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INVENTION
Russian Federation Patent RU2282295

METHOD OF VAR compensator and device implements it

METHOD OF VAR compensator and device implements it

Name of the inventor: Kashirin Vyacheslav (RU); Valery Nikonov (RU); Soltus Konstantin Pavlovich
The name of the patentee: Open Joint Stock Company "All-Russian Research and Design Institute of electric locomotive" (JSC "VELNII")
Address for correspondence: 346413, Rostov region, Novocherkassk, st.. Mechanical Engineers, 3, OAO "VELNII"
Starting date of the patent: 2004.09.20

Use: in electrical engineering, electric rolling on single-phase AC-zone-phase control, as a device for improving the power factor. The technical result is reactive power compensation, consumed by electric locomotive, and reducing energy consumption. reactive power compensator (PFC) is connected alternately to one of the few sections of the secondary winding of traction transformer feeding the respective shoulders rectifier inverter converter. Depending on the reactive power value chain, reactive power section is connected to the power supply source. Device implementing the proposed PFC control method further comprises keys through which to connect sections of ASO traction transformer secondary winding, the key management unit, the operation mode setting unit, the voltage and current sensors, computationally-measuring unit.

DESCRIPTION OF THE INVENTION

The invention relates to electrical engineering, namely for electrical equipment of electric rolling stock (e.p.s.) railways, single-phase AC with zone-phase control, and is intended to increase the capacity utilization of the traction power supply system and, consequently, reduce the consumption of electricity.

One of the problems associated with the introduction of on e.p.s. AC reactive power compensators current (PFC), is to find optimal operating conditions of the ASO can help reduce power consumption for e.p.s. generally.

The need to improve the power factor e.p.s. It can be explained as follows. Assume that e.p.s. It works with power P cos = 1 (active load) with a sinusoidal voltage U. In this case the current in the circuit will be And thermal power loss

In practice, the operation e.p.s. performed cos <1 (mixed load), the current in the circuit will be more

.

An increase in the circuit current increases the heat losses

Thus, power losses are proportional to the square of the cos .

For example, increasing cos = 0.8 15% leads to a decrease in supply loss by 41%!

Along with the reduction of losses in the supply chain, by increasing the power factor, there are significant heat losses in the compensator elements - mainly in the inductor, capacitors and thyristor key. Therefore, the combination of accounting losses from the use of compensating devices is an important task to improve the energy performance e.p.s. modern equipped with ASO.

There is a method of reactive power compensator control (RF patent №2187185), consisting in the fact that the reactive power compensation is performed switching power supply with a source of reactive power through the four-quadrant converter. Such a method significantly improves the power factor, but the use of an additional four-quadrant converter is fraught with complication of the control system, the need to use expensive components and, along with an increase in the power factor for different operating modes of energy conversion is accompanied by additional power losses in the elements of the four-quadrant converter.

An analogue of the considered methods of management (RF patent №2187872) is a method in which the desired size and shape of the instantaneous current in the mains input is achieved by adding together the current reactive power compensator and the compensator output distortion and compensating valves of the rectifier control is carried out by three-time inclusion of each valve in the period mains in points equal periodic reference voltages and control voltages.

With this method of management reduced the efficiency of the system reactive power compensation, because with the increase in the number of switching operations for the period increases the value of network voltage electrical losses.

The closest to the proposed technical solutions is a way to control reactive power compensator, passed as a prototype (RF Patent №2212086), when determining the value of the reactive power of the circuit, depending on the voltage and load current, is connected to a power source (sections traction transformer secondary winding ) source of reactive power, regardless of the control zone, reactive power source is connected to the source with a maximum output power. A method of implementing the device containing the reactive power compensator, consisting of two LC-circuits are connected permanently to power supply with maximum power.

