CN204858573U - Three -phase grid reactive compensation circuit, compensating system - Google Patents

Abstract

The utility model relates to a three -phase grid reactive compensation circuit, compensating system, including three net side inductance, three contravariant inductance, three -phase bridge circuit, the C4 of electric capacity group, three net side inductance includes inductor L1, inductor L2 and inductor L3, three contravariant inductance includes inductor L4, inductor L5 and inductor L6, the one end of three net side inductance respectively with three -phase grid A, B, C connects, the three net side inductance other end corresponds with three contravariant inductance respectively to be connected, the other end of three contravariant inductance is connected with three -phase bridge circuit's contravariant outlet side respectively, the C4 of electric capacity group is the support electric capacity of three -phase bridge circuit direct current side, the utility model discloses an it is low to solve grid system power factor, and the problem of the unable compensation that the transformer is idle proposes the compensation arrangement that improvement electric wire netting platform district power factor, the improvement transformer to three -phase grid is exerted oneself, is reduced the line loss, is stablized circuit voltage, the correction transformer is idle.

Description

Three phase network reactive power compensation circuit, bucking-out system

Technical field

The utility model relates to the improvement of mains supply system power quality, is specifically related to a kind of three phase network reactive-load compensation method and Standard type device.

Background technology

Network system, user mostly is single-phase load, most of load belongs to inductive load, the equipment such as such as electromagnetic oven, air-conditioning, motor, water pump and agricultural electrical equipment, need to draw idle from electrical network, cause that power factor of electric network is low, transformer undercapacity, line loss are large, line end low-voltage problem; Tradition reactive power compensation adopts capacitor switching mode, and capacitor switching easily causes overcompensation, undercompensation problem, easy and electrical network generation resonance.When transformer night is unloaded or transformer load rate is low, the reactive loss of transformer self seems abnormal outstanding, usual reactive power compensator is installed on Circuit Fault on Secondary Transformer, compensation arrangement is by detecting load current, carry out reactive power compensation, but when no-load transformer or load factor low when, transformer secondary lateral load is very little or can't detect load current, and traditional reactive-load compensation equipment cannot run work; Cannot consume by compensator transformer own reactive;

The utility model proposes a kind of Standard type device of power grid flexible reactive power compensation,, transformer undercapacity, line loss low for above-mentioned power factor are large, line end low-voltage problem, can solve above network system Problems existing, more traditional Reactive Compensation Mode solves undercompensation, the overcompensation of existence and cannot carry out the problems such as transformer reactive compensation.

Summary of the invention

The purpose of this utility model is that solution network system power factor is low, the problem that transformer is idle cannot be compensated, and line end low-voltage problem, propose a kind of raising for three phase network electricity net platform region power factor, improve a kind of compensation arrangement that transformer is exerted oneself, reduces line loss, stablized line voltage distribution, compensator transformer is idle.

To achieve these goals, the utility model adopts following technical scheme:

Three phase network reactive power compensation circuit, its special character is: comprise three net side inductance, three inversion inductors, three-phase bridge circuit, capacitance group C4, described three net side inductance comprise inductor L1, inductor L2 and inductor L3, described three inversion inductors comprise inductor L4, inductor L5 and inductor L6, one end of three net side inductance respectively with three phase network A, B, C connects, three net side inductance other ends are corresponding with three inversion inductors respectively to be connected, the other end of three inversion inductors is connected with the inversion outlet side of three-phase bridge circuit respectively, described capacitance group C4 is the Support Capacitor of three-phase bridge circuit DC side,

Inductor L1 is connected with the tie point of inductor L4 R1 and the C1 connected, and inductor L2 is connected with the tie point of inductor L5 R2 and the C2 connected, and inductor L3 is connected with the tie point of inductor L6 R3 and the C3 connected; The other end of described C1, C2, C3 is connected to same point.

Above-mentioned three-phase bridge circuit is made up of 3 IGBT module.

