CN103812113B - A kind of Voltage Drop dynamic compensating device of the feed-forward type based on wind-light-electricity complementary - Google Patents

Abstract

A feed-forward voltage drop dynamic compensation device based on wind-power complementation, including: a controller, a rectifier unit, an H-bridge inverter unit, a bypass switch, a wind power DC voltage sensor, a wind power DC current sensor, an AC voltage transformer, DC boost unit, photoelectric DC voltage sensor, photoelectric DC current sensor, grid-connected inverter. When the power grid is running normally, the wind and solar power feeds electric energy to the grid through the grid-connected inverter, and the output voltage of the series compensator is zero; The amount of compensation voltage can directly and dynamically compensate the voltage drop, so that the voltage at the load end remains unchanged, thereby protecting the load from the influence of the grid fault and maintaining the stability of the DC bus voltage; The complementary feed-forward of photovoltaic power generation and the characteristics of fast compensation for grid voltage changes are smaller in size and lower in cost.

Description

A Feedforward Voltage Drop Dynamic Compensation Device Based on Wind and Power Complementary

technical field

The invention relates to the technical field of power quality, in particular to a feedforward voltage drop dynamic compensation device based on wind and electricity complementarity.

Background technique

Developed countries have very high requirements on power quality. Power quality problems will not only bring great economic losses to the industry, such as shutdown and restart, which will increase production costs, damage responsive equipment, scrap semi-finished products, and reduce product quality. Marketing difficulties will damage the company's image and good business relations with users, etc., and will also bring harm to equipment in important power-consuming departments such as medical care, causing serious production and operation accidents. Research by the American Electric Power Research Institute (EPRI) shows that electric energy Quality problems cause US industry to lose 30 billion dollars in data, materials and productivity every year (Electric Power Research Institute, 1999); Japan and other developed countries also have high requirements for power quality. With the rapid development of my country's high-tech industry, the requirements for power quality are getting higher and higher, and voltage sags (sags, dips) are the main problems. Voltage sags will not only cause voltage quality problems in power systems, but also endanger The safe work of electrical equipment, power system failure, large-scale motor startup, branch circuit short circuit, etc. will cause voltage sag. Although the voltage sag time is short, it will cause interruption or shutdown of the industrial process, and the shutdown period of the industrial process caused It is far longer than the time of the voltage sag accident itself, so the loss caused is very large.

Traditional methods, such as voltage regulators, cannot solve these problems. Although uninterruptible power supply UPS devices can solve these problems, their cost and operating costs are extremely expensive. In order to solve the above problems, dynamic voltage compensators have been developed at home and abroad. Research. Compared with UPS, dynamic voltage compensator can effectively solve the problem of voltage sag. However, the problem of energy storage has always plagued the problem of dynamic voltage compensators. Although advanced methods such as the minimum energy injection method have been proposed, the additional energy storage has always affected its further promotion and development.

Contents of the invention

In view of the above problems, the object of the present invention is to provide a feedforward dynamic compensation device for voltage drop based on wind-solar power complementation. When the power grid is normal, green wind energy and solar energy are used to convert wind energy and solar energy into electrical energy for supply to the power grid; When the grid voltage fails, the corresponding voltage is output to compensate the difference of the grid voltage to ensure that the load voltage does not change, thus protecting the load.

Technical solution of the present invention is as follows:

A feed-forward voltage drop dynamic compensation device based on wind-power complementation, characterized in that it consists of: a controller, a rectifier unit, an H-bridge inverter unit, a bypass switch, a wind power DC voltage sensor, a wind power DC current sensor, an AC voltage Transformer, DC boost unit, photoelectric DC voltage sensor, photoelectric DC current sensor, grid-connected inverter;

The connection relationship of the above components is as follows:

The rectification control terminal of the controller is connected to the input control terminal of the rectification unit, the H-bridge inverter control terminal of the controller is connected to the input control terminal of the H-bridge inverter unit, and the The DC boost control terminal of the controller is connected to the input control terminal of the DC boost unit, and the bypass switch control terminal of the controller (1) is connected to the control terminal of the bypass switch; the control The wind power DC voltage input end of the controller is connected to the output end of the wind power DC voltage sensor, the wind power DC current input end of the controller is connected to the output end of the wind power DC current sensor, and the AC current of the controller The input terminal is connected with the output terminal of the AC voltage transformer, the input terminal of the rotor speed and rotor angle input signal of the controller is connected with the output terminal of the speed measuring code disc of the synchronous generator, and the photoelectric DC voltage of the controller is The input end is connected to the output end of the photoelectric direct current voltage sensor, the photoelectric direct current input end of the controller is connected to the output end of the photoelectric direct current sensor, and the grid-connected inverter control end of the controller is connected to the output end of the photoelectric direct current sensor. The corresponding control terminals of the grid-connected inverter are connected;

