CN106374456A - A power supply recovery method after a fault in a distribution network with distributed power - Google Patents

Abstract

The invention relates to a power supply recovery method of a power distribution network comprising distributed power supplies after a fault. The power supply recovery method is technically characterized by comprising the following steps of (1) splitting the distributed power supply which does not have isolated island operation capability after a large-area power failure condition is caused by the fault of the power distribution network; (2) carrying out isolated island division by using a searching method on the basis of the principle that the distributed power supplies run with surrounding loads, and then enabling an isolated land, with the surrounding load, of the distributed power supply with the isolated island operation capability to run; (3) isolating a fault point and recovering power supply of the remaining sound network; and (4) enabling the distributed power supply or isolated island with a grid-connection condition to run in a grid-connection manner and enabling the isolated land without the grid-connection condition to further run. The effects of the distributed power supplies can be fully developed under the premise of recovering load power supply as much as possible; the important load power supply reliability is improved; meanwhile, the switching action frequency is reduced as few as possible in the power supply recovery process; and the network loss is reduced as much as possible after power supply recovery.

Description

A power supply recovery method after a fault in a distribution network with distributed power

technical field

The invention belongs to the technical field of power distribution automation, in particular to a power supply recovery method after a fault in a power distribution network including a distributed power source.

Background technique

At present, when the distribution network containing distributed generation (DG) fails and a large-scale power outage occurs, the distributed generation is generally removed from the distribution network, and then the power supply is restored to the healthy area of the distribution network, and finally the distributed generation is connected to the grid. However, this approach fails to give full play to the function of distributed power to improve power supply reliability. Therefore, when the distribution network fails and a large-scale power outage occurs, the distributed power with island operation capability will operate in isolated islands with surrounding loads, and does not have the distribution of island operation capabilities. Then the faulty section is isolated, the power supply is restored in the healthy area of the distribution network, and finally the island operation part is connected to the distributed power supply grid, so that when the power grid fails in a large area, the power supply to important loads can be guaranteed without interruption, and the distributed power supply can be fully utilized. advantages of power generation. However, in the power supply recovery process after the fault of the distributed power distribution network, the distributed power only operates in an isolated island with fixed loads, and does not consider the operation of the distributed power with the surrounding load at its maximum capacity and the process of restoring power to healthy areas. , without considering the network loss and the number of switching operations after the distributed power generation is connected to the grid.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a power supply recovery method after a failure of a distributed power distribution network with reasonable design, high reliability of key load power supply, and small load loss and network loss.

The present invention solves its technical problem and realizes by taking the following technical solutions:

A power supply recovery method after a fault in a distribution network including a distributed power supply, comprising the following steps:

Step 1. After a large-scale power outage occurs due to a fault in the distribution network, the distributed power generation that does not have the ability to operate in an isolated manner will be disconnected;

Step 2. Based on the principle that the distributed power supply operates with the surrounding load at its maximum capacity, after using the search method to divide the islands, the distributed power supply with the island operation capability is operated with the surrounding loads in an isolated island;

Step 3. Isolate the fault point and restore the power supply of the remaining sound network;

Step 4. Distributed power sources with grid-connected conditions or isolated islands are connected to the grid, and isolated islands that do not have grid-connected conditions continue to operate in isolation.

Moreover, the specific steps of the island division in step 2 include:

(1) Starting with the distributed power source as the parent node, search for all load child nodes directly connected to the distributed power source, and put the load represented by the child node into the load library W to be restored;

(2) Determine whether the load library W to be restored is empty; if it is not empty, calculate the P _n q _n of all loads in the load library W to be restored, and take out the load m corresponding to the largest P _n q _n from W, and set Put the load m into the pre-selected load library V; if it is empty, the load in the pre-selected load library V is the load within the operating range of the distributed power island, and the island is divided successfully;

(3) Determine whether the distributed power supply and the load in the preselected load library V meet the constraints shown in the following formula; if not, remove the load m from the preselected load library V, and jump to step (2) of step 2 Step; if satisfied, jump to step (4) of step 2;

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; G</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; V</span>}}{<span\; class="notranslate">\; ></span><span\; class="notranslate">\; \&Sigma;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}\\ {\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; G</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; V</span>}}{<span\; class="notranslate">\; ></span><span\; class="notranslate">\; \&Sigma;</span>}{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}\end{array}\right.$

