CN101232187A - Positive and negative order double ring stacking control method of electric power distribution static state synchronous compensator based on instantaneous power balance - Google Patents

Abstract

The invention discloses a positive and negative sequence double-ring superposition control method of distribution static synchronous compensator based on instantaneous power balance, which consists of a positive sequence control ring and a negative sequence control ring. The method comprises following steps: deducing a current-voltage conversion formula in a d-q positive-sequence and negative-sequence coordinate system according to an instantaneous power balance formula to obtain a positive-sequence voltage modulation signal and a negative-sequence voltage modulation signal; superposing the positive-sequence voltage modulation signal and the negative-sequence voltage modulation signal to obtain a DSTATCOM output voltage modulation signal; and modulating by a triangular carrier wave to produce a PWM drive signal to control the action of an intelligent power module IPM to generate a required compensation voltage. The control method can achieve unbalanced three-phase voltage control of a common connection point, and the current-voltage conversion formula in the d-q positive-sequence and negative-sequence coordinate system is deduced by the instantaneous power balance formula, thus obviating complex mathematic operation in conventional current control method and further lowering the cost.

Description

Distribution static synchronous compensator positive and negative order double ring stacking control method based on the instantaneous power balance

Technical field

The present invention relates to a kind of distribution static synchronous compensator control method, particularly a kind of distribution static synchronous compensator (DSTATCOM) positive and negative order double ring stacking control method based on the instantaneous power balance.

Background technology

Along with science and technology development, loads such as rectifier, arc furnace, electric railway constantly increase in the power distribution network.The impact of these loads and disequilibrium use electrical characteristics, caused a series of power quality problems such as voltage fluctuation, flickering and three-phase imbalance of power distribution network.On the other hand, along with the continuous development of modern industrial technology and the extensive use of computer technology, power consumption equipment is responsive more to the quality of power supply, and is also more and more higher to the requirement of the quality of power supply.Inferior power supply quality will cause inferior product quality, and particularly in the essential industry production process, the unexpected interruption of power supply brings enormous economic loss will for enterprise, society.Power quality problem has been not only the basic fundamental problem of voltage and frequency etc. in the electric power system; it has been promoted to safe, stable, economy, the reliability service that is related to whole electric power system and equipment; concern the electric circumstance engineering protection, concern the overall benefit and the development strategy of whole national economy.The effective way that solves power quality problem is that reactive power compensator is installed in electrical network.Distribution static synchronous compensator (DSTATCOM) has been represented the development trend of Future Power System reactive power compensator, also is a kind of important " custom power technology " equipment simultaneously, the multiple power quality problem in the solution power distribution network that can be comprehensive.In the mesolow distribution system, distribution static synchronous compensator adopts the circuit topology based on the VSI-SPWM structure usually.Generally suppose all when design DSTATCOM voltage controller that line voltage is three symmetrical, good performance is arranged during in the line voltage balance at the controller of designing under this condition.Yet, uneven situation ubiquity in the actual electric network, based on the controller performance meeting variation of symmetry hypothesis, more serious situation also can burn out the DSTATCOM device when line voltage is asymmetric.The imbalance control of DSTATCOM can improve the survival ability of DSTATCOM under the asymmetric condition of line voltage, and is significant.

Summary of the invention

Give design DSTATCOM the influence that controller brings for overcoming the power distribution network Voltage unbalance, the invention provides a kind of realize simple, cost is low, have good dynamically and the distribution static synchronous compensator positive and negative order double ring stacking control method based on the instantaneous power balance of static properties.

