CN205724922U - Subsynchronous Oscillation Suppression Device on Grid Side of New Energy Base Sending Through Series Compensation - Google Patents

Abstract

The utility model provides a power grid side secondary synchronous oscillation suppressing device sent by a new energy base through series compensation, comprising a signal extraction module, a signal processing module and a voltage source converter; a signal extraction module, a signal processing module and a voltage source converter The devices are connected in sequence; the input end of the signal extraction module is connected between the collection station of the new energy power generation base and the series compensation sending system; the output end of the voltage source converter is connected to the outgoing transmission line of the collection station. Compared with the prior art, the utility model provides a subsynchronous oscillation suppressing device on the power grid side sent by the new energy base through series compensation, which can avoid the occurrence of subsynchronous oscillation after the large-scale new energy wind power base is connected to the grid through the series compensation system. As a result, a large number of wind turbines are disconnected from the grid, thereby ensuring the safe and stable operation of new energy power transmission.

Description

Subsynchronous Oscillation Suppression Device on Grid Side of New Energy Base Sending Through Series Compensation

technical field

The utility model relates to the technical field of power electronics and power equipment, in particular to a grid-side sub-synchronous oscillation suppression device for a new energy base sending system through series compensation.

Background technique

Based on the rapid development of new energy power generation, China has become the country with the largest wind power grid-connected capacity and the fastest development of photovoltaics. However, due to the reverse distribution of wind/light resources and load centers in my country, new energy power generation technology faces the challenge of how to achieve large-capacity and long-distance transmission. At present, series capacitor compensation technology is mainly used to realize large-capacity and long-distance transmission of electric energy. However, when large-scale new energy power generation is connected to the grid through series compensation, it is very easy to cause subsynchronous oscillation of the grid. For example, in 2009, the world's first sub-synchronous oscillation accident in which new energy was connected to the power grid through series compensation occurred in Texas, the United States, resulting in damage to the distribution unit equipment; Dozens of subsynchronous oscillation faults caused by wind turbines and series compensation have been detected, resulting in abnormal operation of grid equipment and a large number of wind turbines going off-grid, seriously threatening the safe and stable operation of the grid.

Utility model content

Aiming at the subsynchronous oscillation failure caused by the new energy being connected to the grid through series compensation in the prior art, the utility model provides a subsynchronous oscillation suppression device on the grid side sent from the new energy base through series compensation.

The technical scheme of the utility model is:

The device includes a signal extraction module, a signal processing module and a voltage source converter;

The signal extraction module, the signal processing module and the voltage source converter are connected in sequence;

The input end of the signal extraction module is connected between the collection station of the new energy power generation base and the series compensation sending system;

The output end of the voltage source converter is connected to the outgoing transmission line of the collection station.

The preferred technical solution further provided by the utility model is: the input end of the signal extraction module includes two branches:

One of the branches is connected to the transmission line between the collection station and the series compensation sending system, and the other branch is connected to the bus between the collection station and the voltage source converter.

The preferred technical solution further provided by the utility model is: the signal extraction module includes a signal acquisition unit and a signal extraction unit;

The signal acquisition unit collects the voltage u _S and current i _S of the transmission line between the collection station and the series compensation sending system, and collects the current i _L of the bus between the collection station and the voltage source converter;

The signal extraction unit determines a sub-synchronous current signal according to the current i _S and the current i _L.

The preferred technical solution further provided by the utility model is: the signal processing module includes a compensation reference signal calculation unit and a pulse modulation unit;

The compensation reference signal calculation unit receives the output signal of the signal extraction unit, and calculates the compensation reference signal of the collection station according to the output signal;

The pulse modulation unit generates a trigger pulse according to the compensation reference signal and sends it to the voltage source converter; the voltage source converter is used to perform power exchange with the series compensation sending system to Suppresses subsynchronous oscillations.

