• Journal of Electrical Engineering and Technology
• /
• v.12 no.4
• /
• pp.1386-1396
• /
• 2017

In this paper, a new approach is proposed to select the optimal sitting and sizing of distributed solar photovoltaic generation (SPVG) in a radial electrical distribution systems (EDS) considering load/generation uncertainties. Here, distributed generations (DGs) allocation problem is modeled as optimization problem with network loss based objective function under various equality and inequality constrains in an uncertain environment. A boundary power flow is utilized to address the uncertainties in load/generation forecasts. This approach facilitates the consideration of random uncertainties in forecast having no statistical history. Uncertain solar irradiance is modeled by beta distribution function (BDF). The resulted optimization problem is solved by a new Dynamic Harmony Search Algorithm (DHSA). Dynamic band width (DBW) based DHSA is proposed to enhance the search space and dynamically adjust the exploitation near the optimal solution. Proposed approach is demonstrated for two standard IEEE radial distribution systems under different scenarios.

• Proceedings of the KIEE Conference
• /
• 2005.07a
• /
• pp.226-228
• /
• 2005

This paper deals with power system stabilization problem using a network control system in which the control is applied through a communication channel in feedback form. Analysis and synthesis issues are investigated by modeling the packet delivery characteristics of the network as a Bernoulli random variable, which is described by a two state Markov chain. This model assumption yields an overall system which is described by a discrete-time Markov jump linear system. These employ the norm to measure the performance of the system, and they compute the norm via a necessary and sufficient matrix inequality condition.

• International Journal of Control, Automation, and Systems
• /
• v.3 no.spc2
• /
• pp.262-269
• /
• 2005

In this paper, a nonlinear robust control approach is applied to design a controller for the Static Synchronous Compensator (STATCOM). A robust control dynamic model of STATCOM in a one-machine, infinite-bus system is established with consideration of the torque disturbance acting on the rotating shaft of the generator set and the disturbance to the output voltage of STATCOM. A novel recursive approach is utilized to construct the energy storage function of the system such that the solution to the disturbance attenuation control problem is acquired, which avoids the difficulty involved in solving the Hamilton-Jacobi-Issacs (HJI) inequality. Sequentially, the nonlinear disturbance attenuation control strategy of STATCOM is obtained. Simulation results demonstrate that STATCOM with the proposed controller can more effectively improve the voltage stability, damp the oscillation, and enhance the transient stability of power systems compared to the conventional PI+PSS controller.

• Proceedings of the KIEE Conference
• /
• 1999.07c
• /
• pp.1183-1185
• /
• 1999

The basic purpose of economic dispatch problem is that minimize fuel cost with inequality constraint of generator output. To solve this problem it is very important to express power loss equation that have quadratic function of generator output power included B-coefficient. This Paper presents a method in determining B-coefficient by use A-matrix that is calculated by loss re-distribution algorithm (LRDA) considering voltage dependent load model (VDLM)s. The Proposed algorithm is tested with IEEE 6 bus sample system, which shows the result in each cases by the change of load component factor.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.32A no.1
• /
• pp.70-78
• /
• 1995

In order to implement broadband RAM's(Radar Absorbing Materials) made up of multiple dielectricl layers, the design variables such as the dielectrci constaints, the depths and the loss tangents of dielectric are optimized. The wave impedances regarding the reflective wave are found in dielectrics, input impedances and reflection coefficients with multiple dielectric layers are derived from the transmission line circuit theory. Finally, minimum average reflective power and optimum design variables are obtained by applying the numerical technique, called modified Powell method. In case of four dielectric layers with inequality constraints in design variables, a quite favourable and feasible result with the total depth of 1.1 cm, the average reflective power of 0.85% over the bradband frequency range is obtained for a specific example.

• Journal of Power System Engineering
• /
• v.3 no.2
• /
• pp.84-88
• /
• 1999

In this paper, systems described by state-space models are considered. For these systems, author studies the decoupling of linear systems and gives a sufficient condition for a system to be made feedback decouplable. Especially, the condition is given by LMI(Linear Matrix Inequality) form. Based on this condition, it is guaranteed that the system decoupling problem is achieved and the $H_{\infty}$ constraint is satisfied simultaneously. This result can be easily extended to the robust decoupling control system design problems.

• Journal of Power Electronics
• /
• v.12 no.2
• /
• pp.294-304
• /
• 2012

This paper proposes a fuzzy speed tracking controller and a fuzzy rotor angular acceleration observer for a surface-mounted permanent magnet synchronous motor (SPMSM) based on the Takagi-Sugeno (T-S) fuzzy model. The proposed observer-based controller is robust to load torque variations since it utilizes rotor angular acceleration information instead of the load torque value. Linear matrix inequality (LMI) sufficient conditions are given to compute the gain matrices of the speed tracking controller and the observer. In addition, it is mathematically verified that the proposed observer-based control system is asymptotically stable. Simulation and experimental results are presented to confirm that the proposed control algorithm assures a better transient behavior and less sensitivity under model parameter variations than the conventional PI control method.

• Journal of Power Electronics
• /
• v.13 no.4
• /
• pp.712-718
• /
• 2013

This paper proposes a control method for reducing the total harmonic distortion (THD) of the grid current of three-phase grid-connected inverter systems when the grid voltage is distorted. The THD of the grid current caused by grid voltage harmonics is derived by considering the phase delay and magnitude attenuation due to the hardware low-pass filter (LPF). The Cauchy-Schwarz inequality theory is used in order to search more easily for the minimum point of the THD. Both the gain and angle of the compensation voltage at the minimum point of the THD of the grid current are derived with the variation of cut-off frequencies of the hardware LPF. Simulation and experimental results show the validity of the proposed control methods.

• Proceedings of the KIEE Conference
• /
• 1987.11a
• /
• pp.129-132
• /
• 1987

This paper presents an emergency control algorithms for viability crisis following abnormal condition as well as a sudden major supply outage and line outage. The algorithm considers the effect of voltage-reactive power control for determining the load shedding quantities and generation reallocation. The problem is decomposed into a P-problem and a Q-problem. The former minimizes system frequency deviation from nominal value and the latter minimizes voltages violation of load buses. The optimization problem is solved by a reduced gradient technique which can handle a great number of inequality constraints very efficiently. It has been found that the use of the proposed algorithm for 6-Bus system restore the abnormal system during the viability crisis to the normal state.

• International Journal of Reliability and Applications
• /
• v.3 no.1
• /
• pp.17-23
• /
• 2002

The class of “new better than used of a specified age” is a large and practical class of life distributions. Its properties, applicability, and testing was discussed by Hollander, Park and Proschan (1986). Their test, while remaining the yardstick for this class, suffers from weak efficiency and weak power, especially for specified ages below the average age. Thus, it is beneficial to have an alternative testing procedure that would work better for early ages and still work well for later ages. This is exactly the subject of the current note. The test developed here is also simpler than that of Hollander, et. al. (1986).