CN202433442U

CN202433442U - Current harmonic detection system based on improved FBD (Function Block Diagram) algorithm and DSP (Digital Signal Processor) technology

Info

Publication number: CN202433442U
Application number: CN2012200112821U
Authority: CN
Inventors: 马立新; 王月晓; 肖川; 单冠华; 王晓丹
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2012-01-12
Filing date: 2012-01-12
Publication date: 2012-09-12
Anticipated expiration: 2022-01-12

Abstract

The utility model relates to a current harmonic detection system based on an improved FBD (Function Block Diagram) algorithm and a DSP (Digital Signal Processor) technology. Load current and grid current respectively flow through two current transformers and are respectively connected with a pre-filter circuit through two signal lines, and the pre-filter circuit is connected with an input port of an AD (Analog Digital) data acquisition module through a single bus; the A-phase voltage of a grid flows through a voltage sensor which is connected with a zero-crossing comparator circuit through a single signal line, and output ports of the AD data acquisition module and the zero-crossing comparator circuit are connected with an input port of a DSP digital signal processing chip; and the DSP digital signal processing chip outputs sampling frequency signals to the AD data acquisition module. According to the current harmonic detection system based on the improved FBD algorithm and the DSP technology, the problems that the traditional current harmonic method has large detection delay, current spike interference and the like are solved; and through an active power filter, the grid harmonic can be quickly and accurately detected, and harmonic control and reactive power compensation are carried out, so that the quality of power supply of the grid to non-linear loads is greatly improved.

Description

Based on the current harmonics detection system of improving FBD algorithm and DSP technology

Technical field

The utility model relates to a kind of current signal detection technique, and is particularly a kind of based on the current harmonics detection system of improving FBD algorithm and DSP technology.

Background technology

Power electronic equipment with on-off mode work in the power distribution network constantly increases, and non-linear, the conflict property of these loads and unbalancedness etc. are used electrical characteristics, and the voltage of electric system, electric current are distorted, and power supply quality are caused have a strong impact on.(Active Power Filter is a kind of harmonic wave and idle compensating to real-time change APF) to Active Power Filter-APF, improves the effective power electronic equipment of grid supply quality.In order to realize the function of APF preferably, the detection link of harmonic wave and reactive current seems most important.

Present most popular electric current detecting method is based on the detection method of instantaneous reactive power theory, based on the detection method of p-q-r spatial alternation with based on the detection method of FBD method.They all are through detected fundamental current and load current being subtracted each other, obtaining whole harmonic currents and reactive current.But,, produce hysteresis error, thereby influenced the compensation performance of APF because the existence of low-pass filter (LPF) in these detection methods makes the detection time-delay reach 1～2 power cycle.The Kuang Naixing of Zhejiang University etc. on 2006 the 30th phases " Automation of Electric Systems ", publish thesis " a kind of high performance harmonic wave detect wave digital lowpass filter " designed novel low-pass filter and replaced conventional lowpass filter, but increased the complexity of system.The paper " the hysteresis error modeling of FBD algorithm current detecting " that the Ding Zujun of Southeast China University etc. delivered in 2008 the 2nd phases " electrotechnics journal " has been set up the lag model of FBD electric current testing; Introduce the linear transformation backoff algorithm; Kept low-pass filter but improve one's methods; Increase calculated amount, strengthened the computational burden of microprocessor.

Therefore, study and a kind ofly both can accurately detect harmonic wave and reactive current, the current detecting system that the time-delay of testing process less simultaneously, calculated amount is little becomes an emphasis problem of current APF research.

Summary of the invention

The utility model is the problem to harmonic current in the Active Power Filter-APF and Detecting Reactive Current hysteresis; Proposed a kind of based on the current harmonics detection system of improving FBD algorithm and DSP technology; This system designs on the basis of improving FBD algorithm and DSP technology; Promptly can accurately detect harmonic wave and reactive current, the time-delay of testing process simultaneously less, calculated amount is little.

The technical scheme of the utility model is: a kind of based on the current harmonics detection system of improving FBD algorithm and DSP technology; Comprise two current transformers, voltage sensor, zero passage comparator circuit, pre-filtering circuit, AD data acquisition module, DSP digital signal processing chip; Load current and power network current are respectively through behind two current transformers; Link to each other with the pre-filtering circuit through two signal line respectively; The pre-filtering circuit links to each other with the input port of AD data acquisition module through unibus, and electrical network A phase voltage links to each other with the zero passage comparator circuit through the one-channel signal line through overvoltage sensor; The output of AD data acquisition module and zero passage comparator circuit connects DSP digital signal processing chip input port, and DSP digital signal processing chip output sampling frequency rate signal is to the AD data acquisition module.

The AD7656 chip that the TMS320F2812 chip that said DSP digital signal processing chip selects for use American TI Company to produce, AD data acquisition module select for use Analog Device company to produce.