The preferred technical solution further provided by the utility model is: the compensation reference signal calculation unit includes a first PI controller, a second PI controller, a third PI controller and a signal conversion subunit;

The first PI controller, the second PI controller and one input end of the signal conversion subunit are connected in sequence, the third PI controller is connected with the other input end of the signal conversion subunit, and the signal conversion subunit The output of the unit is connected to the voltage source converter.

The preferred technical solution further provided by the utility model is:

The first PI controller performs PI control on the DC deviation signal;

The second PI controller performs PI control on the deviation signal output by the first comparator; the positive input terminal of the first comparator respectively receives the output signal of the first PI controller and the output signal of the signal extraction module The sub-synchronous current i _{Ld_sub} , the negative input terminal receives the current i _Sd output by the signal extraction module;

The third PI controller performs PI control on the deviation signal output by the second comparator; the positive input terminal of the second comparator respectively receives the sub-synchronous current i _{Lq_sub} output by the signal extraction module and the reactive current setting fixed value i _qref , the negative input terminal receives the current i _Sq output by the signal extraction module;

Wherein, the current i _Sd and the current i _Sq are the currents of the current i _S of the transmission line between the collection station and the series compensation sending system in the dq coordinate system.

The preferred technical solution further provided by the utility model is: the signal transformation subunit includes a third comparator, a fourth comparator and a coordinate transformation subunit;

The positive input terminal of the third comparator respectively receives the voltage u _Sd and the current i _Sd output by the signal extraction module, and the negative input terminal receives the output signal of the second PI controller;

The positive input terminal of the fourth comparator respectively receives the voltage u _Sq and the current i _Sq output by the signal extraction module, and the negative input terminal receives the output signal of the third PI controller;

The coordinate conversion subunit performs coordinate conversion on the output signals of the third comparator and the fourth comparator to obtain the voltage u _ma , voltage u _mb and voltage u _mc under abc coordinates;

Wherein, the current i _Sd and the current i _Sq are the currents of the current i _S of the transmission line between the collection station and the series compensation sending system in the dq coordinate system; the voltage u _Sd and the voltage u _Sq are the currents of the transmission line Voltage u _S is the voltage in the dq coordinate system.

The preferred technical solution further provided by the utility model is:

The new energy power generation bases include wind power generation bases and/or photovoltaic power generation bases;

The series compensation sending system includes a series compensation device, which is installed on the outgoing transmission line of the collection station.

Compared with the closest prior art, the beneficial effects of the utility model are:

The utility model provides a sub-synchronous oscillation suppression device on the side of the power grid sent by the new energy base through series compensation, which can avoid a large number of wind turbines going off-grid due to sub-synchronous oscillation after the large-scale new energy wind power base is connected to the grid through the series compensation system. In order to ensure the safe and stable operation of new energy power transmission.

Description of drawings

Figure 1: A schematic diagram of a power grid-side subsynchronous oscillation suppression device sent by a new energy base through series compensation in an embodiment of the utility model;

Fig. 2: In the embodiment of the utility model, the wind power generation base sends four days of power grid side synchronous oscillation suppression schematic diagram through series compensation;

Figure 3: schematic diagram of the principle of the signal extraction module in the embodiment of the utility model;

Figure 4: Schematic diagram of the principle of the signal processing module in the embodiment of the utility model;

Among them, 101: signal extraction module; 102: signal processing module; 1021: first PI controller; 1022: second PI controller; 1023: third PI controller; 1024: first comparator; 1025: third comparison 1026: second comparator; 1027: fourth comparator; 1028: coordinate transformation subunit; 103: voltage source converter; 201: wind power base; 202: collection station; 203: series compensation delivery system.

detailed description

In order to make the purpose, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely explained below in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described The embodiments are some embodiments of the present utility model, but not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

The subsynchronous oscillation suppressing device on the power grid side provided by the embodiment of the utility model, which is sent through series compensation by a new energy base, will be described below in conjunction with the accompanying drawings.

