CN111932139A - Multi-system power quality comprehensive level ranking evaluation method - Google Patents

Abstract

The invention relates to a multi-system power quality comprehensive level ranking evaluation method, and belongs to the field of power system analysis. The method includes the following steps: 1) There are n monitoring points in the system, and the comprehensive power quality level of each monitoring point is PQ _i , where i=1,2,...n; 2) For each monitoring point, calculate: PQ i _{i, left} =PQ _i ‑1, if PQ _{i, left} is less than 0, then let PQ _{i, left} = 0; 3) If all monitoring points of the system PQ _{i, left} = 0, then the system power quality comprehensive index UPQI= The maximum value of PQ _i of each monitoring point; 4) If any monitoring point PQ _i of the system is greater than 1, then the comprehensive power quality index of the system UPQI=1+PQ _{i of each monitoring point, the sum of left} /n; 5) Set a total of Num systems, then for each system k, where k=1,2...Num, adopt the same method as above to obtain the comprehensive power quality index UPQI _k of each system k, where k=1,2...Num,Num is The total number of systems; 6) Rank the comprehensive power quality levels of Num systems according to the size of UPQI _k ; the smaller the UPQI _k , the higher the comprehensive power quality level.

Description

Multi-system power quality comprehensive level ranking evaluation method

technical field

The invention relates to an evaluation method, in particular to a multi-system power quality comprehensive level ranking evaluation method. It belongs to the field of power system analysis.

Background technique

With the continuous development of power quality comprehensive management requirements, the traditional method of evaluating power quality comprehensive indicators for different monitoring points can no longer meet the requirements of power quality management. In practice, it is necessary to carry out power quality comprehensive indicators for different systems and different regions. Sorting and evaluating to judge the overall level of power quality of different systems and different regions, so as to strengthen the comprehensive management of power quality in a targeted manner.

At present, the first method adopted is the evaluation method of a single power quality index with a large probability value at the same voltage level. The high probability value is the target value corresponding to a percentile: set the target value of the Xth percentile to Px, it divides all observations into two parts, of which x% observations are less than Px, (100- x) % observations are greater than Px. It is mainly used to describe the level of a set of data at each percentile position, represented by a set of percentiles such as P5, P25, P50, P75, P95, P99, and P100. Generally, a larger probability value of 95% and above is used. The second method adopted is to use the average value method to summarize multiple power quality comprehensive indicators at the same voltage level, that is, to average the quantification levels of different power quality indicators at the same monitoring point at the same voltage level to obtain a comprehensive index. The third method adopted is to use the maximum value method to summarize multiple power quality comprehensive indicators at the same voltage level, that is, take the maximum value of the quantization levels of different power quality indicators at the same voltage level and the same monitoring point to obtain a comprehensive index. None of the above three methods can realize the comprehensive level ranking evaluation of power quality among multiple systems.

SUMMARY OF THE INVENTION

In order to overcome the disadvantage that the traditional method cannot realize the ranking evaluation of the multi-system power quality hazard degree evaluation. The purpose of the present invention is to provide a multi-system power quality comprehensive level ranking evaluation method. This method can reduce the data of all power quality monitoring points in the system according to their power quality hazard degree, and obtain the calculation method of the only comprehensive power quality index representing the system, so as to carry out comprehensive evaluation and sorting of power quality of different systems. Therefore, the problem of ranking and evaluating the power quality hazards of different systems is solved.

The technical scheme of the present invention is: a multi-system power quality comprehensive level ranking evaluation method, comprising the following steps:

1) Suppose there are n monitoring points in the system, and the comprehensive power quality level of each monitoring point is PQ _i , where i=1,2,...n;

2) For each monitoring point, calculate: PQ _i , _left =PQ _i -1, if PQ _i , _left are less than 0, then let PQ _i , _left =0;

3) If all monitoring points PQ _i of the system, _left = 0, then the comprehensive power quality index UPQI of the system = the maximum value of PQ _i of each monitoring point;

4) If any monitoring point PQ _i of the system is greater than 1, then the system power quality comprehensive index UPQI = 1 + each monitoring point PQ _i , the sum of _left /n;

5) Assuming that there are Num systems in total, then for each system k, where k=1,2...Num, the same method as above is adopted to obtain the comprehensive power quality index UPQI _k of each system k, where k=1,2...Num Num, Num is the total number of systems;

6) Rank the comprehensive power quality levels of Num systems according to the size of UPQI _k ; the smaller the UPQI _k , the higher the comprehensive power quality level.

Further, the power quality indicators of the comprehensive power quality level include: voltage deviation, flicker, three-phase unbalance and harmonics.

Further, if PQ _i of each monitoring point is less than 1, that is, PQ _i , _left =0, it means that each monitoring point does not exceed the standard.

Beneficial effects of the present invention: the method can reduce the data of all the power quality monitoring points in the system according to their power quality hazard degrees, so as to obtain a calculation method representing the unique comprehensive power quality index of the system, so as to develop the power quality of different systems accordingly. Comprehensive evaluation ranking. By applying this method, the problem of sorting and evaluating different systems according to their power quality hazards is solved, and it provides technical support for the comprehensive management of power quality.

Detailed ways

The embodiments of the present invention are described below by specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Terms (including scientific and technical terms) used herein have the commonly understood meanings to those skilled in the art. For example, the terms involved in various embodiments of the present invention are: PQ is power quality (Power quality, PQ). In PQ _i , " _left " in left means the remainder, that is, the part that exceeds 1.

