JP2005134280A - Testing device for actual equipment connected to power distribution system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To test an actual equipment connected to a power distribution system for use, by a space-saving and inexpensive testing device. <P>SOLUTION: An active power interface unit (API) 3 provided between a power distribution system simulation circuit simulating the power distribution system by an electronic circuit and the actual equipment is constituted of a voltage sensor 13 and a current sensor 19 for detecting a voltage VR and a current IR in an actual equipment side, a voltage control unit 18 for controlling a voltage (n/m) VR obtained by multiplying the voltage VR by n/m and the current (N/M) IR obtained by multiplying the current IR by N/M respectively into a voltage VS and a current IS in a power distribution system simulation circuit side, a voltage sensor 16 and a current sensor 20 for detecting the voltage VS and the current IS in the power distribution system simulation circuit side, and a current control unit 17 for controlling the voltage (m/n) VS obtained by multiplying the voltage VS by m/n and the current (M/N) IS obtained by multiplying the current IS by M/N respectively into the voltage VR and the current IR. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a test apparatus for testing an actual device such as a solar power generation system used in connection with a power distribution system, and in particular, by connecting an actual device such as a solar power generation system to a small-scale power distribution system simulation circuit. The present invention relates to a test apparatus capable of testing.

  In recent years, against the background of increasing interest in global environmental problems, photovoltaic power generation (PV) systems installed on the roofs of ordinary households are rapidly spreading and are expected to continue to spread in the future. When connecting a PV system installed in a home to a power system (distribution system), the PV system's isolated operation prevention function, power system protection function, THD (Total Harmonic distortion) Rate) function etc. need to be tested.

  This test can be carried out directly by preparing a real-scale independent simulated power distribution system and connecting the PV system to this simulated power distribution system. However, a real scale simulated power distribution system can only be prepared by some corporations such as electric power companies in terms of scale, and cannot be generally used.

  Although a test can be performed by computer simulation, there is a problem that the test by computer simulation is not a test that is actually performed by connecting the PV system to the power distribution system.

  For this reason, conventionally, as described in Non-Patent Document 1 below, the distribution system is replaced with an equivalent circuit, a distribution system simulator including resistors and inductors is created, and the PV inverter is tested.

  However, this conventional test device is small compared to a real-scale power distribution system, but the load is composed of resistors and inductances that can be directly connected to a real-scale power supply. There is a problem that the change is difficult and the cost is high. Moreover, there is also a problem that the test apparatus becomes large when a test when a large number of PV systems are linked or an inter-system mutual interference test is performed.

Y. Noda, T, Mizuno, H. Koizumi, K. Nagasaka, K. Kurokawa: “The development of a scaled-down simulator for distribution grids and its application for verifying interference behavior among a number of module integrated converters (MIC)” , 29 th IEEEPVSC, pp.1545-1548, May 2002

  It is desired that a test apparatus for testing an actual device that is connected to an electric power system has a small space, low cost, and can easily expand the scale of the electric power system and change the load. For this reason, it is preferable to prepare an ultra-shrinkable distribution system simulation circuit created by an electronic circuit, and to connect the actual device such as a PV inverter directly to the distribution system simulation circuit for testing. However, in this case, the circuit element of the distribution system simulation circuit (electronic circuit) is not destroyed due to the difference between the operation voltage of the distribution system simulation circuit (electronic circuit) and the operation voltage of the actual device. It is necessary to have a structure in which the operating voltage of the simulation circuit faithfully simulates the system voltage of the actual power system.

  The object of the present invention is to perform a test by directly connecting an actual device to a distribution system simulation circuit composed of an electronic circuit, a small space, a low cost, a test capable of easily performing scale expansion and load change. To provide an apparatus.

  The test apparatus of the present invention is a test apparatus for testing an actual device used by being connected to a distribution system, a distribution system simulation circuit simulating the distribution system with an electronic circuit, the actual device, and the distribution system simulation circuit, And an active power interface device connected between the two.

