CN104935013A - Method for calculating voltage distribution of feed line containing DG - Google Patents

Abstract

The present invention relates to a method for calculating voltage distribution of a feed line containing a DG (Distributed Generation), characterized in that calculation of voltage distribution is performed through a superimposed principle, i.e., when a system power supply is in effect and when the DG is in effect, line loss is respectively calculated, then voltage of each node is calculated, and voltage distribution of the feed line is derived. When the plurality of arbitrary DGs are connected, the method also can derive the rule of voltage changes of each node of the feed line. Nowadays, grid connection capacity of the DG is bigger and bigger, the number of the DGs connected in the feed line is correspondingly increased. Therefore, the method can derive the voltage distribution case after the DGs with certain capacity are connected into the feed line, and can derive the optimum position and capacity of the DG when the plurality of DGs are connected into the feed line, thereby solving the problem of node voltage off-limit after connection of the DGs.

Description

Containing the computational methods that the feeder voltage of DG distributes

Technical field

The present invention relates to the computational methods that a kind of feeder voltage containing DG distributes, belong to distribution network technology field.

Background technology

Distributed power source is at energy field in occupation of consequence, and its development alleviates the deterioration process of scarcity of resources and problem of environmental pollution, becomes one of approach that nature regenerative resource effectively utilizes.Its impact on power distribution network is not considered in the access of early stage of development distributed power source, namely " namely connect and namely forget ", but along with the development of distributed generation technology, grid connection capacity is also increasing, original distribution network also becomes complicated, become the active power distribution network of two-way flow from the distribution of power one-way flow, the impact of power distribution network also can not be ignored.Power distribution network can be made to flow into harmonic wave after DG access, cause the quality of power supply defective, all can be able to impact the planning of power distribution network, relaying protection etc. in addition.

The access of following distributed power source will be not only list and power supply duplicate supply, but towards the future development of many plant-grid connection, circuit therefore will be made more complicated.Node voltage can be caused to raise after distributed power source access feeder line, even out-of-limit, rational capacity and on-position configure the voltage condition can improving feeder line, but irrational configuration easily causes feeder voltage change unbalanced and stablize, and even occurs the situation that some node voltage is out-of-limit.Therefore a kind of method is needed to the change in voltage rule of feeder line of deriving with derivation feeder voltage distribution situation.These computational methods can derive the access of feeder line any number of distributed power source time circuit voltage's distribiuting situation, can lay the foundation for the reasonable disposition of further analysis distribution formula position of source and capacity.

Summary of the invention

According to above deficiency of the prior art, the problem to be solved in the present invention is: provide a kind of simplicity of design, easy to use, touch manner can be used to control digital control system and data display, be convenient to secondary development upgrading, enhance robustness and the fail safe of touch control mode, improve the aobvious control equipment integrating based on Intelligent flat and the data communications method thereof of the data transmission efficiency in system.

The technical solution adopted for the present invention to solve the technical problems is:

The computational methods that a kind of feeder voltage containing DG distributes are provided, adopt the principle of superposition to carry out Voltage distribution computation, line loss when namely computing system power supply and distributed power source act on respectively, and then the voltage calculating each node, concrete step is:

After a, distributed power source access feeder line, circuit is divided into some sections, and top node and first distributed power source access point are first paragraph, and the n-th distributed power source access point and endpoint node are one section, and all the other are between every adjacent node be one section;

B, be continuous print function node voltage formula fitting;

C, respectively to the node voltage function differentiate between adjacent distributions formula power supply;

D, the rule of feeder line voltage's distribiuting when analyzing any number of distributed power source access situation.

The described following formula of step b interior joint voltage equation represents:

As k ∈ [0, d ₁] time,

$U_K=U_0-k\frac{\underset{i=k}{\overset{N}{\Σ}}{P}_{i}R+\underset{i=k}{\overset{N}{\Σ}}{Q}_{i}X}{U_N}+k\frac{\underset{j=1}{\overset{n}{\Σ}}{P}_{dj}R}{U_N}---\left(1\right);$

As k ∈ [d _x, d _x+1] time, wherein d _xrepresent the node at an xth DG place.