Three phase network reactive compensation system, comprises three phase network reactive power compensation circuit, detects sampling conditioning unit, control algorithm unit and driver element,

The described sampling conditioning unit that detects is for the output conditioned signal of carrying out nursing one's health from three net side inductance and the LCL filtered circuit at three-phase inversion inductance tie point place, three-phase inversion inductance and the three-phase inversion output current of three-phase bridge circuit junction, the threephase load electric current of external load and three-phase power grid voltage of sampling;

Described control algorithm unit comprises soft phase-locked loop control module, Voltage stabilizing module, extraction module, transformer idle component computing module and SPWM modulation module,

Described Voltage stabilizing module is used for receiving target magnitude of voltage, three-phase power grid voltage is stabilized to target voltage values simultaneously, and sends to SPWM modulation module;

Described transformer idle component computing module, for receiving known transformer parameter, by calculating transformer own reactive electric current, and sends to SPWM modulation module;

Described soft phase-locked loop control module is carried out phase-locked to three-phase power grid voltage, exports synchronizing signal:

Load current, based on instantaneous reactive current detection method, according to synchronizing signal, is decomposed into positive sequence component and negative sequence component by described extraction module; First-harmonic composition in laggard onestep extraction positive sequence component and negative sequence component, obtains the positive sequence reactive current that needs to compensate and negative phase-sequence reactive current, and sends to SPWM modulation module;

Described SPWM modulation module receives the reactive current of threephase load electric current corresponding positive sequence reactive current, negative phase-sequence reactive current and transformer, and SPWM modulation is carried out in above referenced reactive current addition, obtains three road pwm signal level;

Above-mentioned driver element: by three road pwm signal level conversion conditionings, obtain the PWM drive singal of 6 tunnel isolation, control three-phase bridge circuit.

Above-mentioned control algorithm unit also comprises protection module, for foundation voltage, electric current, frequency protection equipment.

Above-mentioned control algorithm unit is based on DSP and FPGA.

Three phase network reactive-load compensation method, comprises the following steps:

1) the output conditioned signal that sampling is carried out nursing one's health from three net side inductance and the three-phase LCL filtered circuit at three-phase inversion inductance tie point place, three-phase inversion inductance and the three-phase inversion output current of three-phase bridge circuit junction, the threephase load electric current of external load and three-phase power grid voltage is gathered; Offered target magnitude of voltage;

2) three-phase power grid voltage is stabilized to target voltage values simultaneously, carries out phase-locked to three-phase power grid voltage simultaneously, export synchronizing signal:

3) according to synchronizing signal, load current is decomposed into positive sequence component and negative sequence component; First-harmonic composition in laggard onestep extraction positive sequence component and negative sequence component, obtains the positive sequence reactive current that needs to compensate and negative phase-sequence reactive current;

4) known transformer parameter is received, by calculating the reactive current of transformer;

5) reactive current of positive sequence reactive current, negative phase-sequence reactive current and transformer is added and carries out SPWM modulation, obtains three road pwm signal level;

6) by three road pwm signal level conversion conditionings, obtain the PWM drive singal of six tunnel isolation, control three-phase bridge circuit, realize line voltage distribution and stablize.

Above-mentioned steps 3 specifically adopts based on instantaneous reactive current detection method.

Above-mentioned steps 2 is specific as follows:

When known transformer parameter, obtained the reactive power △ Q of transformer by following formulae discovery:

$\mathrm{\Δ}Q=Q_0+Q_r=\sqrt{{\left(\frac{I_0\%*S_r}{100}\right)}^2-p_0^2}+I_L^2*X_B$

Wherein:

Q ₀: the excitation loss reactive power of no-load transformer;

Q _r: the excitation reactive power power of the real transformer that load causes;

I _l: transformer secondary apparent current effective value;

P ₀: transformer noload losses;

S _r: transformer capacity (KVA);

I ₀%: no-load transformer electric current perunit value;

X _b: transformer induction reactance;

$X_B=\sqrt{Z_B^2-R_B^2}$

R _b: transformer equivalent resistance;

$R_B=\frac{P_K*U_r^2}{S_r^2}*{10}^3$

P _k: transformer copper loss (KW);

U _r: transformer voltage ratio KV/V;

Z _b: transformer equiva lent impedance:

$Z_B=\frac{U_K{\mathrm{\%U}}_r^2}{100S_r}*{10}^3$

U _k%: transformer short-circuit voltage (KV).

Compared with prior art, advantage is the utility model:

1, the utility model can realize reactive power compensation: by 3 current transformers sampling load currents, extract real-time goes out reactive current, according to load reactive current characteristic, and the idle or capacitive reactive power of perception.If load is that perception is idle, then export capacitive reactive power, if load is capacitive reactive power, then device exports perceptual idle, and amplitude is equal, realizes load compliant reactive power compensation.

2, the utility model there will not be/undercompensation: by detecting load current, extract reactive current, follow load reactive current size and regulate in real time, total reponse time is less than 10ms, and dynamic following is effective, there will not be/undercompensation.Be different from traditional capacitance cabinet compensation way.

