SU1575262A2 - Device for interfacing two power systems - Google Patents

Abstract

The invention relates to the field of electrical engineering, and more specifically to electromechanical frequency converters for flexible communication of power systems with differing frequencies. The aim of the invention is to increase the reliability of the device by ensuring the operation of both machines of the unit with permissible voltage levels of stators. This is achieved by introducing additional blocks 38 and 39, the inputs of which are connected to voltage sensors 30 and 31, and the outputs to the additional inputs of summing elements 10 and 12. When the input voltage of the additional block 38 (or 39) exceeds some acceptable level This block generates a control signal of the required polarity, which is input to the summing element 10 (or 12). This reduces the value of the emf so that the stator voltage of the machine does not exceed the permissible level, i.e. The goal is achieved. 8 il.

Description

calibrated voltage source and a 20 volt that the established mode

adjustable potentiometer connected to the inputs of the operating controller 60, the output of which is through the diode 61

connected to the output of block 38. i

Operational controller 60 is in the simplest case a proportional controller, but can be implemented, for example, in the form of a proportional-differential controller. Diode 61 provides only one polarity signal transmission. When the device is in operation, the elements 16, 20, 24 and 18, 22, 26 provide proportional-integral-differential voltage regulation on the stators of machines 3 and 4. The control signal setter 15 provides the task for the flow of active power through the power line with the proposed device. Elements 17, 21, 25 and 19, 23, 27 realize proportional-integral-differential regulation of the speed (frequency) of the rotation of the shaft of the unit. At the same time, the reference (setpoint) is generated from the signals of sensors 32 and 33 as half the sum of the frequencies of the power systems to be combined. provide the greatest use of controllable, modifiable converters 5 and 6, Output

The sensor 15 is connected to the input of a 50-line or 3-phase short circuit element 12, and through an inverter (no number in FIG. 1) to the input of a summing element 10. Therefore, when the device operates, the signals arriving at the indicated inputs of its sum In addition, machine 3 worked before the failure of elements 10 and 12, have different motor or generator mode, and this determines that one mama. When accelerating or “decelerating, the outboard tire of the unit works as a generator, and a friend is driven. The magnitude of these nostatic signals between the setpoint and the drive, which cause the electromagnetic moment of the machine 4 to drop to zero, the unit begins to accelerate or brake, depending on

for electric machines, the mode with a deviation from the task of 3% is considered; therefore, the device can refuse to regulate by active

5th power. In turn, this makes it possible to identify the regulators of the machines of the device, which has an operational advantage, and to increase stability. Rise of the foundations

This is achieved due to the fact that both machines are controlled by sliding. Therefore, for example, during short circuits and disconnections of communication lines with the power system, there is no need to restructure the regulator structure of the unit remaining in the machine. Moreover, if the perturbation is large and with a given optimal tuning of the control coefficients of the amplifying, differentiating

0

and integrating elements of speed

machines can go beyond the allowable range, additional regulation takes effect with the help of 5 control unit 35, which, according to the estimated value of the slip derivative, reveals the specified large disturbance. With large disturbances in the power system 2, for example, outages

five

line or 3-phase short-circuit, the machine 3 worked before the accident in the motor or generator mode. When accelerating or “braking differentiated in element 23, there is a good signal between setpoint and linkage, which leads to The electromagnetic moment of the machine 4 drops to zero, the unit begins to accelerate or decelerate, depending on

the mud speed of the shaft (i.e.

/ the slip derivative signal is supplied (Fig. 5) to the adders 52 and 53 operating in the comparator mode. Moreover, if this signal is greater than the value determined by the level controllers of the derivative of slip 54 and 55, a signal of a given amplitude and polarity is produced at the output of one of the adders 52 and 53. This signal through a diode (for example, 56) and an amplifier 58, which serves to amplify the signal and decouple the outputs of the adders 52 and 53-, goes to the integrators 25 and 27, which integrate this high amplitude signal and brake the machine .3. As soon as the slip derivative enters the range defined by the setting units 54 and 55, the signal from the output of the adder 58 disappears and the device restores the unit mode by sliding. In this case, as mentioned above, the stability of the unit is maintained due to proportional-integral-differential regulation by elements 17, 21, and 25. As soon as the disturbance is eliminated (after successful APB) and the power line is restored, the asynchronized synchronous machines realize proportional-integral -differential control along the slide together with an additional control signal of large amplitude from the control unit 35. This allows the device to enter the normal load mode, not going beyond the slip range, significantly faster than without the control unit 35. This is achieved, as noted above, by shorting or disconnecting the transmission line, the slip derivative changes immediately, therefore, the control unit 35 generates its additional control signal immediately at the beginning of the disturbance, and not after some time as in the device without block 35. In FIG. 1, the control signal adjuster 15 is shown made in common with the direct and inverting outputs, but each machine can have its own control signal adjuster. The control devices 13, 14 and 15 are made, for example, as sources of calibrated voltage with series-connected adjustable potentiometers.

ten

15

20

25

45

50

55

In the device of FIG. 1, the machine 3 can also contain its own control unit, which can be connected between the output of the differentiating element 21 and the auxiliary input of the integrating element 25. In this case, the control systems of both machines will be identical and mutually independent.

