CN104917189A - Line reactive optimal control method based on optimal reactive transmitting power - Google Patents

Abstract

The invention provides a line reactive optimal control method based on an optimal reactive transmitting power. The method comprises the following steps: (1), obtaining a line parameter, a voltage of a line transmitting end, and a reactive compensation parameter of a line receiving end; (2), on the basis of the parameters, calculating an optimal reactive transmitting power and an upper limit and lower limit thereof; (3), obtaining a reactive power of the line transmitting end, a load of the line receiving end, and a number of reactive compensation device investment groups of the line receiving end; and (4), according to the upper limit and lower limit of the optimal reactive transmitting power, controlling reactive compensation devices at the line receiving end. According to the technical scheme, the line reactive optimal control method is used for replacing the existing method of adjusting the reactive power of the grid gateway based on experience; and thus the line can be operated safely and economically under the circumstances that the reactive power constant value is not modified frequently.

Description

A kind of circuit power-less optimized controlling method based on OPTIMAL REACTIVE POWER power transmission power

Technical field

The present invention relates to the idle operation method of electric power system, particularly a kind of power-less optimized controlling method of circuit.

Background technology

AC electric power systems unavoidably also exists reactive power, and the transmission of reactive power in electrical network can increase the weight of voltage-drop and the active power loss of electrical network.Reasonably control the reactive power in electric power system, line voltage landing and active power loss can be reduced, improve fail safe and the economy of operation of power networks.

At present in the traffic control of electric power system, commonplace way be by the Reactive Power Control of circuit receiving end near 0.Long-term operating experience shows, this way can ensure line voltage safety more effectively.But because this way is regulating by experience, its regulation strategy, not through optimizing, is also having further room for promotion in minimizing active power loss.

In recent years, people propose a lot of method to idle work optimization, attempt solving reactive power optimization control problem theoretically.But mostly optimization method needs iterative computation to solve trend, in real-time idle work optimization, there is long limitation computing time; Or need, through calculating, constantly to revise setting value.

The present invention is based on OPTIMAL REACTIVE POWER power transmission power, fall into interval of acceptance as the target controlled using the reactive power of circuit sending end, idle work optimization is carried out to circuit, can guarantee that circuit is ensureing economical operation under the prerequisite that receiving end voltage is qualified; Meanwhile, optimizing process does not relate to iterative computation, and setting value one as calculated, gets final product Long-Time Service, does not need amendment, can be used in the real-time reactive power optimization of electrical network.

Summary of the invention

The object of the invention is to the Reactive power control problem solving circuit, a kind of circuit power-less optimized controlling method based on OPTIMAL REACTIVE POWER power transmission power is provided, makes the operation of circuit more economically.

A kind of circuit power-less optimized controlling method based on OPTIMAL REACTIVE POWER power transmission power of the present invention, comprises the following steps:

(1) parameter of circuit, the voltage U of circuit sending end is obtained _s, circuit receiving end reactive power compensation parameter; The parameter of described circuit comprises line resistance R _l, line reactance X _lwith Xian Lu electricity Satisfied B _l; The reactive power compensation parameter of described circuit receiving end comprises single pool-size and the quantity of capacitor and reactor;

(2) OPTIMAL REACTIVE POWER power transmission power Q is calculated _s.opt;

(3) computational scheme sending end reactive power lower limit Q _s.minwith upper limit Q _s.max; Circuit receiving end voltage lower limit U is set _load.minwith upper limit U _load.max;

(4) reactive power Q of Real-time Obtaining circuit sending end from electrical network SCADA system _s, circuit receiving end load S _load, circuit receiving end capacitor and reactor the number of throwing group;

(5) Q is judged _sand Q _s.min, Q _s.maxrelation, if Q _s.min≤ Q _s≤ Q _s.max, enter step (10); If Q _s<Q _s.min, enter step (6); If Q _s>Q _s.max, enter step (8);

(6) judge whether circuit receiving end has capacitor not excise, if do not have, then enter step (7); If have, then judge whether excision one group capacitor can cause circuit receiving end voltage to be less than U by Load flow calculation _load.minif, can not, then excise a group capacitor of circuit receiving end, enter step (10); If meeting, then enter step (10);

(7) judge whether circuit receiving end has reactor not drop into, if do not have, then enter step (10); If have, then judge whether input one group of reactor can cause circuit receiving end voltage to be less than U by Load flow calculation _load.minif, can not, then drop into one group of reactor of circuit receiving end, enter step (1000); If meeting, then enter step (10);

