WO2012130008A1

WO2012130008A1 - Svc reactive predictive compensation method for rectifier load

Info

Publication number: WO2012130008A1
Application number: PCT/CN2012/071647
Authority: WO
Inventors: 赵柏品; 张普红; 吴瑶; 林继如; 左强; 焦东亮; 黎军; 王飞义; 李海生; 王晓艳; 安万洙; 司明起; 时伟; 霍健; 金太英; 徐刚
Original assignee: 荣信电力电子股份有限公司; 北京荣科恒阳整流技术有限公司
Priority date: 2011-03-29
Filing date: 2012-02-27
Publication date: 2012-10-04
Also published as: CN102118032B; CN102118032A

Abstract

A static VAR compensator (SVC) reactive predictive compensation method for rectifier load, the method comprises the following steps: 1) a rectifier controller calculating a triggering angle and simultaneously calculating the reactive power to be generated by a load, and transmitting the rectifier load reactive power to an SVC controller; 2) the SVC controller receiving the predicted reactive power sent by the rectifier controller, collecting the switching state of a filter branch circuit breaker, and simultaneously collecting a power grid current and power grid voltage signal for calculating reactive compensation quantity, and finally realizing trigger control compensation with the trigger angle method; and 3) after predictive compensation, compensating a deviation caused by the reactive power calculation via a PI governing loop. The method can effectively compensate a large amount of rapid reactive impact in the working process of the load via a SVC device, and the SVC device has short response time, thus able to achieve the objective of rapid reactive power compensation, and can effectively inhibit the impact of the reaction to the power grid, thereby eliminating voltage flicker.

Description

SVC reactive power prediction compensation method for rectifier load

The present invention relates to a high voltage SVC and high current rectifier device for use in a field where a rectifier is used as a load power supply and requires reactive compensation. Background technique

SVC static reactive power compensation equipment is the most widely used and most mature reactive power compensation equipment. By controlling the thyristor firing angle of the compensation reactor branch to adjust the impedance value of the branch, and matching with the filter, the power is achieved. Reactive power support in the system power supply area or reactive power compensation of large power users. The application of SVC to the power system can enhance the power transmission of the system and improve the stability of the power system. It has functions such as damping power oscillation and suppressing subsynchronous oscillation and power factor compensation.

SVC can be applied to large power users to increase the user's power factor, save money, stabilize the bus voltage, and suppress harmonic injection into the power system.

In the traditional mode, SVC is applied to the large metallurgical load of the rectifier as the power supply. It also detects the grid voltage current operation parameters or directly detects the load voltage and current parameters to calculate the required compensation amount to control the reactive output of the SVC equipment. In the traditional sampling calculation compensation method, subject to the sampling filter delay and the inherent trigger mode of the SVC device, the response time is as fast as 10ms.

When the user's load impact is large and frequent and fast, it is hoped that the reactive power compensation device can compensate more quickly to suppress the voltage flicker and achieve the best compensation effect. SVG equipment can meet the needs of users. However, the price of SVG equipment is much higher than that of SVC equipment. Therefore, the new compensation method of SVC equipment is sought to improve its response time, so as to broaden the application field of SVC equipment and effectively extend the service time of SVC equipment. The urgent task of the manufacturer.

In order to obtain ultra-high temperature for nuclear reactors, the most widely used tokamak device (T _0KaMaK ) is today: a ring-shaped electromagnetic plasma device. This project will be completed in France by several industrial countries in the near future. The name of this project is the International Thermonuclear Experimental Reactor (ITER).

The tokamak device ensures heat generation through the short-circuit winding in the electromagnetic system and its temperature and the current flowing through it (it has a complementary heating system) and ensures the plasma with the help of a strong electromagnetic field.

The Tokamak electromagnetic system uses a DC power supply to ensure plasma generation and correct its polarity, using a thyristor rectifier in the form of a three-phase bridge, which is connected under a power 66kV bus transformer.

The electromagnetic power system and the plasma heating system have rectification characteristics in a pulse state. The storage of energy in the electromagnetic system is at the end of the process and is supplied to the grid in a rectified state in the inverted state. Worked in this There will be a lot of rapid reactive impact in the process.

At present, the reactive power compensation method for SVC equipment for rectifier load has not been reported. Summary of the invention

The object of the present invention is to provide a rectifier load SVC reactive power prediction compensation method based on the International Thermonuclear Experimental Reactor (ITER) project, which predicts load reactive power through a DC power supply, and implements a load tokamak entirely by the SVC device. The effective compensation of a large number of fast reactive power surges during the working process of the device, the short response time of the SVC device can achieve the purpose of rapid compensation of reactive power, can effectively suppress the impact of reactive power on the power grid, and eliminate the occurrence of voltage flicker.