The technical scheme that technical solution problem of the present invention is adopted is: described distribution static synchronous compensator positive and negative order double ring stacking control method based on the instantaneous power balance carries out positive sequence control and negative phase-sequence control respectively, derive the conversion formula of current-voltage in d-q positive sequence and the negative phase-sequence coordinate system according to the instantaneous power balanced type, thereby obtain positive sequence voltage modulation signal and negative sequence voltage modulation signal, at last that positive sequence voltage modulation signal and negative sequence voltage modulation signal is superimposed back as DSTATCOM output voltage modulation signal, the action that generation PWM drive signal goes to control Intelligent Power Module IPM after the triangular carrier modulation produces the bucking voltage that needs, during wherein positive sequence is controlled, points of common connection PCC voltage instruction value U _Pcc ^*, dc capacitor voltage command value U _Dc ^*Error with actual measured value forms the idle instruction current signal of positive sequence i respectively after increment type PI regulates respectively _q ^*+With the meritorious instruction current signal i of positive sequence _d ^*+Positive sequence is idle instruction current signal i _q ^*+And the meritorious instruction current signal i of positive sequence _d ^*+After forward-order current-voltage transitions, obtain the idle command voltage signal of positive sequence e _q ^*+And the meritorious command voltage signal e of positive sequence _d ^*+e _q ^*+, e _d ^*+After the dq+/abc conversion, obtain the positive sequence voltage modulation signal; In the negative phase-sequence control method, points of common connection PCC voltage is through the abc/dq-conversion, extract the negative sequence component of PCC voltage then with second harmonic filtering method, the negative sequence component of PCC voltage follows the error of command signal 0 after PI regulates, and forms the idle instruction current command signal of DSTATCOM inverter output negative phase-sequence i _q ^*-With the meritorious instruction current signal i of negative phase-sequence _d ^*-i _q ^*-, i _d ^*-After negative-sequence current-voltage transitions, obtain the idle command voltage signal of negative phase-sequence e _q ^*-With the meritorious command voltage signal e of negative phase-sequence _d ^*-, after the dq-/abc conversion, obtain the negative sequence voltage modulation signal again.

The present invention is connected to the grid DSTATCOM and adjusts and balance power distribution network voltage behind the LC filter filtering.Wherein the main circuit topology of distribution static synchronous compensator DSTATCOM adopts the structure based on VSI-SPWM, incorporates power distribution network into by coupling transformer again behind the LC filter filtering.Analyze by negative phase-sequence equivalent electric circuit, proposed a kind of new positive and negative order double ring stacking control method based on the instantaneous power balance to DSTATCOM under the power distribution network Voltage unbalance condition.Described dicyclo is meant positive sequence voltage control ring and negative sequence voltage control ring.Wherein to be used for controlling points of common connection voltage be set-point to the positive sequence voltage control ring, and the negative sequence voltage control ring is used for realizing the asymmetric control of points of common connection voltage three-phase.

DSTATCOM positive and negative order double ring stacking control method based on the instantaneous power balance of the present invention has been kept dc capacitor voltage and PCC voltage constant, and has realized the control of points of common connection voltage three-phase imbalance; This control method is derived the conversion of current-voltage in d-q positive sequence and the negative phase-sequence coordinate system according to the instantaneous power balanced type, thereby has avoided complex mathematical computing in the conventional current control method, and does not need current sensor, and then has reduced cost.Can effectively suppress the voltage fluctuation and the flickering of power distribution network based on the DSTATCOM device of this control method, compensation power distribution network imbalance of three-phase voltage can effectively improve the quality of power supply of power distribution network, has good economy and social benefit.

Description of drawings

Fig. 1 is a main circuit schematic diagram of the present invention;

Fig. 2 is a control method schematic diagram of the present invention;

Fig. 3 is a negative phase-sequence equivalent electric circuit of the present invention;

Fig. 4 is a negative-sequence current component command signal flow chart of the present invention.

Embodiment

Below in conjunction with drawings and Examples operation principle of the present invention is described in detail:

As shown in Figure 1, the present invention will be connected to the grid by coupling transformer behind the LC filter filtering based on the DSTATCOM of VSI-SPWM structure again and adjust and balance power distribution network voltage.The main circuit of DSTATCOM is made up of three-phase voltage-type inverter.Device for power switching adopts insulated gate bipolar transistor IGBT, and the DC side energy-storage travelling wave tube is capacitor C, for the work of inverter provides direct voltage to support.High frequency burr for the filtering device for power switching causes has adopted the LC filter circuit in the output circuit of DSTATCOM.DSTATCOM adopts coupling transformer with being connected of electrical network, and the no-load voltage ratio of transformer is 1: 2.The present invention adopts and adjusts and balance power distribution network voltage based on the positive and negative order double ring stacking control method of instantaneous power balance.

As shown in Figure 2, the present invention includes positive sequence voltage control ring and negative sequence voltage control ring based on the instantaneous power balance.Wherein, the positive sequence voltage control ring is used for adjusting points of common connection voltage and dc capacitor voltage is stabilized near the set-point; The negative sequence voltage control ring is used for realizing the control of power distribution network voltage three-phase imbalance.