$U_K=U_0-k\frac{\underset{i=k}{\overset{N}{\Σ}}{P}_{i}R+\underset{i=k}{\overset{N}{\Σ}}{Q}_{i}X}{U_N}+\frac{\underset{j=1}{\overset{x}{\Σ}}{P}_{dj}{\mathrm{Rd}}_i}{U_N}+k\frac{\underset{j=x+1}{\overset{n}{\Σ}}{P}_{dj}R}{U_N}---\left(2\right);$

As k ∈ [d _n, N] time,

$U_K=U_0-k\frac{\underset{i=k}{\overset{N}{\Σ}}{P}_{i}R+\underset{i=k}{\overset{N}{\Σ}}{Q}_{i}X}{U_N}+\frac{\underset{j=1}{\overset{n}{\Σ}}{P}_{dj}{\mathrm{Rd}}_i}{U_N}---\left(3\right);$

Suppose k value be (0, N] on any real number, then U _kthe continuous function on interval can be defined as, and at interval (0, d ₁), (d _x, d _x+1), (d _n, N) namely except the whole story node and distributed power source access point except all can lead,

Now suppose d ₀=0, represent top node, corresponding access capacity P _d0=0; d _n+1=N, represents endpoint node, corresponding access capacity P _{d (n+1)}=0;

Then formula (4) can be merged in formula (1), (2), (3)

$U_K=U_0-k\frac{\underset{i=k}{\overset{N}{\Σ}}{P}_{i}R+\underset{i=k}{\overset{N}{\Σ}}{Q}_{i}X}{U_N}+\frac{\underset{j=1}{\overset{x}{\Σ}}{P}_{dj}{\mathrm{Rd}}_i}{U_N}+k\frac{\underset{j=x+1}{\overset{n}{\Σ}}{P}_{dj}R}{U_N},k\∈\[d_x,d_{x+1}\]---\left(4\right)$

Wherein d _xrepresent the node at an xth DG place, x is the arbitrary integer in [0, n] interval;

Now the span of k in formula (4) is expanded, make it get arbitrary real number, then U in [0, N] _kbecome a continuous print piecewise function, and except arbitrary d _xpoint function all can be led, then by solving the rule of feeder voltage distribution to the mode of piecewise function differentiate piecemeal, step is as follows:

1. first, input d ₁, d ₂d _n, n, N, P _d1, P _d2p _dnvalue and load value size, assignment x=0;

2. ask interval [d _x, d _x+1] i.e. interval [d ₀, d ₁] interior U _kderived function

3. solve d respectively _x, d _x+1the right-hand derivative at place and left derivative, and whether the long-pending of both judgements is greater than 0;

If 3.1 both amassing are greater than 0, then judge whether the right-hand derivative of dx is greater than 0, if be greater than 0, export k at (d _x, d _x+1) increase progressively in interval, if be less than 0, export k at (d _x, d _x+1) successively decrease in interval;

If 3.2 both amassing are less than 0, then judge that k is at [d _x+ 1, d _x+1-1] whether exist in interval and a bit make be 0, if so, then export k at (d _x, d _x+1) first successively decreasing in interval increases progressively afterwards, if do not exist, judges U _dx-U _{d (x+1)}whether be greater than 0;

If be 3.2.1 greater than 0, then export k at (d _x, d _x+1) successively decrease in interval;

If be 3.2.2 less than 0, then export k at (d _x, d _x+1) increase progressively in interval;

4. judge whether x is greater than n, if be greater than n, terminate, if be less than n, then make x=x+1, repeat step and play 2, until x>n;

5. sum up the feeder voltage regularity of distribution.

The beneficial effect that the present invention has is:

When the access of any number of distributed power source, this algorithm can be derived the rule of each node voltage change of feeder line.Now, the grid connection capacity of distributed power source is increasing, and the number accessing distributed power source in feeder line also increases accordingly.Therefore voltage's distribiuting situation after the distributed power source access feeder line utilizing this algorithm can derive under certain capacity, and then the optimum position of DG and capacity during many plant-grid connection in feeder line of can deriving, solve the out-of-limit problem of node voltage after distributed power source access.

The method can Computation distribution formula plant-grid connection distribution feeder time stable state node voltage, and then derivation feed connection node change in voltage trend.When distributed power source accesses the quantity of feeder line and position determines, the rule of voltage's distribiuting during different situations of can deriving.Simultaneously because distributed power source access capacity gets more and more, access quantity is also different, therefore can by analyzing the Voltage Distribution of feeder line and then releasing best on-position and the capacity limit of distributed power source by this algorithm, to avoid node voltage out-of-limit, make line voltage distribution improve effect and reach best.

Accompanying drawing explanation

Fig. 1 is that n DG accesses feeder line schematic diagram;

Fig. 2 is voltage's distribiuting reasoning flow figure;

Embodiment

Below in conjunction with accompanying drawing, embodiments of the invention are described further:

As depicted in figs. 1 and 2, suppose have in n distributed power source access feeder line, the node of access is respectively d ₁, d ₂d _nrepresent the 1st, 2 respectively ... the node of n DG access, access capacity is respectively P _d1, P _d2p _dn.After deriving by analysis, the voltage equation of each node k can point situation represent with formula (1)-(3) respectively.

