Device for automatic control of reactive power

 

(57) Abstract:

Device for automatic control of reactive power can be used on electric rolling composed of alternating current to improve the power factor of the locomotive. The technical result is to increase the reactive power compensation under sinusoidal and non-sinusoidal shape of the supply voltage and current, as well as in various modes of operation of the locomotive due to the approximation of the shape of the input current to the supply voltage taking into account higher harmonics and to simultaneously reduce the ripple consumed by the locomotive current, which reduces energy consumption. Device for automatic control of reactive power includes a load, a source of reactive power, the sensor network mode, the block synchronizing pulses, the unit pulse-phase control, four multiplier, three integrator, the device calculating the square root and the element of comparison. The source of reactive power consists of series-connected inductance, capacitance, and two anti-parallel connected thyristors, the sensor network mode includes a voltage transformer and current transformer. Load pacoste and counter-parallel connected thyristors, the voltage transformer is connected in parallel with the grid, and its output is connected to the first and the second input of the first multiplier, a first input of the third multiplier and the input of the synchronization pulses. The output of the current transformer is connected to the first and the second input of the second multiplier and a second input of the third multiplier. The outputs of the first-third multiplier products connected with the first inputs of the integrators. The outputs of the first and second integrator connected to the corresponding inputs of the fourth multiplier, the output of which is through the calculation of the square root is connected to the first input of the comparison element. The output of the comparison associated with the input of the pulse-phase control. The output of block synchronization pulses is connected to the second inputs of the integrators, the output of the third integrator connected to the second input of the comparison element, the output of pulse-phase control is connected to the thyristors source of reactive power. 1 Il.

The device relates to electrical engineering, and is intended to improve the power factor of consumers, in particular electric rolling stock AC thyristor converters.

One of the drawbacks operated the cue power factor, reaching at best 0,84. The power factor is one of the major energy indicators of the locomotive, which defines the unproductive consumption of reactive power. The work of a locomotive with a low power factor leads to significant energy losses. To improve the power factor applied compensating installation in the form of LC-circuits located on the locomotive and connected directly to the secondary winding it of traction transformer. The compensating device increases the power factor by creating a capacitive load and displacement of the primary current of the locomotive in the direction of advance of the supply voltage.

A device for controlling the compensated rectifier-inverter inverter electric rolling stock [1], which compensates for the reactive power consumed by the load with sinusoidal and non-sinusoidal supply voltage. Compensation is performed by connecting the secondary winding of the transformer locomotive inductive-capacitive LC compensator with fixed parameters of inductance and capacitance. When the inductive nature of the load it is shown what about the current approaches to the supply voltage, increasing the power factor of a locomotive.

The device includes a voltage transformer load, LC compensator, a key element, the forming device pulses the key element, the trigger element And the driver switch-on pulses, the sensor voltage, the protection block, command block.

LC compensator through the key element is connected in parallel with the load and the secondary winding of the voltage transformer, the primary winding of which is connected to the network. The first input element And is connected with the sensor output voltage, the input of which is connected to the network. The protection unit is connected with the second input element And the output of which is connected to the input "R" trigger run. The inputs of the pulse shaper inclusion connected with the capacitor compensator and a secondary winding of the transformer, and the output - input "C" of the trigger is run, the output of which through the pulse shaping key element is connected with the control input of the key element, the command block is connected to the input of a "D" trigger run.

Function key item is to enable or disable compensator device. When this key element is designed in the form of two counter-steam is run through the pulse shaping key element. At enable input "C" trigger start signal from the shaper's output switch-on pulses, which are generated at points of equal voltage on the capacitor compensator and the secondary winding of the voltage transformer. The signal at the output of the trigger start is generated after the filing of the input "D" of the signal of the command block. When this voltage appears at the output of the trigger coincides with the nearest point of equality of the voltages on the capacitor and the transformer.

The closing of the thyristors key element occurs or in case of exceeding the permissible stresses in the network, or when the protection operation. Signals for disabling are formed respectively by the sensor voltage and the protection block. In the presence of at least one of these signals at the input element And, at its output a signal applied to the input "R" to reset the trigger run. This signal leads to the formation of the output trigger signal for the closing of the thyristors key element.

Thus, a key element of the LC compensator permanently connected to the load, while the main purpose of controls is to prevent overcurrent possible when connecting an LC compensator to the I is carried out by removing the control pulses to the thyristors in the event of a dangerous currents and voltages.

