CN105305504A - Transmission section limit solving method based on method for adjusting opposite and equal quantities in pairs - Google Patents

Abstract

The invention belongs to the technical field of power systems and automation thereof and more specifically relates to a transmission section limit solving method based on a method for adjusting opposite and equal quantities in pairs. The solving method is characterized by, firstly, in a normal operating mode, selecting a typical load mode, and forming raw data of ground state power flow; finding an operating branch with the maximum active power, cutting off the branch and transferring the flow of the branch to other branches; finding a branch l<e>, which is the most likely to exceed a limit, from the other branches; calculating the sensitivity of each unit in a sending and receiving end region to the branch l<e>, calculating an adjustment amount until the branch l<e> is overloaded, and making adjustment reversely after the overload until the branch l<e> is not overloaded; and calculating the sum of flow of all the branches at the moment, i.e. the transmission section limit. The solving method sorts all the controllable units according to the sensitivity, and pairs the units with the maximum sensitivity and the minimum sensitivity for each paired adjustment. The adjustment does not rely on a balance machine, and the result is more reasonable and reliable.

Description

Based on the transmission cross-section limit method for solving of equal and opposite quantities in pairs adjusting method

Patent field

The invention belongs to Power System and its Automation technical field, be specifically related to a kind of transmission cross-section limit method for solving based on equal and opposite quantities in pairs adjusting method.

Background technology

In large scale and the complex structure of modern interconnected network, between net, contact is strong and weak different, the conveying capacity of part circuit is inevitably subject to the restriction of the steady limit of heat or the dynamic steady limit, for convenience of analytical calculation and operational management, electrical network is divided into the contact section between some subsystems and system by operations staff usually.Grasp the transmission of electricity limit of each contact section exactly, under the prerequisite ensureing safe operation of power system, can farthest meet the workload demand of all subregion.

The analysis and calculation of power transmitting capability is all the important subject of electric power system research all the time, and existing computational methods are mainly divided into two classes: Deterministic Methods and probabilistic approach.Deterministic Methods mainly contains direct solving method, repeated power flow method, Continuation Method, optimal load flow method, wherein, direct solving method makes circuit overload directly to increase interregional power, cut down survey region more by half and exchange power, its algorithm is simple but precision is not high, be difficult to meet practical application request, although rear several method improves accuracy, but need iteration etc. because solution procedure comprises equation parameter, nonlinear equation process and computational process, cause computational speed excessively slow, engineering reality cannot be applied to; Probabilistic approach mainly contains stochastic programming, enumerative technique and Monte Carlo Analogue Method etc., although these methods have effectively taken into account various uncertain factor, because it depends on a large amount of stochastic production samples, cannot be adapted to the calculating of large-scale power grid.

Summary of the invention

For solving the problem, the invention discloses a kind of transmission cross-section limit method for solving based on equal and opposite quantities in pairs adjusting method, concrete steps are:

Step 1, under normal operating mode, gets a kind of typical load pattern, forms ground state trend initial data: jth bar branch road l _jactive power be P _j, l _jmaximum allowable power be j=1,2,

Step 2 finds out the maximum operation branch road of active power, is set to l _k, disconnected branches l _kthen be equivalent to most catastrophe failure occurs, its power flow transfer to other branch roads, at l _kbranch road l under the state disconnected _jactive power be the now equal nonoverload of all branch roads;

The most out-of-limit branch road that step 3 is found out in other branch roads, i.e. disconnected branches l _kthe difference of the active power of other each branch roads of front and back minimum branch road, is set to branch road l _e, then branch road l _erequired adjustment amount is Δ P _e;

Step 4 calculates and send by unit each in end regions branch road l _esensitivity, and by sensitivity descending formed with reference to adjustment form, the variable capacity descending sort according to unit that sensitivity is identical, is undertaken matching and adjusting by the first unit and last position unit, i-th time match adjustment amount be Δ P _i,

${\mathrm{\&Delta;P}}_i=\min \{\frac{{\mathrm{\&Delta;P}}_e}{S_{e1}-S_{em}},{\mathrm{\&Delta;P}}_1^{\max },{\mathrm{\&Delta;P}}_m^{\max }\},$

In formula, S _e1for the sensitivity of the first unit, S _emfor the sensitivity of last position unit, for the maximum output limit value of the first unit, for the maximum output limit value of last position unit;

Step 5 judges present branch l _eadjustment amount whether exceed Δ P _eif do not exceed, branch road l _edo not transship, the power of a unit must be had to reach limit value in the first unit and last position unit, it is removed from sequencing table, and continue new the first unit and last position unit again to match, return step 4; If exceed, branch road l _etransship, present branch l _eadjustment amount Δ P will reduce Δ P _ito branch road l _enonoverload;

Step 6 calculates now all Branch Power Flow summations, is maximum transfer power.

Beneficial effect

The equal and opposite quantities in pairs adjusting method that the present invention proposes a kind of improvement applies to solve maximum transfer power.Sorted by all controlled units according to level of sensitivity, the unit selecting sensitivity maximum and minimum during each pairing adjustment matches, and does not rely on balancing machine during adjustment, and result is more rationally reliable.