As k ∈ [0, d ₁] time, $U_K=U_0-k\frac{\underset{i=k}{\overset{N}{\Σ}}{P}_{i}R+\underset{i=k}{\overset{N}{\Σ}}{Q}_{i}X}{U_N}+k\frac{\underset{j=1}{\overset{n}{\Σ}}{P}_{dj}R}{U_N}---\left(1\right)$

As k ∈ [d _x, d _x+1] time, wherein d _xrepresent the node at an xth DG place.

$U_K=U_0-k\frac{\underset{i=k}{\overset{N}{\Σ}}{P}_{i}R+\underset{i=k}{\overset{N}{\Σ}}{Q}_{i}X}{U_N}+\frac{\underset{j=1}{\overset{x}{\Σ}}{P}_{dj}{\mathrm{Rd}}_i}{U_N}+k\frac{\underset{j=x+1}{\overset{n}{\Σ}}{P}_{dj}R}{U_N}---\left(2\right)$

As k ∈ [d _n, N] time, $U_K=U_0-k\frac{\underset{i=k}{\overset{N}{\Σ}}{P}_{i}R+\underset{i=k}{\overset{N}{\Σ}}{Q}_{i}X}{U_N}+\frac{\underset{j=1}{\overset{n}{\Σ}}{P}_{dj}{\mathrm{Rd}}_i}{U_N}---\left(3\right)$

Suppose k value be (0, N] on any real number, then U _kthe continuous function on interval can be defined as, and at interval (0, d ₁), (d _x, d _x+1), (d _n, N) namely except the whole story node and distributed power source access point except all can lead.Therefore the derivative that finds a function of by stages, and then solve the change of feeder voltage in respective bins.

Now suppose d ₀=0, represent top node, corresponding access capacity P _d0=0; d _n+1=N, represents endpoint node, corresponding access capacity P _{d (n+1)}=0.

Then formula (4) can be merged in formula (1), (2), (3)

$U_K=U_0-k\frac{\underset{i=k}{\overset{N}{\Σ}}{P}_{i}R+\underset{i=k}{\overset{N}{\Σ}}{Q}_{i}X}{U_N}+\frac{\underset{j=1}{\overset{x}{\Σ}}{P}_{dj}{\mathrm{Rd}}_i}{U_N}+k\frac{\underset{j=x+1}{\overset{n}{\Σ}}{P}_{dj}R}{U_N},k\∈\[d_x,d_{x+1}\]---\left(4\right)$

Wherein d _xrepresent the node at an xth DG place, x is the arbitrary integer in [0, n] interval.

Now the span of k in formula (4) is expanded, make it get arbitrary real number, then U in [0, N] _kbecome a continuous print piecewise function, and except arbitrary d _xpoint function all can be led.Then by solving the rule of feeder voltage distribution to the mode of piecewise function differentiate piecemeal.Step is as follows.

1. first, input d ₁, d ₂d _n, n, N, P _d1, P _d2p _dnvalue and load value size, assignment x=0;

2. ask interval [d _x, d _x+1] i.e. interval [d ₀, d ₁] interior U _kderived function

3. solve d respectively _x, d _x+1right-hand derivative and left derivative, and whether long-pending both judging is greater than 0;

If 3.1 both amassing are greater than 0, then judge d _xright-hand derivative whether be greater than 0, if be greater than 0, export k at (d _x, d _x+1) increase progressively in interval, if be less than 0, export k at (d _x, d _x+1) successively decrease in interval;

If 3.2 both amassing are less than 0, then judge that k is at [d _x+ 1, d _x+1-1] whether exist in interval and a bit make be 0, if so, then export k at (d _x, d _x+1) first successively decreasing in interval increases progressively afterwards, if do not exist, judges U _dx-U _{d (x+1)}whether be greater than 0;

If be 3.2.1 greater than 0, then export k at (d _x, d _x+1) successively decrease in interval;

If be 3.2.2 less than 0, then export k at (d _x, d _x+1) increase progressively in interval;

4. judge whether x is greater than n, if be greater than n, terminate, if be less than n, then make x=x+1, repeat step and play 2, until x>n;

5. sum up the feeder voltage regularity of distribution.

