CN105223442A - A kind of inverse distributed power merit stagnant ring island detection method frequently - Google Patents
A kind of inverse distributed power merit stagnant ring island detection method frequently Download PDFInfo
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- CN105223442A CN105223442A CN201510676530.2A CN201510676530A CN105223442A CN 105223442 A CN105223442 A CN 105223442A CN 201510676530 A CN201510676530 A CN 201510676530A CN 105223442 A CN105223442 A CN 105223442A
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Abstract
A kind of inverse distributed power merit stagnant ring island detection method frequently.It comprises frequency measurement; Determination frequency scope; Judge angular frequency range; Frequency control becomes negative feedback; Calculate reactive power; Determination frequency exceeds threshold value number of times; Frequency control becomes positive feedback; Calculate reactive power; Confirm the stages such as isolated island generation.Effect of the present invention: by the continuous replacement of merit frequency positive and negative feedback control, neither destroy island operation state, the generation of isolated island can also be detected fast, change to plan isolated island fast when unplanned property isolated island is occurred for micro-capacitance sensor and there is positive effect, can reduce power off time and frequency for micro-capacitance sensor internal power user, volume increase is guaranteed the quality.
Description
Technical field
The invention belongs to the islanding detect technical field of micro power network or inverse distributed power, particularly relate to a kind of inverse distributed power merit stagnant ring island detection method frequently.
Background technology
Along with the development of micro-capacitance sensor and a large amount of accesses of distributed power source; the possibility that isolated island occurs is increasing; because unplanned isolated island can produce many adverse effects to user and system, therefore based on the consideration of the reliable aspect of power supply safety, anti-islanding protection is required.The basis of anti-islanding protection is exactly islanding detect, and islanding detect is the prerequisite that micro-capacitance sensor is shifted to intentional islanding by unplanned isolated island, also has important effect to control strategy and relaying configuration in change micro-capacitance sensor.
Existing island detection method is mainly divided three classes: passive detection method, active detecting method and the on off state monitoring method based on mechanics of communication.Passive detection method is also known as internal passive method, and the electric parameters forming front and back point of common coupling (PCC point) due to isolated island can change, and the method is exactly mainly determined whether isolated island produced by the observation voltage of electrical network, the change of frequency.Active detecting method is also known as inner active technique, and the method exports a disturbance to control distributed power source, and the response of monitoring system judges whether unplanned isolated island occurs.On off state detection method mainly utilizes means of communication, or detect isolating switch cut-off state, or send carrier signal in grid side, and the change according to these signals is determined whether to there occurs isolated island by the receiver being arranged on DG side.But above method when the islet operation voltage of micro-capacitance sensor and frequency meet the quality of power supply require time, there will be the phenomenon that cannot detect that isolated island occurs, Here it is check frequency.Although passive detection method principle is simple, check frequency is large; Active detecting method check frequency is less, but larger on the impact of the quality of power supply; On off state monitoring method non-blind area, do not affect the quality of power supply, but implement comparatively complicated or less economical.
When micro-capacitance sensor operates in these so-called islanding detect blind areas time, the quality of power supply in isolated island and electric power supply can meet user and load request in fact.And after the concept of micro-capacitance sensor proposes, owing to encouraging distributed power source islet operation when bulk power grid breaks down, to continue as customer power supply, reduce power failure area, the isolated island being therefore positioned at check frequency should not be destroyed.For the object not destroying island state, active detecting methods most is at present all no longer applicable for the islanding detect of micro-capacitance sensor.
Summary of the invention
In order to solve the problem, the object of the present invention is to provide a kind of inverse distributed power merit stagnant ring island detection method frequently.
In order to achieve the above object, the inverse distributed power merit provided by the invention isolated island detecting device that stagnant ring island detection method adopts frequently is arranged on the combining inverter of inverse distributed power, inverse distributed power is connected with electrical network at point of common coupling place, point of common coupling place is connected with equivalent load and is provided with frequency sensor simultaneously, and described method comprises the following step performed in order:
Step 1) S1 stage of frequency measurement: by being arranged on the frequency sensor frequency acquisition signal at point of common coupling place, and be transferred to the isolated island detecting device be arranged on combining inverter;
Step 2) S2 stage of determination frequency scope: utilize the isolated island detecting device determination frequency f be arranged on combining inverter whether to exceed electrical network permissible value scope, if judged result is "Yes", then next step enters the S9 stage, otherwise next step enters the S3 stage;
Step 3) judge S3 stage of angular frequency range: judge angular frequency whether in range of normal value, if judged result is "Yes", then next step enters the S07 stage, otherwise next step enters the S4 stage;
Step 4) frequency control becomes the degenerative S4 stage: now, frequency f is in allowed band, but angular frequency is not in the normal range and threshold value of setting, makes frequency control be negative feedback and B (k)=-1;
Step 5) calculate S5 stage of reactive power; Calculate reactive power Q inv (k);
Step 6) determination frequency exceeds S6 stage of threshold value number of times: judge in 0.1 second time, whether frequency occurs exceeding threshold value 3 times continuously, if judged result is "Yes", then next step enters the S09 stage, otherwise next step reenters the S1 stage;
Step 7) frequency control becomes S7 stage of positive feedback; Now frequency operates in normal range, and make frequency control be positive feedback, i.e. B (k)=1, next step enters the S8 stage;
Step 8) calculate S8 stage of reactive power; Calculate reactive power Q inv (k), next step reenters the S1 stage, carries out the frequency measurement of next control cycle;
Step 9) confirm the S9 stage that isolated island produces: confirm that isolated island produces, this flow process so far terminates.
