Broadband voltage generator and impedance measuring device for new energy power generation equipment

Abstract

The utility model provides a broadband voltage generator for new energy power generation equipment and an impedance measuring device, the broadband voltage generator is arranged on a path between the new energy power generation equipment and a power grid, is connected in series with the new energy power generation equipment and the power grid, and comprises a plurality of voltage generation branches connected to a current source, each voltage generation branch comprises a rectification unit, an inversion unit, an LC filtering unit and a bypass switch, the LC filtering unit is connected with the rectification unit, the inversion unit and the bypass switch in parallel, and the two ends of the LC filtering unit are connected to a path of the new energy power generation equipment and the power grid; and two ends of the bypass switch are connected to a path of the new energy power generation equipment and the power grid. According to the utility model, rapid and mild access of the broadband voltage generator is realized, and the problem that new energy power generation equipment is possibly damaged by impulse voltage or impulse current and the like is avoided.

Description

TECHNICAL FIELD

[0001] The utility model relates to power system control technology field especially, it is a kind of wideband voltage generator and impedance measuring device for new energy power generation equipment.

BACKGROUND

[0002] With the large access of new energy grid-connected inverter, the inertia and damping of power grid are reduced, and stability problems such as wideband oscillation between new energy power generation equipment and power grid also come, which is not conducive to large-scale consumption of new energy. Impedance analysis method is an important way to study the instability mechanism of new energy grid-connected system, which can solve the "black box" or "gray box" problem of existing new energy power generation equipment and directly obtain the impedance characteristic data of the equipment. Therefore, the development of high-voltage wideband impedance measurement equipment can lay a fine model foundation for solving the stability problem of new energy grid connection by obtaining the impedance output characteristics of the equipment through impedance online measurement method. Among them, whether the wideband voltage generator can be moderately put into the impedance measurement equipment is of great significance.

[0003] In the related art, before impedance measurement, the new energy power generation equipment to be measured can be stopped running first, then the wideband voltage generator is connected in series to the system, the new energy power generation equipment to be measured is started to run after the stable output is 0, and the wideband voltage generator gradually outputs voltage until the expected voltage is output, and then impedance sweep measurement is started. However, in this way, after the wideband voltage generator is stabilized, the new energy power generation equipment is started, which is easy to inject harmonics into the new energy power generation equipment, affects the normal operation of the new energy power generation equipment, and when the new energy power generation equipment is full-load running, large current is generated during switching, which affects the stability of the system.

[0004] Therefore, how to ensure the stability of new energy power generation equipment and even power grid system during impedance measurement and reduce safety risk has become a technical problem to be solved at present.

SUMMARY

[0005] The utility model embodiment provides a kind of wideband voltage generator and impedance measuring device for new energy power generation equipment, to solve the technical problem of negative impact on the stability of new energy power generation equipment and even power grid system when introducing wideband voltage generator for impedance test in the related art.

[0006] In the first aspect, the utility model embodiment provides a kind of wideband voltage generator for new energy power generation equipment, and the wideband voltage generator is arranged on the passage of new energy power generation equipment and power grid, and is connected in series with the new energy power generation equipment and the power grid, including multiple voltage generation branches connected to current source, and each voltage generation branch includes:

[0007] rectifying unit;

[0008] an inverter unit connected in parallel with the rectifier unit;

[0009] an LC filter unit connected in parallel with the rectifier unit and the inverter unit, and both ends of the LC filter unit are connected to the path between the new energy power generation device and the power grid;

[0010] a bypass switch connected in parallel with the LC filter unit, and both ends of the bypass switch are connected to the path between the new energy power generation device and the power grid.

[0011] In an embodiment of the utility model, optionally, a plurality of the voltage generation branches are respectively arranged on a plurality of paths between the new energy power generation device and the power grid.

[0012] In an embodiment of the utility model, optionally, a plurality of the voltage generation branches are connected in parallel to the current source.

[0013] In an embodiment of the utility model, optionally, in each of the voltage generation branches, the inverter unit is connected in series with a voltage dividing inductor at one end close to the power grid.

[0014] In an embodiment of the utility model, optionally, the rectifier unit is connected in parallel with a first voltage stabilizing capacitor at both ends.

[0015] In an embodiment of the utility model, optionally, the inverter unit is connected in parallel with a second voltage stabilizing capacitor at both ends.