In the positive sequence voltage control ring of Fig. 2, can derive the conversion of current-voltage under the positive sequence d-q coordinate system by instantaneous power balance thought.Points of common connection PCC voltage instruction value U _Pcc ^*After regulating, increment type PI forms the idle instruction current signal of positive sequence i with the error of actual measured value _q ^*+Dc capacitor voltage command value U _Dc ^*After regulating, PI forms the meritorious instruction current signal i of positive sequence with the error of actual measured value _d ^*+Positive sequence is idle instruction current signal i _q ^*+And the meritorious instruction current signal i of positive sequence _d ^*+After forward-order current-voltage transitions, obtain the idle command voltage signal of positive sequence e _q ^*+And the meritorious command voltage signal e of positive sequence _d ^*+e _q ^*+, e _d ^*+After the dq+/abc conversion, obtain the positive sequence voltage modulation signal.

In the negative sequence voltage control ring of Fig. 2,, can derive the conversion of current-voltage in the negative phase-sequence d-q coordinate system again by instantaneous power balance thought by setting up the negative phase-sequence equivalent electric circuit of DSTATCOM under the power distribution network Voltage unbalance situation.Points of common connection PCC voltage is through the abc/dq-conversion, extract the negative sequence component of PCC voltage then with second harmonic filtering method, the negative sequence component of PCC voltage follows the error of command signal 0 after PI regulates, and forms the command signal i of DSTATCOM inverter output current negative sequence component _q ^*-, i _d ^*-i _q ^*-, i _d ^*-After negative-sequence current-voltage transitions, obtain e _q ^*-, e _d ^*-, after the dq-/abc conversion, obtain the negative sequence voltage modulation signal again.

In the negative sequence voltage control ring of Fig. 2, the derivation of negative-sequence current-voltage transitions is as follows: during negative sequence component in the compensation network voltage, DSTATCOM must send the negative-sequence current that meets the demands.At this moment, not only contain positive sequence component in the output voltage of DSTATCOM and the output current and also contain negative sequence component.The negative phase-sequence equivalent electric circuit of DSTATCOM as shown in Figure 3 when utilizing symmetrical component method to set up imbalance compensation.

Among Fig. 3, u _{A, b, c} ^-Be the negative sequence component of PCC voltage, e ^*- _{A, b, c}Be the negative sequence component of DSTATCOM output voltage, i ^*- _{A, b, c}Negative sequence component for the DSTATCOM output current.

For negative phase-sequence equivalent electric circuit as shown in Figure 3, the output instantaneous power of DSTATCOM inverter is:

$P_e^{*-}=\frac{3}{2}(e_d^{*-}{i}_d^{*-}+e_q^{*-}{i}_q^{*-})---\left(1\right)$

$Q_e^{*-}=\frac{3}{2}(e_q^{*-}{i}_d^{*-}-e_d^{*-}{i}_q^{*-})---\left(2\right)$

The instantaneous power that connects the consumption of reactor equiva lent impedance is

$P_f^{*-}=\frac{3}{2}{i}^{*-2}{R}_f=\frac{3}{2}(i_d^{*-2}+i_q^{*-2})R_f---\left(3\right)$

$Q_f^{*-}=-\frac{3}{2}{i}^{*-2}{\mathrm{\ωL}}_f=-\frac{3}{2}(i_d^{*-2}+i_q^{*-2}){\mathrm{\ωL}}_f----\left(4\right)$

The negative phase-sequence instantaneous power of points of common connection is:

$P_o^{*-}=\frac{3}{2}(u_q^{-}{i}_q^{*-}+u_d^{-}{i}_d^{*-})---\left(5\right)$

$Q_o^{*-}=\frac{3}{2}(u_q^{-}{i}_d^{*-}-u_d^{-}{i}_q^{*-})---\left(6\right)$

For the negative phase-sequence system, can get by the instantaneous power equilibrium principle:

$P_e^{*-}=P_f^{*-}+P_o^{*-}---\left(7\right)$

$Q_e^{*-}=Q_f^{*-}+Q_o^{*-}---\left(8\right)$

For making PCC voltage become balance, need to drop into DSTATCOM and carry out imbalance compensation by imbalance.One of committed step is exactly to obtain the negative-sequence current that meets the demands that DSTATCOM need send.