In step 3) in, the method of described judgement angular frequency range is: ω=2 π f is the voltage angle frequency of point of common coupling, the threshold value scope of set frequency f within the admissible scope of operation of power networks, namely must will ensure 49.5Hz<f<50.5Hz.
In step 5) in, the computing method of described reactive power Q inv (k) are as follows: due to B (k)=-1, in this computation period to the computing formula that inverter output reactive power controls are:
angular frequency (k) can towards close power frequency angular frequency
0direction change.
In step 8) in, the computing method of described reactive power Q inv (k) are as follows: due to B (k)=1, in this computation period to the computing formula that inverter output reactive power controls are:
angular frequency (k) can towards away from power frequency angular frequency
0direction change.
The effect of the stagnant ring island detection method of inverse distributed power merit frequency provided by the invention:
The present invention is by the continuous replacement of merit frequency positive and negative feedback control, neither destroy island operation state, the generation of isolated island can also be detected fast, change to plan isolated island fast when unplanned property isolated island is occurred for micro-capacitance sensor and there is positive effect, can reduce power off time and frequency for micro-capacitance sensor internal power user, volume increase is guaranteed the quality.
Accompanying drawing explanation
Fig. 1 is the isolated island proving installation main circuit topology figure that the stagnant ring island detection method of inverse distributed power merit provided by the invention frequency adopts;
Fig. 2 is inverse distributed power merit provided by the invention stagnant ring island detection method process flow diagram frequently.
Embodiment
Below in conjunction with the drawings and specific embodiments, the stagnant ring island detection method of inverse distributed power merit frequency provided by the invention is described in detail.
As shown in Figure 1, the isolated island proving installation main circuit topology figure that the stagnant ring island detection method of inverse distributed power merit frequency provided by the invention adopts as shown in Figure 1, isolated island detecting device is arranged on the combining inverter of inverse distributed power, inverse distributed power is connected with electrical network at point of common coupling (PCC point) place and is provided with frequency sensor, and PCC point place is connected with equivalent load simultaneously.
First transformed the control strategy for inverter of inverse distributed power, the reactive power that structure inverse distributed power exports is shown below:
Q
inv(k)＝A(k)
B(k)Q
Load(k-1)(1)
Wherein, A (k) represents the gain coefficient of reactive-load compensation, and ω represents angular frequency, ω
0represent power frequency angular frequency.K represents control cycle number of times, and k-1 represents a control cycle, ω
maxand ω
minit is the isolated island angular frequency threshold value of algorithm setting.Therefore, under such control strategy, the reactive power that in each control cycle, inverter exports is compared a control cycle and can be changed.
As shown in Figure 2, the stagnant ring island detection method of inverse distributed power merit frequency provided by the invention comprises the following step performed in order:
Step 1) S1 stage of frequency measurement: by installing the frequency sensor frequency acquisition signal at point of common coupling (PCC point) place in FIG, and be transferred to isolated island detecting device;
Step 2) S2 stage of determination frequency scope: utilize the isolated island detecting device determination frequency f be arranged on combining inverter whether to exceed electrical network permissible value scope, if judged result is "Yes", then next step enters the S9 stage, otherwise next step enters the S3 stage; The object of this step is whether determination frequency f can not meet operation of power networks requirement, if do not met, then thinks and there occurs unplanned property isolated island.
Step 3) judge S3 stage of angular frequency range: judge angular frequency whether in range of normal value, if judged result is "Yes", then next step enters the S07 stage, otherwise next step enters the S4 stage;
Step 4) frequency control becomes the degenerative S4 stage: now, frequency f is in allowed band, but angular frequency is not in the normal range and threshold value of setting, makes frequency control be negative feedback and B (k)=-1;
Step 5) calculate S5 stage of reactive power; Formula (1) is utilized to calculate reactive power Q inv (k);
Step 6) determination frequency exceeds S6 stage of threshold value number of times: the principle of this step is, when isolated island does not occur, mains frequency is depended in the change of frequency, comparatively stable, can not by the impact of inverter output power, but after isolated island occurs, the output of inverter is then depended in the change of frequency, and pace of change can be very fast.Therefore, judge in 0.1 second time, whether frequency occurs exceeding threshold value 3 times continuously, if judged result is "Yes", then next step enters the S09 stage, otherwise next step reenters the S1 stage;
Step 7) frequency control becomes S7 stage of positive feedback; Now frequency operates in normal range, and make frequency control be positive feedback, i.e. B (k)=1, next step enters the S8 stage;
Step 8) calculate S8 stage of reactive power; Utilize formula (1) to calculate reactive power Q inv (k), next step reenters the S1 stage, carries out the frequency measurement of next control cycle;
Step 9) confirm the S9 stage that isolated island produces: confirm that isolated island produces, this flow process so far terminates.
