reactive power, the future values of the load reactive power are predicted in order to consider the time delay in the compensator control. Also, in closed loop control, two different approaches are considered. The former is based on voltage regulation at the point of common coupling (PCC) and the later is based on enhancement of power factor at PCC. Finally, in order to show the effectiveness of the proposed methodology, the simulation results are provided.

Robust Active Power Control of a Battery-Supported DSTATCOM to Enhance Wind Generation Power Flow

Mahdianpoor, Mohammad,Kiyoumarsi, Arash,Ataei, Mohammad,Hooshmand, Rahmat-Allah The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.8 No.1

The lack of controllability over the wind causes fluctuations in the output power of the wind generators (WGs) located at the wind farms. Distribution Static Compensator (DSTATCOM) equipped with Battery Energy Storage System (BESS) can significantly smooth these fluctuations by injecting or absorbing appropriate amount of active power, thus, controlling the power flow of WGs. But because of the component aging and thermal drift, its harmonic filter parameters vary, resulting in performance degradation. In this paper, Quantitative Feedback Theory (QFT) is used as a robust control scheme in order to deactivate the effects of filter parameters variations on the wind power generation power smoothing performance. The proposed robust control strategy of the DSTATCOM is successfully applied to a microgrid, including WGs. The simulation results obviously show that the proposed control technique can effectively smooth the fluctuations in the wind turbines' (WT) output power caused by wind speed variations; taking into account the filter parameters variations (structural parameter uncertainties).