CN106099916A - The method that a kind of 110kV transformer station load transfer scheme quickly determines - Google Patents

Abstract

The invention relates to a method for quickly determining a load transfer scheme of a 110kV substation, comprising: setting an initial load transfer scheme; obtaining the 10kV loss load rate under the highest load rate; Load transfer scheme. Compared with the prior art, the present invention uses the influence of the dedicated mutual feeder on the load transfer capability of the substation, and combines the parameters of the substation itself to adaptively generate an optimal load transfer scheme, thereby ensuring the stability of main transformer maintenance in different substations.

Description

A Method for Quickly Determining the Load Transfer Scheme of 110kV Substation

technical field

The invention relates to the technical field of power electronics, in particular to a method for rapidly determining a load transfer scheme of a 110kV substation.

Background technique

With the development of social economy and urban construction, the power distribution system in various regions has shown the characteristics of international metropolitan urban power grids such as large load density, dense distribution network, high cable conversion rate, difficult channel site and large investment cost. In recent years, the power consumption growth of power grids in various regions has shown a slowing trend. However, with the development of urban economy and society, the requirements for safe and reliable power supply are increasing. planning and design to improve the transfer capacity of power grids in various regions. Mutual feeders have the functions of preventing power failure of the whole station, making substations meet maintenance mode "N-1" (no short-term load loss) and substations meeting maintenance mode "N-1" (short-time loss of a small amount of load).

Maintenance mode N-1 (namely N-1-1): In the case of a planned outage of one main transformer or one circuit, any associated component (excluding the busbar) in the power grid at the same level is not faulty or disconnected due to a fault . The planned outage should be arranged during the peak load period not exceeding 70%.

Transfer capacity: In a certain power supply area, when the power grid components or substations are out of service, the ability of the grid to transfer loads is generally quantified as the ratio of transferable loads to the total regional load.

Mutual feeder: In order to ensure the restoration of power supply for the station power supply after the entire substation loses power, it connects the medium and low voltage sides of the substation and the power line that can be sent to the opposite end terminal load on both sides.

Contents of the invention

The purpose of the present invention is to provide a method for quickly determining the load transfer scheme of a 110kV substation in order to overcome the above-mentioned defects in the prior art, using the influence of the special mutual feeder on the load transfer capacity of the substation, and combining the parameters of the substation itself, self-adaptive Generate an optimal load transfer scheme to ensure the stability of main transformer maintenance in different substations.

The purpose of the present invention can be achieved through the following technical solutions:

A method for quickly determining the load transfer scheme of a 110kV substation includes the following steps:

1) Set the initial load transfer scheme:

The initial load transfer scheme of 110kV substation includes setting up 10kV dedicated mutual feeder and 10kV tie line;

2) Obtain the 10kV loss load rate under the highest load rate according to the collected substation parameters related to the initial load transfer scheme of the 110kV substation;

3) Adjust the initial load transfer scheme of the 110kV substation according to the transfer load rate under the highest load rate, and output the corresponding adjusted load transfer plan, so that the 10kV loss load rate under the highest load rate is 0.

The substation parameters related to the initial load transfer scheme of the 110kV substation include the number of main transformers in the 110kV substation, the capacity of the main transformers, the highest load rate, the transfer capacity of the 10kV dedicated mutual feeder, the number of 10kV dedicated mutual feeders and the dual power ratio.

The 10kV transfer load rate γ under the maximum load rate satisfies the following formula:

In the formula, A' is the main transformer capacity of the 110kV substation, B' is the highest load rate of the 110kV substation, q is the number of 10kV dedicated mutual feeders, _F4 is the transfer capacity of the 10kV dedicated mutual feeders, is the ratio of dual power sources in the 10kV substation, and N' is the number of main transformers in the 110kV substation.

In the step 3), the initial load transfer scheme of the 110kV substation shall give priority to adjusting the ratio of the 10kV tie line for the 220kV substation with three main transformers, and whether to set up a 10kV dedicated mutual feeder for the 220kV substation with two main transformers. .

Step 4) is also included after the step 3): adding constraints on the main wiring of the substation in the load transfer scheme for adjustment.

The constraints of the main wiring of the substation are:

If the incoming lines of its subordinate 10kV substation all come from this 110kV substation, then its incoming lines come from buses connected to different 110kV transformers and not connected through tie switches.

Compared with the prior art, the present invention has the following advantages:

1) Using the influence of the dedicated mutual feeder on the load transfer capacity of the substation, combined with the parameters of the substation itself, the optimal load transfer scheme is adaptively generated, so as to ensure the stability of the main transformer maintenance of different substations.