During the PCC Voltage unbalance, $u_{a,b,c}^{-}\≠0,$ Promptly $u_{d,q}^{-}\≠0$ (u _{D, q} ^-Be u _{A, b, c} ^-Component under d-q negative phase-sequence coordinate system).The purpose of uneven control is to make the PCC negative sequence voltage become 0.Desire to make u _{A, b, c} ^-Be 0, need make $u_d^{-}=u_q^{-}=0;$ Desire to make $u_d^{-}=u_q^{-}=0,$ Can be with u _d ^-With u _q ^-Make difference with its re-set target 0 respectively and regulate by PI again, the command signal i of the negative-sequence current component that DSTATCOM need export when so just having obtained compensation PCC Voltage unbalance ^* _d ^-, i _* ^q _-(as shown in Figure 4), promptly

$(i_d^{*-},i_q^{*-})\⇔u_d^{-}=u_q^{-}=0---\left(9\right)$

Two of committed step is to obtain current i in the d-q negative phase-sequence coordinate system ^* _d ^-, i ^* _q ^-To voltage e ^* _d ^-, e ^* _q-change type.

(i ^* _d ^-, i ^* _q ^-) and (e ^* _d ^-, e ^* _q ^-) be a kind of mapping relations one to one:

$(e_d^{*-},e_q^{*-})=f(i_d^{*-},i_q^{*-})---\left(10\right)$

By formula (9), (10) can get:

$(e_d^{*-},e_q^{*-})\⇔f(i_d^{*-},i_q^{*-})\⇔u_d^{-}=u_q^{-}=0---\left(11\right)$

Simultaneous (1)-(8) and formula (11) can get

$\left[\begin{array}{c}{e}_d^{*-}\\ e_q^{*-}\end{array}\right]=\left[\begin{array}{cc}{R}_f& \mathrm{\ω}{L}_f\\ -\mathrm{\ω}{L}_f& R_f\end{array}\right]\·\left[\begin{array}{c}{i}_d^{*-}\\ i_q^{*-}\end{array}\right]---\left(12\right)$

When formula (12) has realized compensation PCC Voltage unbalance, current i in d-q negative phase-sequence coordinate system ^* _d ^-, i ^* _q ^-To voltage e ^* _d ^-, e ^* _q ^-Conversion.With i ^* _d ^-, i ^* _q ^-As instruction current, e so ^* _d ^-, e ^* _q ^-It is exactly the negative phase-sequence control ring voltage control instruction of DSTATCOM.

In addition, the derivation that obtains current-voltage conversion formula in the d-q positive-sequence coordinate system according to the instantaneous power balanced type is:

For the positive sequence system, according to the power-balance principle, the power that the power of inverter output should equal injected system and output filter and is connected the power sum of reactance equivalent resistance, reactance consumption, that is:

P _e＝P _o+P _f (13)

Q _e＝Q _o+Q _f (14)

The power of inverter output is:

$P_e=\frac{3}{2}(e_d{i}_d+e_q{i}_q)---\left(15\right)$

$Q_e=\frac{3}{2}(e_q{i}_q-e_d{i}_q)---\left(16\right)$

The power of injected system is:

$P_o=\frac{3}{2}(u_d{i}_d+u_q{i}_q)---\left(17\right)$

$Q_o=\frac{3}{2}(u_q{i}_q-u_d{i}_q)---\left(18\right)$

The power that output filter and connection reactance consume:

$P_f=\frac{3}{2}{i}^2{R}_f=\frac{3}{2}(i^{2}d+i^{2}q)R_f---\left(19\right)$

$Q_f=\frac{3}{2}{i}^2{\mathrm{\ωL}}_f=\frac{3}{2}{({i^2}_d+{i^2}_q)\mathrm{\ωL}}_f---\left(20\right)$

Simultaneous (13)-(20) formula, the d axle and access point (PCC) voltage vector of selection synchronous rotating frame

Overlap, can get:

e _d＝i _dR _f-i _qωL _f+u (21)

e _q＝i _qR _f+i _dωL _f (22)

Current i in the d-q positive-sequence coordinate system has been realized in formula (21), (22) _d, i _qTo voltage e _d, e _qConversion.

