RU51447U1 - FLEXIBLE COMMUNICATION DEVICE FOR NON-SYNCHRONOUS POWER SYSTEMS - Google Patents

Abstract

The utility model relates to the electric power industry, namely, devices for communication of non-synchronous power systems made on the basis of a two-machine asynchronous electromechanical frequency converter (AC EMF), and can be used for flexible communication of two power systems operating with mismatched frequencies and voltages. The objective of the utility model is to provide the possibility of the normalized participation of generating capacities of one energy system in the automatic regulation of the parameters of the electricity of another energy system. The essence of the proposed utility model lies in the fact that the flexible communication device of non-synchronous power systems contains an EFM AC and a control system, the inputs of which are connected to the frequency sensors of the power systems and active power flow between them, while the control system is configured to automatically control the active power flow in a given relationship from the frequency of at least one power system. The utility model has a development similar methods providing the ability to automatically adjust the reactive power of at least one of the machines EMF EMP depending on the voltage on the tires or on the voltage on the tires and the frequency of the corresponding power system. Other development of the utility model related to the particular case of placing the device in a power plant makes it possible, while maintaining the speed of power control using the EMF frequency generator, to automatically redistribute the load of the power system between the EMI frequency converter and the generator units of the power station to minimize the total losses.

Description

Technical field

The utility model relates to the electric power industry, namely, devices for communication of non-synchronous power systems, based on a two-machine asynchronous electromechanical frequency converter (AC EMF), and can be used for flexible communication of two power systems operating with mismatched frequencies and voltages.

State of the art

Known devices for flexible communication of power systems, made on the basis of AS EMF [ed. testimonial. SU 1246239, 1986, SU 1431005, 1988, SU 1473002. 1989, SU 1504720 1989, SU 1575262, 1990, SU 1576976, 1990, SU 1598043, 1990, US Pat. RU 2020689, 1994, application WO 99/29008 - all in the heading of IPC H 02 J 3/06], with the help of which an overflow of active power from one power system to another is provided.

The disadvantage of known devices, including "Device for communication of two power systems" by ed. testimonial. No. 1575262, selected as a prototype, is as follows.

When load changes in each of the connected power systems, independent automatic frequency and voltage regulation is carried out by the generating units of each power system, equipped with their own turbine power controllers that work to maintain frequency, and their own generator excitation controllers that work to maintain voltage. The power transmitted through the EMF system from one power system to another is set and changed by the operator. With this task of power flow, the generating capacities of the transmitting power system do not participate in the automatic (without operator participation) maintenance of frequency and voltage in the receiving power system.

Utility model creature disclosure

The objective of the utility model is to provide the possibility of the normalized participation of generating capacities of one energy system in the automatic regulation of the parameters of the electricity of another energy system.

The essence of the proposed utility model lies in the fact that the flexible communication device of non-synchronous power systems contains an EFM AC and a control system, the inputs of which are connected to the frequency sensors of the power systems and active power flow between them, while the control system is configured to automatically control the active power flow in a given relationship from the frequency of at least one power system.

This makes it possible for one power system to participate in the automatic frequency control of another power system.

The utility model has development.

One of them consists in the fact that the device contains reactive power sensors of at least one of the AC EMF machines and the voltage on the tires of at least one of the power systems connected to the inputs of the control system, which is configured to automatically control the specified reactive power in a given dependence on the voltage on the tires of the corresponding power system.

This allows you to ensure the complexity of the participation of the device in the automatic control of the electric power parameters of the corresponding power system.

Another development is that the device contains reactive power sensors of at least one of the machines of an asynchronized electromechanical frequency and voltage converter on the tires of at least one of the power systems connected to the inputs of the control system, which is configured to automatically control said reactive power in a given dependence on the voltage on the tires and the frequency of the corresponding power system.

This makes it possible to use the capabilities of the AC EMF to change reactive power to optimize the process of automatic regulation of frequency and voltage on the buses of the corresponding power system.

The following three developments of the utility model relate to the particular case of placing the device in power plants and are aimed at minimizing

total losses by redistributing power between the EMPCH AC and the generating units of the power plant while maintaining the speed of regulation of electric parameters using the EMPCH AC.

One of these developments is that the control system can be equipped with means for influencing the power regulator of at least one generator unit connected to one of the power systems, and is configured to automatically control the active power of the specified unit in a given dependence on the frequency of the corresponding power systems and the magnitude of the flow of active power through the AC EMF.

Another development is that the control system can be equipped with means for influencing the excitation regulator of at least one generator unit connected to one of the power systems, and is configured to automatically control the reactive power of the specified unit in a given dependence on the voltage on the tires power system and reactive power of the corresponding machine asynchronous electromechanical frequency converter,

The third development consists in the fact that the control system can be equipped with means for influencing the excitation regulator of at least one generator unit connected to one of the power systems, and is configured to automatically control the reactive power of the specified unit in a given dependence on the voltage on the tires and frequency of the corresponding power system.