Among them, P _DG , Q _DG are distributed power generation with power and reactive load capacity respectively; P _i , P _n are active loads of load i and n respectively; Q _i is reactive load of load i; i is load in V ;q _n is the weight factor assigned to load n according to the importance of load n; n is the load in W;

(4) Determine whether the network formed by the distributed power supply and the pre-selected load library V satisfies the constraints shown in the following formula; if so, start with the load m as the parent node, search for all load child nodes directly connected to the load m, and set Put the load represented by the child node into the load library W to be restored, and jump to step (2) of step 2; if the constraints shown below are not met, take the load m from the pre-selected load library V, and jump to step step (2) of 2;

$\left\{\begin{array}{c}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; j</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}}\end{array}\right.$

Among them, the first constraint is the branch current constraint, I _{max_bij} is the maximum transmission current of the line b _ij ; the second constraint is the node voltage constraint, U _i is the voltage of load i in the pre-selected load library V, U _max , U _min are the maximum and minimum allowable voltages of load i in the pre-selected load library V, respectively.

And, the specific steps of described step 3 include:

(1) Establish the multi-objective optimization function with the least load loss, the least number of switching actions and the least network loss after the power supply is restored. The multi-objective optimization function is as follows:

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; min</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}{<span\; class="notranslate">\; \&Sigma;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}\\ \mathrm{<span\; class="notranslate">\; min</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{<span\; class="notranslate">\; \&Sigma;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{<span\; class="notranslate">\; \&Sigma;</span>}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}\\ \mathrm{<span\; class="notranslate">\; min</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}\end{array}\right.$

Among them, f ₁ , f ₂ , and f ₃ respectively represent the load loss function, the switching action times function, and the network loss function; P _BL is the sum of the multiplication of the load size in the power-off area and its corresponding weight coefficient; Y is the area except for isolated islands The set of remaining network load nodes; P _y is the active load of load y; q _y is the weight factor assigned to load y according to the importance of load y, the more important the load, the greater the weight coefficient; S _s is the set of segmented switches; T _s is the set of contact switches before failure; K _k is the switch state, 0 means disconnected, 1 means closed; P _loss is the network loss except for the isolated island;

Its constraints are as follows:

$\left\{\begin{array}{c}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; \&alpha;S</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; b</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; min</span>}}^{<span\; class="notranslate">\; ,</span>}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}^{<span\; class="notranslate">\; ,</span>}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}^{<span\; class="notranslate">\; ,</span>}\\ \mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}\end{array}\right.$

Among them, the first constraint is the branch capacity constraint; S _{max_b} is the maximum transmission capacity of line b; α is the margin coefficient; the second constraint is the voltage constraint of power quality; U' _y is the remaining network node y voltage; U' _max and U' _min are the maximum and minimum allowable voltages; the third constraint is the distribution network structure constraint; g is the network structure after the power supply of the remaining network is restored; G _R is the network structure composed of the remaining network node branches The set of all possible radial network structures;

(2) Solving according to traditional operations research methods, genetic algorithm or binary particle swarm algorithm can be used to solve the multi-objective optimization function in step (1) of step 3.

Advantage and positive effect of the present invention are:

1. The present invention can give full play to the role of distributed power supply under the premise of restoring load power supply as much as possible, improve the reliability of power supply for important loads, and make distributed power supply run with surrounding loads after a large-scale power outage in the distribution network. At the same time, during the power supply restoration process Reduce the number of switching actions as little as possible, and reduce the network loss as much as possible after the power supply is restored.

2. The patent of the present invention makes full use of the subsection switch and feeder terminal unit (FTU) installed in the current distribution network. The FTU can upload the status of the subsection switch and control its on-off. , the distributed power supply can continue to run with surrounding loads, ensuring that important loads do not stop power outages, reducing the number of switching operations during the restoration of distribution network power supply, improving the service life of segmented switches, and at the same time reducing network losses as much as possible after power supply restoration. In the process of network fault self-healing, the optimization of the three goals of reducing load loss, reducing the number of switching operations, and reducing network loss is realized.