(8) judge whether circuit receiving end has reactor not excise, if do not have, then enter step (9); If have, then judge whether excision one group of reactor can cause circuit receiving end voltage to be greater than U by Load flow calculation _load.maxif, can not, then excise one group of reactor of circuit receiving end, enter step (10); If meeting, then enter step (10);

(9) judge whether circuit receiving end has capacitor not drop into, if do not have, then enter step (10); If have, then judge whether input one group capacitor can cause circuit receiving end voltage to be greater than U by Load flow calculation _load.maxif, can not, then drop into a group capacitor of circuit receiving end, enter step (10); If meeting, then enter step (10);

(10) this cycle Reactive power control is terminated; Wait for setting-up time (as 15 minutes), return step (4).

In the above-mentioned circuit power-less optimized controlling method based on OPTIMAL REACTIVE POWER power transmission power, described OPTIMAL REACTIVE POWER power transmission power, refers to as making the active loss of circuit minimum, the reactive power that circuit sending end should be carried, OPTIMAL REACTIVE POWER power transmission power Q _s.optobtained by formula (1):

$Q_{S.\mathrm{opt}}=-\frac{U_S^2{B}_L}{2}---\left(1\right)$

Formula (1) comprises variable: circuit sending end voltage U _s; Xian Lu electricity Satisfied B _l.

The derivation of formula (1) is as follows:

In the π type equivalent circuit of circuit, P _sfor the active power of circuit sending end, Q _sfor the reactive power of circuit sending end, R _lfor line resistance, P _loadfor the burden with power of circuit receiving end, formula (2) can be obtained according to active power balance:

$P_S-\frac{P_S^2+{(Q_S+U_S^2{B}_L/2)}^2}{U_S^2}{R}_L=P_{\mathrm{Load}}---\left(2\right)$

Formula (2) is considered as about P _squadratic equation with one unknown, solve and choose and make electric power system be in statically stable solution, can P be obtained _sexpression formula such as formula (3):

$P_S=\frac{\frac{U_S^2}{R_L}-\sqrt{{\left(\frac{U_S^2}{R_L}\right)}^2-4[{(Q_S+\frac{U_S^2{B}_L}{2})}^2+\frac{U_S^2{P}_{\mathrm{Load}}}{R_L}]}}{2}---\left(3\right)$

By U _s, P _load, R _l, B _lbe considered as constant, then from formula (3), work as P _sminimum, when namely the active loss of circuit is minimum,

$Q_S=-\frac{U_S^2{B}_L}{2}---\left(4\right)$

According to OPTIMAL REACTIVE POWER power transmission power Q _s.optimplication, Q _s.optthe value of modus ponens (4).

In the above-mentioned circuit power-less optimized controlling method based on OPTIMAL REACTIVE POWER power transmission power, described circuit sending end reactive power lower limit Q _s.minwith upper limit Q _s.max, refer to for judging the condition whether circuit sending end reactive power is qualified, Q _s.minand Q _s.maxobtained by formula (5), formula (6):

Q _S.min＝Q _S.opt-Q _C.max(5)

Q _S.max＝Q _S.opt+Q _C.max(6)

Formula (5), formula (6) comprise variable: OPTIMAL REACTIVE POWER power transmission power Q _s.opt; The maximum single group reactive compensation capacity Q of circuit receiving end _c.max.

The derivation of formula (5), formula (6) is as follows:

In the π type equivalent circuit of circuit, P _sfor the active power of circuit sending end, Q _sfor the reactive power of circuit sending end, X _lfor line reactance, U _loadfor the voltage of circuit receiving end, Q _loadfor the burden with power of circuit receiving end, Q _cOMfor the reactive compensation capacity that circuit receiving end drops into, formula (7) can be obtained according to reactive power equilibrium:

$Q_S+\frac{U_S^2{B}_L}{2}-\frac{P_S^2+{(Q_S+\frac{U_S^2{B}_L}{2})}^2}{U_S^2}{X}_L+\frac{U_{\mathrm{Load}}^2{B}_L}{2}=Q_{\mathrm{Load}}+Q_{\mathrm{COM}}---\left(7\right)$

At Q _s=Q _s.optput on formula (7) both sides Q _cOMdifferentiate, and ignore U _loadchange, can obtain