The control system of the device can be made programmable, for example, based on a computer.

Brief Description of the Figures

Figure 1 presents a block diagram illustrating an example implementation of the device, taking into account the development of the utility model. 2 and 3 illustrate examples of functional dependencies defined in the control system of the device. Figure 4 illustrates the process of in-line power transfer from AC EHF to the generating units of a power plant.

Utility Model Implementation

Figure 1 shows an example of the implementation of flexible communication between power systems according to a utility model, taking into account its development.

The connection between the power systems 1 and 2 is provided by the EMF AS, which includes two asynchronized synchronous machines 3 and 4 mounted on a common shaft. The stator windings of machines 3 and 4 are connected to sections 5 and 6 of a switchgear (RU) operating in power systems 1 and 2, respectively. The rotor windings of machines 3 and 4 are powered by frequency converters 7 and 8 that are part of the AC EMF.

The control system 9 includes blocks 10, 11, 12. The inputs 13 and 14 of the system 9 are connected to the outputs of the sensors 15 and 16 of the frequencies of the power systems 1 and 2, respectively, the inputs 17 and 18 are the outputs of the sensors 19, 20 of the voltage sections 5 and 6, respectively. The input 21 of the system 9 is connected to the output of the sensor 22 of the transmitted or received (overflow) active power, the input of which is included in the stator circuit of one of the machines 3 or 4, and the input 23 of the system 9 is the output of the reactive power sensor 24 included in the specified circuit. In addition, the output of the sensor 26 of the shaft speed of the AC EMF is connected to the input 25 of the system 9.

To sections 5 and 6 can be connected to one or more generator units 27 and 28, operating in power systems 1 and 2, respectively, equipped with their own regulators 29 power and 30 excitation.

Block 10 directly controls the converters 7 and 8, to the control inputs of which the outputs 31 and 32 of block 10 are connected. Block 11 controls the parameters and modes of flexible communication between power systems 1 and 2, and block 12 provides the interface of system 9 with the regulators 29 and 30.

System 9 (in particular, its block 11) can be made programmable, for example, based on a computer.

The device operates as follows.

Each of the power systems 1 and 2 generates electricity with its own frequency and voltage values on the buses of the corresponding sections 5 and 6.

The common shaft of machines 3 and 4, one of which operates in the motor mode, and the other in the generator mode, rotates at a speed that is measured by the sensor 26 and is proportional to the average value of the frequencies measured by the sensors 15 and 16. The connection between the systems is characterized by the amount of active power flow, generated in one power system, through the EMF system in another power system.

Let, for example, in block 11, it is given (programmed) the dependence of the change in the value of the flow of active power into the power system 1 on the frequency measured by the sensor 15, shown in FIG. 2. Then, if the deviation of the frequency from the nominal value is close to zero (does not go beyond the measurement error), block 11, comparing the value of the active power overflow measured by the sensor 22, with the value of the set point (P ₀₁ , P ₀₂ , P ₀₃ in figure 2) acts through the block 10 on the converters 7 and 8 to reduce the mismatch of the compared values and maintain the set value of the active power measured by the sensor 22. If the frequency measured by the sensor 15 deviates from the nominal value by Δf, then the block 11 compares the active power measured by the sensor 22 with a different value deviating from a given setting in accordance with the dependencies shown in figure 2. and, thereby, automatically switches to the mode of maintaining the flow of active power at a new level, for example, P ₀₁ ± ΔР. In this case, the sign and ΔР value depends on the sign and the magnitude of the frequency deviation from the nominal.

Let, for example, in block 11, the dependence of the change in the magnitude of the reactive power supplied by the AC EMF to the power system 1 on the voltage measured by the sensor 19 and the frequency measured by the sensor 15, shown in Fig. 3, is set (programmed). Then, if the deviation ΔU of the voltage from the nominal value is close to zero (does not go beyond the measurement error), block 11, comparing the magnitude of the reactive power measured by the sensor 24, with the value of the set point (Q ₀₁ , Q ₀₂ in figure 3), acts through unit 10 to the converters 7 and 8 to reduce the mismatch of the compared values and maintain a given value of reactive power measured by the sensor 24. If the voltage measured by the sensor 19 deviates from the nominal value by ΔU, then block 11 compares the reactive power measured by the sensor 24 with a different value deviating from the set

settings in accordance with the dependency families shown in FIG. 3, and thereby automatically switches to the mode of maintaining reactive power at a new level, for example, Q ₀₁ ± ΔQ. In this case, the sign and value ΔQ depends on the sign and magnitude of the voltage deviation from the nominal, as well as on the deviation Δf of the frequency measured by the sensor 15 from the nominal, which serves as a parameter of the dependency families shown in Fig.3.

In the case of flexible communication through sections of the power plant RU, on which the device is located, the control system 9 can be equipped with means for influencing (block 12) the power regulator 29 and / or the excitation regulator 30 of one or more generator units 27 of the power plant connected, for example, to section 5. At the same time, the setpoints for the transfer of active power and for the reactive power of the AC EMF can be changed taking into account the capacities given by the entire power plant to system 1 and measured by sensors 33 and 34 of the active and active power respectively.

