Vol 88, No 1 (2017)

Compensation of the inactive components of network current of a rectifier with a capacitive filter or a combination thereof under connection of a parallel active filter with inductive storage based on a current inverter is considered. The active filter allows increasing the power coefficient to the maximum values, and this result may be achieved at high values of storage inductance. Modeling of the “rectifier–active filter” system is carried out by spectral methods. It is shown that correction of the switching algorithm by storage-current feedback provides a decrease by three to four times of inductance at the same values of the power factor of the “rectifier–active filter” system. A multistage active filter consisting of a current inverter and voltage inverter with current stabilization on the direct current is proposed. The total cost for the inductive elements in the multistage active filter may reduced by one order with the same values of power factors. Comparison of voltage inverters based on bridge and half-bridge schemes is carried out. Advantages of half-bridge inverters are shown.

Scientific and technical works on development of transport with magnetic levitation of the vehicle have been reviewed and the main stages of design of such transport have been analyzed. An iterative algorithm for design of the elecFtromagnets used in systems of magnetic levitation and lateral stabilization of high-speed ground transportation has been constructed. The algorithm is based on solving the inverse problems of the theory of an electromagnetic field. Relationships for calculating the initial values of the sought parameters, which are very close to the exact solution, have been suggested. An additional stage of minimizing the electromagnet mass is introduced into the algorithm; as a result, the useful weight of a vehicle can be increased. In addition, the necessary and sufficient conditions for the object of design to have minimal mass were used. An example of implementation of the algorithm during design of a levitation electromagnet has been considered. The influence of eddy currents induced in the ferromagnetic rail during movement of a vehicle on the levitation force has been determined. A coefficient that allows one to take into account this effect has been determined. To justify the formula for calculations of a ferrorail width, the dependences of levitation-force components that arise upon shifting the electromagnet in respect to the ferrorail axis have been obtained. The results of investigations show that the methodology based on solving the inverse problems in designing electromagnets of levitation and lateral-stabilization systems is highly efficient. The proposed algorithm for optimal design of the electromagnets can be used in the design of similar devices in electric-instrument engineering.

State estimation is a mathematical tabulation procedure widely used for EPS calculation based on measurement data. The state-estimation problem provides a correct solution only in cases in which remote measurements do not contain serious errors. Serious errors may be caused by both random factors related to a failure in the data-collection system, personnel errors, etc., and deliberate attempts (cyberattacks) on the system of data collection and transfer, databases, and state-estimation software. This paper focuses on the possible implications of cyberattacks the state-estimation results. The notion of the cyber-vulnerability index of the state-estimation problem is introduced. An approach to determination of its levels and values is proposed. The study shows that the combined application of remote measured SCADA and TVM data for EPS state estimation allows improving the efficiency of a detection algorithm for serious errors during remote measurements and accuracy of the obtained estimates, thus decreasing the state-estimation problem’s vulnerability to cyberattacks.

The design and operating principle of an active-current three-phase measuring transducer based on differentiating induction-current transducers without using integrated filters are considered. The dependence of the measurement accuracy of the active component of load current of a synchronous generator on the value of EMF of a differential induction-current transducer is determined. A scheme of computer simulation of a three-phase measuring transducer of active current is described. The results of computer simulation and experimental studies of the device confirming the ability of the transducer under consideration to replace the traditional solutions based on current transformers for marine electric-power systems are presented.

In this paper, a proposed Non-dominated Sorting Hybrid Cuckoo Search Algorithm (NSHCSA) for multi objective optimal power flow problem with FACTS devices namely Thyristor Controlled Series Compensator (TCSC) and Static Synchronous Series Compensator (SSSC) with different objective functions including the installation cost of FACTS devices are presented. The practical and operating constraints are considered for this analysis. The location of the FACTS device is selected to enhance the system security with respect to minimizing line overloads and bus voltage violations. The proposed Hybrid Cuckoo Search Algorithm (HCSA) is the combination of Cuckoo Search Algorithm (CSA) and Genetic Algorithm (GA). For multi objectives selected Pareto front is obtained by using the fuzzy decision making tool. The effectiveness of the proposed method is tested on standard IEEE-30 bus test system in the presence of the TCSC and SSSC. The results are analyzed and compared with existing methods.