Testing device compensation VL 85 [2] showed that when the power compensator 520 kVAr (1475 UF) average power factor of the locomotive is at the level of 0.92. With this increase the power factor of the locomotive is provided almost two-fold reduction in the consumption of reactive energy for traction of trains.

Thus, the use of LC-compensator of reactive power can significantly improve the power factor of the locomotive and to reduce energy losses by reducing the consumption of reactive power.

However, the application of LC-compensator with constant current compensation improves the power factor of the locomotive only under certain (nominal) load currents. The load deflection of the locomotive from the nominal causes incomplete compensation of reactive power, which reduces the efficiency of use of the device and the power factor is 0,82-0,85.

In addition, the amount of current compensation device is not affected by higher harmonic components of current and voltage circuit. It is known, however, that the magnitude of these harmonics determine the phase shift between the supply voltage and potrebljaemyj">

It is also known a device for automatic control of reactive power [3], which allows you to change the current compensator by regulating the opening angle of the thyristors. When the opening angle of the thyristors is determined by the phase fragile shift between the main harmonics of the network current and voltage. The current compensator is controlled so as to provide minimum phase shift between the input current and the mains voltage. This improves the power factor of an electric locomotive at different load currents.

Device for automatic control of reactive power includes a load, a source of reactive power, the sensor network mode, the block synchronizing pulses, a control unit and a unit pulse-phase control. The load uses a thyristor Converter. The source of reactive power consists of series-connected inductance, capacitance, and two anti-parallel connected thyristors. The sensor network mode includes a voltage transformer and current transformer.

The load is connected to the mains supply through a current transformer and in parallel to the source of reactive power. Transformer, Ihad which is connected with the first inputs of the control unit and the unit pulse-phase control. The output of the current transformer is connected with the second input of the control unit. The output control unit connected to the second input of the pulse-phase control. The output of pulse-phase control associated with the thyristors source of reactive power.

Reactive power compensation is due to the creation of the capacitive component of the load current conducted through the source of reactive power. The magnitude of this current is determined by the opening angle of the thyristors included in the source of reactive power.

Measuring the power factor of the load is largest phase angle shift between current and voltage of the supply network. This method of measurement is implemented using a sensor of reactive power, a control unit and a unit pulse-phase control. The output control unit is formed by a voltage proportional to the load power factor. With this voltage and pulse voltage sync input to the input unit pulse-phase control, conversion voltages in the phase control thyristors IP is th shift angle between the grid current and voltage, the device automatically changes the opening phase of the thyristors. Changing the opening angle of the thyristors leads to an increase in the capacitive component of the current source reactive power flowing out of phase with the inductive component of the current consumed by the load. This causes a decrease of the phase shift angle between the supply voltage and the resulting load current, thereby improving the power factor of the load. So is the compensation of the reactive power load in all modes of operation of the locomotive.

Thus, the known device can compensate for reactive power in all modes of operation of the locomotive.

However, full compensation of reactive power in the device is possible only with sinusoidal voltage and current. This is because with sinusoidal voltage and current, the power factor is determined by the angle shift between these values. In this case, not considered of higher harmonic components of current and voltage. When distorted (non-sinusoidal) form of the supply current and voltage characteristic of the railroads alternating current, the power factor is defined as the ratio between active and is oiste, causes a measurement error with non-sinusoidal shape of the voltage and current, as active and full power also determine and higher harmonic components associated with the distortion of voltage and current. For this reason, the phase angle shift between only the main harmonics of voltage and current are not fully determines the load power factor. This leads to incomplete compensation of reactive power and poor energy performance of the locomotive, so the power factor in this case is 0.85-0.88 to.

The basis of the invention is a device for automatic control of reactive power, which allows to compensate the reactive power of any sinusoidal and non-sinusoidal) voltage and current, as well as in various modes of operation of the locomotive due to the approximation of the shape of the input current to the supply voltage taking into account higher harmonics and to simultaneously reduce the ripple consumed by the locomotive power.

The problem is solved in that the device for automatic control of reactive power, containing the load, which is used is Yunosti, capacity and two anti-parallel connected thyristors, the sensor network mode, which includes a voltage transformer and a current transformer, block sync pulses, the unit pulse-phase control, and the load connected to the mains via the sensor network mode and parallel to the source of reactive power, the first sensor output mode network is connected to the input of the sync pulses, the output of pulse-phase control associated with the thyristors source of reactive power, it added four multiplier, three integrator, the device calculating the square root and the comparison element, the first sensor output mode network connected to the first and the second input of the first multiplier and the first input of the third multiplier, the second sensor output mode network connected to the first and the second input of the second multiplier and a second input of the third multiplier, the outputs of the first - third multiplier products connected with the first inputs of the integrators, the outputs of the first and second integrator connected to the corresponding inputs of the fourth multiplier, the output of which is through the calculation of the square root connected to the first input element cf is Sov connected to the second inputs of the integrators, the output of the third integrator connected to the second input of the comparison element.