Claims (2)

1. containing the computational methods that the feeder voltage of DG distributes, it is characterized in that, adopt the principle of superposition to carry out Voltage distribution computation, line loss when namely computing system power supply and distributed power source act on respectively, and then the voltage calculating each node, concrete step is:

After a, distributed power source access feeder line, circuit is divided into some sections, and top node and first distributed power source access point are first paragraph, and the n-th distributed power source access point and endpoint node are one section, and all the other are between every adjacent node be one section;

B, be continuous print function node voltage formula fitting;

C, respectively to the node voltage function differentiate between adjacent distributions formula power supply;

D, the rule of feeder line voltage's distribiuting when analyzing any number of distributed power source access situation.

2. the computational methods that distribute of the feeder voltage containing DG according to claim 1, it is characterized in that, the described following formula of step b interior joint voltage equation represents:

As k ∈ [0, d ₁] time,

$U_K=U_0-k\frac{\underset{i=k}{\overset{N}{\Σ}}{P}_{i}R+\underset{i=k}{\overset{N}{\Σ}}{Q}_{i}X}{U_N}+k\frac{\underset{j=k}{\overset{N}{\Σ}}{P}_{dj}R}{U_N}---\left(1\right);$

As k ∈ [d _x, d _x+1] time, wherein d _xrepresent the node at an xth DG place.

$U_K=U_0-k\frac{\underset{i=1}{\overset{N}{\Σ}}{P}_{i}R+\underset{i=1}{\overset{N}{\Σ}}{Q}_{i}X}{U_N}+\frac{\underset{j=1}{\overset{x}{\Σ}}{P}_{dj}{\mathrm{Rd}}_i}{U_N}+k\frac{\underset{j=x+1}{\overset{n}{\Σ}}{P}_{dj}R}{U_N}---\left(2\right);$

As k ∈ [d _n, N] time,

$U_K=U_0-k\frac{\underset{i=k}{\overset{N}{\Σ}}{P}_{i}R+\underset{i=k}{\overset{N}{\Σ}}{Q}_{i}X}{U_N}+\frac{\underset{j=1}{\overset{n}{\Σ}}{P}_{dj}{\mathrm{Rd}}_i}{U_N}---\left(3\right);$

Suppose k value be (0, N] on any real number, then U _kthe continuous function on interval can be defined as, and at interval (0, d ₁), (d _x, d _x+1), (d _n, N) namely except the whole story node and distributed power source access point except all can lead,

Now suppose d ₀=0, represent top node, corresponding access capacity P _d0=0; d _n+1=N, represents endpoint node, corresponding access capacity P _{d (n+1)}=0;

Then formula (4) can be merged in formula (1), (2), (3)

$U_K=U_0-k\frac{\underset{i=k}{\overset{N}{\Σ}}{P}_{i}R+\underset{i=k}{\overset{N}{\Σ}}{Q}_{i}X}{U_N}+\frac{\underset{j=1}{\overset{n}{\Σ}}{P}_{dj}{\mathrm{Rd}}_i}{U_N}+k\frac{\underset{j=x+1}{\overset{n}{\Σ}}{P}_{dj}R}{U_N},k\∈\[d_x,d_{x+1}\]---\left(4\right)$

Wherein d _xrepresent the node at an xth DG place, x is the arbitrary integer in [0, n] interval;

Now the span of k in formula (4) is expanded, make it get arbitrary real number, then U in [0, N] _kbecome a continuous print piecewise function, and except arbitrary d _xpoint function all can be led, then by solving the rule of feeder voltage distribution to the mode of piecewise function differentiate piecemeal, step is as follows:

(1). first, input d ₁, d ₂d _n, n, N, P _d1, P _d2p _dnvalue and load value size, assignment x=0;

(2). ask interval [d _x, d _x+1] i.e. interval [d ₀, d ₁] interior U _kderived function

(3). solve respectively at d _x, d _x+1the right-hand derivative at place and left derivative, and whether the long-pending of both judgements is greater than 0;

If 3.1 both amassing are greater than 0, then judge d _xright-hand derivative whether be greater than 0, if be greater than 0, export k at (d _x, d _x+1) increase progressively in interval, if be less than 0, export k at (d _x, d _x+1) successively decrease in interval;

If 3.2 both amassing are less than 0, then judge that k is at [d _x+ 1, d _x+1-1] whether exist in interval and a bit make be 0, if so, then export k at (d _x, d _x+1) first successively decreasing in interval increases progressively afterwards, if do not exist, judges U _dx-U _{d (x+1)}whether be greater than 0;

If be 3.2.1 greater than 0, then export k at (d _x, d _x+1) successively decrease in interval;

If be 3.2.2 less than 0, then export k at (d _x, d _x+1) increase progressively in interval;

(4). judge whether x is greater than n, if be greater than n, terminate, if be less than n, then make x=x+1, repeat step and play 2, until x>n;

(5). sum up the feeder voltage regularity of distribution.