Fig. 1 is a schematic diagram of a subsynchronous oscillation suppression device on the power grid side sent by a new energy base through series compensation in an embodiment of the utility model. As shown in the figure, the subsynchronous oscillation suppression device in this embodiment includes a signal extraction module 101, a signal processing module 102 and voltage source converter 103 . in,

The signal extraction module 101, the signal processing module 102 and the voltage source converter 103 are connected in sequence, the input end of the signal extraction module 101 is connected between the collection station of the new energy power generation base and the series compensation sending system, and the voltage source converter 103 The output terminal is connected to the outgoing transmission line of the collection station.

The signal extraction module 101 and the signal processing module 102 will be specifically described below in conjunction with the accompanying drawings.

1. Signal extraction module 101

In this embodiment, the input end of the signal extraction module 101 is connected between the collection station of the new energy power generation base and the serial compensation sending system: the input end of the signal extraction module 101 includes two branches, and one branch is connected to the collection station and the serial compensation system. The transmission line between the supplementary sending system, and the other branch is connected to the bus between the collection station and the voltage source converter, and the voltage source converter is used for power exchange with the series compensation sending system to suppress subsynchronous oscillation.

The signal extraction module 101 in this embodiment includes a signal acquisition unit and a signal extraction unit. in,

(1) Signal acquisition unit

The signal acquisition unit is used to collect the voltage u _S and current i _S of the transmission line between the collection station and the series compensation sending system, and collect the current i _L of the bus between the collection station and the voltage source converter.

(2) Signal extraction unit

The signal extraction unit determines the sub-synchronous current signal according to the current i _S and the current i _L. Specifically:

Carry out coordinate transformation on the current i _L of the bus bar between the collection station and the voltage source converter 103 to obtain the current i _Ld and current i _Lq in the dq coordinate system; Perform coordinate transformation to obtain the voltage and current in the dq coordinate system;

Obtain the phase θ _p of the current i _S of the transmission line between the collection station and the series compensation sending system;

The sub-synchronous current i Ld_sub of the current i _Ld and the sub-synchronous current i _{Lq_sub} of the current i _Lq are _extracted , and phase compensation is performed on the sub-synchronous currents i _{Ld_sub} and i _{Lq_sub} .

Fig. 3 is a schematic diagram of the principle of the signal extraction module in the embodiment of the present invention. As shown in the figure, the signal extraction unit in the present embodiment performs three-phase current i _La , i _Lb and i _Lc performs coordinate transformation, and performs coordinate transformation on the voltage and current of the transmission line between the collection station and the series compensation sending system to obtain the voltage and current in the dq coordinate system, and obtains the connection between the collection station and the series compensation sending system through the phase-locked loop PLL The phase θ _p of the current i _S of the transmission line between the transmission lines, and finally according to the current i _Ld and current i _Lq after the coordinate transformation, extract the sub-synchronous current i Ld_sub of the current i _Ld and the sub-synchronous current i _{Lq_sub} of the current i _Lq , and _compare the Synchronous currents i _{Ld_sub} and i _{Lq_sub} perform phase compensation.

2. Signal processing module 102

In this embodiment, the signal processing module 102 includes a compensation reference signal calculation unit and a pulse modulation unit. in,

(1) Compensation reference signal calculation unit

The compensation reference signal calculation unit receives the output signal of the signal extraction unit, and calculates the compensation reference signal of the collection station according to the output signal. The compensation reference signal calculation unit includes a first PI controller 1021, a second PI controller 1022, a third PI controller 1023 and a signal conversion subunit;

The first PI controller 1021, the second PI controller 1022 are sequentially connected to one input end of the signal conversion subunit, the third PI controller 1023 is connected to the other input end of the signal conversion subunit 1028, and the signal conversion subunit 1028 The output terminal of is connected to the voltage source converter 103. in,

The first PI controller 1021 performs PI control on the DC deviation signal. As shown in FIG. 4 , the DC deviation signal is the deviation between the DC set value u _dcref and the DC actual value u _dc .

The second PI controller 1022 performs PI control on the deviation signal output by the first comparator 1024; the positive input terminal of the first comparator 1024 respectively receives the output signal of the first PI controller 1021 and the secondary synchronization output by the signal extraction module 102 The negative input terminal of the current i _{Ld_sub} receives the current i _Sd output by the signal extraction module 102 .