  The active power interface device of the test apparatus of the present invention is such that when the voltage on the actual device side is VR, the current is IR, the voltage on the distribution system simulation circuit side is VS, and the current is IS, the actual device side A first voltage sensor and a first current sensor that constantly detect the voltage VR and current IR, respectively, and a voltage (n / m) VR and current obtained by multiplying the detected voltage VR and current IR by n / m and N / M, respectively. (N / M) a voltage control unit that controls IR to be the voltage VS and current IS, and a second voltage sensor and a second current sensor that constantly detect the voltage VS and current IS on the side of the distribution system simulation circuit, respectively. Then, the detected voltage VS and current IS are controlled so that the voltage (m / n) VS and current (M / N) IS obtained by multiplying the detected voltage VS and current IS by m / n and M / N become the voltage VR and current IR, respectively. With current control unit And wherein the Rukoto. Note that n, m, N, and M are arbitrary numbers.

  According to the present invention, the actual device can be tested by directly connecting to the power distribution system simulation circuit via the active power interface device, so that the actual device can be easily tested. Moreover, since the distribution system simulation circuit is composed of an electronic circuit, a small space and low cost of the test apparatus can be realized.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of a test apparatus according to an embodiment of the present invention. This test apparatus tests an actual device to be tested, such as a photovoltaic power generation system (PV system) 1, an electronic circuit (distribution system simulation circuit) 2 that simulates a distribution system that actually connects the PV system, and An active power interface device (API) 3 interposed between the distribution system simulation circuit 2 and the PV system 1 is supplied with electric power from a commercial power source 4.

  Since the distribution system that actually connects the PV system 1 is large and cannot be used in the test, the circuit 2 that simulates the distribution system is configured by creating elements such as resistors, capacitors, and inductances by electronic circuits. . For example, FIG. 2 is a simulation circuit of a single-phase two-wire low-voltage distribution system. The simulation circuit 2 includes a line impedance 6 connected to a commercial power supply 4 and a load circuit 7 including a resistor R, a capacitor C, and an inductance L connected in parallel to simulate an electric load in a general household.

  FIG. 3 is a block diagram of the active power interface device (API) 3, and FIG. 4 is a detailed circuit diagram thereof. The active power interface device 3 has a function of faithfully reducing or amplifying the voltage and current of one connection terminal and outputting the voltage and current from the other connection terminal, and an actual PV system 1 having different power levels. Are equivalently connected to the distribution system simulation circuit 2. That is, the active power interface device 3 is configured to control so that the relationship between the voltage and current of both connection terminals is always m: n and M: N, respectively.

  3, the active power interface device 3 includes a first voltage sensor 13 that detects a voltage between the ground terminal 11 and the connection terminal 12 to which the PV system 1 is connected, and the distribution system simulation circuit 2 is connected thereto. A second voltage sensor 16 that detects a voltage between the ground terminal 14 and the connection terminal 15 is provided. The output of the current control unit 17 is connected to the connection terminal 12, and the output of the voltage control unit 18 is connected to the connection terminal 15.

  The active power interface device 3 further flows through a first current sensor 19 that detects a current flowing through a wiring connecting the connection terminal 12 and the current control unit 17, and a wiring connecting the connection terminal 15 and the voltage control unit 18. A second current sensor 20 for detecting current is provided, and the detected values of both current sensors 19, 20 are output to the current control unit 17. Further, the detected voltage value of the first voltage sensor 13 and the detected voltage value of the second voltage sensor 16 are output to the voltage control unit 18.

  As shown in FIG. 3, the current control unit 17 includes an operational amplifier 21, a comparator 22 provided at the input stage of the operational amplifier 21, and a resistor 23 connected to the output of the operational amplifier 21. A value obtained by subtracting the detection value of the first current sensor 19 from the detection value of the second current sensor 20 is output to the operational amplifier 21.

  In this example, the comparator 22 is composed of an operational amplifier as shown in FIG. 4, the detection value of the first current sensor 19 is applied to the inverting input terminal of the operational amplifier 22, and the second current sensor 20 is connected to the non-inverting input terminal. A detection value is applied. In addition, the operational amplifier 21 (FIG. 3) includes two operational amplifiers 21a and 21b (FIG. 4), resistors, and the like in this example. The current ratio between the terminals 12 and 15 can be arbitrarily controlled by varying the gains of the operational amplifiers 21a and 22 in FIG.

  As shown in FIG. 3, the voltage control unit 18 includes an operational amplifier 25, a comparator 26 provided at the input stage of the operational amplifier 25, and a resistor 27 connected to the output of the operational amplifier 25. A value obtained by subtracting the detection value of the second voltage sensor 16 from the detection value of the first voltage sensor 13 is output to the operational amplifier 25.