3. The patent of the present invention makes full use of the actual conditions of the application of smart meters in the current grid and the automatic collection function of operating data, and proposes the equivalent average load sharing method of daily operation for the calculation of the theoretical line loss of 10kV power grid on the basis of the capacity sharing method. This method can well solve the shortcomings of the traditional capacity apportionment method that the calculation method is simple and the calculation result is inaccurate, so the loss of the line and transformer cannot be accurately calculated. It adapts to the new situation of the current power grid development and makes full use of the current power grid. The power consumption information collection system greatly improves the calculation accuracy, and the calculation amount is small, which promotes the development and improvement of the 10kV theoretical line loss calculation system. Compared with the traditional method, it has obvious advantages and has good engineering application value.

Description of drawings

Fig. 1 is a schematic diagram of connections of a distribution network system in a normal operation mode according to an embodiment of the present invention.

detailed description

Embodiments of the present invention are described in further detail below in conjunction with the accompanying drawings:

In this embodiment, the distribution network system shown in Figure 1 is taken as an example for illustration. The distribution network system is connected with two distributed power sources; where DG1 and DG2 are two distributed power sources; S is the distribution network Substation; 1 is the outlet circuit breaker of the distribution network substation, 2, 3, 4...14 are section switches, 15, 16 are distributed power side circuit breakers (black solid squares represent closed, hollow squares represent open ); in general, FTU is installed at the section switch, which can be remotely controlled on and off; (1), (2)...(9) are distribution transformers; · are distribution transformer switches.

A power supply recovery method after a fault in a distribution network including a distributed power supply, comprising the following steps:

Step 1. After a large-scale power outage occurs due to a fault in the distribution network, the distributed power generation that does not have the ability to operate in an isolated manner will be disconnected;

In this embodiment, a permanent fault occurs in the line between the section switches 2, 3, and 11, the circuit breaker 1 is turned off, and the power distribution network system shown in Fig. 1 is completely cut off. DG1 does not have the islanding operation capability, disconnect the circuit breaker 15 on the distributed power supply side, and DG1 is directly disconnected from the distribution network.

Step 2. Based on the principle that the distributed power supply operates with the surrounding load at its maximum capacity, after using the search method to divide the islands, the distributed power supply with the island operation capability is operated with the surrounding loads in an isolated island;

The specific steps of the island division include:

(1) Starting with the distributed power source as the parent node, search for all load child nodes directly connected to the distributed power source, and put the load represented by the child node into the load library W to be restored;

(2) Determine whether the load library W to be restored is empty; if it is not empty, calculate the P _n q _n of all loads in the load library W to be restored, and take out the load m corresponding to the largest P _n q _n from W, and set Put the load m into the pre-selected load library V; if it is empty, the load in the pre-selected load library V is the load within the operating range of the distributed power island, and the island is divided successfully;

(3) Determine whether the distributed power supply and the load in the preselected load library V meet the constraint conditions shown in formula (1); if not, remove the load m from the preselected load library V, and jump to step 2. (2) step; if satisfied, then jump to step (4) of step 2;

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; G</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; V</span>}}{<span\; class="notranslate">\; ></span><span\; class="notranslate">\; \&Sigma;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}\\ {\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; G</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; V</span>}}{<span\; class="notranslate">\; ></span><span\; class="notranslate">\; \&Sigma;</span>}{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, P _DG , Q _DG are distributed power generation with power and reactive load capacity respectively; P _i , P _n are active loads of load i and n respectively; Q _i is reactive load of load i; i is load in V ;q _n is the weight factor assigned according to the importance of load n, that is, load n; n is the load in W;

(4) Determine whether the network formed by the distributed power supply and the pre-selected load library V satisfies the constraints shown in formula (2); if so, start with the load m as the parent node, and search for all load sub-nodes directly connected to the load m node, put the load represented by the child node into the load library W to be restored, and jump to step (2) of step 2; if the constraint conditions shown in formula (2) are not met, take the load from the pre-selected load library V m, jump to step (2) of step 2;

$\left\{\begin{array}{c}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; j</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them, the first constraint is the branch current constraint, I _{max_bij} is the maximum transmission current of the line bij; the second constraint is the node voltage constraint, U _i is the voltage of load i in the pre-selected load library V, U _max , U _min are the maximum and minimum allowable voltages of load i in the pre-selected load library V, respectively.