The AC input end of the rectification unit is connected to the output end of the wind power synchronous generator, and the DC output end of the rectification unit is connected to the DC output end of the DC step-up unit;

The DC output terminal of the rectification unit is connected to the DC output terminal of the DC boost unit and then connected to the DC bus terminal of the grid-connected inverter and the DC bus terminal of the H-bridge inverter unit;

The two ends of the bypass switch are connected to the AC output end of the H-bridge inverter unit, and connected in series to the transmission line of the power grid, and connected to the power supply end and the load end of the power grid respectively;

The input end of the wind power DC voltage sensor is connected to the DC output end of the rectification unit;

The input terminal of the wind power DC current sensor is connected in series with the DC output terminal of the rectification unit;

The input end of the AC voltage transformer is connected to the grid common point voltage;

The DC input terminal of the DC boost unit is connected to the output terminal of the photovoltaic cell panel, the DC output terminal of the DC boost unit is connected to the input terminal of the photoelectric DC voltage sensor, the photoelectric DC current sensor The input terminal is connected to the DC input terminal of the H-bridge inverter unit;

The DC bus terminal of the grid-connected inverter is connected to the DC bus terminal of the H-bridge inverter unit, and the AC output terminal of the grid-connected inverter is connected in parallel with the grid common point voltage.

The controller is realized by a central processing unit, the core of which is a digital signal processor, a single-chip microcomputer or a computer.

The method for performing dynamic compensation using the feed-forward voltage drop dynamic compensation device based on wind-power complementary, is characterized in that the method includes the following specific steps:

1) The controller measures the AC supply voltage U _S , the DC voltage U _w and DC current I _w output by the rectifier unit, the DC voltage U _PV and DC current _IPV output by the DC boost unit, the synchronous generator speed and rotor angle;

2) Calculate the output active power P _w of the rectifier unit: P _w = U _w × I _w ;

3) Calculating the output active power P _PV of the DC step-up unit: P _PV = U _PV × I _PV ;

4) Control the rectifier unit and the DC boost unit for complementary output of wind and solar:

Wind energy maximum power tracking: judge whether the output active power P _w of the rectifier unit is greater than the previous output value, if so, continue to increase the synchronous generator speed; otherwise, maintain the synchronous generator speed unchanged;

Solar maximum power tracking: judge whether the active power _PPV output by the DC boost unit is greater than the last output value, if so, continue to increase the duty cycle; otherwise, keep the duty cycle unchanged;

5) Let U _S0 be the AC power supply voltage value when the power grid is normal:

If the power grid is normal, that is, when the AC power supply voltage U _S is equal to or higher than 90% of the normal voltage U _S0 , the bypass switch is controlled to be turned on and the H-bridge inverter unit is controlled to have no output, so that the voltage injected into the power supply AC line is zero; Control the grid-connected inverter to inject wind power and photovoltaic power into the grid and feed it back to the grid;

If the power grid fails, that is, when the AC supply voltage U _S is lower than 90% of the normal voltage U _S0 , the bypass switch is controlled to be closed, and the H-bridge inverter unit is controlled so that the output voltage meets: U _j =(U _S0 -U _S ), excess wind power and photovoltaics will inject power into the grid by controlling the grid-connected inverter, if wind power and photovoltaics are not enough, then inject power into the DC bus through the grid-connected inverter, so as to maintain the stability of the DC bus voltage.

Compared with prior art, characteristics of the present invention are as follows:

1. When the grid voltage drops, the output voltage is connected in series to protect important loads;

2. The series transformer is canceled, which makes the cost lower and the volume smaller;

3. Utilize the complementary effects of wind energy and solar energy to solve the energy storage problem of compensation for grid voltage dips (sudden dips, dips).

4. The grid-connected inverter adopts a feed-forward method, so that the capacity of the series transformer and the series-compensated inverter unit are not additionally increased.

Description of drawings

FIG. 1 is a schematic structural diagram of a feedforward voltage drop dynamic compensation device based on wind-power complementation according to the present invention.

Fig. 2 is a topological diagram of the single-phase H-bridge inverter unit of the present invention.

Fig. 3 is a topological diagram of the grid-connected inverter of the present invention.

Fig. 4 is a block diagram of series compensation control in the present invention.

