Photovoltaic power station electric energy quality detection and positioning device and method

Abstract

The invention discloses a photovoltaic power station electric energy quality detection and positioning device and method. The device comprises a DSP processor, a two-way current acquisition module, a two-way voltage acquisition module, a keyboard module, a display module, a storage module and a 220kV power supply module. When the electric energy quality of the photovoltaic power station is unqualified, source positioning of unqualified voltage electric energy quality and unqualified current electric energy quality is carried out respectively, and source positioning of unqualified electric energy quality is carried out respectively under the SVG input and quit operation conditions; the unqualified voltage electric energy quality comprises unqualified voltage harmonic waves, unqualified flicker and unqualified three-phase imbalance, and the unqualified current electric energy quality mainly refers to unqualified current harmonic waves. The system is simple to operate and convenient to use, can detect two-loop voltage and current signals, meets the requirements of two-loop transmission lines and a wind-solar-storage combined new energy field station, shortens the detection time, can automatically detect information such as voltage harmonic waves, current harmonic waves, flicker and the degree of unbalance, and locates the source of unqualified electric energy quality.

Description

Technical Field

[0001] The invention belongs to the technical field of photovoltaic power automation monitoring, and relates to a photovoltaic power station power quality detection and positioning device and method. Background Art

[0002] Renewable energy is mainly composed of power electronic equipment. In addition, the intermittent and uncertain nature of renewable energy power generation has an adverse effect on the power quality of the power system. After renewable energy is connected to the power grid, it causes problems such as grid voltage fluctuation, flicker or excessive harmonics, which reduces the power quality of the power grid, reduces the utilization rate of transformers, causes local parallel resonance and series resonance in the grid, leads to malfunction of relay protection and automatic devices, and makes electrical test instruments measure inaccurately, affecting the normal operation of various electrical equipment in the user's own station, and even damaging equipment.

[0003] Most new energy stations have two outgoing transmission lines, or one outgoing transmission line and one incoming transmission line from other new energy stations; the existing special power quality detection devices only have one voltage and one current collection circuit; especially for the situation where the power quality needs to be measured for one new energy outgoing transmission line and one incoming transmission line from other new energy stations, two sets of power quality detection devices are required. Therefore, it is necessary to develop a device that is applicable to the power quality detection of existing new energy stations.

[0004] With the large-scale commissioning of new energy sources, many new energy sites have experienced unqualified power quality, but there is a lack of methods to locate the source of unqualified power quality. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a photovoltaic power station power quality detection and positioning device and method, which solves the problem that traditional power quality detection devices cannot meet the power quality detection of existing new energy sites, makes up for the shortcomings of existing power quality detection equipment and has more collection channels, and realizes the source positioning of unqualified power quality.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a photovoltaic power station power quality detection and positioning device, which includes a DSP processor, a 2-way current acquisition module, a 2-way voltage acquisition module, a keyboard module, a display module, a storage module and a 220kV power supply module; the 220kV power supply module, the 2-way current acquisition module and the 2-way voltage acquisition module are electrically connected to the DSP processor, and the DSP processor is also connected to the keyboard module and the display module, and the data of the DSP processor is input to the storage module; the 220kV power supply module includes an electrically connected step-down transformer, a rectifier circuit and a voltage stabilizing circuit; 220V AC voltage is input into the step-down transformer, and the rectifier current is input after being stepped down by the step-down transformer, and the rectifier circuit outputs a DC voltage signal to a regulated voltage, and after passing through the voltage stabilizing circuit, a DC voltage of 24V is stably output.

[0007] The two current acquisition modules each include three-phase current acquisition channels A, B, and C, and each channel is: each phase current acquisition channel uses a clamp-type current transformer; each phase current acquisition clamp-type current transformer can sample 0~5A current and is connected to the I / O port of the DSP processor respectively.

[0008] The two voltage acquisition modules each include A, B, C, and N voltage acquisition channels, and each channel is: U1 is connected to the A phase voltage port, U2 is connected to the B phase voltage port, U3 is connected to the C phase voltage port, and Un is connected to the N phase voltage port. U1, U2, and U3 are respectively connected to one end of the primary side of the voltage transformer PT1, PT2, and PT3, and Un is connected to the other secondary end of the primary side of the voltage transformer PT1, PT2, and PT3; one end of the secondary side of the voltage transformer PT1, PT2, and PT3 is connected to the I / O port of the DSP processor.