For the case of placing the device in a power plant, we consider its operation in two modes: stationary and transitional.

In the stationary mode, depending on the direction of the power flow, the EMF can be in three main states:

- power is transmitted from power system 1 to power system 2;

- power is transmitted from power system 2 to power system 1;

- power is not transmitted through the AC EMF.

The presence of an EMPF AC in one of these states is determined by the ratio of excess or deficit of power in power systems. The location of the device inside the power plant allows you to cover the power shortage of one power system at the expense of another, as well as to use the AC EFM when putting any unit in reserve or for repair work.

Figure 4 shows curves illustrating this process:

a is the dependence of power in the power system 1 on time;

b - the dependence of the frequency in the power system 1 on time;

in - the dependence of the power at the output of the AC EMF (power flow) from time to time;

g is the dependence of the power of units 27 on time.

Suppose that the power system 1 operates with a power value P ₁ and a frequency value f ₁ . At the same time, power is not transmitted through the EMF system, and the units 27 connected to section 5 generate power P ₁ . Consider the case when the load power in the power system 1 at the time t ₁ increased from the value of P ₁ to the value of P ₂ By the time t _{2 the} frequency in the system decreased to the value of f ₂ . At this point, the flexible communication device begins to work out the disturbance in the power system 1, changing the active power flow through the EFM AC as a function of frequency (see Fig. 2), acting on the generators 27, starts the transfer of the power system 1 to the power generation state P ₂ . By the time t _{3, the} transient in the power system 1 ends, while the AC EFM transfers from the power system 2 to the power system 1 a certain power P ₃ = P ₂ -P ₁ , which helps to establish a new frequency value f ₃ in accordance with the given dependence.

At time t ₂ also begins the process of regulating the power of the units 27 depending on the frequency of the system 1 and the magnitude of the overflow - power through the AC EMF. However, due to the low speed of the units 27, their contribution to the regulation process is negligible and only at time t ₃ they begin to make a significant contribution to the regulation process. It can be said that at this moment, the process of in-line transfer of power P ₃ from the AC EFM to the units 27 begins. By the time t _{4, the} units 27 generate additional power P ₂ -P ₁ , but the power is not transmitted through the AC EFM.

The considered algorithm of in-plant power transfer from the EMF to the generating units 27 is not the only possible one, but depends on the control principles adopted in a particular power system. For example, it is possible to prevent the frequency from falling to a value of f ₂ , and to ensure its smooth change from a value of f ₁ to a value of f ₃ according to a given dependence or to regulate the AC EMF not start at time t ₂ but at a time in the interval t ₁ ≤t ≤t ₂ .

The process of in-line conversion of reactive power is carried out similarly.

The feasibility of power transfer is determined in each case separately.

The advantages of the proposed device significantly expand the functionality of flexible communication between power systems, which allows it to be used to satisfy a variety of requirements for the interaction of connected power systems, including requirements for interaction algorithms in emergency situations.

Claims (7)

1. A flexible communication device for non-synchronous power systems, comprising a two-machine asynchronous electromechanical frequency converter and a control system, to the inputs of which are connected the frequency sensors of the power systems and the active power flow between them, while the control system is configured to automatically control the active power flow in a given frequency dependence, at least one power system. 2. The device according to claim 1, containing reactive power sensors of at least one of the machines of an asynchronized electromechanical frequency and voltage converter on the tires of at least one of the power systems connected to the inputs of the control system, which is configured to automatically control said reactive power in a given dependence on the voltage on the tires of the corresponding power system. 3. The device according to claim 1, containing reactive power sensors of at least one of the machines of an asynchronized electromechanical frequency and voltage converter on the tires of at least one of the power systems connected to the inputs of the control system, which is configured to automatically control said reactive power in a given dependence on the voltage on the tires and the frequency of the corresponding power system. 4. The device according to claim 1, intended for placement in a power plant, in which the control system is equipped with means for influencing the power regulator of at least one generator unit connected to one of the power systems, and is configured to automatically control the active power of the specified unit in a given dependence on the frequency of the corresponding power system and the amount of active power flow through an asynchronous electromechanical frequency converter. 5. The device according to claim 4, in which the control system is equipped with means for influencing the excitation controller of at least one generator unit connected to one of the power systems, and is configured to automatically control the reactive power of the specified unit in a predetermined dependence on the voltage on the tires corresponding power system and reactive power of the corresponding machine asynchronous electromechanical frequency converter. 6. The device according to claim 4, in which the control system is equipped with means for influencing the excitation regulator of at least one generator unit connected to one of the power systems, and is configured to automatically control the reactive power of the specified unit in a predetermined dependence on the voltage on the tires and frequency of the corresponding power system. 7. The device according to claim 1, in which the control system is made programmable, for example, based on a computer.