This method has a drawback: LC-circuit is permanently connected to a power source. When working with small loads the value of its own losses in the reactive power compensator ( P CC) exceeds the amount of decrease in supply chain losses from the application of the compensator ( P O). Energy management feature of this method is shown in Figure 2. It shows that with increasing chain reactive power Q d absolute loss P O of reactive power compensation in the power supply circuit is reduced more rapidly than grow their own losses in the compensator P CG. Therefore, in the range of operation, which is a sign of a negative difference P CG - About P, reactive power compensation system is inefficient, because the increase in losses in the compensator reactive elements predominates over the decline in losses of reactive power compensation. The value of the reactive power Q O is the point of equilibrium of their own loss of power compensator and the magnitude of decrease in losses from the use of reactive power compensation circuit power. When Q d> Q O observed the effectiveness of reactive power compensation.

Device implementing the method of management comprises a traction transformer, rectifier-inverter drive electric it is attached to the drive motor, two sources of reactive power, consisting of a series connected inductance and capacitance network mode sensor includes a voltage sensor and a current sensor unit clock control unit and a switch. Such a device has the following problem - LC-chain constant reactive power compensator connected to the total voltage of all power sources, although when dealing with fairly small loads powered by one or more (but not all) of the power sources. The obstacle to this is the inability to switch the LC-compensator on the best food sources. Therefore, when working with low load loss value may exceed the energy savings from the use of PFC, which can not guarantee a stable favorable balance of electricity consumption due to overcompensation of reactive power.

The object of the invention is to reduce the consumption of electricity consumed e.p.s.

The stated object is achieved by the control method in which the set value of the minimum allowable reactive power of the reactive power source, and a maximum value of reactive power of the reactive power source when connected to different power supplies, for each working traction motor voltage regulation zone defined value of reactive power of the load, compare the maximum reactive power reactive power source for running on different power sources with the actual value of the load reactive power and connect minimally superior to the value of the load reactive power reactive power source to the appropriate power source, with a decrease in the value of reactive power source of reactive power below the minimum value cut off the source of reactive power from the power source. In order to reduce the inrush current at the times between switching from one source to the other, or at times prior to reconnecting the reactive power source to the power supply, to avoid at oscillation Q d a possible bounce in values Q About, Q KU1 and Q KU2 to supply reactive power for a time equal to, for example, 5 seconds, the time constant determined by the capacity of the discharge on the active PFC circuit resistance, connect a resistive load.

Device for reactive power compensation includes a traction transformer with several sections of the secondary windings, load, made in the form of a rectifier-inverter converter locomotive with the connected primarily multiple traction motors, reactive power source, which is a PFC and consisting of series-connected inductance and capacitance sensor voltage and current sensors, a thyristor switch and a thyristor key control unit. The device further introduced the keys to connect the reactive power source to the appropriate power source, the key management unit, mode dial to specify the number of voltage regulation zones and computationally-measuring unit for determining the moment of switching to the respective PFC power supplies.

New in the proposed technical solution, in contrast to the prior art, it is that the PFC is only connected to the power source by running the converter. In order to reduce power consumption is excluded work ASO low loads, in which their own losses may exceed the ASO reduction of losses in the chain from its use.

This allows us to conclude that the causal link between the set of essential features and achieved technical result.

In the annexed drawings showing:

Figure 1 - wiring diagram of the compensator of reactive power to the power supply;
Figure 2 - Energy characteristics of the work of MRC;
Figure 3 - a device for performing the PFC control method.

Figure 4 - Block diagram of the control algorithm based on the proposed PFC control method.

