CN103633654B - Near-optimal relaxation reactive power control method for radiation type power grid - Google Patents

Abstract

The invention provides Near-optimal relaxation reactive power control method for radiation type power grid, comprise the steps: first, electrical network is decoupled into multiple " circuit-transformer " unit; Secondly, each unit operational factor of Real-time Collection; Again, with the load or burden without work of each unit for independent variable, adopt climbing method to ask for successively and make the minimum corresponding critical point reactive power of the active loss of each " circuit-transformer " unit under Real-time Load level; Finally, the critical point reactive power of being tried to achieve by previous step and singly organize reactive compensation capacity, determines that critical point reactive power allows bound in real time, in conjunction with busbar voltage bound, become nine-zone diagram when obtaining, and then obtain the control command of transformer gear and reactive-load compensation equipment.The present invention proposes Near-optimal relaxation reactive power control method for radiation type power grid, can be used for the reactive power voltage control of radial system, while the switching frequency reducing equipment, reduce network loss better, make electrical network safety and economic operation under different load level.

Description

Near-optimal relaxation reactive power control method for radiation type power grid

Technical field

The present invention relates to the idle operation method of electric power system, particularly a kind of Near-optimal relaxation reactive power control method for radiation type power grid comprising discrete device.

Background technology

At present, in electric power system, VQC is widely used Control Strategy of Voltage-Reactive Power, and its basic theories is that nine-area control is theoretical.Voltage, reactive power are divided into too low, qualified, too high three kinds of states by nine-area control theory respectively, by voltage, reactive power different conditions be combined to form nine regions, zones of different take corresponding transformer gear regulate and reactive-load compensation equipment switching.VQC divides layer equilibration to the adjustment of critical point reactive power based on experienced reactive power, and its strategy, without optimization, cannot adapt to the needs that different load level is run saving energy and decreasing loss.VQC plays important effect to raising rate of qualified voltage, but also needs to improve in reduction active loss.

In recent years, experts and scholars propose many classical mathematics algorithms and intelligent algorithm to idle work optimization, but due to Reactive Power Optimazation Problem be the mixing nonlinear programming problem of a multivariable, multiple constraint, limit to below current optimized algorithm ubiquity:

(1) computing time is long, cannot meet real-time optimization requirement;

(2) an optimization aim normally state point, may cause the frequent movement of discrete device in real-time optimal control;

(3) for complex large-sized electrical network, the accumulated error that the whole network reactive power flow calculates is very large, have impact on accuracy and the precision of control, usually causes controlling result and produces the out-of-limit problem of node voltage.

In sum, existing power-less optimized controlling method also needs further improvement.

Summary of the invention

The object of the invention is to solve existing power-less optimized controlling method length computing time, discrete device frequent movement, calculate the large problem of cumulative errors, aim to provide a kind of real-time reactive power optimization control method of practicality.

The present invention proposes a kind of Near-optimal relaxation reactive power control method for radiation type power grid, comprises the following steps:

(1) connected mode of radial system circuit and transformer is obtained;

(2) radial system is pressed " circuit-transformer " unit decoupling zero; And " circuit-transformer " unit is numbered from 1 to n, n is the number of " circuit-transformer " unit; Definition k=1 ~ n, and the initial value of k is 1;

(3) service data of kth " circuit-transformer " unit is gathered; Described service data comprises node voltage, line parameter circuit value, transformer parameter, load parameter, reactive-load compensation equipment parameter; Node voltage comprises mains side node voltage V _swith load bus voltage V _l; Line parameter circuit value comprises line resistance r _l, line reactance x _lwith line-to-ground electricity Satisfied b _l; Transformer parameter comprises transformer resistance r _t, transformer reactance x _t, Bian depressor electricity Satisfied b _t, transformer conductance g _t, transformer equivalence no-load voltage ratio k _t, tap number n _twith span Δ T; Load parameter includes workload P, load or burden without work Q and critical point reactive power Q _g; Reactive-load compensation equipment parameter comprises the Capacitor banks number n of each node _cwith every pool-size Q _c, each node Reactor banks number n _lwith every pool-size Q _land the switching state of each reactive-load compensation equipment, maximum single group reactive-load compensation equipment capacity Q _com.max;

(4) take Q as independent variable, with mains side node for balance node, adopt climbing method to ask for and make the minimum corresponding load or burden without work Q of the active loss of kth " circuit-transformer " unit _opt;

(5) P, Q is utilized _optdo Load flow calculation to kth " circuit-transformer " unit, the critical point reactive power drawn is designated as optimum critical point reactive power Q _g.opt;

(6) the critical point reactive power upper limit arranging kth " circuit-transformer " unit is , lower limit is , with transformer low voltage bus voltage upper limit and lower limit unine-zone diagram is become during formation;

(7) according to the nine-zone diagram that step (6) obtains, in conjunction with conventional VQC control strategy, obtain a kth transformer tapping gear of " circuit-transformer " unit and the control command of reactive-load compensation equipment, according to control command, transformer and reactive-load compensation equipment are operated;

(8) check k whether to equal n, if k is not equal to n, make k=k+1, return step (3); If k equals n, the reactive power terminating one-period controls, and waits setting-up time, returns step (1), and the reactive power starting next cycle controls.