${\frac{{\mathrm{dQ}}_S}{{\mathrm{dQ}}_{\mathrm{COM}}}|}_{Q_S=Q_{S.\mathrm{opt}}}-\frac{{2P}_S{X}_L}{U_S^2}\frac{{\mathrm{dP}}_S}{{\mathrm{dQ}}_{\mathrm{COM}}}{|}_{Q_S=Q_{S,\mathrm{opt}}}-\frac{2(Q_S+U_S^2{B}_L/2)X_L}{U_S^2}\frac{{\mathrm{dQ}}_S}{{\mathrm{dQ}}_{\mathrm{COM}}}{|}_{Q_S=Q_{S.\mathrm{opt}}}=1---\left(8\right)$

According to Q _s.optimplication, have

$\frac{{\mathrm{dP}}_S}{{\mathrm{dQ}}_{\mathrm{COM}}}{|}_{Q_S=Q_{S.\mathrm{opt}}}=0---\left(9\right)$

Can be obtained by formula (8), formula (9)

$\frac{{\mathrm{dQ}}_S}{{\mathrm{dQ}}_{\mathrm{COM}}}{|}_{Q_S=Q_{S.\mathrm{opt}}}=1---\left(10\right)$

According to formula (10) local linearization, with Q _s.optfor the idle allowed band center of circuit sending end, be superimposed with the variable quantity of the circuit sending end reactive power caused at the maximum single group reactive compensation capacity of circuit receiving end switching one group, can Q be obtained _s.minand Q _s.maxfor

Q _S.min＝Q _S.opt-Q _C.max(11)

Q _S.max＝Q _S.opt+Q _C.max(12)

The circuit sending end reactive power lower limit that through type (11), formula (12) obtain and the upper limit, can make the reactive power of circuit circuit sending end after carrying out Reactive power control near OPTIMAL REACTIVE POWER power transmission power, and the problem of reactive-load compensation equipment switching repeatedly can not be caused.

In the above-mentioned circuit power-less optimized controlling method based on OPTIMAL REACTIVE POWER power transmission power, described circuit sending end and circuit receiving end are that active power flows to circuit receiving end from circuit sending end with the walking direction of circuit active power.

Compared with prior art, beneficial effect of the present invention is:

(1) efficiently solve the Reactive Power Optimazation Problem of circuit, make circuit keep accomplishing economical operation under the qualified prerequisite of voltage;

(2) the power-less optimized controlling method simple, intuitive proposed, optimizing process does not relate to iterative computation, and setting value one as calculated, gets final product Long-Time Service, does not need amendment, can be used in the real-time reactive power optimization of electrical network.

Accompanying drawing explanation

Fig. 1 is the schematic flow sheet of the circuit power-less optimized controlling method based on OPTIMAL REACTIVE POWER power transmission power.

Embodiment

Below in conjunction with accompanying drawing and example, specific embodiment of the invention is described further.

Fig. 1 reflects the idiographic flow of the circuit power-less optimized controlling method based on OPTIMAL REACTIVE POWER power transmission power.Circuit power-less optimized controlling method based on OPTIMAL REACTIVE POWER power transmission power comprises:

(1) parameter of circuit, the voltage U of circuit sending end is obtained _s, circuit receiving end reactive power compensation parameter; The parameter of described circuit comprises line resistance R _l, line reactance X _ljie Di electricity Satisfied B _l; The reactive power compensation parameter of described circuit receiving end comprises capacity and the quantity of capacitor and reactor;

(2) OPTIMAL REACTIVE POWER power transmission power Q is calculated _s.opt;

Q _s.optobtained by following formula:

$Q_{S.\mathrm{opt}}=-\frac{U_S^2{B}_L}{2}$

In formula, U _sfor circuit sending end voltage, B _lfor line-to-ground electricity Satisfied;

(3) computational scheme sending end reactive power lower limit Q _s.minwith upper limit Q _s.max; Circuit receiving end voltage lower limit U is set _load.minwith upper limit U _load.max;

Q _s.minand Q _s.maxby two formulas acquisitions below:

Q _S.min＝Q _S.opt-Q _C.max

Q _S.max＝Q _S.opt+Q _C.max

In formula, Q _s.optfor OPTIMAL REACTIVE POWER power transmission power, Q _c.maxfor circuit receiving end maximum list group reactive compensation capacity;