To achieve the above object, the present invention is achieved by the following technical solutions:

A rectifier load SVC reactive power prediction compensation method, the method comprising the following steps:

1) The rectifier controller calculates the reactive power to be generated while calculating the firing angle, and converts the rectifier reactive power into a standard signal of 4 mA to 20 mA, and transmits it to the SVC controller;

2) The SVC controller receives the predicted reactive power from the rectifier controller, collects the switching state of the filter branch circuit breaker, and simultaneously collects the grid current and the grid voltage signal for the calculation of the reactive compensation amount, and finally uses the firing angle mode. Implement trigger control compensation;

3) SVC reactive power prediction compensation mode control strategy: The SVC controller determines whether the filter branch is put into operation by detecting the switching state of the filter branch circuit breaker. When the filter branch circuit breaker is closed, the Sfcn status indication is 1 ; When the filter path breaker is opened, the Sfcn state value is 0; multiply the state quantity of each filter branch by the reactive power fixed compensation amount of the branch and then sum, then obtain the filter branch without Workload

4) After the predicted compensation, the system reactive power has a stable deviation, and the deviation caused by the reactive power calculation is compensated by the PI adjustment link.

The calculation formula of each of the six-pulse rectifier load reactive power is:

^; The load reactive power of a six-pulse rectifier is the primary side bus voltage rating of the rectifier transformer. The commutation overlap angle of the rectifier at the firing angle « The trigger angle for the rectifier is the DC current reference value, ie the rectifier control DC target value: for the rectifier transformer ratio

^ is the primary side system inductance value of the rectifier transformer

The reactive power of the rectifier series-parallel group composed of multiple six-pulse rectifiers is the sum of the reactive power of each rectifier, and the calculation formula is - 4 QwS +, " Φ 3⁄4:^: s

Among them: 1, 2, . . . . 1 is the first, second, and nth six-pulse rectifiers.

Compared with the prior art, the beneficial effect of the invention is that the rectifier controller calculates the reactive power to be generated by the load while calculating the firing angle, and transmits the reactive power to the SVC controller; When calculating the reactive power of the load, the reactive power compensation can be accurately triggered in advance, which effectively reduces the response time of the SVC and achieves the purpose of fast compensation of reactive power. The application on the rectifier device shows that the reactive power compensation response time of the invention can be shortened to about 3ms, effectively suppressing the impact of reactive power on the power grid and eliminating the occurrence of voltage flicker. DRAWINGS

1 is a structural block diagram of a SVC reactive power prediction compensation method for a rectifier load;

2 is a control block diagram of a SVC reactive power prediction compensation method for a rectifier load;

Figure 3 is a basic structure diagram of a series of parallel connection of multiple three-phase full-controlled bridge rectifiers;

Figure 4 is a block diagram of the control strategy of the SVC reactive power prediction compensation method for rectifier load. detailed description

See Figure 1 - Figure 4, SVC reactive power prediction compensation method for rectifier load. The technical key of this method lies in: First, how the rectifier controller accurately predicts the reactive power value of the DC load response on the grid side; Second, SVC control The system monitors the state of the filter branch; the third is the correction of the SVC compensation accuracy. 4. The time difference between the time when the reactive power is generated by the SVC device and the reactive power generated by the rectifier is 3ms~4ms, and the response time is short.

If the rectifier reactive power calculation is not accurate, it will directly affect the suppression of flicker. Therefore, when calculating the reactive power of the load, the rectifier controller fully considers the influence of the voltage drop caused by the commutation impedance of the rectifier, and adjusts the calculation method in the presence of the SVC reactive power compensation device. The calculation method of rectifier load reactive power is as follows:

The calculation formula for the reactive power of each six-pulse rectifier is:

Γ l « K 6 D 1 3 where - ^; is the reactive power of a six-pulse rectifier

^∞ is the primary side bus voltage rating of the rectifier transformer

^ is the commutation overlap angle of the rectifier at the firing angle. Rectifier firing angle «/ is the DC current reference value, that is, the rectifier control DC target value ^ is the rectifier transformer ratio s is the rectifier side primary side system inductance value

The reactive power of the series-parallel group of rectifiers composed of multiple six-pulse rectifiers is the sum of the reactive power of each rectifier, and the calculation formula is -

― + +...+ where: 1, 2, . . . . 1 is the first, second, and nth six-pulse rectifiers.