In this embodiment, as shown in FIG. 1 , DG2 has the capability of island operation. Through island division, DG2 operates in an island with load (6)(2)(3)(4), and switches 8, 4, and 7 are turned off.

Step 3. Isolate the fault point and restore the power supply of the remaining sound network;

The concrete steps of described step 3 include:

(1) Establish the multi-objective optimization function with the least load loss, the least number of switching actions, and the least network loss after the restoration of power supply. The least scheme, the second is the switching action, and the last is the network loss.

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; min</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; B</span>}\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}{<span\; class="notranslate">\; \&Sigma;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}\\ \mathrm{<span\; class="notranslate">\; min</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{<span\; class="notranslate">\; \&Sigma;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{<span\; class="notranslate">\; \&Sigma;</span>}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}\\ \mathrm{<span\; class="notranslate">\; min</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Among them, f ₁ , f ₂ , and f ₃ respectively represent the load loss function, the switching action times function, and the network loss function; P _BL is the sum of the multiplication of the load size in the power-off area and its corresponding weight coefficient; Y is the area except for isolated islands The set of remaining network load nodes; P _y is the active load of load y; q _y is the weight factor assigned to load y according to the importance of load y, the more important the load, the greater the weight coefficient; S _s is the set of segmented switches; T _s is the set of contact switches before failure; K _k is the switch state, 0 means open, 1 means closed; P _loss is the network loss except for the isolated island.

Its constraints are shown in formula (4):

$\left\{\begin{array}{c}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; \&alpha;S</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; b</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; min</span>}}^{<span\; class="notranslate">\; ,</span>}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}^{<span\; class="notranslate">\; ,</span>}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}^{<span\; class="notranslate">\; ,</span>}\\ \mathrm{<span\; class="notranslate">\; g</span>}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Among them, the first constraint is the branch capacity constraint; S _{max_b} is the maximum transmission capacity of line b; α is the margin coefficient; the second constraint is the voltage constraint of power quality; U' _y is the remaining network node y voltage; U' _max and U' _min are the maximum and minimum allowable voltages; the third constraint is the distribution network structure constraint; g is the network structure after the power supply of the remaining network is restored; G _R is the network structure composed of the remaining network node branches The set of all possible radial network structures.

(2) Solving according to the traditional operations research method, genetic algorithm or binary particle swarm optimization algorithm can be used to solve the multi-objective optimization function in step (1).

In this embodiment, switches 2, 3, and 11 in FIG. 1 are turned off to isolate the fault point, and the circuit breaker 1 is turned on.

Step 4. Distributed power sources with grid-connected conditions or isolated islands are connected to the grid, and isolated islands that do not have grid-connected conditions continue to operate in isolation.

In this embodiment, as shown in Figure 1, the isolated island has the conditions for grid-connected operation, and switch 8 is closed for isolated island grid-connected operation; switches 4, 7, and 14 are closed sequentially to restore (1)(5)(7)(8) (9) Load power supply; DG1 has the conditions for grid connection, close the circuit breaker 15, and DG1 runs in grid connection.

It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive, so the present invention includes but not limited to the embodiments described in the specific implementation manner, and those skilled in the art according to the technology of the present invention Other implementations derived from the scheme also belong to the protection scope of the present invention.

Claims (3)

1. after a kind of distribution network failure containing distributed power source service restoration method it is characterised in that: comprise the following steps:

After large-area power-cuts situation in step 1, distribution network failure, do not possessed the distributed power source solution of island operating capacity Row；

Step 2, based on distributed power source with the principle of load operation around maximum capacity band, isolated island is carried out using searching method and draws After point, will be provided with load islet operation around the distributed power source band of island operating capacity；

Step 3, isolated fault point, recover the power supply that residue perfects network；

Step 4, possess the distributed power source of grid-connected conditions or isolated island is incorporated into the power networks, do not possess grid-connected conditions isolated island continue lonely Island is run.

