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With rapid increase of photovoltaic (PV) penetration in distribution system, and the fact that distributed generators may involve in voltage regulation according to IEEE standard 1547, it is necessary to check the stability of PV generator integration, especially utility PV farms. To apply generalized Nyquist Criteria (GNC) based on impedances on D-Q frame, output impedances of PV farm is derived...
As negative incremental resistance caused by constant power behavior of power converters may bring stability problem to distributed systems, stability of PV integration to distributed system attracts more and more attention. Compared to the widely used positive impedance method, D-Q Frame impedance matrix method is more accurate for integration of PV generator that has non-symmetrical control in DQ...
Inverter-based voltage regulation is gaining importance to alleviate emerging reliability and power-quality concerns related to distribution systems with high penetration of photovoltaic (PV) systems. This paper seeks contribution in the domain of reactive power compensation by establishing stability of local Volt/VAr controllers. In lieu of the approximate linear surrogate used in the existing work,...
Droop control methods are widely used in dc microgrids due to its simplicity and easy implementation. However, DC bus voltage deviation increases as the droop gain increases although accuracy of power sharing is improved. In order to overcome this paper proposes an improved voltage regulation method under high droop gain circumstance with consideration of cable impedance. It allows accurate power...
The Vietnamese power system is growing rapidly both in terms of scale and complexity. The load growth rate averages to 14% for the last 10 years. The development of the Extra High Voltage network of 500kV and interconnections with neighboring grids are the main characteristic of such growths. However the fast growth rate also brings problems in operating the network, for instance the short-circuit...
This paper investigates the islanding operation of mini-hydro generation connected in a Provincial Electricity Authority (PEA) distribution network. A real test system with three mini-hydro generating units was set up to examine their dynamic and steady state performance. Voltage and frequency regulation of the generating units were inspected. Test results show that mini-hydro generating units connected...
The closed-loop control stability of a switching converter can be compromised when the source voltage is not an ideal voltage source, but presents finite Theacutevenin impedance. This phenomenon is called source subsystem interaction. As an active approach to improve the stability degraded by the source subsystem interaction, the positive feedforward (PFF) control is proposed for the peak-current-mode-controlled...
This paper studies the effects of the presence of a current-sharing loop in a system of parallel-connected dc/dc buck converters under democratic current-sharing control. Under this control scheme, the reference current is generated by a typical proportional- integral (PI) controller for voltage regulation and the currents in individual converters are programmed by a built-in interleaving switching...
This paper presents the direct feedback linearization (DFL) technique as a simple and flexible nonlinear control method in designing robust nonlinear excitation controllers for stability enhancement and voltage regulation of power systems. This technique offers considerable flexibility in designing controllers for all relevant variables. The main advantage of this technique is the possibility of selecting...
This paper presents the nonlinear robust-optimal control for the attitudes of a two-degree-of-freedom (2DOF) helicopter. First, a Takagi-Sugeno (T-S) fuzzy model is employed to approximate the nonlinear 2DOF helicopter. The LMI-based relaxed stability conditions are applied to design the nonlinear fuzzy controller. Using the method of parallel distributed compensator (PDC), the nonlinear fuzzy controller...
This paper describes the coexisting attractors of parallel connected boost switching converters under a master-slave current sharing scheme. We present the basins of attraction of desired and undesired attractors, which provide design information on the conditions for hot-swap operations. The system employs a typical proportional-integral (PI) controller for regulation. It is shown that the system...
In a single inductor double output (SIDO) boost converter, power is fed to both the outputs through the same inductor and hence the control requirements on output voltages are inter-dependent, causing complexity in modeling and control design of such converters. But, there is some flexibility in disguise due to the increased number of controlled devices and storage elements. This is utilized in this...
In a single inductor double output (SIDO) boost converter, power is fed to both the outputs through the same inductor and hence the control requirements on output voltages are inter-dependent, causing complexity in modeling and control design of such converters. But, there is some flexibility in disguise due to the increased number of controlled devices and storage elements. This is utilized in this...
This paper describes the coexisting attractors of parallel connected boost switching converters under a master-slave current sharing scheme. We present the basins of attraction of desired and undesired attractors, which provide design information on the conditions for hot-swap operations. The system employs a typical proportional-integral (PI) controller for regulation. It is shown that the system...
A new decentralized nonlinear voltage controller for multimachine power systems is proposed in this paper. The nonlinear n-machine power system model is first linearized and decoupled over the whole operating region by using the direct feedback linearization (DFL) technique. Then a decentralized nonlinear voltage controller is developed by use of the robust control theory. Performance of the proposed...
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