A device that implements the method of management (3), contains a traction transformer 1, preferably with multiple secondary windings acting as power supplies, rectifier, inverter converter (VCSEL) electric 2 with the connected primarily multiple traction motors (TD) 3 , reactive power compensator (PFC) 4, the sensor contact voltage (DV) 5, the loop current sensor traction motors (DT), 6 keys (CK) 7, consisting of K1 and K2 key wrench, working in opposite states, the key management unit (BUSK) 8, the thyristor switch (TK) 9, the control unit thyristor key (bootkit) 10, dial mode, for which the controller e.p.s. driver can be used (KM) 11, to specify the number of regulation zones, computationally-measuring unit (BVI) 12 to determine when PFC switching to the appropriate power source. At the same time PFC capacitor 4 through normally closed keys 13 and 14, a resistor 15 is connected to the remaining capacity of the discharge points in the PFC switch 4 from one source to another in order to avoid substantial current surges. reactive power compensator 4 is a modular and consists of the LC-circuit, managed switches 7 and 9, to connect it to the secondary windings of traction transformer 1. As driven keys 7 contactors can be used, providing a step change in the reactive power, and thyristors 9, to ensure a smooth change in reactive power compensating device. MRC provides two levels of reactive power depending on the connection to the terminals of the windings of traction transformer 1. The key management unit 8 provides the enabling and disabling key 7 on the signals coming from the computationally-measuring unit 12, and a switch on and off the power key 7 without current interruption. Block thyristor key control 10 ensures the formation of control signals in accordance with algorithms which implement this method of control, unstressed connection LC-circuits ASO 4 to the winding of the traction transformer 1 at the moment when the voltage at the thyristor key 9 through zero, and disabling LC-circuits ASO 4 by winding of traction transformer 1 at the time of transfer thyristor key current 9 through zero. Setting number of the working area the Nz power, characterizing the level of the supply voltage generated connecting certain voltage source to the load is carried out by switching the positions of the electromechanical driver controller 11. When connecting the MRC 4 to the power source 1, one of the key pairs managed 7 K1 or K2 are disconnected from the normal one closed keys K1 K2 13 or 14 in order to divide the discharge circuit of the resistor 15, which is a purely resistive load. These additional losses are eliminated in the ASO 4. In practice, the discharge time to an acceptable level is selected to be 5 seconds.

Computational-measuring unit 12, according to information received from the current sensors 6 voltage and 5, the dial mode (CM) 11 performs a measurement of the actual reactive power at the pantograph of an electric locomotive, the definition of the reactive power generated by the MRC, generates a signal to switch the required PFC stage, but also ASO will trip or a module by removing the control pulses for violations specified (normal) mode. BVI 12 carries and and protection against switching overvoltage on thyristors key elements of the over-current, from external and internal short-circuit, ground fault, and and over-voltage on the capacitors LC-circuits in excess of the rated voltage.

BVI 12 consists of a microprocessor, a random access memory (RAM), read only memory (ROM), analog-to-digital converter (ADC) and timer-counters. The microprocessor, RAM, ROM, ADC, timers and counters may be made on the basis of the industrial controller M167-1h (catalog of products of JSC "cascode" "Airborne and industrial electronics," 189625, St. Petersburg, Pavlovsk, Filtrovskoe Highway 3 (tel. (812) 466-5784, (812) 476-0795), p.66).

Device implementing the proposed method for controlling a reactive power compensator operates as follows. When power begins work computationally-measuring unit 12, and determine the size of the load reactive power on the basis of information from the sensors according to the formula Q d = P d tg Where P d = I d U d, I d - load current, U d - load voltage determined depending on the I d on the external characteristics of the converter, written in the ROM 12 BVI, - The phase shift between current and voltage of the power supply. When the electric reactive power Q d above the lower limit connect one MRC section to a power source with the lowest value (Uist1) and then again determined reactive power circuit Q d and comparing its value to reactive power value operating section Q KU1 (Figure .1). If you exceed the reactive power load on the compensator output value of the switching section of the compensator to a source with higher voltage (Uist2), and then compared with the output value of the value chain of the reactive power compensator Q KU2, and if it is lower, then perform switching compensator on voltage source with a lower value (Uist1), and in its short times of switching the active resistance 15 (discharge resistor), so that if necessary it to reconnect the power supply to prevent the inrush current circuit. The process is repeated cyclically.

Method of implementing the algorithm in Figure 4. Performing it occurs cyclically, the program start automatically when the supply voltage on computationally-measuring unit.