[0009] The step-down transformer steps down the 220V AC and inputs it into the rectifier circuit. After being rectified by the rectifier circuit, the DC power is input into the voltage stabilizing circuit, and the stable current outputs a stable 24V DC voltage to power the DSP processor.

[0010] The rectifier circuit is a rectifier bridge D1 composed of four Schottky diodes connected together.

[0011] The voltage stabilizing circuit is composed of an inductor L, a MOS tube, a single chip microcomputer, a freewheeling diode D2, an electrolytic capacitor C, resistors R1, R2, R3, and an operational amplifier Q which are electrically connected.

[0012] The 220V AC voltage is input to the primary side of the step-down transformer B, the secondary side of the step-down transformer B is connected to the AC input end of the rectifier bridge D1, the positive pole of the DC output end of the rectifier bridge D1 is connected to the inductor L, the positive pole of the freewheeling diode D2 at the other end of the inductor L is connected to the drain of the MOSFET, the source of the MOSFET is grounded, and the gate of the MOSFET is connected to the PWM port of the single-chip microcomputer.

[0013] The cathode of the freewheeling diode D2 is connected to the anode of the electrolytic capacitor C, and the cathode of the electrolytic capacitor C is grounded; the resistor R1 and the resistor R2 are connected in series and connected to the output end, the series node of the resistor R1 and the resistor R2 is connected to the internal AD port of the single-chip computer, the resistor R3 is connected in series to the cathode of the output end, one end of the resistor R3 is connected to the in-phase input end of the operational amplifier Q, and the other end of the resistor R3 is connected to the inverting input end of the operational amplifier Q.

[0014] The method for locating the power quality harmonic source of the power quality detection and positioning device of the photovoltaic power station as described above comprises the following steps: SA1: When the voltage harmonics, flicker and three-phase unbalance are unqualified, after the PV power station SVG is shut down, re-check whether the voltage harmonics, flicker and three-phase unbalance at the PV power station grid connection point are qualified; SA2: When the voltage harmonics, flicker, and three-phase imbalance at the PV power station grid connection point are re-tested and found to be qualified, the source of the unqualified voltage and power quality is SVG, and the SVG needs to be rectified; SA3: When the voltage harmonics, flicker and three-phase imbalance of the PV power station grid connection point are re-tested and found to be unqualified, the SVG is put into operation to re-test the voltage and power quality of the PV power station grid connection point at night; SA4: When the voltage harmonics, flicker, and three-phase imbalance of the PV power station grid connection point are tested again at night after the SVG is put into operation and found to be qualified, the source of the unqualified voltage and power quality is the inverter, and the inverter needs to be rectified; SA5: When the voltage harmonics, flicker and three-phase imbalance of the PV power station grid connection point are still unqualified after the SVG is put into operation and re-tested at night, the SVG will be shut down and the voltage and power quality of the PV power station grid connection point will be re-tested at night. SA6: When the voltage harmonics, flicker, and three-phase imbalance at the PV power station grid connection point are retested at night after the SVG is put into operation and found to be qualified, it means that the voltage and power quality of the PV power station are unqualified due to the combined effect of the SVG and the inverter; SA7: After SVG is put into operation and the voltage harmonics, flicker and three-phase imbalance of the PV power station grid connection point are re-tested at night, if they are still unqualified, it means that the power quality of the grid voltage is unqualified, and power quality management is required on the grid side.