(4) reactive power Q of Real-time Obtaining circuit sending end from electrical network SCADA system _s, circuit receiving end load S _load, circuit receiving end capacitor and reactor the number of throwing group;

(5) Q is judged _sand Q _s.min, Q _s.maxrelation, if Q _s.min≤ Q _s≤ Q _s.max, enter step (10); If Q _s<Q _s.min, enter step (6); If Q _s>Q _s.max, enter step (8);

(6) judge whether circuit receiving end has capacitor not excise, if do not have, then enter step (7); If have, then judge whether excision one group capacitor can cause circuit receiving end voltage to be less than U by Load flow calculation _load.minif, can not, then excise a group capacitor of circuit receiving end, enter step (10); If meeting, then enter step (10);

(7) judge whether circuit receiving end has reactor not drop into, if do not have, then enter step (10); If have, then judge whether input one group of reactor can cause circuit receiving end voltage to be less than U by Load flow calculation _load.minif, can not, then drop into one group of reactor of circuit receiving end, enter step (10); If meeting, then enter step (10);

(8) judge whether circuit receiving end has reactor not excise, if do not have, then enter step (9); If have, then judge whether excision one group of reactor can cause circuit receiving end voltage to be greater than U by Load flow calculation _load.maxif, can not, then excise one group of reactor of circuit receiving end, enter step (10); If meeting, then enter step (10);

(9) judge whether circuit receiving end has capacitor not drop into, if do not have, then enter step (10); If have, then judge whether input one group capacitor can cause circuit receiving end voltage to be greater than U by Load flow calculation _load.maxif, can not, then drop into a group capacitor of circuit receiving end, enter step (10); If meeting, then enter step (10);

(10) this cycle Reactive power control is terminated; Wait for next control cycle, return step (4).

Be below an example of the inventive method, emulate for a certain control cycle of certain 220kV circuit.

(1) line resistance R is obtained to obtain _l, line reactance X _l, Xian Lu electricity Satisfied B _lfor:

R _L＝6.5Ω，X _L＝37.6Ω，B _L＝5.1×10 ^-4S

The voltage U of circuit sending end _sfor:

U _S＝231kV

The reactive power compensation parameter of circuit receiving end is:

The reactive power compensation parameter of table 1 circuit receiving end

(2) OPTIMAL REACTIVE POWER power transmission power Q is calculated _s.optfor:

$Q_{S.\mathrm{opt}}=-\frac{U_S^2{B}_L}{2}=-\frac{{231}^2\&times;5.1\&times;{10}^{-4}}{2}=-13.61\left(\mathrm{Mvar}\right)$

(3) circuit sending end reactive power lower limit Q is calculated _s.minwith upper limit Q _s.maxfor:

Q _S.min＝Q _S.opt-Q _C.max＝-13.61-10＝-23.61(Mvar)

Q _S.max＝Q _S.opt+Q _C.max＝-13.61+10＝-3.61(Mvar)

Circuit receiving end voltage lower limit U is set _load.minwith upper limit U _load.maxfor:

U _Load.min＝213.4kV，U _Load.max＝235.4kV

(4) reactive power Q of circuit sending end is obtained to obtain _sfor:

Q _S＝0.04Mvar

The load S of circuit receiving end _loadfor:

S _Load＝350+j72MVA

The number of throwing group of circuit receiving end capacitor is 14 groups, and the number of throwing group of reactor is 0 group;

(5) Q is judged to obtain _s>Q _s.max;

(6) judge circuit receiving end does not have reactor not excise;

(7) judge circuit receiving end has capacitor not drop into, after judging input one group capacitor by Load flow calculation, circuit receiving end voltage is 228.05kV, is less than U _load.max(235.4kV) group capacitor of circuit receiving end, therefore, is dropped into

(8) this cycle Reactive power control is terminated; Wait for next control cycle, return step (4).

For embodying beneficial effect of the present invention further, table 2 gives circuit regulates reactive power Comparative result by two schemes, scheme 1 is regulate reactive power by the method based on OPTIMAL REACTIVE POWER power transmission power of the present invention, scheme 2 is that the method for pressing near circuit receiving end Reactive Power Control to 0 regulates reactive power, the control interval arranged is [-10,10] Mvar.

Table 2 Comparative result

	Circuit active loss (MW)
		Scheme 1	16.35
Scheme 2	17.47

As shown in Table 2, adopt scheme 1 than employing scheme 2 circuit active loss decline 6.85% (1.12MW), illustrate and adopt the method based on OPTIMAL REACTIVE POWER power transmission power of the present invention that circuit really can be made more economic to run.

