BG4271U1 - Device for assessment of pulse power in power supply systems asymmetry - Google Patents

Abstract

The device according to the utility model relates to the field of electrical measuring devices and will find application in power supply systems. The device comprises a voltage measuring unit (1) and a current measuring unit (2) connected to a phase converter (3), the outputs of which are connected to a power torque unit (4), the output of which is connected to a pulse power forming unit (5), which is connected by its output to a final measurement result registration unit (6). The voltage measuring unit (1) consists of three voltage transformers (1.1) and the current measuring unit (2) consists of three current transformers (2.1). The phase converter (3) consists of a voltage phase converter unit (3.1) and a current phase converter unit (3.2). The torque power converter unit (4) comprises two multipliers (4.1) whose outputs are connected to the inputs of an adder (4.2). The pulsed power forming unit (5) includes an average value unit (5.1) and a peak detector unit (5.2) whose outputs are connected to the two inputs of the subtraction unit (5.3). The final measurement result registration unit (6) includes an analogue-to-digital converter (6.1) whose output is connected to an indication unit (6.2).

Description

(54) DEVICE FOR ASSESSMENT OF PULSATING POWER IN CASE OF UNSYMMETRY IN ELECTRICAL SUPPLY SYSTEMS

Field of technique

The device according to the utility model refers to the field of electrotechnical measuring devices and will find application in electrical supply systems (ESS).

Prior art

From practice, a device is known for evaluating the inactive power in the ESS arising as a consequence of the asymmetry, called pulsating "N", containing a voltage measuring unit consisting of three voltage transformers and a current measuring unit consisting of three current transformers, which are connected to the three inputs of blocks for forming the effective value of voltage and current, respectively for phases "a", "b" and "c". The blocks for forming the effective value of the voltage and the current are each equipped with three outputs, which are connected to the three inputs of two blocks of vector generators of the three phase voltages and the current for the phases "a", "b" and "c". The three-phase voltage and current vector generator blocks are provided with three outputs connected to the three inputs of forward voltage and current sequence blocks and to the three inputs of reverse voltage and current sequence blocks. The output of the forward voltage sequence block and the output of the reverse current sequence block are connected to the two inputs of a first vector multiplication block. The output of the reverse voltage sequence block and the output of the forward current sequence block are connected to the two inputs of a second vector multiplication block. The outputs of the two vector multipliers are connected to the two inputs of an adder whose output is connected to the input of an absolute value block.

The output of this block is connected to the input of an analog-to-digital converter whose output is connected to an indication block.

The analog-digital converter and the display block connected to its output are components of a block for recording the final result of the measurement.

In the known device, the pulsating power is evaluated by forming and decomposing the vectors of the three phase voltages and currents into symmetrical components, according to [1] and the international standard [2]. The accuracy of the described solution is limited by the fact that the individual blocks of the device are characterized by complexity caused by the relatively large number of elements included in the composition of each of them, as sub-blocks. This causes a significant increase in the resulting error when determining the pulsating power.

Technical nature of the utility model

The purpose of the utility model is to create an instrument for evaluating the pulsating power in power supply systems with a simplified device, by means of which a smaller effective measurement error can be achieved.

The goal was achieved by means of a proposed utility model device for evaluating the pulsating power in asymmetrically loaded power supply systems, including a voltage measuring unit and a current measuring unit connected to a phase converter, the outputs of which are connected to an instantaneous power unit. The output of the latter is connected to a pulsating power generator block, which is connected with its output to a block for recording the final result of the measurement. The voltage measuring unit consists of three voltage transformers and the current measuring unit consists of three current transformers. The phase converter consists of a voltage phase converter block and a current phase converter block to convert the three-phase system into an equivalent two-phase orthogonal system with real and imaginary phase signals. The inputs of the voltage phase converter block are connected to the three voltage transformers and the inputs of the current phase converter block are connected to the three current transformers. The instantaneous power block includes two multipliers whose outputs are connected to the inputs of an adder. The real phase signal output of the voltage phase converter block and the real phase signal output of the current phase converter block are connected to the two inputs of one multiplier. The output for the imaginary phase of the signal of the voltage phase converter block and the output for the imaginary phase of the signal of the current phase converter block are connected to the two inputs of the second multiplier. The ripple power shaper block includes an average value block and a peak detector block whose outputs are connected to the two inputs of a subtraction block. The connection between the instantaneous power block and the pulsating power shaper block is made with the output of the adder connected to the input of the average value block and to the input of the maximum detector block. The unit for recording the final result of the measurement includes an analog-to-digital converter whose output is connected to an indication unit. The connection between the pulsating power generator block and the final result registration block is made by the output of the subtraction block being connected to the input of the analog-to-digital converter.

The device for evaluating the pulsating power at unsymmetry in power supply systems according to the utility model is based on the evaluation of instantaneous power in three-phase systems. It is characterized by a simplified device, compared to the device known from the state of the art, by means of which a significantly smaller resulting measurement error is achieved.

Explanation of the attached figure

Figure 1 shows a block diagram of the device for evaluating the pulsating power in power supply systems, according to the utility model.