[0015] The method for locating the source of unqualified current harmonics of the photovoltaic power station power quality detection and positioning device as described above comprises the following steps: SB1, when SVG is out of operation and the inverter is operating normally, re-detect the current harmonics of the PV power station grid connection point; SB2: If the current harmonics of the photovoltaic power station grid-connected point are unqualified after re-testing, it means that the inverter causes the grid-connected current harmonics of the photovoltaic power station to exceed the standard, and the inverter needs to be rectified; SB3: If the current harmonics of the photovoltaic power station grid connection point are still qualified after re-testing, the output current harmonics of the SVG will be tested when the SVG is put into operation; SB4: When the harmonics of the SVG output current are unqualified, it means that the SVG causes the harmonics of the PV power station grid-connected current to exceed the standard, and the SVG needs to be rectified; SB5: When the harmonics of the SVG output current are qualified, it means that the current harmonics exceed the standard due to the combined effect of the SVG and the inverter. It is necessary to rectify the inverter and SVG, or add power quality equipment.

[0016] The main beneficial effects of the present invention are: Detect the power quality of two circuits at the same time. It can meet the needs of new energy stations with two existing circuits for outgoing transmission, one outgoing transmission and one incoming transmission, and "wind, solar and storage" combined transmission, and detect the power quality at the same time, avoiding the use of multiple sets of equipment together, shortening the detection time and improving the detection efficiency.

[0017] It can realize automatic detection. It can automatically detect voltage harmonics, current harmonics, flicker, unbalance and other information, and locate the source of harmonics with unqualified power quality; shorten the time of locating the source of excessive harmonics in photovoltaic power stations to avoid greater economic losses.

[0018] It can be used for power quality detection and positioning in various occasions. It can be used in wind farms, photovoltaic power stations, energy storage power stations, "wind, light and storage" combined power stations, hydropower stations, thermal power stations, distributed new energy, substations and user side.

[0019] Simple operation and easy to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0021] Figure 1 It is a schematic block diagram of the structure of the present invention.

[0022] Figure 2 This is a flow chart for locating the source of unqualified power quality according to the present invention.

[0023] Figure 3 This is a schematic diagram of current collection in the present invention.

[0024] Figure 4 This is a schematic diagram of voltage collection according to the present invention.

[0025] Figure 5 This is a schematic diagram of the 220V power supply module of the present invention.

[0026] Figure 6 This is the circuit diagram of the 220V power supply module of the present invention.

[0027] Markings in the figure: 1 is a DSP processor, 2 is a 2-way current acquisition module, 3 is a 2-way voltage acquisition module, 4 is a keyboard module, 5 is a display module, 6 is a storage module, 7 is a 220V power supply module, 8 is a step-down transformer, 9 is a rectifier circuit, 10 is a voltage stabilizing circuit, and 11 is a single-chip microcomputer.

[0028] The letters in the figure: I1, I2, I3 represent the clamp circuit transformers collecting A, B, C phase currents respectively, U1, U2, U3, Un represent the collection of A, B, C, N phase voltages respectively, PT1, PT2, PT3 represent voltage transformers; R1, R2, R3 are fixed value resistors, B is a step-down transformer, D1 is a rectifier bridge, D2 is a freewheeling diode, L is an inductor, MOS is a mos tube, C is an electrolytic capacitor, and Q is an operational amplifier. DETAILED DESCRIPTION

[0029] like Figure 1 to Figure 6 A photovoltaic power station power quality detection and positioning device includes a DSP processor, a 2-way current acquisition module, a 2-way voltage acquisition module, a keyboard module, a display module, a storage module and a 220kV power supply module; the 220kV power supply module, the 2-way current acquisition module and the 2-way voltage acquisition module are electrically connected to the DSP processor, the DSP processor is also connected to the keyboard module and the display module, and the data of the DSP processor is input to the storage module; the 220kV power supply module includes an electrically connected step-down transformer, a rectifier circuit and a voltage stabilizing circuit; 220V AC voltage is input to the step-down transformer, and after being stepped down by the step-down transformer, a rectifier current is input, and the rectifier circuit outputs a DC voltage signal to a regulated voltage, and after passing through the voltage stabilizing circuit, a DC voltage of 24V is stably output.

[0030] Embodiment 1, The use steps of the present invention are: Step 1: Enter the new energy station and prepare to start power quality testing.

[0031] Step 2: The 220V power supply module (7) is connected to 220V AC power, and after passing through a step-down transformer (8), a rectifier circuit (9), and a voltage stabilizing circuit (10), 24V DC power is output.

[0032] Step 3: The DSP processor (1) starts working.