In above-mentioned Near-optimal relaxation reactive power control method for radiation type power grid, described " circuit-transformer " unit refers to the unit that 1 circuit (comprising twice or multi circuit transmission lines arranged side by side) of through-put power and the transformer of load side connection thereof form.

In above-mentioned Near-optimal relaxation reactive power control method for radiation type power grid, described decoupling zero refers to resolves into multiple " circuit-transformer " unit by electrical network, carries out Reactive power control respectively to " circuit-transformer " unit.

In above-mentioned Near-optimal relaxation reactive power control method for radiation type power grid, the described lax discreteness referred to as adapting to idle control appliance, distribute to make reactive power to enter and optimize the interval target as idle control, be not strict with power system reactive power and equal some state points (fixed value).To each " circuit-transformer " unit, optimize interval width for being somebody's turn to do the maximum single group reactive-load compensation equipment capacity of " circuit-transformer " unit.

In above-mentioned Near-optimal relaxation reactive power control method for radiation type power grid, described in excellent referring to of becoming optimize interval mobile with the difference of burden with power level, make power system reactive power toward the minimum interval convergence of active loss.Optimize interval width constant, interval midpoint is Q _g.opt.

In above-mentioned Near-optimal relaxation reactive power control method for radiation type power grid, described critical point refers to the boundary of power equipment assets and management scope between regional grid.

In above-mentioned Near-optimal relaxation reactive power control method for radiation type power grid, described climbing method is a kind of intelligent search algorithm of conventional solving-optimizing model optimal solution.

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

(1) optimization of full electric network is avoided to calculate by the whole network being decoupled into " circuit-transformer " unit, calculating after decoupling zero reduces the calculating dimension of idle work optimization, and the error accumulation problem avoided in the calculating of bulk power grid reactive power flow, improve computational efficiency and optimize precision;

(2) the excellent control that becomes makes optimization interval different and mobile with load level, and when can ensure electrical network under varying duty, idle control regulates with the least possible discrete control appliance and realizes dynamic electrical network energy-saving run;

(3) the lax target controlled electric network state is entered optimize interval, is not strict with electric network state and equals some state points.Due in continuous print control cycle, critical point reactive power is interval often mutually intersects and has certain width, idle control is carried out by reactive power interval, such critical point, both can meet the minimized optimization demand of real-time tracking active loss, can ensure again that discrete control appliance did not need frequent starting switching.

Accompanying drawing explanation

Fig. 1 is the schematic flow sheet of the Near-optimal relaxation reactive power control method for radiation type power grid of a control cycle.

Fig. 2 is certain 110kV radial system schematic diagram.

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 Near-optimal relaxation reactive power control method for radiation type power grid of a control cycle.Near-optimal relaxation reactive power control method for radiation type power grid comprises:

(1) connected mode of radial system circuit and transformer is obtained;

(2) radial system is pressed " circuit-transformer " unit decoupling zero; And " circuit-transformer " unit is numbered from 1 to n, n is the number of " circuit-transformer " unit; Definition k=1 ~ n, and the initial value of k is 1;

(3) service data of kth " circuit-transformer " unit is gathered; Described service data comprises node voltage, line parameter circuit value, transformer parameter, load parameter, reactive-load compensation equipment parameter; Node voltage comprises mains side node voltage V _swith load bus voltage V _l; Line parameter circuit value comprises line resistance r _l, line reactance x _lwith line-to-ground electricity Satisfied b _l; Transformer parameter comprises transformer resistance r _t, transformer reactance x _t, Bian depressor electricity Satisfied b _t, transformer conductance g _t, transformer equivalence no-load voltage ratio k _t, tap number n _twith span Δ T; Load parameter includes workload P, load or burden without work Q and critical point reactive power Q _g; Reactive-load compensation equipment parameter comprises the Capacitor banks number n of each node _cwith every pool-size Q _c, each node Reactor banks number n _lwith every pool-size Q _land the switching state of each reactive-load compensation equipment, maximum single group reactive-load compensation equipment capacity Q _com.max;