Accompanying drawing explanation

Fig. 1 is the flow chart of the method for the invention;

Fig. 2 is the reference adjustment sequence list in the present invention;

Fig. 3 is IEEE39 node modular system winding diagram in the embodiment of the present invention;

Embodiment

Below in conjunction with Figure of description and one group of specific embodiment, the present invention will be further described.

Fig. 1 is the flow chart of the method for the invention.Concrete steps of the present invention are:

Step 1, under normal operating mode, gets a kind of typical load pattern, forms ground state trend initial data: jth bar branch road l _jactive power be P _j, l _jmaximum allowable power be j=1,2,

Step 2 finds out the maximum operation branch road of active power, is set to l _k, disconnected branches l _kthen be equivalent to most catastrophe failure occurs, its power flow transfer to other branch roads, at l _kbranch road l under the state disconnected _jactive power be the now equal nonoverload of all branch roads;

The most out-of-limit branch road that step 3 is found out in other branch roads, i.e. disconnected branches l _kthe difference of the active power of other each branch roads of front and back minimum branch road, is set to branch road l _e, then branch road l _erequired adjustment amount is Δ P _e;

Step 4 calculates and send by unit each in end regions branch road l _esensitivity, and by sensitivity descending formed with reference to adjustment form, the variable capacity descending sort according to unit that sensitivity is identical, is undertaken matching and adjusting by the first unit and last position unit, i-th time match adjustment amount be Δ P _i,

${\mathrm{\&Delta;P}}_i=min\{\frac{{\mathrm{\&Delta;P}}_e}{S_{e1}-S_{em}},{\mathrm{\&Delta;P}}_1^{max},{\mathrm{\&Delta;P}}_m^{max}\},$

In formula, S _e1for the sensitivity of the first unit, S _emfor the sensitivity of last position unit, for the maximum output limit value of the first unit, for the maximum output limit value of last position unit;

Step 5 judges present branch l _eadjustment amount whether exceed Δ P _eif do not exceed, branch road l _edo not transship, the power of a unit must be had to reach limit value in the first unit and last position unit, it is removed from sequencing table, and continue new the first unit and last position unit again to match, return step 4; If exceed, branch road l _etransship, present branch l _eadjustment amount Δ P will reduce Δ P _ito branch road l _enonoverload;

Step 6 calculates now all Branch Power Flow summations, is maximum transfer power.

Equal and opposite quantities in pairs method is a kind of method based on sensitivity, and its implication is: when adjustment System active power, and for each increases, node that the node of exerting oneself finds a minimizing to exert oneself matches with it, and vice versa; The node active power of pairing to add decrement equal.So, the unbalanced power brought when sensitivity class methods in the past can be avoided to adjust unit output is all born by balancing machine, causes the situation that balancing machine power is out-of-limit.Simultaneously, the concept of balancing machine is there is not in engineering reality, only be concerned about during scheduling that the plus-minus of concrete unit during adjustment is exerted oneself situation, and system power balance after ensureing adjustment, therefore equal and opposite quantities in pairs method meets the scheduling rule in engineering reality, and once adjust a pair node, the efficiency of algorithm can be improved.

Sorted by all controlled units according to level of sensitivity, the unit selecting sensitivity maximum and minimum during each pairing adjustment matches, and does not rely on balancing machine during adjustment, and result is more rationally reliable.Detailed process is as follows:

If the active power that branch road l need adjust is Δ P _l, meritorious controlled unit number is m, carries out descending order arrangement according to it to the sensitivity of branch road road l, form reference adjustment sequence list as shown in Figure 2, one end that sensitivity is large is head end, and the other end is end, and the variable capacity according to unit when sensitivity is identical sorts.

The first unit and last position unit is selected to be one group during pairing.The first unit sensitivity is S _l1, increase is exerted oneself, and the unit sensitivity of last position is S _lm, minimizing is exerted oneself, and it is equal that two units add and subtract out force value, then the first unit to the sensibility in practice of branch road l is:

S′ _l1＝S _l1-S _lm(1)

S ' _l1>0, above formula can find out S ' _l1size and balancing machine choose that it doesn't matter.

The adjustment amount of unit is:

${\mathrm{\&Delta;P}}_1^{\&prime;}=\left|\frac{{\mathrm{\&Delta;P}}_l}{S_{l1}^{\&prime;}}\right|=\left|\frac{{\mathrm{\&Delta;P}}_l}{S_{l1}-S_{lm}}\right|={\mathrm{\&Delta;P}}_m^{\&prime;}---\left(2\right)$

And in real system, once match adjustment process adjustment time should consider that the minimax of unit is exerted oneself limit value, therefore, actual adjustment amount is the minimum value in following three:

${\mathrm{\&Delta;P}}_i=min\{\frac{{\mathrm{\&Delta;P}}_l}{S_{l1}-S_{lm}},{\mathrm{\&Delta;P}}_1^{max},{\mathrm{\&Delta;P}}_m^{max}\}---\left(3\right)$

Obtain Δ P _iafter, the active power that correction need adjust, if adjustment of once matching fails to meet the demands, then a power of the assembling unit must be had to reach limit value in the first unit or last position unit, it is removed from sequencing table, and continue new the first unit and last position unit again match and adjust, until the adjustment amount of branch road l satisfies the demands.