  In this example, the comparator 26 is composed of an operational amplifier as shown in FIG. 4, the detection value of the first voltage sensor 13 is applied to the non-inverting input terminal of the operational amplifier 26, and the second voltage sensor 16 is applied to the inverting input terminal. A detection value is applied. In addition, the operational amplifier 25 (FIG. 3) includes two operational amplifiers 25a and 25b (FIG. 4), resistors, and the like in this example. The voltage ratio between the terminals 12 and 15 can be arbitrarily controlled by varying the gains of the operational amplifiers 26 and 25a shown in FIG.

  As shown in FIG. 2, the active power interface device 3 having such a configuration has the PV system 1 side voltage of the active power interface device 3 as VR, the current as IR, the distribution system simulation circuit 2 side voltage as VS, and the current as In the case of IS, the voltage VR and current IR on the PV system 1 side are constantly measured by the first voltage sensor 13 and the first current sensor 19, and the measured voltage VR and current IR are respectively multiplied by n / m, N / The voltage control unit 18 controls the voltage (n / m) VR and current (N / M) IR multiplied by M so as to become the voltage VS and current IS on the connection terminal 15 side.

  At the same time, the voltage VS and current IS of the connection terminal 15 are always measured by the second voltage sensor 16 and the second current sensor 20, and the measured voltage VS and current IS are multiplied by m / n and M / N, respectively. The current control unit 17 controls the voltage (m / n) VS and the current (M / N) IS to be the voltage VR and current IR on the connection terminal 12 side.

  The voltage and current at both ends of the active power interface device 3 are determined as follows. That is, the current at the connection terminal 12 is determined by the resistor 23 inserted between the operational amplifier 21 and the connection terminal 12, and the voltage at the connection terminal 12 is obtained by subtracting the voltage drop at the resistor 23 from the output voltage of the operational amplifier 21. Voltage.

  The same applies to the connection terminal 15 side, and the voltage at the connection terminal 15 is determined by the resistor 27 inserted between the operational amplifier 25 and the connection terminal 15, and is obtained by subtracting the voltage drop of the resistor 27 from the output voltage of the operational amplifier 25. Become.

  The first voltage sensor 13 detects the voltage of the connection terminal 12, the second voltage sensor 16 detects the voltage of the connection terminal 15, the voltage control unit 18 compares both detection voltage values, and the voltage of the terminal 12 and the terminal 15 The voltage control unit 18 performs feedback control so that the voltage relationship of m: n becomes m: n, and controls the output voltage of the operational amplifier 25.

  At the same time, the first current sensor 19 detects the current at the terminal 12 as a voltage, the second current sensor 20 detects the current at the terminal 15 as a voltage, and the current control unit 17 compares both the detected current values. The current control unit 17 performs feedback control so that the value relationship is M: N, and controls the output voltage of the operational amplifier 21. At this time, since the voltage relationship between the terminal 12 and the terminal 15 is destroyed due to the voltage drop caused by the resistor 23, the voltage control unit 18 controls the voltage of the terminal 12 and the terminal 15 again, and at the same time, the current control unit 17 Thus, the current of the terminal 12 and the terminal 15 is controlled, and the control is repeated until the relationship between the voltage and current of the terminal 12 and the terminal 15 is always m: n and M: N.

  By using this active power interface device 3, it is possible to equivalently connect the super-reduction type distribution system simulation circuit 2 constituted by an electronic circuit and the actual PV inverter 1.

  FIG. 5 is a configuration diagram of a test circuit used in an experiment conducted for examining the direct current characteristics of the active power interface device 3 according to the above-described embodiment. In this test circuit, a DC power supply 32 is connected to the left terminal of the active power interface device 3 via a resistor 31, and a capacitor 34 is connected to the right terminal via a resistor 33.

  With this test circuit, it was examined whether the transient response by the RC circuit can be controlled by the active power interface device 3. As an example, adjustment is performed so that the relationship between the power levels of the left end and the right end of the active power interface device 3 is 4: 1, and the relationship between the voltage and current at the left end and the right end is 2: 1. Then, when the voltage 5 V was applied from the DC power supply 32, the resistance 31 was 40Ω, the resistance 33 was 10Ω, and the capacitor 34 was 47 μF, the time response of the voltage and current at both ends of the active power interface device 3 was measured.

