RU2588058C1 - Method for phase control of voltage in electrical system - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering and can be used in electric energy systems and in power supply systems. Technical result is high efficiency of phase control of electric system voltage. Mechanical moment of absolute movement of rotor of synchronous machine electric system is divided on relative and portable. Portable control moment is performed by specified voltage phase shift in accordance with required mode parameters.

EFFECT: technical result is achieved by fact that in method of phase control of voltage in electric network required operating parameters of electric system are set.

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Description

The present invention relates to the field of electric power and can be used in electric power systems and power supply systems for more efficient phase control of voltage in the electric system, synchronous electric machines (synchronous generators, synchronous compensators and synchronous motors).

A known method of phase control voltage in an electrical system (US Pat. 2295817, H02J 3/24. A method of increasing the dynamic stability of synchronous electric machines / Cheban V.M.), in which synchronous electric machines are additionally accelerated or slowed down and thereby the resulting magnetic flux is offset rotor simultaneously with the mechanical rotation of the stator in the direction of relative deviation of the rotor during the disturbance.

However, this method has the following disadvantage: they are not set by the required operational parameters of the phase-controlled electrical system, which does not make it possible to increase the efficiency of the phase voltage control.

In addition, there is a method of phase control voltage in an electrical system (ed. Certificate SU 858175, H02J 3/24. A method of increasing the stability of electrical systems / L.P. Kalinin, V.A. Boshnyaga, V.M. Postolati and I. T. Commandant), which is the prototype of the invention, in which the angle of the phase displacement voltage of the phase-shifting transformer is set, corresponding to the current value of the generator load.

However, the disadvantage is that in this method, the required operational parameters of the phase-controlled electrical system are not set, which does not make it possible to increase the efficiency of the phase voltage control.

The objective (technical result) of the present invention is to increase the efficiency of phase control of the voltage of the electrical system.

The problem is achieved in that in the known method of phase control voltage in the electrical system are set by the required operating parameters of the electrical system with phase control, the mechanical moment of the absolute motion of the rotor of the synchronous machine of the electrical system is divided into relative and portable, control of the portable moment is carried out by the specified phase voltage offset in accordance with the required operational parameters.

In FIG. 1 presents a functional diagram that implements the proposed method.

In FIG. 2 is a diagram and a vector diagram of an electrical system without phase voltage control, explaining the method.

In FIG. 3 is a diagram and a vector diagram of an electrical system with phase voltage control, explaining the method.

The method is as follows (Fig. 1). The required operational parameters of the phase-controlled electrical system are set (1), based on the required operational parameters of the phase-controlled electrical system, a phase displacement control law (2) is formed, according to which the voltage phase displacement is performed (3). The mechanical moment of the absolute motion of the rotor (4) of the synchronous machine in the electrical system is divided into relative (6) and portable (5). The phase shift of the voltage, being an integral part of the mechanical moment of the portable movement of the rotor of the synchronous machine (6), changes it. Since relative (6) and portable (5) mechanical moments are interconnected and make up the absolute mechanical moment of the rotor (4) movement of the synchronous machine (Fig. 1), changing the portable moment (5), the relative (6) is changed. The changing mechanical moment of the relative motion of the rotor (6) determines the mode of the electrical system, giving it the required operating parameters (7).

Thus, they increase the efficiency of phase control of voltage in the electrical system, forming a phase displacement in accordance with the required operating parameters.

To clarify the essence of the proposed method, the simplest mathematical model of an electrical system is presented, which is used to describe electromechanical transients (Venikov A.A. Transient electromechanical processes in electrical systems: Textbook for electric power. Special universities. - 4th ed., Revised) . and add. - M .: Higher school, 1985. - p. 72).

It consists of a differential equation describing the motion of the rotor of a synchronous machine, and its relationship with the algebraic equation of state of the electrical network.