In step 3) in, the method of described judgement angular frequency range is: ω=2 π f is the voltage angle frequency of PCC point, the threshold value scope of set frequency f must within the admissible scope of operation of power networks, namely 49.5Hz<f<50.5Hz will be ensured, such as can get threshold value scope is 49.8Hz<f<50.2Hz, i.e. ω
min=2 π × 49.8rad/s ω
max=2 π × 50.2rad/s.。
In step 5) in, the computing method of described reactive power Q inv (k) are as follows: due to B (k)=-1, in this computation period to the computing formula that inverter output reactive power controls are:
angular frequency (k) can towards close power frequency angular frequency
0direction change.
In step 8) in, it is as follows that described reactive power Q inv (k) obtains computing method: due to B (k)=1, in this computation period to the computing formula that inverter output reactive power controls is:
angular frequency (k) can towards away from power frequency angular frequency
0direction change.
Islanding detect algorithm provided by the invention can detect the generation of isolated island fast on the basis not destroying micro-capacitance sensor islet operation condition, and detection speed is fast, and check frequency is minimum.
Claims (4)
1. an inverse distributed power merit stagnant ring island detection method frequently, the isolated island detecting device that the method adopts is arranged on the combining inverter of inverse distributed power, inverse distributed power is connected with electrical network at point of common coupling place, and point of common coupling place is connected with equivalent load and is provided with frequency sensor simultaneously; It is characterized in that: described inverse distributed power merit frequently stagnant ring island detection method comprises the following step performed in order:
Step 1) S1 stage of frequency measurement: by being arranged on the frequency sensor frequency acquisition signal at point of common coupling place, and be transferred to isolated island detecting device;
Step 2) S2 stage of determination frequency scope: utilize the isolated island detecting device determination frequency f be arranged on combining inverter whether to exceed electrical network permissible value scope, if judged result is "Yes", then next step enters the S9 stage, otherwise next step enters the S3 stage;
Step 3) judge S3 stage of angular frequency range: judge angular frequency whether in range of normal value, if judged result is "Yes", then next step enters the S07 stage, otherwise next step enters the S4 stage;
Step 4) frequency control becomes the degenerative S4 stage: now, frequency f is in allowed band, but angular frequency is not in the normal range and threshold value of setting, makes frequency control be negative feedback and B (k)=-1;
Step 5) calculate S5 stage of reactive power; Calculate reactive power Q inv (k);
Step 6) determination frequency exceeds S6 stage of threshold value number of times: judge in 0.1 second time, whether frequency occurs exceeding threshold value 3 times continuously, if judged result is "Yes", then next step enters the S09 stage, otherwise next step reenters the S1 stage;
Step 7) frequency control becomes S7 stage of positive feedback; Now frequency operates in normal range, and make frequency control be positive feedback, i.e. B (k)=1, next step enters the S8 stage;
Step 8) calculate S8 stage of reactive power; Calculate reactive power Q inv (k), next step reenters the S1 stage, carries out the frequency measurement of next control cycle;
Step 9) confirm the S9 stage that isolated island produces: confirm that isolated island produces, this flow process so far terminates.
2. inverse distributed power merit according to claim 1 stagnant ring island detection method frequently, it is characterized in that: in step 3) in, the method of described judgement angular frequency range is: ω=2 π f is the voltage angle frequency of point of common coupling, the threshold value scope of set frequency f within the admissible scope of operation of power networks, namely must will ensure 49.5Hz<f<50.5Hz.
3. inverse distributed power merit according to claim 1 stagnant ring island detection method frequently, it is characterized in that: in step 5) in, the computing method of described reactive power Q inv (k) are as follows: due to B (k)=-1, in this computation period to the computing formula that inverter output reactive power controls are:
angular frequency (k) can towards close power frequency angular frequency
0direction change.
4. inverse distributed power merit according to claim 1 stagnant ring island detection method frequently, it is characterized in that: in step 8) in, the computing method of described reactive power Q inv (k) are as follows: due to B (k)=1, in this computation period to the computing formula that inverter output reactive power controls are:
angular frequency (k) can towards away from power frequency angular frequency
0direction change.
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Cited By (1)
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| CN106383297A (en) * | 2016-11-07 | 2017-02-08 | 燕山大学 | Frequency acceleration positive feedback island detection method with hysteresis |
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| CN102412591A (en) * | 2011-08-19 | 2012-04-11 | 华北电力大学 | Island detection method based on negative sequence power positive feedback |
| CN103064035A (en) * | 2013-01-08 | 2013-04-24 | 天津大学 | Active island detection method of multi-distributed power supply tied-grid |
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