CN103683278A - Power distribution network load calibration method applied to on-line loop closing trend optimization analysis - Google Patents

Abstract

The invention discloses a distribution network load calibration method applied to the optimization analysis of the online closed-loop power flow, which comprises the following steps: step 1, adjusting all load values of the distribution network to the rated load of the distribution transformer; step 2, obtaining The current value of the feeder at full load; step 3, get the actual load rate of the feeder; step 4, calculate: Scap, S _load , Tcap, T _load1 , T _load2 , Tcap; step 5, refresh all distribution transformers in the same iterative calculation After the load value, recalculate the new load value at the head end of the feeder, and compare whether the difference between the new load value and the actual measured value at the head end of the feeder is equal. If the requirements are not met, recalculate and adjust the distribution transformer load until the convergence accuracy requirements are met. The invention calculates the load of the transformer and calibrates the load of the power grid through the quantity at the head end of the feeder, so as to ensure the accuracy of the analysis result of the online loop closing power flow optimization.

Description

A Load Calibration Method for Distribution Networks Applied in On-Line Closing Power Flow Optimization Analysis

technical field

The invention relates to a distribution network load calibration method applied to online loop closing power flow optimization analysis.

Background technique

In order to simplify the operation mode of the power grid, suppress the level of short-circuit current, improve the reliability of the power supply of the power grid, and maintain the safe and economic operation of the power grid, the power supply and distribution networks of 110kV and below in my country generally adopt the ring network design and open-loop operation mode. When the load needs to be transferred or the power supply is to be restored after maintenance, the operation mode of closing the loop first and then releasing the loop is generally adopted to avoid power outages for users and improve the reliability of power supply for users.

Due to the large loop closing power flow may be generated during the loop closing operation, which may cause equipment overload or relay protection action, resulting in loop closing operation failure or power failure. If the protection refuses to operate, it may cause damage to the equipment or the protection action of the upper level, expanding the scope of power failure. Since the operation status of the power grid after the loop is closed is opaque to the dispatching operators, it is difficult for the dispatching and operating personnel to judge the reliability of the loop closing operation in advance based on experience. Ultimately, the loop closing operation fails, causing power outages for users or damage to electrical equipment. Due to the difficulty of directly predicting the power flow of the closed loop, in order to prevent equipment damage, sometimes the principle of break before make is used to operate, resulting in short-term power outages for users, which sacrifices the reliability of power grid power supply, which is unacceptable in important load power supply areas such as urban areas of. Therefore, before the loop closing operation, the loop closing power flow budget should be carried out, and the situation after the loop closing should be well known to ensure the success of the loop closing operation and improve the reliability of power supply. If conditions permit, the online monitoring of the loop closure power flow should be used to track the change of the loop closure power flow with time, and the loop closure solution operation should be performed at the moment when the loop closure flow is small, so as to improve the success rate of the loop closure operation .

The transmission network usually has a comprehensive measurement system, and there is redundancy in the electrical quantity of the equipment. However, the distribution network lacks monitoring means and insufficient operating electrical data. It is difficult to conduct a more accurate analysis of the distribution network. State estimation and other analysis.

Contents of the invention

The technical problem to be solved by the present invention is to provide a distribution network load calibration method applied to the optimization analysis of the online loop closing power flow, so as to ensure the accuracy of the online loop closing power flow optimization analysis results.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solution: a distribution network load calibration method applied to online closed-loop power flow optimization analysis, including the following steps:

Step 1, adjusting all load values of the distribution network to the rated load of the distribution transformer;

Step 2: After the power flow calculation, the current value at the head end of the feeder is obtained as the full-load current value of the feeder;

Step 3, use the actual measured current of the feeder and the full load current of the feeder to calculate the actual load rate of the feeder;

Step 4: After obtaining the actual load rate of the feeder, calculate: the measured load at the head end when the Scap feeder is fully loaded, the actual measured load of the S _load feeder, the rated capacity of the Tcap distribution transformer, the current load of the T _load1 distribution transformer, and the calculation of the T _load2 distribution transformer The new load of Tcap distribution transformer load;

Step 5: After refreshing all the distribution transformer load values in the same iterative calculation, recalculate to obtain the new load value at the head end of the feeder, and compare whether the difference between the new load value and the actual measured value at the head end of the feeder line is equal, and if it does not meet the requirements Recalculate and adjust the distribution transformer load until the convergence accuracy requirements are met.

Preferably, the new load calculation formula obtained from distribution transformer calculation is:

$\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="T\; load"\; filenames="HDA0000407678550000011.png,HDA0000407678550000012.png"\; state="\{\{state\}\}">T\; load</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; load</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; load</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; cap</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; cap</span>}}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; cap</span>}}<span\; class="notranslate">\; .</span>$

The invention calculates the load of the transformer and calibrates the load of the power grid through the quantity at the head end of the feeder, so as to ensure the accuracy of the analysis result of the online loop closing power flow optimization.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and specific embodiment:

Figure 1 is a diagram of the process and results of distribution network load calibration;

Figure 2 is a distribution diagram of feeder power flow;

Figure 3 is a load calibration current distribution diagram.