3, the utility model can realize phase splitting compensation: network load mostly is single-phase load, due to the otherness of the temporal otherness of loaded work piece and threephase load, system three-phase imbalance, by current transformer sampling three-phase electric current, extract three-phase reactive current size respectively, can phase splitting compensation, according to the difference of the every phase reactive current of load, dynamic phase splitting compensation in real time;

4, the utility model can realize transformer reactive compensation: in the unloaded or underloading situation in electric net platform region, only has the reactive power consumption of transformer self, step down side current transformer cannot sample electric current, cannot consume by compensator transformer own reactive: by setting the relevant parameter of transformer, obtain transformer by DSP computing idle, produce pwm control signal, drive IGBT module, export corresponding transformer reactive compensation electric current, idle by low-pressure side compensator transformer.

Accompanying drawing explanation

Fig. 1 is three phase network reactive power compensation circuit figure of the present utility model;

Fig. 2 is that symmetrical component method decomposes the idle principle schematic of positive sequence negative phase-sequence;

Fig. 3 is three phase network reactive compensation system schematic diagram of the present utility model.

Embodiment

Describe structure of the present utility model and operation principle with reference to the accompanying drawings in detail below.Because load in network system causes the imbalance of reactive power, be cause because the negative phase-sequence idle component in load current is superimposed upon in positive sequence component.Making reactive power equilibrium to compensate, these unbalanced components will be extracted from total current.

The utility model device is current source converter.As shown in Figure 1, three phase network reactive power compensation circuit, comprise three net side inductance, three inversion inductors, three-phase bridge circuit, capacitance group (C4, C5), three net side inductance comprise inductor L1, inductor L2 and inductor L3, three inversion inductors comprise inductor L4, inductor L5 and inductor L6, one end of three net side inductance respectively with three phase network A, B, C connects, three net side inductance other ends are corresponding with three inversion inductors respectively to be connected, the other end of three inversion inductors is connected with the inversion outlet side of three-phase bridge circuit respectively, capacitance group (C4, C5) be the Support Capacitor of three-phase bridge circuit DC side,

Inductor L1 is connected with the tie point of inductor L4 R1 and the C1 connected, and inductor L2 is connected with the tie point of inductor L5 R2 and the C2 connected, and inductor L3 is connected with the tie point of inductor L6 R3 and the C3 connected; The other end of C1, C2, C3 is connected to same point.Filter circuit, mainly filtering switch time high-frequency signal.

Main circuit is three-phase bridge two level current mode current transformer composition, device for power switching adopts igbt (IGBT) module, DC side adopts electrochemical capacitor to support as direct voltage energy storage, the output loop of device adopts LCL filtering, main filtering device for power switching high frequency switching noise, equipment is connected with electrical network by reactor, and device can not produce resonance with electrical network.

The utility model in order to compensate caused by load idlely add transformer reactive current, the given of the reactive current compensated is needed as system, DSP is utilized to carry out SPWM modulation, generate a series of pwm signal, drive the three-phase bridge circuit be made up of IGBT module through drive circuit, send the offset current of needs.Potentiostatic mode can also be operated in addition, solve the problem of line voltage distribution wide fluctuations, especially the low-voltage problem of line end, by arranging voltage stabilizing desired value, equipment passes through output capacitive reactive power or perception is idle, reach the function of stable line voltage distribution, by detecting the deviation of voltage stabilizing desired value and actual electric network voltage, obtain the referenced reactive current needing to export, utilize DSP to carry out SPWM modulation, generate a series of pwm signal, drive IGBT module through drive circuit, by exporting the mode of reactive current, realizing line voltage distribution and stablizing.

Three phase network reactive-load compensation method, comprises the following steps:

1) the output conditioned signal that sampling is carried out nursing one's health from three net side inductance and the three-phase LCL filtered circuit at three-phase inversion inductance tie point place, three-phase inversion inductance and the three-phase inversion output current of three-phase bridge circuit junction, the threephase load electric current of external load and three-phase power grid voltage is gathered; Offered target magnitude of voltage;

2) three-phase power grid voltage is stabilized to target voltage values simultaneously, carries out phase-locked to three-phase power grid voltage simultaneously, export synchronizing signal;

3) based on instantaneous reactive current detection method, according to synchronizing signal, load current is decomposed into positive sequence component and negative sequence component; First-harmonic composition in laggard onestep extraction positive sequence component and negative sequence component, obtains the positive sequence reactive current that needs to compensate and negative phase-sequence reactive current;

4) known transformer parameter is received, by calculating the reactive current of transformer;

5) reactive current of positive sequence reactive current, negative phase-sequence reactive current and transformer is added and carries out SPWM modulation, obtains three road pwm signal level;

6) by three road pwm signal level conversion conditionings, obtain the PWM drive singal of six tunnel isolation, control three-phase bridge circuit, realize line voltage distribution and stablize.