The beneficial effect of the utility model is: the utility model is based on the current harmonics detection system of improving FBD algorithm and DSP technology; Problems such as the detection time-delay that has solved the humorous wave method of conventional current is big, the interference of electric current spine; Can let Active Power Filter-APF can detect mains by harmonics rapidly and accurately; Carry out harmonic wave control and reactive-load compensation, greatly improved the power supply quality of electrical network nonlinear load.

Description of drawings

Fig. 1 is that the utility model is based on the current harmonics detection system theory diagram that improves FBD algorithm and DSP technology;

Fig. 2 is that the utility model improves FBD algorithm software process flow diagram based on the current harmonics detection system of improving FBD algorithm and DSP technology.

Embodiment

Systematic schematic diagram as shown in Figure 1, the utility model comprise 5,8, voltage sensors 2 of two current transformers, zero passage comparator circuit 3, pre-filtering circuit 9, AD data acquisition module 10, DSP digital signal processing chip 6.Consider the digital computation processing power, the TMS320F2812 chip that dsp chip selects for use American TI Company to produce.In order to improve sampling precision, system does not select 12 inner integrated ADC module of TMS320F2812 for use, AD the data acquisition module 10 and AD7656 chip that has been to use Analog Device company to produce is sampled to signal.For fear of the losing lock phenomenon of phaselocked loop, system design zero cross detection circuit, through detecting the phase zero points of A phase phase voltage 1, trigger AD data acquisition module 10AD7656 and begin sampling, can obtain the real time data of degree of precision.

Through voltage sensor senses A phase phase voltage 1, voltage sensor 2 obtains sine wave signal less with A phase phase voltage 1 amplitude and that phase place is identical, and behind zero passage testing circuit 3, obtaining amplitude is the identical 50Hz square-wave signal of 5V, frequency and sine wave signal.Again this square wave is delivered to the mouth of catching of DSP digital signal processing chip 6, its rising edge is caught.Through to the catching the cycle that can obtain AC signal of twice rising edge of square-wave signal, through the software frequency multiplication, the SF of 12.8kHz is delivered to the SF of AD7656 data acquisition module 10 as sampling module, guarantee the synchronism of each road sampled signal.Sending into AD data acquisition module 10AD7656 chip after 9 filtering of entering pre-filtering circuit behind two

current transformer

5,8 circuitry for signal measurement of threephase load electric current 4 and power network current 7 inflows samples.Pass through signal condition again, send into DSP digital signal processing chip 6.

Improvement FBD algorithm software process flow diagram as shown in Figure 2 in DSP digital signal processing chip 6, calculates above-mentioned data as the input data of improving the FBD algorithm.At first,, obtain the phasing degree of electrical network A phase voltage 1, obtain the phasing degree of three-phase voltage according to the positive sequence definition according to the square-wave signal of catching.The vector of unit length of power taking net voltage is a reference quantity, and promptly amplitude is 1, the phasing degree is constant.Then,, utilize load current and Voltage Reference amount, calculate instantaneous meritorious electricity and lead with the instantaneous reactive electricity and lead, carry out meritorious DC quantity and the idle DC quantity that filtering obtains the fundamental current correspondence through running integral again according to the definition of the instantaneous power of FBD algorithm.Reference quantity with DC quantity and voltage multiplies each other then, obtains three-phase positive sequence fundamental current.Through comparing power network current and positive sequence fundamental current, when the difference of amplitude is less than or equal to the compensation threshold value, load current and fundamental current are subtracted each other, obtain harmonic current and reactive current sum, otherwise, repeat said process.

The utility model will be quickly and accurately FBD algorithm and high performance data-handling capacity combine, reduced the latency issue of traditional detection method, improved the precision and the speed that detect significantly, strengthened the real-time computing of system preferably.The utility model hardware circuit is simple and reliable, real-time performance good, and the high computing velocity of software systems precision is fast, conveniently is applied to three-phase system and non-three-phase system, has very strong practical applications property.

Claims

1. one kind based on improving FBD algorithm and the technological current harmonics detection system of DSP; It is characterized in that; Comprise two current transformers, voltage sensor, zero passage comparator circuit, pre-filtering circuit, AD data acquisition module, DSP digital signal processing chip; Load current and power network current link to each other with the pre-filtering circuit through two signal line respectively respectively through behind two current transformers, and the pre-filtering circuit links to each other with the input port of AD data acquisition module through unibus; Electrical network A phase voltage is through overvoltage sensor; Link to each other with the zero passage comparator circuit through the one-channel signal line, the output of AD data acquisition module and zero passage comparator circuit connects DSP digital signal processing chip input port, and DSP digital signal processing chip output sampling frequency rate signal is to the AD data acquisition module.

2. according to claim 1 based on the current harmonics detection system of improving FBD algorithm and DSP technology; It is characterized in that; The AD7656 chip that the TMS320F2812 chip that said DSP digital signal processing chip selects for use American TI Company to produce, AD data acquisition module select for use Analog Device company to produce.