Consider the operation of the device with the adopted law of machine control of the unit according to the connection scheme of Fig. 7.

The control system (CP-, 2) of each machine receives a signal (besides the standard ones, without which the device cannot function) of the voltage reference vector (U) from any node of the power system. In this case, the key K is closed, and the key K2 is open. For simplicity, consider the mode when the power of the machine M2 is equal to the power of the load and along the lines between buses with voltages i2 and U

no flow (at the same time

RA +

jXrt, “0).

The vector diagram of this mode is shown in Fig. 8, where the 0V vector is the EMF of the nominal mode (En),

30 vector SW is the vector jXriH of the nominal mode, vector OD is the voltage drop vector on the active load resistance (R, iH), DC vector is the voltage drop vector on the inductor

,,. load resistance (jXHiH). In this case, the vectors of the voltages igg and b coincide and occupy the position of the OS. Let the key K be turned off. As before, the mode of the machine and the load was

4Q is balanced, then practically after switching off the key K {nothing will happen and the vector diagram will retain its original position. If, further, with the key K ,, short-circuit part of the load, then the load at the same voltage cos remains unchanged, the current in the circuits of the circuit increases and the full vector diagram (Fig. 8) would have to occupy the position of ODCBAO, because . the voltage drop vector on the inductive resistance of the machine increases to the value - SA. Accordingly, the EMF vector increases to OA (vector E). The control, as noted, is carried out in the x-U2 axis of the U2 voltage and the signal in the qU2 axis is constant (Food const), since in the channel of the electromagnetic moment control

y1

carried out only on the speed of rotation of the shaft. Therefore, the ODCBAO vector diagram cannot exist. Obviously, due to an increase in the current, the voltage on the tires of the 11G4 machine decreases, which causes a change in the Ejy signal, which tends to maintain the voltage Ugl in accordance with the setting. Change EJJ. point B of the vector diagram is shifted to point A, which is equivalent to rotating the entire vector diagram to a new position OD C A O. In this case, the stress vector Urg will take a new position

wasp (s).

Another ACM (Ml) while working as follows.

If the load ramp (reset) is insignificant, then the speed controller due to the imbalance between the setpoint and the true rotor speed caused by the specified load ramp (reset) due to the integral part, will change its total signal so that the power balance in the device will be restored. If the load (discharge) load is large, which would cause the machine to go to the ceiling voltage, then the control unit 35 comes into play, which in terms of the slip derivative generates an additional signal at the integrator input and thus contributes to maintaining the excitation voltage within the ceiling value . When the circuit is restored (when the key K is closed), regardless of the position of the key K, the ACM2 will take on a load determined only by a value that, as accepted, is constant. However, this significantly increases the reactive power of the AFM2, since The end of vector E is at point A, therefore the voltage regulator with voltage reduction to the setpoint value will return the machine to its original mode, as determined by the ODCBO vector diagram. Another machine of the unit will take it as a load shedding (load) and will work in the manner described,

I

Obviously, if the load surges cause an increase in the emf and the vector Ur2 begins to lag behind the q axis when the set value is preserved, then a load shedding will cause a reverse rotation of the vector diagram (i.e., in the direction of advance),

2 | P

In Fig. 8, a vector diagram C of ElCGO is rocked with the same cosCJn and Еа const, even when the load decreases, it is possible to maintain the equality of the OS of the game.

those. U. In the limit, i.e. when idling, EoU2, which greatly exceeds the permissible stator voltage level of the machine. When exceeding the value of the voltage UG2

at the input of an additional block 38 (or 39) of control of the signal of the generator 59 of the allowable voltage level, the iDOP operating regulator 60 generates a control signal of the desired polarity, entering through

diode 61 to the input of the summing element 10. Thus, the value of the EMF Eait.t is reduced so that the stator voltage of the machine does not exceed the allowable

level The goal is achieved.

Overloading and dumping can be any, therefore the advantage of the proposed control is

that there is no need to adjust any settings for power or voltage - the mode is always set by itself.

The proposed device makes it possible to increase the reliability of intersystem communications based on two asynchronized synchronous machines, i.e. improve the working conditions of consumers by reducing interruptions in energy supply by increasing stability in the event of large disturbances in the interconnected power system.

Claims (1)

Invention Formula 45 A device for the connection of two power systems by auth.St. No. 1431005, t. It is characterized by the fact that, in order to increase the reliability of the device by ensuring that both machines operate with an acceptable stator voltage level, it is equipped with two identical additional control units, and the summing elements The electromagnetically controlled torque control channels of both controllers are each made with an additional POSITION connected via the corresponding additional control unit to the output of the voltage sensor of each machine; the additional control unit contains a proportional or proportional-differential control, voltage tolerance unit diode, in this case, jb) et 9 & pt the input of the additional control unit and the output of the unit of the allowable voltage level are connected to the input of the said regulator, the output of which through the diode is connected to the output of the additional control unit. 2 e (b) c-UpK Fig.Z I I1 / .. jr -J Fie.7 Fa in (It