When the supply voltage to the computationally-measuring unit 12 launches the control program (block 16) and the input values of the magnitude of reactive power, which can provide the MRC 4 on the first Q KU1 and second Q KU2 regulation levels and values of the minimum allowable reactive power source of reactive power Q O (block 17). Then, the input value of current traction motors I d and the regulation band VCSEL 7 N Z (block 18), voltage detection on traction motors U d for the external characteristics VIP 7 (block 19), the determination of the actual net power P d (block 20) and determination of the component of the reactive power Q d of the actual net power (block 21).

After determining Q d value of reactive power being compared with the values of Q O and Q KU1 (blocks 22 and 23) and determines to which power supply is necessary to connect the LC-circuit, respectively, setting a sign of the inclusion of the required level (block 25 and block 26). If you want to disable the PFC 4, the sign is set to disable the PFC 4, that is a sign set to include a zero stage (stage 0) (block 24).

After determination of the desired level regulation is compared with the current state of the compensator (block 27) and, if required, and the current status are the same, then, maintaining the current value of the compensator 17 proceeds to block, otherwise switch to implement the desired level. Inspect the compensator (block 28) if the compensator is enabled, disable compensator (block 29), removing the control signals from the thyristor 9 and the key 7. After disabling keys compensator timer is started (block 30), counting down the switching time required to compensator capacity discharged to the discharge resistor 15, and during the switching time continue to control the amount of reactive power Q d. Switching time and provides hysteresis by which is possible to avoid "bounce" keys, the appearance of which it is possible, if the value of reactive power Q d will range in the region of the boundary values About Q and Q KU1. After the switching time (block 31) includes a compensator to the desired level (block 32) by supplying control signals to the keys 7 and thyristor switch 9. Once the program automatically switches to the compensator unit 18 to provide continuous monitoring of the control parameters.

ASO options:

the first step: U = 638, Q = 94 kvar KU1;

the second step: U = 928 B, Q KU1 = 200 kvar.

Thus, the proposed method of controlling a reactive power compensator device and its implements, provide improved power factor and reduced power consumption e.p.s.

commercially acceptable

The proposed method and MRC control device, it is implemented on a pilot-tested two-section section of an electric locomotive VL80 TK -1338, showed a reduction in energy consumption by 6-8%. The invention can be applied to the AC electric rolling traction chains and to the auxiliary drive.

CLAIM

1. A method for controlling a reactive power compensator, consisting in the fact that, for each traction motor operating voltage regulation zone defined quantity of reactive power loads, depending on the voltage and load current power source connected to the source of reactive power, characterized in that the minimum allowable value is set reactive power source of reactive power, but also the maximum value of reactive power source of reactive power when connected to different power sources for each work of traction motors voltage regulation zones determine the amount of reactive power load, compared to the maximum value of reactive power reactive power source for running on different power sources the actual value of the load reactive power and connect minimally superior to the value of the reactive power load reactive power source to the appropriate power source, with a decrease in the value of reactive power source of reactive power below the minimum values ​​disable the source of reactive power from the power source, and in the times between switching from one source to another, or prior reconnecting reactive power source to the power source to the reactive power supply is connected resistive load.

2. A method of controlling reactive power compensator according to claim 1, characterized in that switching from one source to another or re-connection of the power source to the reactive power supply is performed with a time delay of, for example, 5 seconds.

3. A device for compensation of reactive power comprising a traction transformer with several sections of the secondary winding, the load is designed as a rectifier-inverter with electric transducer connected thereto preferably more traction motors, a thyristor switch and a thyristor control unit key source of reactive power, consisting of series-connected inductance and capacitance, voltage sensor connected to the primary winding of a traction transformer, characterized in that it further comprises keys, through which a reactive power compensator connected to the sections of the traction transformer secondary winding, the key management unit, the dial mode, the current sensor circuit traction motor computationally-measuring unit, which are connected to the thyristor control unit key, the key management unit, the operation mode setting unit, the voltage and current sensors.

print version
Publication date 15.02.2007gg