[0016] In a second aspect, the utility model provides a kind of impedance measuring device for new energy power generation device, comprising:

[0017] The wideband voltage generator of any one in the above first aspect;

[0018] Controller is connected to the wideband voltage generator, and is configured to perform impedance measurement calculation based on the stable voltage output by the wideband voltage generator.

[0019] The above technical solution, for the technical problem that new energy power generation device and even power grid system stability has negative influence when introducing wideband voltage generator for impedance test in related technology, the rapid and gentle access of wideband voltage generator is realized, the safety of pre-work of impedance measurement is improved, avoid the problem that new energy power generation device can be damaged by impact voltage or impact current etc. in this process, guarantee the smooth progress of impedance measurement work while providing guarantee for power grid safety.

DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings described in the following are only some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0021] Figure 1 A schematic diagram of a wideband voltage generator for a new energy power generation device according to an embodiment of the present application is shown.

DETAILED DESCRIPTION

[0022] The technical scheme in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort are within the scope of protection of the present application.

[0023] Figure 1 A schematic diagram of a wideband voltage generator for a new energy power generation device according to an embodiment of the present application is shown.

[0024] As shown in Figure 1 , the wideband voltage generator 100 for the new energy power generation device is arranged on the passage of the new energy power generation device 200 and the power grid 300, and is connected in series with the new energy power generation device 200 and the power grid 300.

[0025] The wideband voltage generator 100 includes a plurality of voltage generation branches connected to a current source, wherein each voltage generation branch includes a rectifying unit 102, an inverting unit 104, an LC filter unit 106 and a bypass switch 108. The inverting unit 104 is connected in parallel with the rectifying unit 102, the LC filter unit 106 is connected in parallel with the rectifying unit 102 and the inverting unit 104, and the two ends of the LC filter unit 106 are connected to the passage of the new energy power generation device 200 and the power grid 300. The bypass switch 108 is connected in parallel with the LC filter unit 106, and the two ends of the bypass switch 108 are connected to the passage of the new energy power generation device 200 and the power grid 300.

[0026] The current source is used to convert other forms of energy into electrical energy and provide the electrical energy to the circuit where the wideband voltage generator 100 is arranged. The rectifying unit 102 is used to convert alternating current from the current source into direct current. The inverting unit 104 is used to convert the direct current into alternating current again. The LC filter unit 106 can be a capacitor, and the bypass switch 108 is a switching device connected across the direct current terminals of one or more converter bridges.

[0027] Meanwhile, the plurality of voltage generating branches are respectively arranged on a plurality of paths between the new energy power generation device 200 and the power grid 300, and the plurality of voltage generating branches are connected in parallel to the current source, so that when any voltage generating branch fails, the wideband voltage generator 100 can still complete the work through the remaining voltage generating branches, and the impedance detection work can be ensured to run smoothly.

[0028] In a possible design, the first voltage stabilizing capacitor 110 is connected in parallel across the rectifying unit 102, and the first voltage stabilizing capacitor 110 is configured to filter out the AC ripple component in the rectified DC current, and the connection of the first voltage stabilizing capacitor 110 helps to improve the stability and purity of the DC current output by the rectifying unit 102.

[0029] In another possible design, the second voltage stabilizing capacitor (not shown in the figure) is connected in parallel across the inverting unit 104, and the second voltage stabilizing capacitor can reduce the current peak value of the inverting unit 104, reduce the heat and loss of the entire circuit, and thus prolong the service life of the wideband voltage generator 100. Figure 1

[0030] In addition, it should be noted that, in each voltage generating branch, the inverting unit 104 is connected in series with a voltage dividing inductor at one end close to the power grid 300.

[0031] In the related art, the new energy power generation equipment is first stopped, and then the new energy power generation equipment is started after the wideband voltage generator 100 is stabilized, which is easy to inject harmonics into the new energy power generation equipment, affects the normal operation of the new energy power generation equipment, and a large current is generated when the full-load operation of the new energy power generation equipment encounters switching, which affects the system stability. To this end, on the basis of the foregoing technical solutions of the utility model, the new energy power generation equipment in the idle state is first connected to the power grid 300, then the bypass switch 108 is disconnected, the wideband voltage generator 100 is connected in series to the entire circuit, and the output of the wideband voltage generator 100 at this time is set to 0, then the new energy power generation equipment gradually generates power until full load. Finally, the wideband voltage generator 100 gradually generates voltage until the output voltage value reaches the expected voltage, and enters the impedance measurement stage.