Since the SVC reactive power prediction compensation method of the rectifier load of the present invention does not directly rely on detecting the voltage and current of the system for reactive power adjustment, in addition to the load reactive power compensation of the rectifier, the reactive branch is also required according to the filter branch. Investing and reversing the situation to adjust the compensation amount to avoid reactive power shock during the SVC input and exit process.

As shown in Figure 4, the SVC controller determines whether the filter branch is put into operation by detecting the switching state of the filter branch. When the filter branch circuit breaker is closed, the Sfcn status is indicated as 1; when the filter is disconnected After the device is opened, the Sfcn status value is 0. By multiplying the state quantities of the respective filter branches by the reactive power fixed compensation amount of the branch and then summing, the reactive power of each filter branch is obtained. The reactive power of the filter branch is capacitive reactive. In the SVC reactive power prediction compensation mode, the capacitive reactive power is defined as positive, and the inductive reactive power is defined as negative.

The working process of the SVC reactive power compensation compensation mode control strategy is as follows: When the filter branch is input, the amount of reactive power to be compensated by the SVC increases, the TCR firing angle becomes smaller, and the corresponding inductive reactive power is output; , SVC needs The compensated reactive power is reduced, the TCR firing angle is increased, and the output corresponding inductive reactive power is reduced. When the load inductive reactive power increases, the total amount of reactive power to be compensated by the SVC decreases, the TCR firing angle becomes larger, and the output corresponding inductive reactive power decreases. If the system reactive power has a stable deviation after the predicted compensation, the PI adjustment link is activated to eliminate the stability error of the compensation.

In Figure 4: Qfcn is the compensation reactive power value of each filter channel.

Sfcn is the switching state of each filter channel

Qyc calculates the reactive power output for the rectifier controller.

Qsr is the system incoming line SVC reactive power compensation target reactive power value

Qs is the reactive power detection value of the system incoming line

Us is the system bus voltage

Is the system incoming current value

The integrated load compensated by the SVC equipment includes the filter FC, the Tokemark device powered by the rectifier, and other auxiliary power loads under the same busbar power supply. If the load other than the rectifier main power source is not considered, the SVC device effect will appear. Certain deviation. Therefore, while receiving the rectifier to predict the reactive power, the SVC device adds integral adjustment to ensure the steady-state compensation effect of the SVC compensator, and also corrects the compensation deviation caused by the reactive power calculation error of the rectifier controller.

If the reactive power of the SVC device does not match the reactive power generated by the rectifier, the lead compensation or the lag compensation will not achieve the desired flicker suppression effect. In order to ensure that there is no capacitive reactive power shock, but to obtain a fast response time, the final response time is determined to be 3ms~4ms, which fully achieves the compensation effect of preventing reactive shock and suppressing flicker.

The compensation effect under the traditional compensation mode of the SVC device with rectifier load is compared with the compensation effect under the SVC reactive power prediction compensation mode of the rectifier load of the present invention. The results are as follows:

Test conditions: The voltage on the AC side of the rectifier is 113V, and the DC current is reduced from 40kA at 1000kA/s to the SVC compensation effect of the process.

In the traditional compensation mode of the SVC device, the response time is about 10ms, and the full compensation time is about 60ms.

In the reactive power compensation mode, the response time is only 3ms~4ms, and the full compensation time is about 20ms. The experiment proves that the compensation method has the remarkable characteristics of fast response time compared with the traditional SVC compensation method. It can effectively suppress the system voltage flicker problem under the condition of reactive power shock load with fast and large capacity.

Claims

^ ^

A SVC reactive power prediction compensation method for a rectifier load, characterized in that the method comprises the following steps:

2. The rectifier load SVC reactive power prediction compensation method according to claim 1, wherein the calculation formula of each of the six-pulse rectifier load reactive power is:

f . f X谨 1 3

. ' ■ if I

Where - 3⁄4 = the load reactive power of a six-pulse rectifier is the primary side bus voltage rating of the rectifier transformer. The commutation overlap angle of the rectifier at the firing angle « is the rectifier firing angle for the DC current reference value, ie the rectifier controls the DC Target value

K is the rectifier transformer ratio. The inductance value of the primary side of the rectifier transformer.

The reactive power of the series-parallel group of rectifiers composed of multiple six-pulse rectifiers is the sum of the reactive power of each rectifier, and the calculation The formula is - 》 : i Qyc2 +... + o3⁄4

Among them: 1, 2, ...! 1 is the first, second, and nth six-pulse rectifiers.

3 . The rectifier load SVC reactive power prediction compensation method according to claim 1 , wherein the time difference between the reactive power moment of the SVC device and the reactive power generated by the rectifier is 3 ms to 4 ms, and the response time is short. .