Introduction in the device array of new elements (four multiplier products, three integrators, device, square root calculation and comparison element) and their interrelations allows you to accurately measure the power factormlocomotive with non-sinusoidal current and voltage, as well as various modes of operation, which increases the power factor TO amwhile the reactive power consumption is minimized.

This is because the set of features of the device for automatic control of reactive power allows you to define the period of the mains voltage and active and apparent power consumed by the locomotive. When non-sinusoidal shape of the voltage and current power factormlocomotive, calculated over one period of the mains voltage is determined by the ratio of the active P it's full power. Full capacity is defined in the device as the product of the effective values of voltage U and current I for one period of the mains voltage:

Km=P/S=P/UI (1)

where P = uidt,

U, I - effective values of voltage and current, determine the characteristic non-sinusoidal currents and voltages.

Them= P/S also true with sinusoidal current and voltage. In this case, the active power is determined by the ratio P = UIcos, therefore, in accordance with (1) Km= cos, where is the phase shift between voltage and current, i.e., in this case, the power factor can be defined as the cosine of the angle shift between current and voltage.

Thus, the power factormcharacterized by the degree of consumption of the locomotive active and reactive power respectively, i.e., an increasempromotes active power and the simultaneous reduction of reactive. The appearance of reactive power caused by the offset phase input current relative to voltage. Therefore, to reduce the reactive power necessary to approximate the shape of the input current to the shape of the mains voltage.

In addition, the reactive power compensator controlled thyristors allows to compensate reactive power in all modes of operation of the locomotive. With the change of the operation mode is changed inductive component of the load current with the reactive nature. The device by changing the phase of the thyristors opening ismen. The load voltage changes automatically causes a change in the current compensator of reactive power, providing reactive power compensation in all modes of operation of the locomotive.

Based on the value of the network voltage u and current i, the device calculates the active P and apparent power S consumed by the locomotive for the period of the mains voltage ( formulas 1, 2). The difference of the computed values is formed, the opening angle of the thyristor compensator of reactive power, causing the flow through him capacitive current. The direction of this current is in opposite phase with the inductive component of the load current, so the sum of these currents decreases the total reactive load current. Due to this form consumed by the locomotive current approaches to the supply voltage, causing a reduction in the consumed reactive power and improve the power factor of the locomotive. When the opening angle of the thyristor compensator of reactive power is controlled so as to provide maximum compensation of reactive power and increase the power factor of the electric locomotive.

Thus, the device compensates reactive power and increases the power factor of the locomotive when Rome this, due to the approximation curve of the input current i to the form of the network voltage u switching input current i (change of current direction on the opposite occurs at low instantaneous values of voltage u. This helps to reduce ripple input current i, which is evaluated by the ratio of ripple current TOp. It is known [7] that the reduction TOpless than 0.4 - 0.5 causes an increase in cos and power factormelectric locomotive. When these values TOppower factormlocomotive reaches a consistently high level, significantly above this value when the values TOplarge of 0.4 - 0.5.

Thus, increasing the power factor TO amlocomotive is both due to the approximation of the shape of the consumed current i and voltage u, and by reducing the ratio of ripple TOpconsumed current i.

The drawing shows a diagram of the device for automatic control of reactive power.

Device for automatic control of reactive power contains the boot 1, the source of reactive power 2, the sensor network mode 3, the unit sinhroniziruete square root of 13, and the comparison element 14. The source of reactive power 2 consists of series-connected inductance 15, capacitance 16 and two anti-parallel connected thyristors 17, 18. The sensor network mode 3 includes a voltage transformer 19 and the current transformer 20.

Load 1 is connected to the network through the current transformer 20 and parallel to the chain of series-connected inductance 15, the vessel 16 and the counter-parallel connected thyristors 17, 18. The voltage transformer 19 is connected in parallel with the grid, and its output is connected to the first and the second input of the first multiplier 6, the first input of the third multiplier 8 and the input of the block synchronization pulses 4. The output of the current transformer 20 is connected to the first and the second input of the second multiplier 7 and the second input of the third multiplier 8. The outputs of the first-third multiplier products 6-8 connected with the first inputs of the integrators 10-12. The outputs of the first 10 and second 11 integrator connected to the corresponding inputs of the fourth multiplier 9, the output of which is through the calculation of the square root of 13 is connected to the first input of the comparison element 14. The output of the comparison element 14 is connected with the input of the pulse-phase control 5. The output of block synchronization pulses 4 Conn is of 14. The output of pulse-phase control 5 is connected to the thyristors 17, 18 reactive power compensator 2.