Detailed ways

The present invention will be further described below in conjunction with the embodiments and accompanying drawings, but the protection scope of the present invention should not be limited thereby.

Please refer to FIG. 1 first. FIG. 1 is a schematic structural diagram of a feed-forward voltage drop dynamic compensation device based on wind-power complementation according to the present invention. It can be seen from the figure that a feed-forward dynamic compensation device for voltage drop based on wind power complementation includes: controller 1, rectifier unit 2, H-bridge inverter unit 3, bypass switch 4, wind power DC voltage sensor 5, wind power A DC current sensor 6 , an AC voltage transformer 7 , a DC boost unit 8 , a photoelectric DC voltage sensor 9 , a photoelectric DC current sensor 10 , and a grid-connected inverter 11 .

The rectification control end of the controller 1 is connected to the input control end of the rectification unit 2, the H-bridge inverter control end of the controller 1 is connected to the input control end of the H-bridge inverter unit 3 connected, the DC boost control terminal of the controller 1 is connected to the input control terminal of the DC boost unit 8, the bypass switch control terminal of the controller (1) is connected to the control terminal of the bypass switch 4 The wind power DC voltage input end of the controller 1 is connected to the output end of the wind power DC voltage sensor 5, and the wind power DC current input end of the controller 1 is connected to the output of the wind power DC current sensor 6. The AC current input terminal of the controller 1 is connected with the output terminal of the AC voltage transformer 7, and the rotor speed and rotor angle input signal input terminals of the controller 1 are connected with the speed measuring code of the synchronous generator. Disk output terminal is connected, the photoelectric DC voltage input terminal of described controller 1 is connected with the output terminal of described photoelectric DC voltage sensor 9, the photoelectric direct current input terminal of described controller 1 is connected with described photoelectric direct current sensor 10 connected to the output terminal of the controller 1, and the grid-connected inverter control terminal of the controller 1 is connected to the corresponding control terminal of the grid-connected inverter 11;

The AC input end of the rectification unit 2 is connected to the output end of the wind power synchronous generator, and the DC output end of the rectification unit 2 is connected to the DC output end of the DC step-up unit 8;

The DC output end of the rectification unit 2 is connected to the DC output end of the DC boost unit 8 and then connected to the DC bus end of the grid-connected inverter 11 and the DC bus end of the H-bridge inverter unit 3;

The two ends of the bypass switch 4 are connected to the AC output end of the H-bridge inverter unit 3, and connected in series in the transmission line of the power grid, and connected to the power supply end and the load end of the power grid respectively;

The input end of the wind power DC voltage sensor 5 is connected to the DC output end of the rectification unit 2;

The input terminal of the wind power DC current sensor 6 is connected in series with the DC output terminal of the rectification unit 2;

The input terminal of the AC voltage transformer 7 is connected to the grid common point voltage;

The DC input terminal of the DC boost unit 8 is connected to the output terminal of the photovoltaic panel, the DC output terminal of the DC boost unit 8 is connected to the input terminal of the photoelectric DC voltage sensor 9, the photoelectric The input terminal of the DC current sensor 10 is connected to the DC input terminal of the H-bridge inverter unit 3;

The DC bus terminal of the grid-connected inverter 11 is connected to the DC bus terminal of the H-bridge inverter unit 3, and the AC output terminal of the grid-connected inverter 11 is connected in parallel with the grid common point voltage .

The specific implementation is as follows:

Each phase of the bypass switch 4 is composed of a pair of anti-parallel thyristors, the on and off of which are controlled by the controller 1, and the controller 1 controls the rectifier unit 2 to track the maximum power of wind energy, synchronously The alternating current output by the generator is converted into direct current, and the controller 1 controls the direct current step-up unit 8 to perform maximum power tracking on the solar energy, and raises the direct current output by the photovoltaic power generation to direct current, and the output terminal of the rectification unit 2 is connected with the direct-current step-up unit The output end of the unit 8 is connected to the DC bus of the H-bridge inverter unit 3 and the grid-connected inverter 11; the AC output end of the H-bridge inverter unit 3 is connected to both ends of the bypass switch 4 , the bypass switch 4 is connected in series in the transmission line of the power grid, and is connected to the power supply end and the load end of the power grid respectively, and the AC output end of the grid-connected inverter 11 is connected to the power grid; the DC voltage input of the controller 1 terminals are respectively connected to the output terminals of the wind power DC voltage sensor 5 and the photoelectric DC voltage sensor 9, and the DC current input terminals of the controller 1 are connected to the output terminals of the wind power DC current sensor 6 and the photoelectric DC current sensor 10 respectively, The voltage sensor 5 and the DC current sensor 6 measure the DC voltage and the DC current output by the rectifier unit 2 respectively; the DC voltage and the DC current output by the DC boost unit 8 are measured respectively by the DC voltage sensor 9 and the DC current sensor 10; the control The AC voltage input terminal of the device 1 is connected to the output terminal of the AC voltage transformer 7, and the AC voltage of the grid is measured through the AC voltage transformer 7.