When known transformer parameter, obtained the reactive power △ Q of transformer by following formulae discovery:

$\mathrm{\Δ}Q=Q_0+Q_r=\sqrt{{\left(\frac{I_0\%*S_r}{100}\right)}^2-p_0^2}+I_L^2*X_B$

Wherein:

Q ₀: the excitation loss reactive power of no-load transformer;

Q _r: the excitation reactive power power of the real transformer that load causes;

I _l: transformer secondary apparent current effective value;

P ₀: transformer noload losses;

S _r: transformer capacity (KVA);

I ₀%: no-load transformer electric current perunit value;

X _b: transformer induction reactance;

$X_B=\sqrt{Z_B^2-R_B^2}$

R _b: transformer equivalent resistance;

$R_B=\frac{P_K*U_r^2}{S_r^2}*{10}^3$

P _k: transformer copper loss (KW);

U _r: transformer voltage ratio KV/V;

Z _b: transformer equiva lent impedance:

$Z_B=\frac{U_K{\mathrm{\%U}}_r^2}{100S_r}*{10}^3$

U _k%: transformer short-circuit voltage (KV).

Three phase network one improves power factor of electric network, and compensator transformer is idle, stablizes the method for line voltage distribution, comprises the following steps:

1] based on instantaneous reactive current detection method:

According to threephase load electric current, based on instantaneous reactive current detection method, be decomposed into positive sequence component and negative sequence component, extracted first-harmonic composition further, thus obtained the positive sequence reactive current and negative phase-sequence reactive current that need to compensate.Realize phase-splitting reactive compensation, effectively administer for unbalanced power supply.

2] transformer is idle:

When known transformer parameter, obtained the reactive power △ Q of transformer by following formulae discovery:

$\mathrm{\Δ}Q=Q_0+Q_r=\sqrt{{\left(\frac{I_0\%*S_r}{100}\right)}^2-p_0^2}+I_L^2*X_B$

Wherein:

Q ₀: the excitation loss reactive power of no-load transformer;

Q _r: the excitation reactive power power of the real transformer that load causes;

I _l: transformer secondary apparent current effective value;

P ₀: transformer noload losses;

S _r: transformer capacity (KVA);

I ₀%: no-load transformer electric current perunit value;

X _b: transformer induction reactance;

$X_B=\sqrt{Z_B^2-R_B^2}$

R _b: transformer equivalent resistance;

$R_B=\frac{P_K*U_r^2}{S_r^2}*{10}^3$

P _k: transformer copper loss (KW);

U _r: transformer voltage ratio KV/V;

Z _b: transformer equiva lent impedance:

$Z_B=\frac{U_K{\mathrm{\%U}}_r^2}{100S_r}*{10}^3$

U _k%: transformer short-circuit voltage (KV).

3] Phase Lock Technique:

Utilize the soft phase-locked loop control module of DSP, carry out phase-locked to line voltage, as control system synchronizing signal, the various impact load of network system is many, voltage ripple of power network scope is large, and line voltage exists larger phase frequency skew, and this phase-locked loop adds stabilization and phase deviation process for power grid application, adapt to wider mains frequency fluctuation range, can 48Hz ~ 52Hz be reached;

4] a kind of method of the raising electrical network terminal voltage stability based on active compensation technology:

Mains supply system, change by bearing power, scope range of the fluctuation of voltage is large, and especially when bearing power is large, end low-voltage problem is serious, this device can be installed to line end low-voltage end Standard type, this device Real-Time Monitoring line voltage, if tail end line voltage is lower than state's net low-voltage limit value, device runs on potentiostatic mode automatically, export capacitive reactive power electric current, by Network Voltage Stability to target voltage values; If tail end line voltage is higher than state's net height voltage limits, device runs on potentiostatic mode automatically, exports perceptual reactive current, by Network Voltage Stability to target voltage values.

5] active electric current generation technique:

By detecting load three-phase current ia, ib, the positive sequence that ic obtains the uneven composition of three-phase current corresponding is respectively idle, negative phase-sequence is idle and transformer reactive current, above referenced reactive current is added, again by d, q ordinate transform is to three phase coordinate systems, obtain the current-order of three phase coordinate systems, SPWM modulation is carried out based on DSP, obtain three road pwm signals, the pwm signal level that DSP exports is 3.3V, amplify through signal in outside, obtain+15V, 6 road drive singal of the band dead band isolation of-10V level, 63 groups, tunnel drive singal drive IGBT work, inversion exports and connects electrical network by inductor, adopt closed-loop control system, accurately obtain the electric current needing to export.