2. service restoration method after a kind of distribution network failure containing distributed power source according to claim 1, its feature exists In: the concrete steps that the isolated island of described step 2 divides include:

(1) power supply starts for father node in a distributed manner, searches for all load child nodes being joined directly together with distributed power source, by son The load of node on behalf puts into load storehouse w to be restored；

(2) judge whether load storehouse w to be restored is empty；If not empty, calculate the p of all loads in load storehouse w to be restored_nq_n, from P is taken out in w_nq_nThe corresponding load m of middle the maximum, load m is put into pre-selection load storehouse v；If it is empty, load in pre-selection load storehouse v For distributed generator islanding range of operation internal loading, isolated island divides successfully；

(3) judge whether distributed power source meets, with the load in pre-selection load storehouse v, the constraints being shown below；If discontented Foot, then elimination capacity m from pre-selection load storehouse v, jumps to (2nd) step of step 2；If meeting, jump to the of step 2 (4) step；

$\left\{\begin{array}{c}{p}_{dg}>\underset{i\&element;v}{\&sigma;}{p}_i\\ q_{dg}>\underset{i\&element;v}{\&sigma;}{q}_i\end{array}\right.$

Wherein, p_dg、q_dgIt is respectively that distributed power source band is active, load or burden without work ability；p_i、p_nIt is respectively the active negative of load i, n Lotus；q_iLoad or burden without work for load i；I is load in v；q_nBe the significance level according to load n, be load n distribution weight because Son；N is load in w；

(4) judge whether the network that distributed power source is formed with pre-selection load storehouse v meets the constraints being shown below；If full Foot, then started with load m for father node, searches for all load child nodes being joined directly together with load m, by bearing that child node represents Lotus puts into load storehouse w to be restored, jumps to (2nd) step of step 2；If being unsatisfactory for constraints as follows, from pre-selection Take out load m in the v of load storehouse, jump to (2nd) step of step 2；

$\left\{\begin{array}{c}\left|i_{bij}\right|<i_{\max \_bij}\\ u_{\min }\&le;u_i\&le;u_{max}\end{array}\right.$

Wherein, first constraint formula constrains for branch current, i_{max_bij}For circuit b_ijMaximum transmitted electric current；Second constraint formula For node voltage constraint, u_iFor the voltage of load i in pre-selection load storehouse v, u_max、u_minIt is respectively load i in pre-selection load storehouse v Maximum, minimum permission voltage.

3. service restoration method after a kind of distribution network failure containing distributed power source according to claim 1 and 2, its feature It is: the concrete steps of described step 3 include:

(1) set up respectively and minimum, switch motion least number of times is lost with the afterload that restores electricity and the minimum multiple target of network loss is excellent Change function, this multi-goal optimizing function is as follows:

$\left\{\begin{array}{c}\min f_1=p_{bl}-\underset{y\&element;y}{\&sigma;}{p}_y{q}_y\\ \min f_2=\underset{k\&element;s_s}{\&sigma;}(1-k_k)+\underset{k\&element;t_s}{\&sigma;}{k}_k\\ \min f_3=p_{loss}\end{array}\right.$

Wherein, f₁、f₂、f₃Represent load loss function, switch motion frequency function, network loss function respectively；p_blFor in outage area Sum after the corresponding weight coefficient multiplication of payload；Y is except the set of isolated island region rest network load bus；p_yIt is negative The burden with power of lotus y；q_yIt is the weight factor that the significance level according to load y is distributed for load y, load its weight coefficient more important Bigger；s_sFor block switch set；t_sFor interconnection switch set before fault；k_kFor on off state, 0 represents disconnection, and 1 represents closure； p_lossIt is except isolated island part network loss；

Its constraints is as follows:

$\left\{\begin{array}{c}\left|s_b\right|<{\mathrm{\&alpha;s}}_{\max \_b}\\ u_{\min }^{,}\&le;u_y^{,}\&le;u_{\max }^{,}\\ g\&element;g_r\end{array}\right.$

Wherein, first constraint formula constrains for tributary capacity；s_{max_b}Maximum transfer capacity for circuit b；α is nargin coefficient；The Two constraint formulas are the voltage constraint of the quality of power supply；u^’ _yVoltage for rest network node y；u^’ _max、u^’ _minPermit for maximum, minimum Permitted voltage；3rd constraint formula constrains for distribution net work structure；G is the network structure after rest network service restoration；g_rIt is by remaining The set of all possible radial networks structure of remaining network node branch road composition；

(2) carry out solving, genetic algorithm or binary particle swarm algorithm can be adopted to step 3 according to traditional operational research Methods The described multi-goal optimizing function of (1st) step is solved.