With IEEE39 node modular system for research example, model above and computational methods are verified and analyzes.This system comprises 39 nodes, 10 generators, 12 transformers, and 34 circuits can be divided into 3 regions, and balance node is Bus31.Reference voltage is 100kV, and reference power is 100MVA.System wiring figure and Region dividing are as Fig. 3.

As can be seen from ground state trend operation result, region 1 is powered region, and region 3 is feeding section, and region 1 and region 3 discontinuity surface comprise 3 transmission lines, be respectively Bus16-19, Bus21-22, Bus16-24, zoning 1 is to the maximum transfer power in region 3.BPA is adopted to carry out Power flow simulation adjustment.

Disconnect the branch road Bus21-22 that trend under basic operational mode is maximum, its active power is transferred to other two branch roads.After ground state trend and disconnected branches Bus21-22, section tidal current is as shown in table 1 below:

Table 1

As can be seen from Table 1, branch road Bus16-19 is the most out-of-limit branch road, Δ P _16-19=45.4MW.Calculate adjustable unit to the sensitivity of Bus16-19 and by descending arrangement formation with reference to adjustment form, as shown in table 2 below.

Table 2

As can be seen from upper table 2, the B of Unit us34 that sensitivity is maximum, the minimum unit of sensitivity is Bus38, and therefore first time carries out the unit of oppositely pairing adjustment is Bus34 and Bus38.Increase exerting oneself of Node B us34, its variable capacity is 102MW, and reduce exerting oneself of Node B us38, its variable capacity is 830MW, and the adjustment amount calculated according to formula (7) is 48.5561MW, and it is 48.5561MW that formula (8) obtains final adjustment amount.After first time adjustment, branch road Bus16-19 gains merit for 501.7MW, out-of-limit.Unit equal and opposite quantities in pairs adjustment result is as shown in table 3 below.

Table 3

According to above-mentioned computational process, setting Δ P=2MW, proceed equal and opposite quantities in pairs adjustment, but object makes branch road Bus16-19 again not out-of-limit, and now branch road sum of gaining merit is maximum transfer power.After second time adjustment, branch road effective power flow is as shown in following form 4.

Table 4

As can be seen from Table 4, region 1 is 1189.3MW to the maximum transfer power in region 3.

Regional internet has become the inexorable trend of power system development, and between Power System Interconnection rear region, the problem of electrical grid transmission ability becomes affects bulk power grid development key factor.Use improvement equal and opposite quantities in pairs adjusting method to solve the problem of maximum transfer power under N-1 Static Security Constraints rapidly and accurately, the feature fast and accurately of the method can be applied in engineering reality.

Claims (1)

1., based on a transmission cross-section limit method for solving for equal and opposite quantities in pairs adjusting method, it is characterized in that, concrete steps are

Step 1, under normal operating mode, gets a kind of typical load pattern, forms ground state trend initial data: jth bar branch road l _jactive power be P _j, l _jmaximum allowable power be j=1,2,

Step 2 finds out the maximum operation branch road of active power, is set to l _k, disconnected branches l _kthen be equivalent to most catastrophe failure occurs, its power flow transfer to other branch roads, at l _kbranch road l under the state disconnected _jactive power be the now equal nonoverload of all branch roads;

The most out-of-limit branch road that step 3 is found out in other branch roads, i.e. disconnected branches l _kthe difference of the active power of other each branch roads of front and back minimum branch road, is set to branch road l _e, then branch road l _erequired adjustment amount is Δ P _e;

Step 4 calculates and send by unit each in end regions branch road l _esensitivity, and by sensitivity descending formed with reference to adjustment form, the variable capacity descending sort according to unit that sensitivity is identical, is undertaken matching and adjusting by the first unit and last position unit, i-th time match adjustment amount be Δ P _i,

${\mathrm{\&Delta;P}}_i=\min \{\frac{{\mathrm{\&Delta;P}}_e}{S_{e1}-S_{em}},{\mathrm{\&Delta;P}}_1^{\max },{\mathrm{\&Delta;P}}_m^{max}\},$

In formula, S _e1for the sensitivity of the first unit, S _emfor the sensitivity of last position unit, for the maximum output limit value of the first unit, for the maximum output limit value of last position unit;

Step 5 judges present branch l _eadjustment amount whether exceed Δ P _eif do not exceed, branch road l _edo not transship, the power of a unit must be had to reach limit value in the first unit and last position unit, it is removed from sequencing table, and continue new the first unit and last position unit again to match, return step 4; If exceed, branch road l _etransship, present branch l _eadjustment amount Δ P will reduce Δ P _ito branch road l _enonoverload;

Step 6 calculates now all Branch Power Flow summations, is maximum transfer power.