Example implementation of the utility model

An exemplary implementation of the device for evaluating the pulsating power (N) in power supply systems according to the utility model is shown in figure 1. The device consists of a voltage measuring unit 1 and a current measuring unit 2 connected to a phase converter 3, the outputs of which are switched to the instantaneous power block 4, the output of which is connected to the pulsating power generator block 5, which is connected with its output to the final measurement result registration block 6. The voltage measuring block 1 consists of three voltage transformers 1.1, to which are connected the inputs of the voltage phase converter block 3.1, representing a part of the phase converter 3, and the current measuring block 2 consists of three current transformers 2.1, to which the inputs of the current phase converter block 3.2, also part of the phase converter 3, are connected. The instantaneous power block 4 includes two multipliers 4.1, the outputs of which are connected to the sum inputs ator 4.2. The output for the real phase of the signal of the voltage phase converter block 3.1 and the output for the real phase of the signal of the current phase converter block 3.2 are connected to the two inputs of the one1 multiplier 4.1. The output for the imaginary phase of the signal of the voltage phase converter block 3.1 and the output for the imaginary phase of the signal of the current phase converter block 3.2 are connected to the two inputs of the second multiplier 4.1. The pulsating power generator block 5 includes an average value block 5.1 and a maximum detector block 5.2, the outputs of which are connected to the two inputs of the subtraction block 5.3. The connection between the block of instantaneous power 4 and the block of generator of the pulsating power 5 is realized, and the output of the adder 4.2 is connected to the input of the average value block 5.1 and to the input of the block of the maximum detector 5.2. The unit for recording the final measurement result 6 includes an analog-to-digital converter 6.1, the output of which is connected to an indication unit 6.2. The connection between the pulsating power generator block 5 and the final result registration block 6 is made by the output of the subtraction block 5.3 being connected to the input of the analog-to-digital converter 6.1.

Using the utility model

The device according to the utility model works by measuring the voltages and currents from the three-phase system with the three voltage transformers 1.1 and the three current transformers 2.1. The outputs of the two types of measuring transformers are converted into proportional voltage signals corresponding to the voltages and currents of a three-phase system. The two three-phase electrical systems, voltage and current through the phase converters 3.1 and 3.2 are transformed into two-phase orthogonal systems with real and imaginary phase of the signals equivalent to the three-phase systems. These electrical signals are fed separately to the inputs of the two multipliers 4.1, and the real phases of the signals from the outputs of the converters 3.1 and 3.2 are fed to the inputs of the first multiplier 4.1, and the imaginary phases of the signals from the outputs of the converters are fed to the inputs of the second multiplier 4.1 3.1 and 3.2, whereby the signals from the outputs of the two multipliers 4.1 are fed to the two inputs of the adder 4.2, and from its output the signal enters the input of the average value formation block 5.1, and the input of the maximum detector block 5.2. From the outputs of the blocks 5.1 and 5.2, the signals are fed to the two inputs of the subtraction block 5.3, in which an output signal from this block is formed, which corresponds to the pulsating power "N". The analog signal from the output of the block 5.3 is fed to the analog-to-digital converter block 6.1, the output signal of which goes to the input of the display block 6.2.

Claims (1)

1. Apparatus for evaluating the pulsating power in case of asymmetry in power supply systems, including a voltage measuring unit consisting of three voltage transformers and a current measuring unit consisting of three current transformers, as well as a unit for recording the final result of the measurement consisting of an analog-to-digital converter, the output of which is connected to an indication unit, characterized in that the voltage measuring unit (1) and the current measuring unit (2) are connected to a phase converter (3), the outputs of which are connected to an instantaneous unit power (4), the output of which is connected to a pulsating power generator block (5), which is connected with its output to the block for recording the final result of the measurement (6), and the phase converter (3) consists of a phase converter block of the voltage (3.1) and current phase converter block (3.2), in which the connection between the voltage measuring block (1) and the phase converter (3) is realized vein, as the inputs of the voltage phase converter block (3.1) are connected to the three voltage transformers (1.1), and the connection between the current measuring block (2) and the phase converter (3) is made, as the inputs of the current phase converter block ( 3.2) are connected to the three current transformers (2.1), and the instantaneous power block (4) includes two multipliers (4.1), the outputs of which are connected to the inputs of an adder (4.2), whereby the connection between the phase converter (3) and the instantaneous power block power (4) is accomplished by connecting the real phase signal output of the voltage phase converter block (3.1) and the real phase signal output of the current phase converter block (3.2) to the two inputs of one multiplier (4.1) , and the output for the imaginary phase of the signal of the voltage phase converter block (3.1) and the output for the imaginary phase of the signal of the current phase converter block (3.2) are connected to the two inputs of a second multiplier (4.1), the pulsating power generator block (5) includes an average value block (5.1) and a maximum detector block (5.2), the outputs of which are connected to the two inputs of a subtractor block (5.3), where the connection between the block instantaneous power (4) and the pulsating power generator block (5) is implemented, the output of the adder (4.2) is connected to the input of the average value block (5.1) and to the input of the maximum detector block (5.2), whereby the connection between the generator block of the pulsating power (5) and the block for recording the final result of the measurement (6) is made, and the output of the subtraction block (5.3) is connected to the input of the analog-to-digital converter (6.1).