(4) take Q as independent variable, with mains side node for balance node, adopt climbing method to ask for and make the minimum corresponding load or burden without work Q of the active loss of kth " circuit-transformer " unit _opt;

(5) P, Q is utilized _optdo Load flow calculation to kth " circuit-transformer " unit, the critical point reactive power drawn is designated as optimum critical point reactive power Q _g.opt;

(6) the critical point reactive power upper limit arranging kth " circuit-transformer " unit is , lower limit is , with transformer low voltage bus voltage upper limit and lower limit unine-zone diagram is become during formation;

(7) according to the nine-zone diagram that step (6) obtains, in conjunction with conventional VQC control strategy, obtain a kth transformer tapping gear of " circuit-transformer " unit and the control command of reactive-load compensation equipment, according to control command, transformer and reactive-load compensation equipment are operated;

(8) check k whether to equal n, if k is not equal to n, make k=k+1, return step (3); If k equals n, the reactive power terminating one-period controls, and waits 15 minutes, returns step (1), and the reactive power starting next cycle controls.

Be below an example of calculation of the inventive method, carry out simulation calculation for certain 110kV radial system, Fig. 2 shows the topological structure of this electrical network.

(1) know that power supply point is connected to 4 circuits by Fig. 2, the load side of every bar circuit is connected to 1 two-winding transformer;

(2) electrical network can be divided into 4 " circuit-transformer " unit, as shown in the figure, is numbered from 1 to 4 " circuit-transformer " unit; Definition k=1 ~ 4, and the initial value of k is 1;

(3) service data of kth " circuit-transformer " unit is gathered; Described service data comprises node voltage, line parameter circuit value, transformer parameter, load parameter, reactive-load compensation equipment parameter; Node voltage comprises mains side node voltage V _swith load bus voltage V _l; Line parameter circuit value comprises line resistance r _l, line reactance x _lwith line-to-ground electricity Satisfied b _l; Transformer parameter comprises transformer resistance r _t, transformer reactance x _t, Bian depressor electricity Satisfied b _t, transformer conductance g _t, transformer equivalence no-load voltage ratio k _t, tap number n _twith span Δ T; Load parameter includes workload P, load or burden without work Q and critical point reactive power Q _g; Reactive-load compensation equipment parameter comprises the Capacitor banks number n of each node _cwith every pool-size Q _c, each node Reactor banks number n _lwith every pool-size Q _land the switching state of each reactive-load compensation equipment, maximum single group reactive-load compensation equipment capacity Q _com.max; This sentences the 1st " circuit-transformer " unit is example, has:

V _S=115.00kV，V _L=10.34kV，

r _L=13.1999Ω，x _L=38.6000Ω，b _L=2.7402*10 ^-04S，

r _T=0.1191Ω，x _T=15.5788Ω，b _T=0.1719*10 ^-04S，g _T=0.0281*10 ^-04S，

k _T=1，n _T=17，ΔT=1.25%，

P=40.00MW，Q=10.00Mvar，Q _g=12.67Mvar，

n _C=4，Q _C=5Mvar，n _C=0，Q _L=0，Q _com.max=5Mvar。

Every group capacitor is excision state.

(4) take Q as independent variable, with mains side node for balance node, adopt climbing method to ask for and make the minimum corresponding load or burden without work Q of the active loss of kth " circuit-transformer " unit _opt; This sentences the 1st " circuit-transformer " unit is example, has:

Q _opt=-5.56Mvar。

(5) P, Q is utilized _optdo Load flow calculation to kth " circuit-transformer " unit, the critical point reactive power drawn is designated as optimum critical point reactive power Q _g.opt; This sentences the 1st " circuit-transformer " unit is example, has:

Q _g.opt=-3.31Mvar。

(6) the critical point reactive power upper limit arranging kth " circuit-transformer " unit is , lower limit is , with transformer low voltage bus voltage upper limit and lower limit unine-zone diagram is become during formation; This sentences the 1st " circuit-transformer " unit is example, has:

$\begin{array}{c}{Q}_{g.\mathrm{opt}}+\frac{1}{2}\left|Q_{\mathrm{com}.\max }\right|=1.69\mathrm{Mvar},Q_{g.\mathrm{opt}}-\frac{1}{2}\left|Q_{\mathrm{com}.\max }\right|=-8.31\mathrm{Mvar},\\ \stackrel{\‾}{U}=10.70\mathrm{kV},\underset{\‾}{U}=9.7\mathrm{kV}.\end{array}$

(7) according to the nine-zone diagram that step (6) obtains, in conjunction with conventional VQC control strategy, obtain a kth transformer tapping gear of " circuit-transformer " unit and the control command of reactive-load compensation equipment, according to control command, transformer and reactive-load compensation equipment are operated; This sentences the 1st " circuit-transformer " unit is example, operates in the following order:

1. 2 group capacitors are thrown;

2. transformer rises 2 gears;

3. 1 group capacitor is thrown;

4. transformer rises 2 gears.