[0033] Step 4: According to the display module (5), the keyboard module (4) is used to respectively set and collect information such as the transformation ratio of the two-circuit voltage and current of the new energy station, the detection time, etc.; Step 4: 2-way current acquisition (2) and 2-way voltage acquisition (3) are connected to the secondary voltage and circuit loop of the location to be detected in the new energy station. Step 5: The information collected by the two-way current collection (2) and the two-way voltage collection (3) is input into the DSP processor (1). The DSP processor (1) analyzes the voltage harmonics, current harmonics, flicker, unbalance and other information and stores them into the storage module (6).

[0034] Step 6: After the test is completed, remove the 2-way current collection (2) and 2-way voltage collection (3) loops, and disconnect the 220V power supply module (7).

[0035] Step 7: Analyze the power quality test results of the photovoltaic power station connected to the grid. When the power quality test results are unqualified, use the method of the present invention to locate the source of the unqualified power quality.

[0036] Embodiment 2, When the power quality of the photovoltaic power station is unqualified, the source of the unqualified voltage power quality and the unqualified current power quality are located respectively, and the source of the unqualified power quality is located when the SVG is put into operation and exited from operation respectively; the unqualified voltage power quality includes unqualified voltage harmonics, unqualified flicker, and unqualified three-phase unbalance, and the unqualified current power quality mainly refers to unqualified current harmonics.

[0037] When the power quality detection fails, the source of the unqualified voltage power quality and the unqualified current power quality are located respectively.

[0038] like Figure 2 In the power quality inspection, the voltage power quality failure includes voltage harmonic failure, flicker failure, and three-phase unbalance failure. The specific steps for locating the power quality harmonic source are as follows: 1) When the voltage harmonics, flicker and three-phase unbalance are unqualified, after the SVG of the PV power station is shut down, re-test the voltage harmonics, flicker and three-phase unbalance of the PV power station grid connection point to see if they are qualified; 2) When the voltage harmonics, flicker, and three-phase imbalance of the PV power station grid connection point are re-tested and found to be qualified, the source of the unqualified voltage and power quality is caused by SVG, and the SVG needs to be rectified.

[0039] 3) When the voltage harmonics, flicker, and three-phase imbalance of the PV power station grid connection point are re-tested and found to be unqualified, the SVG is put into operation and the voltage and power quality of the PV power station grid connection point is re-tested at night.

[0040] 4) When the SVG is put into operation and the voltage harmonics, flicker, and three-phase imbalance of the photovoltaic power station grid connection point are re-tested at night and are found to be qualified, the source of the unqualified voltage and power quality is the inverter, and the inverter needs to be rectified.

[0041] 5) When the SVG is put into operation and the voltage harmonics, flicker and three-phase imbalance of the PV power station grid connection point are re-tested at night and still fail to meet the standards, the SVG will be shut down and the voltage and power quality of the PV power station grid connection point will be re-tested at night.

[0042] 6) When the SVG is put into operation and the voltage harmonics, flicker, and three-phase imbalance at the PV power station grid connection point are re-tested at night and found to be qualified, it means that the voltage and power quality of the PV power station are unqualified due to the combined effect of the SVG and the inverter.

[0043] 7) When the voltage harmonics, flicker, and three-phase imbalance of the PV power station grid connection point are still unqualified after the SVG is put into operation and re-tested at night, it means that the power quality of the grid voltage is unqualified, and power quality management is required on the grid side.

[0044] Embodiment 3, like Figure 2 In the current power quality, unqualified current harmonics mainly refer to unqualified current harmonics. The specific steps for locating the source of unqualified current harmonics are as follows: 1) When the SVG is out of operation and the inverter is operating normally, re-detect the current harmonics at the grid connection point of the PV power station.

[0045] 2) If the current harmonics of the PV power station grid-connected point are found to be unqualified after re-testing, it means that the inverter causes the grid-connected current harmonics of the PV power station to exceed the standard, and the inverter needs to be rectified.

[0046] 3) If the current harmonics of the PV power station grid connection point are still qualified after re-testing, the output current harmonics of the SVG are tested when the SVG is put into operation.

