Robust tuning of power system stabilizer for small signal stability enhancement using metaheuristic bat algorithm

CIGRE WG C4.605 : “Modelling and aggregation of loads in flexible power networks”

A comprehensive review of dynamic voltage restorers

The parameters of electrical energy such as voltage amplitude are very important, particularly from the viewpoint of the final consumer and sensitive loads connected to the grid. The dynamic states in the power grid-deep voltage sags and swells-might cause faults and defects in sensitive loads. This paper deals with a three-phase hybrid transformer (HT) without dc energy storage to compensate voltage sags and swells and to protect sensitive loads against the rapid and extensive changes in supply voltage amplitude. The analyzed HT contains two main units: the first one is the conventional electromagnetic transformer, realizing an electromagnetic coupling, and the second one is the buck-boost matrix-reactance chopper, realizing an electrical coupling in the HT unit. In the presented solution, output voltage is transformed in two ways-electromagnetically and electrically. This paper presents an operational description, the theoretical analysis, and the experimental test results from a 2-kVA laboratory model. On the basis of the authors' research, it can be stated that the HT makes it possible to compensate deep voltage sags (deeper than 50% of nominal source voltage) and overvoltages (up to 140% of nominal source voltage) while maintaining good dynamic properties. The main advantages of the proposed solution, in comparison to other conventional solutions, are the ability to control the output voltage in the range of 0.66-3.5 US, good dynamics (transient state during source voltage uS amplitude change is shorter than 10 ms), and galvanic separation between source and load (such as in the case of the conventional electromagnetic transformer).

AC Voltage Sag/Swell Compensator Based on Three-Phase Hybrid Transformer With Buck-Boost Matrix-Reactance Chopper

Dynamic genetic algorithms for robust design of multimachine power system stabilizers

In this paper a Dynamic Voltage Restorer (DVR) based on a matrix converter without energy storage devices is proposed to cope with voltage fluctuations. The ac/ac power converter takes energy from the grid during voltage sag/swell. By connecting the matrix converter's input terminals on the load-side and injecting the compensation voltages on the supply-side, it is possible to hold a constant input voltage, resulting in an efficient solution for compensating deep voltage sags and swells. Thus, the proposed topology has the ability to compensate balanced and unbalanced voltage fluctuations and to eliminate the energy storage elements. The space-vector modulation (SVM) technique is utilized to fulfill the input and output requirements. Numerical simulation results are presented to validate the approach.

A novel Dynamic Voltage Restorer based on matrix converters

A strategy to simultaneously tune power system stabilizers

Dynamic equivalence by an optimal strategy

The first dynamic voltage restorer (DVR) was introduced in 1994 as a result of collaborative effort between Westinghouse (presently Siemens), EPRI, and Duke Power. The dynamic voltage restorer's application has been already demonstrated and is extensively reported, much of the research on DVRs has focused on dc link-based voltage source converters (VSC). These converters have evolved rapidly in the field of industrial AC motor drives. Thus, the importance of the DVR is well recognized. This paper deals with applications related to voltage compensation in order to satisfy the future smart grid's standards.

Rosa E. Correa

Papers

A novel Dynamic Voltage Restorer based on matrix converters

A strategy to simultaneously tune power system stabilizers

Dynamic equivalence by an optimal strategy

Voltage compensation for common disturbances at the distribution level

Experimental design for a large power system vulnerability estimation