[0032] In a possible design, the new energy power generation device 200 is a wind turbine.

[0033] In the initial state, the power grid 300 is powered on, the bypass switch 108 is in the closed state, and the wind turbine is not connected to the power grid 300. The duration of this state is between 0-0.3s.

[0034] Then, the wind turbine is connected to the power grid 300 under the condition that the bypass switch 108 is in the closed state, and the wind turbine is in the idle state from 0.3s to 0.5s.

[0035] ​At this time, the bypass switch 108 is turned off, the wide-band voltage generator 100 is connected in series to the entire system, accesses the path of the power grid 300 and the fan, and the output voltage of the wide-band voltage generator 100 is set to 0V. This process lasts from 0.5s to 0.8s.

[0036] Then, the fan gradually emits power from 0.8s to 2.5s until full load.

[0037] Finally, the wide-band voltage generator 100 gradually emits voltage from 2.5s to 3.5s until the output voltage reaches the desired voltage.

[0038] The entire process of the wide-band voltage generator 100 completing the gentle input takes 3.5s, realizes fast and gentle access, and improves the safety of the pre-work of impedance measurement. Therefore, the input mode of the wide-band voltage generator 100 is gentle, avoids the problem that the impact voltage or impact current may damage the new energy power generation equipment 200, and provides a guarantee for the safety of the power grid 300.

[0039] In addition, the utility model also proposes a kind of impedance measurement device for new energy power generation equipment 200, including Figure 1 The wide-band voltage generator 100 and the controller of the embodiment, the controller is connected to the wide-band voltage generator 100, and is configured to perform impedance measurement calculation based on the stable voltage output by the wide-band voltage generator 100. The impedance measurement device has all the technical effects described above, and will not be repeated here.

[0040] It should be understood that although the terms first, second, etc. are used in the embodiments of the utility model to describe the voltage stabilizing capacitors, these voltage stabilizing capacitors should not be limited to these terms. These terms are only used to distinguish the voltage stabilizing capacitors from each other. For example, the first voltage stabilizing capacitor can also be referred to as the second voltage stabilizing capacitor without departing from the scope of the embodiments of the utility model, and similarly, the second voltage stabilizing capacitor can also be referred to as the first voltage stabilizing capacitor.

[0041] The terms used in the embodiments of the utility model are only for the purpose of describing specific embodiments, and are not intended to limit the utility model. The singular forms "a", "said" and "the" used in the embodiments of the utility model and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0042] The above-described embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A wideband voltage generator for a new energy power generation device, characterized by, The wide-band voltage generator is arranged on a path between a new energy power generation device and a power grid, and is connected in series with the new energy power generation device and the power grid, comprising a plurality of voltage generation branches connected to a current source, each of the voltage generation branches comprising: a rectifier unit; an inverter unit connected in parallel with the rectifier unit; an LC filter unit connected in parallel with the rectifier unit and the inverter unit, and both ends of the LC filter unit being connected to the path between the new energy power generation device and the power grid; a bypass switch connected in parallel with the LC filter unit, and both ends of the bypass switch being connected to the path between the new energy power generation device and the power grid.

2. The wideband voltage generator of claim 1, wherein, Each of the plurality of voltage generation branches is arranged on a plurality of paths between the new energy power generation device and the power grid.

3. The wideband voltage generator of claim 1, wherein, The plurality of voltage generation branches are connected in parallel to the current source.

4. The wideband voltage generator of claim 1, wherein, In each of the voltage generation branches, a voltage dividing inductor is connected in series with the inverter unit at a side close to the power grid.

5. The wideband voltage generator of claim 4, wherein, Both ends of the rectifier unit are connected in parallel with a first voltage stabilizing capacitor.

6. The wideband voltage generator of claim 4, wherein, Both ends of the inverter unit are connected in parallel with a second voltage stabilizing capacitor.

7. An impedance measuring device for a new energy power generation apparatus, characterized by comprising: comprising: the wide-band voltage generator according to any one of claims 1 to 6; a controller connected to the wide-band voltage generator and configured to perform impedance measurement calculation based on a stable voltage output by the wide-band voltage generator.

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