The superimposed back of positive sequence voltage modulation signal and negative sequence voltage modulation signal is as DSTATCOM output voltage modulation signal, the action that generation PWM drive signal goes to control Intelligent Power Module (IPM) after the triangular carrier modulation produces the bucking voltage that needs, thereby kept dc capacitor voltage and PCC voltage constant, and be used for realizing the control of points of common connection voltage three-phase imbalance.

Claims (3)

1. distribution static synchronous compensator positive and negative order double ring stacking control method based on the instantaneous power balance, it is characterized in that, described control method is made of positive sequence control ring and negative phase-sequence control ring, derive the conversion formula of electric current one voltage in d-q positive sequence and the negative phase-sequence coordinate system according to the instantaneous power balanced type, thereby obtain positive sequence voltage modulation signal and negative sequence voltage modulation signal, at last that positive sequence voltage modulation signal and negative sequence voltage modulation signal is superimposed back as DSTATCOM output voltage modulation signal, produce the action that the PWM drive signal goes to control Intelligent Power Module IPM through triangular carrier modulation back and produce the bucking voltage that needs, wherein positive sequence is controlled the step that obtains the positive sequence voltage modulation signal and is comprised: points of common connection PCC voltage instruction value U _Pcc ^*, dc capacitor voltage command value U _Dc ^*Error with actual measured value forms the idle instruction current signal of positive sequence i respectively after increment type PI regulates respectively _q ^*+With the meritorious instruction current signal i of positive sequence _d ^*+Positive sequence is idle instruction current signal i _q ^*+And the meritorious instruction current signal i of positive sequence _d ^*+After forward-order current-voltage transitions, obtain the idle command voltage signal of positive sequence e _q ^*+And the meritorious command voltage signal e of positive sequence _d ^*+e _q ^*+, e _d ^*+After the dq+/abc conversion, obtain the positive sequence voltage modulation signal; Wherein the negative phase-sequence control step that obtains the negative sequence voltage modulation signal comprises: points of common connection PCC voltage process

Conversion, with the negative sequence component of second harmonic filtering method extraction PCC voltage, the negative sequence component of PCC voltage follows the error of command signal 0 after PI regulates then, forms the idle instruction current command signal of DSTATCOM inverter output negative phase-sequence i _q ^*-With the meritorious instruction current signal i of negative phase-sequence _d ^*-i _q ^*-, i _d ^*-After negative-sequence current one voltage transitions, obtain the idle command voltage signal of negative phase-sequence e _q ^*-With the meritorious command voltage signal e of negative phase-sequence _d ^*-, after the dq-/abc conversion, obtain the negative sequence voltage modulation signal again.

2. according to the described distribution static synchronous compensator positive and negative order double ring stacking control method of claim 1, it is characterized in that described negative-sequence current based on the instantaneous power balance. the process of voltage transitions is as follows:

The negative phase-sequence equivalent electric circuit of DSTATCOM when 1) at first utilizing symmetrical component method to set up imbalance compensation;

The output instantaneous power of DSTATCOM inverter is:

$P_e^{*-}=\frac{3}{2}(e_d^{*-}{i}_d^{*-}+e_q^{*-}{i}_q^{*-})---\left(1\right)$

$Q_e^{*-}=\frac{3}{2}(e_q^{*-}{i}_d^{*-}-e_d^{*-}{i}_q^{*-})---\left(2\right)$

The instantaneous power that connects the consumption of reactor equiva lent impedance is

$P_f^{*-}=\frac{3}{2}{i}^{*-2}{R}_f=\frac{3}{2}(i_d^{*-2}+i_q^{*-2})R_f---\left(3\right)$

$Q_f^{*-}=-\frac{3}{2}{i}^{*-2}{\mathrm{\ωL}}_f=-\frac{3}{2}(i_d^{*-2}+i_q^{*-2}){\mathrm{\ωL}}_f----\left(4\right)$

The negative phase-sequence instantaneous power of points of common connection is:

$P_o^{*-}=\frac{3}{2}(u_q^{-}{i}_q^{*-}+u_d^{-}{i}_d^{*-})---\left(5\right)$

$Q_o^{*-}=\frac{3}{2}(u_q^{-}{i}_d^{*-}-u_d^{-}{i}_q^{*-})---\left(6\right)$

For the negative phase-sequence system, can get by the instantaneous power equilibrium principle:

$P_e^{*-}=P_f^{*-}+P_o^{*-}---\left(7\right)$

$Q_e^{*-}=Q_f^{*-}+Q_o^{*-}---\left(8\right)$

During the PCC Voltage unbalance, $u_{a,b,c}^{-}\≠0,$ Promptly $u_{d,q}^{-}\≠0$ (u _{D, q} ^-Be u _{A, b, c} ^-Component under d-q negative phase-sequence coordinate system); Desire to make $u_d^{-}=u_q^{-}=0,$ With u _d ^-With u _q ^-Make difference with its re-set target 0 respectively and regulate the command signal i of the negative-sequence current component that DSTATCOM need export when being compensated the PCC Voltage unbalance again by PI ^* _d ^-, i ^* _q ^-, promptly

$(i_q^{*-},i_q^{*-})\⇔u_d^{-}=u_d^{-}=0---\left(9\right)$

2) obtain current i in the d-q negative phase-sequence coordinate system ^* _d ^-, i ^* _q ^-To voltage e ^* _d ^-, e ^* _q ^-Change type: (i ^* _d ^-, i ^* _q ^-) and (e ^* _d ^-, e ^* _q ^-) be a kind of mapping relations one to one:

$(e_d^{*-},e_q^{*-})=f(i_d^{*-},i_q^{*-})---\left(10\right)$

By formula (9), (10) can get:

$(e_d^{*-},e_q^{*-})\⇔f(i_d^{*-},i_q^{*-})\⇔u_d^{-}=u_q^{-}=0---\left(11\right)$

Simultaneous (1)-(8) and formula (11) can get

$\left[\begin{array}{c}{e}_d^{*-}\\ e_q^{*-}\end{array}\right]=\left[\begin{array}{cc}{R}_f& \mathrm{\ω}{L}_f\\ -\mathrm{\ω}{L}_f& R_f\end{array}\right]\·\left[\begin{array}{c}{i}_d^{*-}\\ i_q^{*-}\end{array}\right]---\left(12\right)$

When formula (12) has realized compensation PCC Voltage unbalance, current i in d-q negative phase-sequence coordinate system ^* _d ^-,

i ^* _q ^-To voltage e ^* _d ^-, e ^* _q ^-Conversion, with i ^* _d ^-, i ^* _q ^-As instruction current, e so ^* _d ^-, e ^* _q ^-It is exactly the negative phase-sequence control ring voltage control instruction of DSTATCOM.

3. according to the described distribution static synchronous compensator positive and negative order double ring stacking control method of claim 1, it is characterized in that the process of described forward-order current-voltage transitions is based on the instantaneous power balance:

For the positive sequence system, the power that the power of inverter output should equal injected system and output filter and is connected the power sum of reactance equivalent resistance, reactance consumption, that is:

P _e＝P _o+P _f (13)

Q _e＝Q _o+Q _f (14)

The power of inverter output is:

$P_e=\frac{3}{2}(e_d{i}_d+e_q{i}_q)---\left(15\right)$

$Q_e=\frac{3}{2}(e_q{i}_d-e_d{i}_q)---\left(16\right)$

The power of injected system is:

$P_o=\frac{3}{2}(u_d{i}_d+u_q{i}_q)---\left(17\right)$

$Q_o=\frac{3}{2}(u_q{i}_d-u_d{i}_q)---\left(18\right)$

The power that output filter and connection reactance consume:

$P_f=\frac{3}{2}{i}^2{R}_f=\frac{3}{2}({i^2}_d+{i^2}_q)R_f---\left(19\right)$

$Q_f=\frac{3}{2}{i}^2{\mathrm{\ωL}}_f=\frac{3}{2}({i^2}_d+{i^2}_q){\mathrm{\ωL}}_f---\left(20\right)$

Simultaneous (13)-(20) formula, the d axle and access point (PCC) voltage vector of selection synchronous rotating frame

Overlap, can get:

e _d＝i _dR _f-i _qωL _f+u (21)

e _q＝i _qR _f+i _dωL _f (22)

Current i in the d-q positive-sequence coordinate system has been realized in formula (21), (22) _d, i _qTo voltage e _d, e _qConversion.

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