The third PI controller 1023 performs PI control on the deviation signal output by the second comparator 1026; the positive input terminal of the second comparator 1026 respectively receives the sub-synchronous current i _{Ld_sub} and the reactive current set value output by the signal extraction module 102 i _qref , the negative input terminal receives the current i _Sq output by the signal extraction module, that is, the input signal of the second comparator 1026 is i _{Ld_sub} +i _qref −i _Sq .

The signal transformation subunit includes a third comparator 1025, a fourth comparator 1027 and a coordinate transformation subunit 1028:

The positive input terminal of the third comparator 1025 respectively receives the voltage u _Sd and the current i _Sd output by the signal extraction module 102, and the negative input terminal receives the output signal p ₂ of the second PI controller 1022, that is, the input signal of the third comparator 1025 is u _Sd +i _Sd -p ₂ .

The positive input terminal of the fourth comparator 1027 respectively receives the voltage u _Sq and the current i _Sq output by the signal extraction module 102, and the negative input terminal receives the output signal p ₃ of the third PI controller 1023, that is, the input signal of the fourth comparator 1027 is u _Sq +i _Sq -p ₃ .

The coordinate conversion subunit 1028 performs coordinate conversion on the output signals of the third comparator 1025 and the fourth comparator 1027 to obtain the voltage u _ma , the voltage u _mb and the voltage u _mc under the abc coordinates;

Among them, the current i _Sd and the current i _Sq are the current i _S of the transmission line between the collection station and the series compensation sending system in the dq coordinate system; the voltage u _Sd and the voltage u _Sq are the voltage u _S of the above transmission line at dq The voltage in the coordinate system.

(2) Pulse modulation unit

The pulse modulation unit generates a trigger pulse according to the compensation reference signal and sends it to the voltage source converter 103 .

Figure 4 is a schematic diagram of the principle of the signal processing module in the embodiment of the utility model, as shown in the figure, the compensation reference signal calculation unit in this embodiment outputs voltage u _ma , voltage u _mb and voltage u _mc , voltage u _ma , voltage u _mb and The voltage u _mc is the compensation reference signal, and the pulse modulation unit generates trigger pulses according to the voltage u _ma , the voltage u _mb and the voltage u _mc .

The new energy power generation base in the utility model includes a wind power generation base and/or a photovoltaic power generation base, and the series compensation sending system includes a series compensation device installed on the outgoing transmission line of the gathering station. The working process of the subsynchronous oscillation suppression device provided by the present invention will be described below by taking a wind power generation base as an example. Fig. 2 is a schematic diagram of the subsynchronous oscillation suppression of the power grid side sent by the wind power generation base for four days through series compensation in the embodiment of the utility model. 202 is connected to the series compensation sending system 203. One input branch of the signal extraction module 101 is connected between the collection station 202 and the series compensation sending system 203 , and the other input branch is connected between the collection station 202 and the voltage source converter 103 . In this embodiment, the voltage source converter 103 can adopt an H-bridge cascaded structure based on a fully-controlled device. After receiving the trigger pulse issued by the signal processing module 102, it controls the switch and/or shutdown of the fully-controlled device, and injects corresponding The current exchanged power with the system, so as to suppress the subsynchronous oscillation.

Obviously, those skilled in the art can make various changes and modifications to the utility model without departing from the spirit and scope of the utility model. In this way, if these modifications and variations of the utility model fall within the scope of the claims of the utility model and equivalent technologies thereof, the utility model is also intended to include these modifications and variations.

Claims (8)

1. A power grid side subsynchronous oscillation suppression device for a new energy base sent out through series compensation is characterized by comprising a signal extraction module, a signal processing module and a voltage source converter;

the signal extraction module, the signal processing module and the voltage source converter are sequentially connected;

the input end of the signal extraction module is connected between a collection station of the new energy power generation base and the series compensation output system;

the output end of the voltage source converter is connected with the outgoing power transmission line of the collection station.