Owing to there is a large amount of single-phase loads in electrical network, single-phase load puts into operation and will cause the imbalance of three phase reactive power.The utility model is by extracting the unbalanced component in three-phase current.First utilize symmetrical component method, the threephase load electric current of measurement be transformed to order components by phase component, obtain the negative sequence component electric current and the positive sequence component electric current that need compensation:

Mains supply system, change by bearing power, scope range of the fluctuation of voltage is large, and especially when bearing power is large, end low-voltage problem is serious, this device can be installed to line end low-voltage end Standard type, this device Real-Time Monitoring line voltage, if tail end line voltage is lower than state's net low-voltage limit value, device runs on potentiostatic mode automatically, export capacitive reactive power electric current, by Network Voltage Stability to target voltage values; If tail end line voltage is higher than state's net height voltage limits, device runs on potentiostatic mode automatically, exports perceptual reactive current, by Network Voltage Stability to target voltage values.

Claims (5)

1. three phase network reactive power compensation circuit, it is characterized in that: comprise three net side inductance, three inversion inductors, three-phase bridge circuit, capacitance group C4, described three net side inductance comprise inductor L1, inductor L2 and inductor L3, described three inversion inductors comprise inductor L4, inductor L5 and inductor L6, one end of three net side inductance respectively with three phase network A, B, C connects, three net side inductance other ends are corresponding with three inversion inductors respectively to be connected, the other end of three inversion inductors is connected with the inversion outlet side of three-phase bridge circuit respectively, described capacitance group C4 is the Support Capacitor of three-phase bridge circuit DC side,

Inductor L1 is connected with the tie point of inductor L4 R1 and the C1 connected, and inductor L2 is connected with the tie point of inductor L5 R2 and the C2 connected, and inductor L3 is connected with the tie point of inductor L6 R3 and the C3 connected; The other end of described C1, C2, C3 is connected to same point.

2. three phase network reactive power compensation circuit according to claim 1, is characterized in that: described three-phase bridge circuit is made up of 3 IGBT module.

3. adopt the three phase network reactive compensation system of three phase network reactive power compensation circuit described in claim 1 or 2, it is characterized in that: comprise three phase network reactive power compensation circuit, detect sampling conditioning unit, control algorithm unit and driver element,

The described sampling conditioning unit that detects is for the output conditioned signal of carrying out nursing one's health from three net side inductance and the LCL filtered circuit at three-phase inversion inductance tie point place, three-phase inversion inductance and the three-phase inversion output current of three-phase bridge circuit junction, the threephase load electric current of external load and three-phase power grid voltage of sampling;

Described control algorithm unit comprises soft phase-locked loop control module, Voltage stabilizing module, extraction module, transformer idle component computing module and SPWM modulation module,

Described Voltage stabilizing module is used for receiving target magnitude of voltage, three-phase power grid voltage is stabilized to target voltage values simultaneously, and sends to SPWM modulation module;

Described transformer idle component computing module, for receiving known transformer parameter, by calculating transformer own reactive electric current, and sends to SPWM modulation module;

Described soft phase-locked loop control module is carried out phase-locked to three-phase power grid voltage, exports synchronizing signal:

Load current, based on instantaneous reactive current detection method, according to synchronizing signal, is decomposed into positive sequence component and negative sequence component by described extraction module; First-harmonic composition in laggard onestep extraction positive sequence component and negative sequence component, obtains the positive sequence reactive current that needs to compensate and negative phase-sequence reactive current, and sends to SPWM modulation module;

Described SPWM modulation module receives the reactive current of threephase load electric current corresponding positive sequence reactive current, negative phase-sequence reactive current and transformer, and SPWM modulation is carried out in above referenced reactive current addition, obtains three road pwm signal level;

Described driver element: by three road pwm signal level conversion conditionings, obtain the PWM drive singal of 6 tunnel isolation, control three-phase bridge circuit.

4. three phase network reactive compensation system according to claim 3, is characterized in that: described control algorithm unit also comprises protection module, for foundation voltage, electric current, frequency protection equipment.

5. the three phase network reactive compensation system according to claim 3 or 4, is characterized in that: described control algorithm unit is based on DSP and FPGA.