[0047] 4) When the harmonics of the SVG output current are unqualified, it means that the SVG causes the harmonics of the PV power station grid-connected current to exceed the standard, and the SVG needs to be rectified.

[0048] 5) When the harmonics of the SVG output current are qualified, it means that the current harmonics exceed the standard due to the combined effect of the SVG and the inverter. It is necessary to rectify the inverter and SVG, or add power quality equipment.

[0049] The above method solves the problem that traditional power quality detection devices cannot meet the power quality detection requirements of existing new energy stations, makes up for the shortcomings of existing power quality detection equipment, has more collection channels, and realizes the source positioning of unqualified power quality.

[0050] Detect the power quality of two circuits at the same time. It can meet the needs of new energy stations with two existing circuits for outgoing transmission, one outgoing transmission and one incoming transmission, and "wind, solar and storage" combined transmission, and detect the power quality at the same time, avoiding the use of multiple sets of equipment together, shortening the detection time and improving the detection efficiency.

[0051] It can realize automatic detection. It can automatically detect voltage harmonics, current harmonics, flicker, unbalance and other information, and locate the source of harmonics with unqualified power quality; shorten the time of locating the source of excessive harmonics in photovoltaic power stations to avoid greater economic losses.

[0052] It can be used for power quality detection and positioning in various occasions. It can be used in wind farms, photovoltaic power stations, energy storage power stations, "wind, light and storage" combined power stations, hydropower stations, thermal power stations, distributed new energy, substations and user side.

[0053] The above-mentioned embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments of the present application can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A photovoltaic power station power quality detection and positioning device, characterized by: It includes a DSP processor, a 2-way current acquisition module, a 2-way voltage acquisition module, a keyboard module, a display module, a storage module and a 220kV power supply module; the 220kV power supply module, the 2-way current acquisition module and the 2-way voltage acquisition module are electrically connected to the DSP processor, and the DSP processor is also connected to the keyboard module and the display module, and the data of the DSP processor is input to the storage module; the 220kV power supply module includes an electrically connected step-down transformer, a rectifier circuit and a voltage stabilizing circuit; a 220V AC voltage is input into a step-down transformer, a rectifier current is input after being stepped down by the step-down transformer, the rectifier circuit outputs a DC voltage signal to a regulated voltage, and a DC voltage of 24V is stably output after passing through the voltage stabilizing circuit.

2. The photovoltaic power station power quality detection and positioning device according to claim 1 is characterized in that: The two current acquisition modules each include three-phase current acquisition channels A, B, and C, and each channel is: each phase current acquisition channel uses a clamp-type current transformer; each phase current acquisition clamp-type current transformer can sample 0~5A current and is connected to the I / O port of the DSP processor respectively.

3. The photovoltaic power station power quality detection and positioning device according to claim 1 is characterized in that: The two voltage acquisition modules each include A, B, C, and N voltage acquisition channels, and each channel is: U1 is connected to the A phase voltage port, U2 is connected to the B phase voltage port, U3 is connected to the C phase voltage port, and Un is connected to the N phase voltage port. U1, U2, and U3 are respectively connected to one end of the primary side of the voltage transformer PT1, PT2, and PT3, and Un is connected to the other secondary end of the primary side of the voltage transformer PT1, PT2, and PT3; one end of the secondary side of the voltage transformer PT1, PT2, and PT3 is connected to the I / O port of the DSP processor.

4. The photovoltaic power station power quality detection and positioning device according to claim 1 is characterized in that: The step-down transformer steps down the 220V AC and inputs it into the rectifier circuit. After being rectified by the rectifier circuit, the DC power is input into the voltage stabilizing circuit, and the stable current outputs a stable 24V DC voltage to power the DSP processor.

5. The photovoltaic power station power quality detection and positioning device according to claim 1 is characterized in that: The rectifier circuit is a rectifier bridge D1 composed of four Schottky diodes connected together.

6. The photovoltaic power station power quality detection and positioning device according to claim 1 is characterized in that: The voltage stabilizing circuit is composed of an inductor L, a MOS tube, a single chip microcomputer, a freewheeling diode D2, an electrolytic capacitor C, resistors R1, R2, R3, and an operational amplifier Q which are electrically connected.