2. The device as claimed in claim 1, wherein the input terminal of the signal extraction module includes two branches:

one branch circuit is connected to a power transmission line between the collection station and the series compensation output system, and the other branch circuit is connected to a bus between the collection station and the voltage source converter.

3. The device for suppressing the grid-side subsynchronous oscillation of a new energy base after series compensation as claimed in claim 1, wherein the signal extraction module comprises a signal acquisition unit and a signal extraction unit;

the signal acquisition unit acquires the voltage u of the power transmission line between the collection station and the series compensation output system _SAnd current i_SAnd collecting the current i of the bus between said collection station and the voltage source converter_L；

The signal extraction unit is used for extracting a current i according to the current_SAnd current i_LA subsynchronous current signal is determined.

4. The device for suppressing the grid-side subsynchronous oscillation of a new energy base after series compensation as claimed in claim 1, wherein the signal processing module comprises a compensation reference signal calculating unit and a pulse modulation unit;

the compensation reference signal calculation unit receives the output signal of the signal extraction unit and calculates the compensation reference signal of the collection station according to the output signal;

the pulse modulation unit generates a trigger pulse according to the compensation reference signal and sends the trigger pulse to the voltage source converter; and the voltage source converter is used for carrying out power exchange with the series compensation output system so as to inhibit subsynchronous oscillation.

5. The device for suppressing the grid-side subsynchronous oscillation of a new energy base after series compensation as claimed in claim 4, wherein the compensation reference signal calculating unit comprises a first PI controller, a second PI controller, a third PI controller and a signal transforming subunit;

the first PI controller, the second PI controller and one input end of the signal conversion subunit are sequentially connected, the third PI controller is connected with the other input end of the signal conversion subunit, and the output end of the signal conversion subunit is connected with the voltage source converter.

6. The device for suppressing the grid-side subsynchronous oscillation of a new energy base after series compensation as claimed in claim 5,

the first PI controller is used for carrying out PI control on the direct current deviation signal;

the second PI controller is used for carrying out PI control on the deviation signal output by the first comparator; the positive input end of the first comparator receives the output signal of the first PI controller and the subsynchronous current i output by the signal extraction module respectively_{Ld_sub}The negative input end receives the current i output by the signal extraction module_Sd；

The third PI controller is used for carrying out PI control on the deviation signal output by the second comparator; the positive input end of the second comparator receives the subsynchronous current i output by the signal extraction module respectively_{Lq_sub}And a reactive current setpoint i_qrefThe negative input end receives the current i output by the signal extraction module_Sq；

Wherein the current i_SdAnd current i_SqFor supplying the current i of the transmission line between the collecting station and the series_SCurrent in d-q coordinate system.

7. The device for suppressing the grid-side subsynchronous oscillation of a new energy base after series compensation as claimed in claim 5, wherein the signal conversion subunit comprises a third comparator, a fourth comparator and a coordinate conversion subunit;

The positive input ends of the third comparators respectively receive the voltage u output by the signal extraction module_SdAnd current i_SdThe negative input end receives an output signal of the second PI controller;

the positive input end of the fourth comparator receives the voltage u output by the signal extraction module respectively_SqAnd current i_SqThe negative input end receives an output signal of the third PI controller;

the coordinate transformation subunit performs coordinate transformation on output signals of the third comparator and the fourth comparator to obtain a voltage u under abc coordinates_maVoltage u_mbAnd voltage u_mc；

Wherein the current i_SdAnd current i_SqFor supplying the current i of the transmission line between the collecting station and the series_SCurrent in d-q coordinate system; the voltage u_SdAnd voltage u_SqIs the voltage u of the transmission line_SVoltage in d-q coordinate system.

8. The device for suppressing the grid-side subsynchronous oscillation of a new energy base after series compensation as claimed in claim 1,

the new energy power generation base comprises a wind power generation base and/or a photovoltaic power generation base;

the series compensation delivery system comprises a series compensation device which is arranged on an outgoing power transmission line of the collection station.