As the multiplier used chip CPS, the integrator is made on the basis of the operational amplifier COD, square root calculation is made on the basis of operational amplifiers and described in [5]. Block synchronization pulses made by the patent [6].

Device for automatic control of reactive power is as follows.

The output of voltage transformers 19 and current 20 is formed by a voltage proportional to the instantaneous values of voltage u and the current consumption i. Using multiplier products 6-8 conversion is performed on these signals. At the output of the multiplier 6, a signal is generated that is proportional to u2. The output signal of the multiplier 7 is the value of the i2. The signal at the output of the multiplier 8 is proportional to the product ui input current and supply voltage. Using integrators 10-12 is the integration of the signals at their inputs. At the end of each period of the mains voltage signal at the output of the integrators 10-12, respectively: u2dt, i2dt-isovaline for the period of the mains voltage. The multiplier 9 and the device calculating the square root of 13 is used to evaluate signal proportional to full power S consumed by the Converter during the period of the mains voltage. The signal proportional to the total S and active P power is supplied to the first and the second input of the comparison element 14, respectively, with the outputs of the device to compute the square root of 13, and the third integrator 12. At the output of the comparison element 14 is formed by a voltage proportional to the difference of these signals. The output of the comparison element 14 is fed to the input of block-pulse phase control 5, where the conversion of the input signal to the phase control pulses of the thyristors 17, 18 reactive power compensator 2. When this regulation is reduced to decrease the output voltage comparison element 14, which corresponds to a maximum reduction of reactive power consumed by the Converter by creating a capacitive current component Converter using thyristors 17, 18. Synchronous operation of the integrators 10-12 provides block synchronization pulses 4.

Thus, using the principle of regulating the value of the difference between active and full input power is Agen form of network voltage and current.

Device for automatic control of reactive power has been tested in the depot Belogorsk Transbaikalian railway the locomotive VL. The operation of the device is allowed to increase the power factor of the locomotive to 0.9 to 0.92 in all it's modes, which, in turn, led to the reduction of energy consumption by 10-12%.

Sources of information:

1. A. C. 1468791. Device to control the compensated rectifier-inverter inverter electric rolling stock. The inventors Century A. Kuchumov, C. A. Tatarnikov, N. N. Shirochenko, H., Babaneuri. - Publ. in B. I. N 12 1989, MCI 60 L 9/12.

2. N. N. Shirochenko, C. A. Tatarnikov, H., Babaneuri. Improvement in energy AC locomotives. - Railroad transport, 1988, N 7. C. ZZ.

3. A. C. 1674306. Device for automatic control of reactive power. The inventors A. C. Kopanev, B. M. Naumov, I. K. Yurchenko. - Publ. in B. I. N 32 1991 MCI H 02 J 3/18.

4. L. A. Bessonov. Theoretical foundations of electrical engineering. - M.: Higher school , 1984.

5. E. A. Particularly. Microelectronic means for processing analog signals. - M.: Radio and communication, 1991.

6. Patent N 2118038. Shaper synchronise the static converters. M : Public transport railway publishing house, 1958.

Device for automatic control of reactive power, containing the load, which uses a thyristor Converter, a source of reactive power, consisting of series-connected inductance, capacitance, and two anti-parallel connected thyristors, the sensor network mode, which includes a voltage transformer and a current transformer, block sync pulses, the unit pulse-phase control, and the load connected to the mains supply through a current transformer and in parallel with the source of reactive power, and the output of the voltage transformer connected to the input of the sync pulses, the output of pulse-phase control associated with the thyristors source of reactive power, characterized in that it additionally introduced four multiplier, three integrator, the device calculating the square root and the comparison element, the first sensor output mode network connected to the first and the second input of the first multiplier and the first input of the third multiplier, the second sensor output mode network connected to the first and second entrance pour connected with the first inputs of the integrators, the outputs of the first and second integrator connected to the corresponding inputs of the fourth multiplier, the output of which is through the calculation of the square root is connected to the first input of the comparison element, the output of which is connected with the input of the pulse-phase control, the output of block synchronization pulses is connected to the second inputs of the integrators, the output of the third integrator connected to the second input of the comparison element.

 

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