Example 1

The multi-system power quality comprehensive level ranking evaluation method includes the following steps:

1) Suppose there are n monitoring points in the system, and the comprehensive power quality level of each monitoring point is PQ _i (i=1,2,...n);

2) For each monitoring point, calculate: PQ _i , _left =PQ _i -1, if PQ _i , _left are less than 0, then let PQ _i , _left =0 (i=1, 2,...n);

3) If all monitoring points PQ _i of the system, _left = 0 (i=1, 2, ... n), then the comprehensive power quality index UPQI of the system = the maximum value of each monitoring point PQ _i (i = 1, 2, ... n) n);

If the PQ _i of each point is less than 1, that is, PQ _i , _left = 0 (i=1, 2,...n), it means that each point does not exceed the standard. In this case, the maximum value of PQ _i of each monitoring point represents the most serious system. Therefore, the comprehensive index UPQI = the maximum value of PQ _i of each monitoring point.

4) If any monitoring point PQ _i of the system is greater than 1, then the comprehensive power quality index of the system UPQI=1+PQ _i of each monitoring point, the sum of _left /n, (i=1,2,...n);

Here "1" represents exceeding the standard, and "the sum of PQ _i and _left of each monitoring point/n" represents the allocation of the exceeding part to each monitoring point.

5) Assuming that there are Num systems in total, then for each system k, where k=1,2...Num, the same method as above is adopted to obtain the comprehensive power quality index UPQI _k of each system k, where k=1,2...Num Num, Num is the total number of systems;

6) Rank the comprehensive power quality levels of Num systems according to the size of UPQI _k ; the smaller the UPQI _k , the higher the comprehensive power quality level.

Further, the power quality indicators of the comprehensive power quality level include: voltage deviation, flicker, three-phase unbalance and harmonics.

Further, assuming that the standard is 1, if PQ _i , _left =PQ _i -1 is less than 0, it means that it does not exceed the standard, otherwise it exceeds the standard, and there are different processing methods for the subsequent steps of exceeding the standard or not exceeding the standard. No description is given in this embodiment.

Example 2

Examples of application scenarios

There are three systems, subsystem 1 contains three monitoring points, subsystem 2 contains three monitoring points, and subsystem 3 is composed of subsystem 1 and subsystem 2 combined, including 6 monitoring points.

For subsystem 1: PQ _1,left =0.8-1=-0.2<0, order: PQ _1,left =0

PQ _2,left =1.8-1=0.8>0, order: PQ _2,left =0.8

PQ _1,left =1.4-1=0.4>0, order: PQ _3,left =0.4

Then: UPQI ₁ =1+(0.4+0.8)/3=1.4

Likewise, for subsystem 2: UPQI ₂ =1.2

For subsystem 3 constituted by "subsystem 1+subsystem 2", UPQI ₃ =1.27.

The method of the present invention is used to obtain the power quality indicators of each system as shown in Table 1:

Table 1: Sorting and Analysis Results of Comprehensive Power Quality Indexes of Three Systems

In Table 1, UPQI1=1.4, UPQI2=1.2, and UPQI3=1.27. The above results are used for sorting: UPQI ₂ <UPQI ₃ <UPQI ₁ , indicating that subsystem 2 has the best power quality, subsystem 3 is the second, and subsystem 1 has the worst power quality. This conclusion is explained as follows: subsystem 1 actually has 2 The number of points exceeds the standard (greater than 1), and subsystem 2 actually has one point exceeding the standard, indicating that the power quality of subsystem 2 is better than that of subsystem 1; subsystem 3 is composed of "subsystem 1 + subsystem 2", and its power quality level must somewhere in between. This conclusion is consistent with reality.

This method can reduce the data of all power quality monitoring points in the system according to their power quality hazard degree, and obtain the calculation method of the only comprehensive power quality index representing the system, so as to carry out comprehensive evaluation and sorting of power quality of different systems. By applying this method, the problem of sorting and evaluating different systems according to their power quality hazards is solved, and it provides technical support for the comprehensive management of power quality.

The process steps and components that are not described in detail in this embodiment are common means or well-known components in the industry, and will not be described one by one here.

Claims (3)

1. The comprehensive horizontal ranking evaluation method for the multi-system power quality is characterized by comprising the following steps: the method comprises the following steps:

1) setting n monitoring points in the system, wherein the comprehensive power quality level of each monitoring point is PQ_iWherein i is 1,2, … n;

2) for each monitoring point, calculating: PQ_i，_left＝PQ_i1, if PQ_i，_leftIf less than 0, then PQ is asserted_i，_left＝0；

3) If all monitoring points PQ of the system are present_i，_leftIf it is 0, the system power quality integrated index UPQI is equal to each monitoring point PQ_iMaximum value of (d);

4) if any monitoring point PQ of the system_iIf the power quality comprehensive index UPQI of the system is larger than 1, the power quality comprehensive index UPQI of the system is 1 plus each monitoring point PQ_i，_leftSum/n;

5) if a total Num of systems are provided, the same method is adopted for each system k, wherein k is 1, and 2 … Num is adopted to obtain the power quality comprehensive index UPQI of each system k_kWherein k is 1,2 … Num, Num is the total number of the system;

6) according to UPQI_kSorting the comprehensive levels of the power quality of the Num systems; UPQI_kThe smaller the size, the higher the comprehensive level of the electric energy quality.

2. The multi-system power quality comprehensive level ranking evaluation method of claim 1, characterized by: the electric energy quality indexes of the comprehensive electric energy quality level comprise: voltage deviations, flicker, three-phase unbalances and harmonics.

3. The multi-system power quality comprehensive level ranking evaluation method of claim 1, characterized by: if each monitoring point PQ_iLess than 1, i.e. PQ_i，_leftAnd if the value is 0, indicating that all monitoring points do not exceed the standard.