Above-described embodiment is the present invention's preferably execution mode; but embodiments of the present invention are not restricted to the described embodiments; other are any do not deviate from Spirit Essence of the present invention and principle under do amendment, modification, substitute, combination, to simplify; all should be the substitute mode of equivalence, all should be included within protection scope of the present invention.

Claims (3)

1., based on a circuit power-less optimized controlling method for OPTIMAL REACTIVE POWER power transmission power, it is characterized in that comprising the following steps:

(1) parameter of circuit, the voltage U of circuit sending end is obtained _s, circuit receiving end reactive power compensation parameter; The parameter of described circuit comprises line resistance R _l, line reactance X _lwith Xian Lu electricity Satisfied B _l; The reactive power compensation parameter of described circuit receiving end comprises single pool-size and the quantity of capacitor and reactor;

(2) OPTIMAL REACTIVE POWER power transmission power Q is calculated _s.opt;

(3) computational scheme sending end reactive power lower limit Q _s.minwith upper limit Q _s.max; Circuit receiving end voltage lower limit U is set _load.minwith upper limit U _load.max;

(4) reactive power Q of Real-time Obtaining circuit sending end from electric network data collection and Monitor and Control (SCADA) system _s, circuit receiving end load S _load, circuit receiving end capacitor and reactor the number of throwing group;

(5) Q is judged _sand Q _s.min, Q _s.maxrelation, if Q _s.min≤ Q _s≤ Q _s.max, enter step (10); If Q _s<Q _s.min, enter step (6); If Q _s>Q _s.max, enter step (8);

(6) judge whether circuit receiving end has capacitor not excise, if do not have, then enter step (7); If have, then judge whether excision one group capacitor can cause circuit receiving end voltage to be less than U by Load flow calculation _load.minif, can not, then excise a group capacitor of circuit receiving end, enter step (10); If meeting, then enter step (10);

(7) judge whether circuit receiving end has reactor not drop into, if do not have, then enter step (10); If have, then judge whether input one group of reactor can cause circuit receiving end voltage to be less than U by Load flow calculation _load.minif, can not, then drop into one group of reactor of circuit receiving end, enter step (10); If meeting, then enter step (10);

(8) judge whether circuit receiving end has reactor not excise, if do not have, then enter step (9); If have, then judge whether excision one group of reactor can cause circuit receiving end voltage to be greater than U by Load flow calculation _load.maxif, can not, then excise one group of reactor of circuit receiving end, enter step (10); If meeting, then enter step (10);

(9) judge whether circuit receiving end has capacitor not drop into, if do not have, then enter step (10); If have, then judge whether input one group capacitor can cause circuit receiving end voltage to be greater than U by Load flow calculation _load.maxif, can not, then drop into a group capacitor of circuit receiving end, enter step (10); If meeting, then enter step (10);

(10) this cycle Reactive power control is terminated; Wait for setting-up time, return step (4).

2. the circuit power-less optimized controlling method based on OPTIMAL REACTIVE POWER power transmission power according to claim 1, it is characterized in that: step (2) described OPTIMAL REACTIVE POWER power transmission power, refer to as making the active loss of circuit minimum, the reactive power that circuit sending end should be carried, OPTIMAL REACTIVE POWER power transmission power Q _s.optobtained by formula (1):

$Q_{S.\mathrm{opt}}=-\frac{U_S^2{B}_L}{2}---\left(1\right)$

Formula (1) comprises variable: circuit sending end voltage U _s; Xian Lu electricity Satisfied B _l.

3. the circuit power-less optimized controlling method based on OPTIMAL REACTIVE POWER power transmission power according to claim 1, is characterized in that: step (3) described circuit sending end reactive power lower limit Q _s.minwith upper limit Q _s.max, refer to for judging the condition whether circuit sending end reactive power is qualified, Q _s.minand Q _s.maxobtained by formula (2), formula (3):

Q _S.min＝Q _S.opt-Q _C.max(2)

Q _S.max＝Q _S.opt+Q _C.max(3)

Formula (2), formula (3) comprise variable: OPTIMAL REACTIVE POWER power transmission power Q _s.opt; The maximum single group reactive compensation capacity Q of circuit receiving end _c.max.