(8) check k is not equal to n, return step (3).

2nd " circuit-transformer " unit is identical with the Reactive power control flow process of the 1st " circuit-transformer " unit to the Reactive power control flow process of the 4th " circuit-transformer " unit, repeats no more herein.

For embodying beneficial effect of the present invention further, table 1 gives the 1st " circuit-transformer " unit regulates receiving end critical point reactive power Comparative result by two schemes, scheme 1 is for regulating and controlling by the excellent powerless control method that relaxes of the present invention, scheme 2 is for by reactive power interval, critical point being [-2.5Mvar, 2.5Mvar] regulation and control.

Table 1 Comparative result

As shown in Table 1, scheme 1 and scheme 2 can make voltage qualified, and adopt scheme 1 than employing scheme 2 circuit active loss decline 2.19%(and 0.04MW), illustrate and adopt the excellent power-less optimized controlling method that relaxes of the present invention that electrical network 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 (2)

1. Near-optimal relaxation reactive power control method for radiation type power grid, the described lax discreteness referred to as adapting to idle control appliance, distributes to make power system reactive power to enter and optimizes the interval target as idle control, be not strict with power system reactive power and equal fixed value; To each " circuit-transformer " unit, optimize interval width for being somebody's turn to do the maximum single group reactive-load compensation equipment capacity of " circuit-transformer " unit; Described become excellent referring to optimize interval mobile with the difference of burden with power level, make reactive power distribute toward the minimum interval convergence of active loss; Optimize interval width constant, interval midpoint is Q _g.opt;

It is characterized in that described control method comprises the following steps:

(1) connected mode of radial system circuit and transformer is obtained;

(2) radial system is pressed " circuit-transformer " unit decoupling zero; And " circuit-transformer " unit is numbered from 1 to n, n is the number of " circuit-transformer " unit; Definition k=1 ~ n, and the initial value of k is 1; Described " circuit-transformer " unit refers to the unit that 1 circuit of through-put power and the transformer of load side connection thereof form, and described 1 circuit comprises twice or multi circuit transmission lines arranged side by side;

(3) service data of kth " circuit-transformer " unit is gathered; Described service data comprises node voltage, line parameter circuit value, transformer parameter, load parameter, reactive-load compensation equipment parameter; Node voltage comprises mains side node voltage V _swith load bus voltage V _l; Line parameter circuit value comprises line resistance r _l, line reactance x _lwith line-to-ground electricity Satisfied b _l; Transformer parameter comprises transformer resistance r _t, transformer reactance x _t, Bian depressor electricity Satisfied b _t, transformer conductance g _t, transformer equivalence no-load voltage ratio k _t, tap number n _twith span Δ T; Load parameter includes workload P, load or burden without work Q and critical point reactive power Q _g; Reactive-load compensation equipment parameter comprises the Capacitor banks number n of each node _cwith every pool-size Q _c, each node Reactor banks number n _lwith every pool-size Q _land the switching state of each reactive-load compensation equipment, maximum single group reactive-load compensation equipment capacity Q _com.max;

(4) take Q as independent variable, with mains side node for balance node, adopt climbing method to ask for and make the minimum corresponding load or burden without work Q of the active loss of kth " circuit-transformer " unit _opt;

(5) P, Q is utilized _optdo Load flow calculation to kth " circuit-transformer " unit, the critical point reactive power drawn is designated as optimum critical point reactive power Q _g.opt;

(6) the critical point reactive power upper limit arranging kth " circuit-transformer " unit is lower limit is nine-zone diagram is become when forming with transformer low voltage bus voltage upper limit U and lower limit U;

(7) according to the nine-zone diagram that step (6) obtains, in conjunction with VQC control strategy, obtain a kth transformer tapping gear of " circuit-transformer " unit and the control command of reactive-load compensation equipment, according to control command, transformer and reactive-load compensation equipment are operated;

(8) check k whether to equal n, if k is not equal to n, make k=k+1, return step (3); If k equals n, the reactive power terminating one-period controls, and waits setting-up time, returns step (1), and the reactive power starting next cycle controls.

2. Near-optimal relaxation reactive power control method for radiation type power grid according to claim 1, is characterized in that: described decoupling zero refers to resolves into multiple " circuit-transformer " unit by electrical network, carries out Reactive power control respectively to " circuit-transformer " unit.