7. The photovoltaic power station power quality detection and positioning device according to claim 6 is characterized in that: The 220V AC voltage is input to the primary side of the step-down transformer B, the secondary side of the step-down transformer B is connected to the AC input end of the rectifier bridge D1, the positive pole of the DC output end of the rectifier bridge D1 is connected to the inductor L, the positive pole of the freewheeling diode D2 at the other end of the inductor L is connected to the drain of the MOSFET, the source of the MOSFET is grounded, and the gate of the MOSFET is connected to the PWM port of the single-chip microcomputer.

8. The photovoltaic power station power quality detection and positioning device according to claim 6 is characterized by: The cathode of the freewheeling diode D2 is connected to the anode of the electrolytic capacitor C, and the cathode of the electrolytic capacitor C is grounded; the resistor R1 and the resistor R2 are connected in series and connected to the output end, the series node of the resistor R1 and the resistor R2 is connected to the internal AD port of the single-chip computer, the resistor R3 is connected in series to the cathode of the output end, one end of the resistor R3 is connected to the in-phase input end of the operational amplifier Q, and the other end of the resistor R3 is connected to the inverting input end of the operational amplifier Q.

9. The method for locating the power quality harmonic source of the photovoltaic power station power quality detection and positioning device according to any one of claims 1 to 8, characterized in that: The steps include: SA1: When the voltage harmonics, flicker and three-phase unbalance are unqualified, after the PV power station SVG is shut down, re-check whether the voltage harmonics, flicker and three-phase unbalance at the PV power station grid connection point are qualified; SA2: When the voltage harmonics, flicker, and three-phase imbalance at the PV power station grid connection point are re-tested and found to be qualified, the source of the unqualified voltage and power quality is SVG, and the SVG needs to be rectified; SA3: When the voltage harmonics, flicker and three-phase imbalance of the PV power station grid connection point are re-tested and found to be unqualified, the SVG is put into operation to re-test the voltage and power quality of the PV power station grid connection point at night; SA4: When the voltage harmonics, flicker, and three-phase imbalance of the PV power station grid connection point are tested again at night after the SVG is put into operation and found to be qualified, the source of the unqualified voltage and power quality is the inverter, and the inverter needs to be rectified; SA5: When the voltage harmonics, flicker and three-phase imbalance of the PV power station grid connection point are still unqualified after the SVG is put into operation and re-tested at night, the SVG will be shut down and the voltage and power quality of the PV power station grid connection point will be re-tested at night. SA6: When the voltage harmonics, flicker, and three-phase imbalance at the PV power station grid connection point are retested at night after the SVG is put into operation and found to be qualified, it means that the voltage and power quality of the PV power station are unqualified due to the combined effect of the SVG and the inverter; SA7: After SVG is put into operation and the voltage harmonics, flicker and three-phase imbalance of the PV power station grid connection point are re-tested at night, if they are still unqualified, it means that the power quality of the grid voltage is unqualified, and power quality management is required on the grid side.

10. The method for locating the source of unqualified current harmonics of the photovoltaic power station power quality detection and positioning device according to any one of claims 1 to 8, characterized in that: The steps include: SB1, when SVG is out of operation and the inverter is operating normally, re-detect the current harmonics at the grid connection point of the PV power station; SB2: If the current harmonics of the photovoltaic power station grid-connected point are found to be unqualified after retesting, it means that the inverter causes the grid-connected current harmonics of the photovoltaic power station to exceed the standard, and the inverter needs to be rectified; SB3: If the current harmonics of the photovoltaic power station grid connection point are still qualified after re-testing, the output current harmonics of the SVG will be tested when the SVG is put into operation; SB4: When the harmonics of the SVG output current are unqualified, it means that the SVG causes the harmonics of the PV power station grid-connected current to exceed the standard, and the SVG needs to be rectified; SB5: When the harmonics of the SVG output current are qualified, it means that the current harmonics exceed the standard due to the combined effect of the SVG and the inverter. It is necessary to rectify the inverter and SVG, or add power quality equipment.

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