2) Take the 10kV transfer load rate as an index to evaluate the 10kV load transfer capacity of the 110kV substation, and then put forward the corresponding optimal plan, so as to improve the 10kV load transfer capacity of the 110kV substation.

3) In addition to the impact of the dedicated mutual feeder on the load transfer capacity of the grid, the restrictions on the transfer by the main wiring of the substation are also considered, making the adjustment of the load transfer scheme more comprehensive and perfect.

Description of drawings

Fig. 1 is the flowchart of the method of the present invention.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is carried out on the premise of the technical solution of the present invention, and detailed implementation and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

As shown in Figure 1, a method for quickly determining the load transfer scheme of a 110kV substation includes the following steps:

1) Set the initial load transfer scheme:

The initial load transfer scheme of 110kV substation includes setting up 10kV dedicated mutual feeder and 10kV tie line.

2) Obtain the 10kV loss load rate under the highest load rate according to the collected substation parameters related to the initial load transfer scheme of the 110kV substation.

The substation parameters related to the initial load transfer scheme of the 110kV substation include the number of main transformers in the 110kV substation, the capacity of the main transformer, the highest load rate, the transfer capacity of the 10kV dedicated mutual feeder, the number of 10kV dedicated mutual feeders and the ratio of dual power sources in the 10kV substation .

The 10kV transfer load rate γ under the highest load rate satisfies the following formula:

In the formula, A' is the main transformer capacity of the 110kV substation, B' is the highest load rate of the 110kV substation, q is the number of 10kV dedicated mutual feeders, _F4 is the transfer capacity of the 10kV dedicated mutual feeders, is the ratio of dual power sources in the 10kV substation, and N' is the number of main transformers in the 110kV substation.

3) Adjust the initial load transfer scheme of the 110kV substation according to the transfer load rate under the highest load rate, and output the corresponding adjusted load transfer plan, so that the 10kV loss load rate under the highest load rate is 0.

Step 3), the initial load transfer scheme of the 110kV substation prioritizes the adjustment of the proportion of 10kV tie lines for the 220kV substation with three main transformers, and whether to set up a 10kV dedicated mutual feeder for the 220kV substation with two main transformers.

4) Add the constraints of the main wiring of the substation to the scheme of adjusting the load transfer. The constraints of the main wiring of the substation are:

If the incoming lines of its subordinate 10kV substation all come from this 110kV substation, then its incoming lines come from buses connected to different 110kV transformers and not connected through tie switches.

Example: Taking 110/35kV special mutual feeder to improve the transfer capacity of Shanghai 110kV substation as an example, the method of the present invention is used for research:

At present, the 10kV dedicated mutual feeder between the 110kV substations in Shanghai generally adopts 3×400mm ² cables, and the transmission capacity is 6.24MVA, but the function of the original mutual feeder is mainly to ensure the substation power supply. Here, the requirements of the power grid for the transfer capacity are considered , a large transmission capacity is required to meet the load transfer demand during the maintenance of the main transformer N-1, so the special mutual feeder studied in this section is a double-parallel 3×400mm ² cable with a transmission capacity of 12.48MVA. The method of the invention is used to analyze the influence of the 10kV mutual feeder on the 10kV load transfer capacity of the 110kV substation under the N-1 state of maintenance of the main transformer of the 110kV substation. The load that cannot be transferred by the 10kV mutual feeder needs to be transferred through the 10kV inter-station tie line, and the current ratio of the 10kV tie line in Shanghai is about 30%.

For the 110kV transformers of two main transformers, the capacity of the main transformer is A′, the maximum load rate is B′, and the load rate is 70% of the maximum load when the main transformer is overhauled. At this time, when one main transformer is overhauled, one main transformer When the power is off, the two main transformers need to transfer a load of 2*A′*B′*0.7 in total. Here, 110kV substations with main transformer capacities of 31.5MVA, 50MVA and 110MVA are discussed respectively. Transfer 10kV load rate = 1-10kV load loss rate.

Table 10 N-1 10kV load transfer table under maintenance of 110kV substation with 2 main transformers Unit: %

Note: The transferable capacity in Table 10-11 is calculated as 12.48MVA. There is no power plant in the lower power supply area. This table only considers the 10kV load rate transferred by the 10kV dedicated mutual feeder.

From the above analysis, it can be seen that if the main transformer of the 110kV substation with two main transformers is overhauled at N-1, the 10kV mutual feeder can only transfer a lower proportion of the load, and the proportion of the 10kV tie line must be increased to ensure that the main transformer of the 110kV substation is N-1. , Normal power supply of 10kV load.