Detailed ways

In the distribution network, the data necessary for power flow calculation include: the 3-phase active and reactive power values of the loads of each distribution transformer, the bus voltage at the feeder outlet, and the electrical parameters of all components of the line.

It is very difficult to collect accurate load values of all loads in the actual distribution network, but all feeder outlet measurements of the distribution network are collected, that is, active power, reactive power, power factor, and feeder current at the feeder outlet. Therefore, it is necessary to calculate the load of the transformer by the amount at the head end of the feeder.

The power (active power and reactive power) at the head end of the feeder is equal to the sum of all load powers on the feeder and their line loss power, namely:

Among them, S: is the apparent power S=P+jQ; I is the complex number of the current, which has amplitude and phase angle.

The following takes Figure 1 as an example to illustrate the process and results of distribution network load calibration.

The measured data are: distribution transformer 2# load per phase P+jQ=200+j100; the current and power factor measured at the outlet of the feeder are I=96.18A (converted success rate), COS=0.9, and the bus voltage of the feeder U =10.5kV; the load of distribution transformer 1# is unknown; the load flow distribution diagram of the feeder as shown in Figure 2 is obtained through state estimation based on these data loads.

From the load calibration current distribution diagram shown in Figure 3, it can be seen that the load of the 1# distribution transformer is automatically adjusted to 319+j140, and the active power at the head end of the feeder is equal to the sum of the load power and the line loss power.

In the specific calculation, first adjust all the load values of the distribution network to the rated load of the distribution transformer, so that the current value at the head end of the feeder obtained after the power flow calculation is the full-load current value of the feeder, and the actual measured current of the feeder and the full-load current of the feeder are used Calculate the actual load rate of the feeder.

The load rate of the feeder reflects the distribution transformer load rate of the entire feeder. In the absence of other data, the state estimation is carried out according to the default condition of distribution transformer load rate balance on the entire feeder.

Calculate after getting the load rate:

Scap馈线满载时首端量测负荷；

When the Scap feeder is fully loaded, the load is measured at the head end;

S_load馈线实际量测负荷；

S _load The actual measured load of the feeder;

Tcap distribution transformer rated capacity;

T _load1 distribution transformer current load;

T_load2配变计算得到的新负荷；

T _load2 is the new load calculated by distribution transformer;

Tcap配变的负荷。

Load of Tcap distribution transformer.

Note: All load values here are plural.

The formula for calculating a distribution transformer after knowing the full load of the feeder and the actual measured load is:

$\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="T\; load"\; filenames="HDA0000407678550000011.png,HDA0000407678550000012.png"\; state="\{\{state\}\}">T\; load</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; load</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; load</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; cap</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; cap</span>}}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; cap</span>}}$

After refreshing all the distribution transformer load values in the same iterative calculation, recalculate the new load value at the head end of the feeder, and compare whether the difference between the new load value and the actual measured value at the head end of the feeder is equal (the difference is less than the convergence accuracy), if If the requirements are not met, recalculate and adjust the distribution transformer load until the convergence accuracy requirements are met.

Claims (2)

1. A distribution network load calibration method applied to online loop closure power flow optimization analysis, characterized in that it comprises the following steps: Step 1, adjusting all load values of the distribution network to the rated load of the distribution transformer; Step 2: After the power flow calculation, the current value at the head end of the feeder is obtained as the full-load current value of the feeder; Step 3, use the actual measured current of the feeder and the full load current of the feeder to calculate the actual load rate of the feeder; Step 4: After obtaining the actual load rate of the feeder, calculate: the measured load at the head end when the Scap feeder is fully loaded, the actual measured load of the S _load feeder, the rated capacity of the Tcap distribution transformer, the current load of the T _load1 distribution transformer, and the calculation of the T _load2 distribution transformer The new load of Tcap distribution transformer load; Step 5: After refreshing all the distribution transformer load values in the same iterative calculation, recalculate to obtain the new load value at the head end of the feeder, and compare whether the difference between the new load value and the actual measured value at the head end of the feeder line is equal, and if it does not meet the requirements Recalculate and adjust the distribution transformer load until the convergence accuracy requirements are met. 2. A distribution network load calibration method applied to online loop closure power flow optimization analysis according to claim 1, characterized in that: the new load calculation formula obtained by distribution transformer calculation is: $\mathrm{<span\; class="notranslate">\; T\; load</span>}\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; load</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; load</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; cap</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; cap</span>}}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; cap</span>}}<span\; class="notranslate">\; .</span>$

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