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Studies aimed at ensuring synchronous parallel operation of permanent magnet generators of a micro HPP in a self-contained power system that use a controlled flexible coupling between the turbine and generator were carried out. The need of carrying out this study is stemming, among other things, from the problem of ensuring electromechanical compatibility during parallel operation of generators having different parameters of the mechanical inertia time constants of electrical machine rotors. Possible versions of solving this problem are reviewed, and their advantages and drawbacks are analyzed. The concept based on using a controlled flexible coupling between the generator and turbine is proposed as a promising solution of this problem. The mathematical models of the system are presented, and the laws and algorithms for automatically controlling the generator rotation frequency are drawn up. The simulation and physical modeling oscillograms presented in the article show how synchronous parallel operation of permanent magnet synchronous generators is maintained in a self-contained electric power system under the conditions of a three-phase short-circuit fault in points located at different electrical distances.

The urgency of developing renewable power generation in Russia is associated with the presence of a large number of regions with a low degree of electrification. More than two-thirds of the territory of Russia is located in the area of decentralized power supply, where the main source of energy is imported diesel fuel or associated gas from local fields. At present, one of the directions for the development of renewable power generation in Russia is the implementation of a hybrid power supply system for autonomous power systems of remote regions. However, along with the possibility of using renewable energy sources, it is important for such regions to generate heat from co-generation of diesel power plants, since there is an urgent problem of heat supply for remote regions, especially located in the Far North of Russia. This article presents an analysis of the influence of using renewable energy sources in autonomous power systems on co-generation of diesel power plants.

The paper is devoted to investigations of dynamic processes in a local power system consisting of wind turbines with a magnetic continuously variable transmission. Due to low inertia of wind turbine generator rotors, there is a problem of ensuring dynamic stability at sharp load changes or at short circuits in an autonomous power system. To increase dynamic stability of the system, two algorithms for controlling a magnetic continuously variable transmission are presented. The first algorithm stabilizes a rotation speed of the high-speed rotor of a magnetic continuously variable transmission from the generator side in a local power system consisting of wind turbines with uniform synchronous generators with permanent magnets having equal moments of inertia. Undoubtedly, local power systems having only the wind turbines with equal mechanical inertia time constants are not widely used due to stochastic nature of wind energy. Therefore, wind power systems are combined with a diesel generator or a gas-turbine unit. Investigations show that the use of the only speed stabilization algorithm is not enough for such power systems, because there is a possibility for occurrence of asynchronous operation under specific power changes due to the difference in moments of inertia of generator rotors. Thus, the second algorithm uses the phase shift compensation in accordance with a primary generator in an autonomous power system consisting of non-uniform generators having different mechanical inertia time constants. As a primary generator, a diesel generator or a gas-turbine unit having a primary speed controller may be used. It should be noted that algorithms of stabilization for speed and phase angle are extended by an inertial circuit of aerodynamic compensation for torque of rotation from the wind turbine side to reduce loading on an energy storage unit of the magnetic continuously variable transmission at disturbances from the generator side and the turbine side.

The present paper is devoted to investigations of the influence of the initial response of wind energy and its importance for system reliability. This problem is especially relevant for autonomous power systems with wind turbines. The energy stored in rotating masses of wind turbines and inertial wind energy contribute to the power system inertia. It was found that the decrease of system inertia in the case of higher levels of renewable generation does not have a significant influence on frequency responses in comparison with the regulator action. Wind turbines contribute to the inertial and primary frequency response during the frequency drop in the power system. However, the fast support for the changing frequency with the controlled inertia of wind energy will facilitate the return of the frequency to the normal operating range that allows avoiding load disconnection at low frequencies in the system. The paper also presents comparative characteristics of frequency responses for a wind turbine with a magnetic gearbox and a mechanical gearbox. The aim of the study is to analyze and give a quantitative estimation for frequency responses of wind power plants having various technologies of turbines and transmissions, namely variable-speed of wind wheel rotation, magnetic speed reduction and a synchronous generator with permanent magnets.

Modern development of distributed sources of electricity in Russia is impossible without the development of means to improve its dynamic stability during sudden changes of regime. In this paper a solution of using a pseudo-direct drive is proposed. The relevance of the study is related to the fact that Russia distributed energy sources in isolated power systems have little power. Unfortunately, there are some drawbacks of such power systems in terms of electricity problems associated with the loss of dynamic stability during short circuits.

The paper considers the principle of stabilization for the rotation speed with the use of a magnetic CVT in the form of a magnetic gearbox providing the required reduction coefficient. The paper is devoted to investigations of transients in a autonomous power system consisting of wind turbines with synchronous generators with permanent magnets under sudden change wind speed. The investigation involves the change of wind turbine power under the conditions of inconsistent increase of a wind speed due to remote position of wind turbines. Nowadays, this problem is being solved by the use of DC-links. There is a number of problems concerned with DC-links. One of them is generation of higher harmonics to the network. The paper considers the use of a magnetic continuously variable transmission for coupling of parallel operating turbines without a DC-link. The purpose of the study is dynamic stability stoke increase of local wind energy system by usage magnetic continuous variable transmission. However, there are problems concerned with resonance occurrence conditions that should be considered as constraints. Synthesis of this system with consideration of the magnetic coupling was performed with the development of the algorithm for stabilization of the specified rotation speed with above mentioned constraints. A tandem algorithm of rotation speed stabilization for an electric generator is presented. Note that a magnetic reducer represents a two-mass electromechanical system that may reduce the influence of a turbine torque on a transient process. The first section of the paper states the problem. The second section describes the proposed solution. The third section is concerned with investigations of transients under a variable wind speed.

Nowadays, wind power engineering is developing in two equal directions. The first one is the increase of rated power for a single wind turbine by mass and dimensions parameters of a wind turbine with the use of high-voltage generators. The second one is modernization of wind turbine elements and implementation of modern control systems for a whole wind turbine and for its elements to enhance power generation. These power sources are characterized by the low inertia and the small margin of dynamic stability under sharp power variations, for example, under short circuits. The present paper is devoted to the use of a magnetic continuously variable transmission for synchronization of generators in the power system under transient processes.

The relevance of the research is caused by the fact that more than two thirds of territories in Russia do not have centralized power supply. There are small isolated power systems consisting of several loads ranging from 1 to 15 MW. Unfortunately, the share of small power plants in the world does not exceed 25%. Another part is large gas turbine generators with powers over 20 MW. One of the reasons for the limited use of small power plants is their small margin of dynamic stability due to their low inertia. Note that the loss of dynamic stability occurs under abrupt load changes or short circuits. This paper presents the method for maintaining a synchronous speed of the generator with the use of an electromechanical complex based on a magnetic gear with a variable gear ratio as a part of a wind turbine.