  6 and 7 are graphs showing measurement results. FIG. 6 shows voltage characteristics at both ends of the active power interface device 3, and FIG. 7 shows current characteristics thereof. It can be seen that the relationship between the characteristics I and II in FIG. 6 is always controlled to 2: 1. In addition, the time constant of this test circuit is RC = 2.35 ms, and it can be seen that the values measured from the characteristics I and II almost coincide with each other. Also from FIG. 7, it can be seen that the relationship between the characteristics III and IV is always controlled to 2: 1, and the time constants of the circuits also coincide.

  Next, the AC characteristics of the active power interface device 3 were tested. This test was performed by replacing the DC power source 32 shown in FIG. 5 with an AC voltage source. The test conditions were the same as those when the DC characteristics were examined, but a 5 V, 50 Hz sine wave was input from the AC voltage source to the test circuit. And the time response of the voltage of the both ends of the active power interface apparatus 3 and an electric current was measured.

  8 and 9 are graphs showing measurement results. FIG. 8 shows voltage characteristics at both ends of the active power interface device 3, and FIG. 9 shows current characteristics thereof. It can be seen that there is no phase shift in the waveforms of the characteristics V and VI in FIG. 8, and the size is always controlled to 2: 1. Further, even in a current waveform that is out of phase with the voltage waveform due to the capacitor 34 being connected to the test circuit, the waveforms of the characteristics VII and VIII in FIG. 9 have no phase shift, and the magnitude is always controlled to 2: 1. You can see that

  From the above results, it can be seen that the active power interface device 3 of the present embodiment operates with high accuracy regardless of whether DC or AC is input. For this reason, by using this active power interface device, it is possible to test a distribution system connection device by equivalently connecting an actual distribution system connection device having a different power level and a distribution system simulation circuit composed of electronic circuits. it can.

  The test apparatus according to the present invention can test an actual device that is used by being connected to a power distribution system like a photovoltaic power generation system by directly connecting to a power distribution system simulation circuit constituted by an electronic circuit. It is useful as a testing device for equipment.

It is a lineblock diagram of a testing device concerning one embodiment of the present invention. It is a circuit diagram which shows an example of the power distribution system simulation circuit used with the test apparatus which concerns on one Embodiment of this invention. It is a block diagram of the active power interface apparatus shown in FIG. FIG. 4 is a circuit diagram of the active power interface device shown in FIG. 3. FIG. 4 is a test circuit diagram of the active power interface device shown in FIG. 3. It is a graph which shows the DC voltage characteristic of the active power interface apparatus measured with the test circuit shown in FIG. It is a graph which shows the direct-current characteristic of the active power interface apparatus measured with the test circuit shown in FIG. It is a graph which shows the alternating voltage characteristic of the active power interface apparatus shown in FIG. It is a graph which shows the alternating current characteristic of the active power interface apparatus shown in FIG.

Explanation of symbols

1 Solar power generation system (PV system)
2 Power Distribution System Simulation Circuit 3 Active Power Interface Device 4 Commercial Power Supply 11, 14 Ground Terminal 12, 15 Connection Terminal 13, 16 Voltage Sensor 17 Current Control Unit 18 Voltage Control Unit 19, 20 Current Sensor

Claims (2)

In a test apparatus for testing an actual device used by being connected to a power distribution system, a power distribution system simulation circuit simulating the power distribution system with an electronic circuit, and an active device connected between the real device and the power distribution system simulation circuit A test apparatus for an actual device connected to a power distribution system, comprising a power interface device. When the voltage on the actual device side is VR, the current is IR, the voltage on the distribution system simulation circuit side is VS, and the current is IS, the active power interface device has the voltage VR and current IR on the actual device side. The first voltage sensor and the first current sensor for constantly detecting the voltage VR, the current IR, and the voltage (n / m) VR and current (N / M) obtained by multiplying the detected voltage VR and current IR by n / m and N / M, respectively. A voltage control unit that controls the IR to be the voltage VS and the current IS, and a second voltage sensor and a second current sensor that constantly detect the voltage VS and the current IS on the power distribution system simulation circuit side, respectively. A voltage control unit for controlling the voltage (m / n) VS and the current (M / N) IS obtained by multiplying the voltage VS and the current IS by m / n and M / N, respectively, to become the voltage VR and the current IR; Features Actual device test apparatus connected to the power distribution system of claim 1,.

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