For the 110kV transformers of three main transformers, the capacity of the main transformer is A′, the maximum load rate is B′, and the load rate is 70% of the maximum load when the main transformer is overhauled. At this time, when one main transformer is overhauled, one main transformer When power is lost, the total load that the third main transformer can carry is A′ (overload is not considered), the total load of the 110kV substation is 3*A′*B′*0.7, and the 35kV side load that the remaining main transformer cannot bear It is 2.1*A'*B'-A', and this part of the load is transferred by 10kV tie line or 10kV dedicated mutual feeder. The 10kV side load that can be transferred by the 10kV dedicated mutual feeder is F ₄ , then the total 10kV side load that the dedicated mutual feeder and the remaining main transformer can bear is A′+F ₄ , and the proportion of the total 10kV load is (A′+F ₄ )/(2.1*A'*B'), as shown in Table 10. Here, the 110kV substations with main transformer capacities of 31.5MVA, 50MVA and 110MVA are discussed respectively. The proportion of the 10kV dedicated mutual feeder and the load that can be transferred by the third main transformer to the total 10kV load is discussed.

Table 11 10kV dedicated mutual feeder and 110kV substation load ratio table of the third main transformer Unit: %

From the above analysis, it can be seen that if the main transformer of the 110kV substation with three main transformers is overhauled N-1, when the load rate is as low as about 50% at the initial stage of substation commissioning, the 10kV mutual feeder can meet the demand for load transfer. However, with the increase of the load rate of the 110kV substation, the 10kV tie line is still needed to transfer the load, so as to ensure that the 10kV load will not lose power when the main transformer of the 110kV substation is overhauled at N-1.

The ratio of the load that the third main transformer can carry to the total load is A'/(3*A'*B'*0.7), which is 1/(B'*2.1), which has nothing to do with the capacity of the main transformer. If there is no 10kV Table 12 shows the loss rate of 10kV side load for dedicated mutual feeder and 10kV tie line.

Table 12 N-1 10kV load loss rate under maintenance of 110kV substation without considering mutual feeder unit: %

At present, the proportion of dual power sources in 10kV stations in Shanghai has reached 30%. According to the results obtained in the above table, for a 110kV substation with 3 main transformers, all loads can be transferred only by relying on 10kV tie lines.

Claims (6)

1. the method that a 110kV transformer station load transfer scheme quickly determines, it is characterised in that comprise the following steps:

1) initial load turning solution is set:

The initial load turning solution of 110kV transformer station includes arranging the special mutual feeder line of 10kV and 10kV interconnection；

2) maximum load rate is obtained according to the Substation parameters that the initial load turning solution with 110kV transformer station gathered is relevant Under 10kV lose rate of load condensate；

3) adjust the initial load turning solution of 110kV transformer station according to the transfer load rate under maximum load rate, and export phase The Load adjustment turning solution answered so that the 10kV loss rate of load condensate under maximum load rate is 0.

The method that a kind of 110kV transformer station the most according to claim 1 load transfer scheme quickly determines, its feature exists In, the described Substation parameters relevant with the initial load turning solution of 110kV transformer station includes the pricinpal variable of 110kV transformer station Transfer capacity, the number of the special mutual feeder line of 10kV and the 10kV of the special mutual feeder line of amount, main transformer capacity, high capacity rate, 10kV become Power station dual power supply ratio.

The method that a kind of 110kV transformer station the most according to claim 2 load transfer scheme quickly determines, its feature exists Below equation is met in, 10kV transfer load rate γ under described maximum load rate:

In formula, A ' is the main transformer capacity of 110kV transformer station, and B ' is the high capacity rate of 110kV transformer station, and q is that 10kV is special mutually The number of feeder line, F₄For the transfer capacity of the special mutual feeder line of 10kV,For 10kV transformer station dual power supply ratio, N ' is 110kV power transformation The main transformer quantity stood.

The method that a kind of 110kV transformer station the most according to claim 1 load transfer scheme quickly determines, its feature exists In, described step 3), the initial load turning solution of 110kV transformer station is excellent for the 220kV transformer station that main transformer quantity is three First adjust the ratio of 10kV interconnection, for the 220kV transformer station that main transformer quantity is two, preferentially regulateing whether, 10kV is set special Use mutual feeder line.

The method that a kind of 110kV transformer station the most according to claim 1 load transfer scheme quickly determines, its feature exists In, described step 3) also include step 4 afterwards): in Load adjustment turning solution, add the constraint of Substation Bus Arrangement.

The method that a kind of 110kV transformer station the most according to claim 5 load transfer scheme quickly determines, its feature exists In, being constrained to of described Substation Bus Arrangement:

If its subordinate 10kV station inlet wire is all from this 110kV transformer station, then its inlet wire from access different 110kV transformator and The bus being connected not over interconnection switch.