When the power grid is normal, the controller 1 controls the bypass switch 4 to be turned on, controls the H-bridge inverter unit 3 to have no output, and controls the grid-connected inverter 11 so that wind power and photovoltaics are injected into the grid through the grid-connected inverter 11; When the grid voltage is lower than 90% of the normal voltage, the bypass switch 4 is quickly closed, and the H-bridge inverter unit 3 is controlled to perform series voltage compensation. The grid-connected inverter 11 is used to inject excess wind power and photovoltaic into the grid. When the photoelectricity is insufficient, the power is fed back to the DC bus through the grid, so as to maintain the constant voltage of the DC bus.

Fig. 4 is a block diagram of the series compensation control method. Through the measured DC voltage and DC current, the output power _Pw and _PPV of wind power and photovoltaic power generation are calculated, and the maximum power tracking control of wind power and photovoltaic power generation is carried out; by detecting the AC voltage of the power grid, Determine whether the AC voltage of the grid is normal. When a fault is found in the grid, the controller 1 controls the inverter unit 3 to output the corresponding AC voltage variation, and controls the grid-connected inverter 11 to inject wind power and photovoltaics into the grid.

Specific steps are as follows:

1) The controller 1 measures the AC supply voltage U _S , the DC voltage U _w and the DC current I _w output by the rectification unit 2 , the DC voltage U _PV and the DC current I _PV output by the DC boost unit 8 , the synchronous generator speed and the rotor angle;

2) Calculate the active power P _w output by the rectification unit 2: P _w = U _w × I _w ;

3) Calculating the active power P _PV output by the DC step-up unit 8: P _PV = U _PV × I _PV ;

4) Control the rectification unit 2 and the DC step-up unit 8 to perform complementary output of wind and solar:

Wind energy maximum power tracking: judge whether the active power _Pw output by the rectifier unit 2 is greater than the previous output value, if so, continue to increase the synchronous generator speed; otherwise, keep the synchronous generator speed unchanged;

Solar energy maximum power tracking: judge whether the active power _PPV output by the DC boost unit 8 is greater than the last output value, if so, continue to increase the duty cycle; otherwise, keep the duty cycle unchanged;

5) Let U _S0 be the AC power supply voltage value when the power grid is normal:

If the power grid is normal, that is, when the AC power supply voltage U _S is equal to or higher than 90% of the normal voltage U _S0 , then the bypass switch 4 is controlled to be turned on and the H-bridge inverter unit 3 is controlled to have no output, so that the voltage injected into the power supply AC line is Zero; control the grid-connected inverter 11 to inject wind power and photoelectricity into the grid, and feed back to the grid;

If the power grid fails, that is, when the AC power supply voltage U _S is lower than 90% of the normal voltage U _S0 , the bypass switch 4 is controlled to be closed, and the H-bridge inverter unit 3 is controlled so that its output voltage meets: U _j =( U _S0 -U _S ), excess wind power and photovoltaics inject power into the grid by controlling the grid-connected inverter 11, if wind power and photovoltaics are not enough, inject power into the DC bus through the grid-connected inverter 11, thereby maintaining the DC bus The voltage is stable.

Claims (3)

1. based on a Voltage Drop dynamic compensating device for the feed-forward type of wind-light-electricity complementary, be characterised in that formation comprises: controller (1), rectification unit (2), H bridge inverter unit (3), by-pass switch (4), wind power direct current voltage sensor (5), wind power direct current current sensor (6), AC voltage transformer (7), DC boosting unit (8), photoelectricity direct current voltage sensor (9), photoelectric direct current transducer (10), combining inverter (11);

The annexation of above-mentioned parts is as follows:

The rectify control end of described controller (1) is connected with the input control end of described rectification unit (2), the H bridge inversion control end of described controller (1) is connected with the input control end of described H bridge inverter unit (3), the DC boosting control end of described controller (1) is connected with the input control end of DC boosting unit (8), and the by-pass switch control end of described controller (1) is connected with the control end of described by-pass switch (4), the wind power direct current voltage input end of described controller (1) is connected with the output of described wind power direct current voltage sensor (5), the wind power direct current current input terminal of described controller (1) is connected with the output of described wind power direct current current sensor (6), the alternating current input of described controller (1) is connected with the output of described AC voltage transformer (7), the wind-powered electricity generation synchronous generator rotor rotating speed of described controller (1), rotor angle input signal input is connected with the code-disc output that tests the speed of wind-powered electricity generation synchronous generator, the photoelectricity DC voltage input end of described controller (1) is connected with the output of described photoelectricity direct current voltage sensor (9), the photoelectric direct current input of described controller (1) is connected with the output of described photoelectric direct current transducer (10), the parallel network reverse control end of described controller (1) is connected with the corresponding control end of described combining inverter (11),

The ac input end of described rectification unit (2) is connected with the output of wind-powered electricity generation synchronous generator, and the DC output end of described rectification unit (2) is connected with the DC output end of described DC boosting unit (8);

Be connected with the DC bus end of described combining inverter (11), the DC bus end of H bridge inverter unit (3) after the DC output end of described rectification unit (2) is connected with the DC output end of DC boosting unit (8);

The two ends of described by-pass switch (4) are connected with the ac output end of described H bridge inverter unit (3), and being serially connected in the power transmission line of electrical network, the ac output end of described H bridge inverter unit (3) is connected with load end with the feeder ear of electrical network respectively;

The input of described wind power direct current voltage sensor (5) is connected with the DC output end of described rectification unit (2);

The input of described wind power direct current current sensor (6) is serially connected with the DC output end of described rectification unit (2);

The input of described AC voltage transformer (7) is connected with electrical network common point;

The direct-flow input end of described DC boosting unit (8) is connected with the output of photovoltaic battery panel, the DC output end of described DC boosting unit (8) is connected with the input of described photoelectricity direct current voltage sensor (9), and the input of described photoelectric direct current transducer (10) is connected with the direct-flow input end of described H bridge inverter unit (3);

The DC bus end of described combining inverter (11) is connected with the DC bus end of described H bridge inverter unit (3), and the ac output end of described combining inverter (11) is connected with electrical network common point.

2. the Voltage Drop dynamic compensating device of the feed-forward type based on wind-light-electricity complementary according to claim 1, it is characterized in that, described controller (1) is realized by CPU, and its core is digital signal processor, single-chip microcomputer or computer.

3. utilize the Voltage Drop dynamic compensating device of the feed-forward type based on wind-light-electricity complementary described in claim 1 to carry out the method for dynamic compensation, it is characterized in that, the method comprises following concrete steps:

1) alternating supply voltage U measured by controller (1) _s, the direct voltage U that exports of rectification unit (2) _wwith direct current I _w, the direct voltage U that exports of DC boosting unit (8) _pVwith direct current I _pV, wind-powered electricity generation synchronous generator rotor rotating speed and rotor angle;

2) rectification unit (2) active power of output P is calculated _w: P _w=U _w× I _w;

3) DC boosting unit (8) active power of output P is calculated _pV: P _pV=U _pV× I _pV;

4) control rectification unit (2) and carry out honourable complementary output with DC boosting unit (8):

Wind energy maximal power tracing: judge this rectification unit (2) active power of output P _wwhether be greater than output valve last time, if then continue to increase wind-powered electricity generation synchronous generator rotor rotating speed; Otherwise, maintain wind-powered electricity generation synchronous generator rotor rotating speed constant;

Solar maximum power is followed the tracks of: judge this DC boosting unit (8) active power of output P _pVwhether be greater than output valve last time, if then continue to increase duty ratio; Otherwise, maintain duty ratio constant;

5) U is established _s0for electrical network normal time alternating supply voltage value:

If electrical network is normal, i.e. alternating supply voltage U _sbe equal to or higher than normal voltage U _s090% time, then control by-pass switch (4) conducting and control H bridge inverter unit (3) no-output, make the voltage of injection supply and AC circuit be zero; Control combining inverter (11) and wind-powered electricity generation, photoelectricity are injected electrical network, feed back to electrical network;

If electric network fault, i.e. alternating supply voltage U _slower than normal voltage U _s090% time, then control by-pass switch (4) close, the voltage that the H bridge inverter unit (3) described in control makes it export meet: U _j=(U _s0-U _s), unnecessary wind-powered electricity generation, photoelectricity, by controlling combining inverter (11) to electrical network injecting power, if wind-powered electricity generation, photoelectricity are inadequate, then pass through combining inverter (11) to DC bus injecting power, thus maintenance DC bus-bar voltage are stablized.