For the simplest electrical system (Fig. 2), consisting of buses of constant voltage (U), coupling resistance (X) and a synchronous machine (CM) having a constant inertia T _J and EMF E. The generally accepted differential equation in synchronously rotating axes ω _o looks in the following way:

where T _J is the constant of mechanical inertia of the SM rotor;

- ускорение ротора СМ (вектора ЭДС Е) относительно синхронно вращающейся оси;

- acceleration of the rotor SM (EMF vector E) relative to a synchronously rotating axis;

δ is the absolute angle that determines the position of the rotor SM (EMF vector E);

δ _Rel - the relative angle between the vector EMF E CM and the buses of constant voltage U;

P ₀ - turbine power;

P _max sin δ _rel - the algebraic equation of state of the electrical network,

- максимальная электромагнитная мощность, передаваемая по сопротивлению связи (X).Where

- maximum electromagnetic power transmitted by the coupling resistance (X).

To solve the differential equation of motion of the electrical system, the relative angle is equated to the absolute (δ _rel = δ).

The introduction (Ф) of the phase displacement (γ) between the buses of constant voltage (U) and voltage (U _Ф ) supplied to the coupling resistance (X) leads to a violation of the equality of absolute δ and relative δ _relative angles in the electrical system (Fig. 3) .

In physics (http://dic.academic.ru/dic.nsf/ruwiki/759581), when considering complex motion, one of the reference systems for the basic (“absolute”) is usually chosen, the other is called “moving” and the following terms are introduced:

- absolute movement is the movement of a point / body in the basic frame of reference,

- relative motion is the movement of a point / body relative to a moving reference frame,

- figurative movement is the movement of the second reference systems relative to the first. The concepts and terms of the corresponding speeds and accelerations are also introduced.

Then, on the basis of the presented vector diagram of the voltage of the electric system with phase control (Fig. 3), the relationship between δ - the absolute angle and δ _rel - the relative angle of the electric network can be written in the following form:

where γ is the angle of the phase shift of the voltage or the portable angle by the definition of complex motion.

Then the relationship of the speeds of the absolute and relative angles:

and accelerations:

As a result, the differential equation in the relative coordinate system, taking into account (1), will look as follows:

or

, управляемый ускорением фазового смещения напряжения

в соответствии с требуемыми режимными параметрами системы и относительный

, определяющий заданный режим (P_maxsinδ_отн) в электрической системе.The mechanical moment of the absolute movement of the rotor of the synchronous machine of the electrical system is divided into portable

controlled by the acceleration of the phase shift of the voltage

in accordance with the required operational parameters of the system and relative

defining a given mode (P _max sinδ _rel ) in the electrical system.

The method of phase voltage control in an electric system with phase control is as follows.

Set the required operational parameters of the electrical system. For example, an electrical system with phase-voltage control should have an aperiodic nature of transients. Such a system is represented by the following differential equation:

where L is the damping coefficient.

Subtract from the equation of motion (6) of the electrical system with phase control of the voltage, equation (7) with the required operating parameters of the electrical system, get the equation for the law of control of the phase shift of the voltage:

, получают закон управления ускорением фазового смещения напряжения:Equate equation (8) for acceleration

get the law of control of the acceleration of the phase shift of the voltage:

Substitute the expression for the law of control of the acceleration of the phase shift of the voltage (9) in (6), and obtain an electrical system with the required operating parameters (7). To implement the control law, it is necessary to have information on δ _rel .

Thus, the technical result of the invention is to increase the efficiency of phase control of voltage in the electrical system, due to the formation of phase displacement in accordance with the required operating parameters of the electrical system.

Claims (1)

The method of phase control of voltage in an electrical system, in which a phase shift of voltage is created, characterized in that it is set by the required operating parameters of the electrical system, the mechanical moment of the absolute rotor motion of the synchronous machine of the electrical system is divided into relative and portable, and the portable torque is controlled by the specified phase shift of voltage in according to the required operational parameters.

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