Power supply system and method for substation equipment

Abstract

The invention discloses a power supply system and method for substation equipment, and relates to the technical field of substation power supply, and the system comprises a data collection module which is used for synchronously collecting three-phase voltage and current signals of a substation load; the harmonic characteristic analysis module is used for carrying out harmonic analysis on the collected signals and calculating the amplitude and phase dispersion of each harmonic; the dynamic weight calculation module is used for calculating a dynamic harmonic weight factor according to the harmonic analysis result; the equivalent reactive power decision module is used for calculating equivalent reactive power and generating an optimal capacitor switching instruction in combination with harmonic weight and temperature compensation; the temperature compensation module is used for monitoring the temperature of the capacitor in real time and calibrating the actual capacity of the capacitor; and the flexible switching execution module is used for triggering a thyristor near the voltage zero crossing point. By constructing the harmonic phase dispersion analysis mechanism and the harmonic weight factor dynamic correction model, the transient characteristic and steady-state distortion difference of the load harmonic can be analyzed more accurately.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of substation power supply, and particularly relates to a power supply system and method for substation equipment. BACKGROUND

[0002] In the field of reactive power compensation in substations, the traditional capacitor bank power supply method mainly takes total harmonic distortion (THD) as the basis for judging the severity of harmonic pollution. However, the harmonics generated by industrial loads usually have obvious phase randomness and transient mutation characteristics, and it is difficult to distinguish between steady-state distortion and transient harmonic interference only by relying on the THD index.

[0003] This limitation leads to the following defects: the traditional method ignores the discrete distribution characteristics of the phases of harmonics, and treats transient harmonics with dramatic phase fluctuations and background harmonics with stable phases equally; the phase-unstable harmonic components can cause deviations in the measurement results of fundamental reactive power, leading to incorrect switching of capacitor banks, and further causing over-compensation or under-compensation; therefore, the following solution is proposed to solve the above problems. SUMMARY

[0004] The purpose of the present application is to provide a power supply system and method for substation equipment, which can accurately analyze the transient characteristics and steady-state distortion differences of load harmonics by constructing a harmonic phase dispersion analysis mechanism and a dynamic harmonic weight factor correction model, thereby solving the problem of compensation amount misjudgment caused by ignoring the randomness of harmonic phases in existing methods.

[0005] To solve the above technical problems, the present application is realized by the following technical scheme:

[0006] The present application is a power supply system for substation equipment, which comprises:

[0007] A data acquisition module for synchronously acquiring three-phase voltage and current signals of the load of the substation;

[0008] A harmonic feature analysis module for performing harmonic analysis on the acquired signals and calculating the amplitude and phase dispersion of each harmonic;

[0009] A dynamic weight calculation module for calculating a dynamic harmonic weight factor based on the harmonic analysis results to suppress the influence of phase-unstable harmonics;

[0010] An equivalent reactive power decision module for calculating equivalent reactive power and generating optimal capacitor switching instructions in combination with harmonic weight and temperature compensation;

[0011] A temperature compensation module for monitoring the temperature of the capacitor in real time and calibrating the actual capacity of the capacitor;

[0012] The flexible switching execution module is used for triggering the thyristor near the voltage zero-crossing point to realize the no-inrush switching of the capacitor.

[0013] A power supply method of a substation device, in particular comprising the following steps:

[0014] Step S1, real-time acquisition of electrical parameters: using high-precision sensors to synchronously acquire three-phase current and bus voltage signals of the load, and generating discrete sequences through an analog-to-digital converter;

[0015] Step S2, harmonic spectrum and phase analysis: performing spectrum analysis on the current signal, extracting fundamental and harmonic components, and calculating the discrete degree of the phase of each harmonic;

[0016] Step S3, generating a harmonic weight factor: dynamically generating a weight factor in combination with the harmonic amplitude and phase stability, and performing nonlinear correction on the fundamental reactive power based on the factor;

[0017] Step S4, optimization of capacitor switching decision: disabling the easy-resonance branch according to the harmonic risk, and selecting a combination scheme that meets the reactive power demand and has the least switching action;

[0018] Step S5, temperature drift capacity calibration: real-time monitoring of the capacitor temperature, and calibration of the actual capacity through a nonlinear model;

[0019] Step S6, execution of flexible switching and verification: accurate triggering of the thyristor switching at the voltage zero-crossing point, and returning to step S1 for effect verification after a delay.

[0020] Further, the step S1, real-time acquisition of electrical parameters, specifically comprises the following steps:

[0021] Step S11: using a high-precision current sensor to acquire three-phase current signals i a (t),i b (t),i c (t) of the load;

[0022] Step S12: synchronously acquiring bus voltage signals v a (t),v b (t),v c (t) of the load;

[0023] Step S13: converting the analog signals into discrete sequences i a [n],v a [n] through a 16-bit ADC.

[0024] Further, the step S2, harmonic spectrum and phase analysis, specifically comprises the following steps:

[0025] Step S21: Perform an FFT transform on the discrete sequence to obtain the fundamental component I1∠θ1 and each harmonic component I1. h ∠θ h (h = 2, 3, ..., 50);

[0026] Step S22: Calculate the phase dispersion factor of each harmonic:

[0027]

[0028] In the formula, δ h Let θ be the phase dispersion of the h-th harmonic, h be the harmonic order, M be the total number of power grid cycles within the sliding window, k be the cycle number, and θ be the phase dispersion of the h-th harmonic. h [k] is the instantaneous phase angle of the h-th harmonic in the k-th period. Let |·| be the average phase of the h-th harmonic over M periods. 2 This is for the modulo squaring operation.

[0029] Furthermore, step S3, generating the dynamic harmonic weighting factor, specifically includes the following steps:

[0030] Step S31: Generate dynamic harmonic weighting factors based on the harmonic spectrum features extracted in step S2, using the following formula:

[0031]

[0032] In the formula, K H For dynamic harmonic weighting factor, I h Ih is the amplitude of the h-th harmonic current, I1 is the amplitude of the fundamental current, and δh is the amplitude of the fundamental current. h The phase dispersion inherited from step S2, where λ is the attenuation coefficient. For exponential decay function, ∈ is a minimum value to prevent the denominator from being zero;

[0033] Step S32: Based on the harmonic weighting factor, perform nonlinear correction on the fundamental reactive power to suppress the overcompensation risk caused by harmonic pollution and ensure that the output value accurately reflects the actual compensation requirements. The formula is as follows:

[0034] Q eff =Q fund ×(1+α×arctan(K H )), (α=0.15);

[0035] In the formula, Q eff Q is the corrected equivalent reactive power. fund Let α be the fundamental reactive power, and arctan(K) be the nonlinear correction coefficient. H ) is the arctangent function.

[0036] Further, the step S4, the specific steps of optimizing the capacitor switching decision are:

[0037] Establish switching priority rules:

[0038] Rule 1: When K H >0.3, disable the capacitor branch with 5 / 7 harmonic resonance risk to avoid risk;

[0039] Rule 2: Traverse all feasible capacitor combination schemes, select an optimal switching scheme, and output the corresponding capacitor number instruction, select the switching combination C k satisfy:

[0040] min|Q eff -∑C k |+β×(switching action times);

[0041] In the formula, Q eff is the equivalent reactive power of step S4, ∑C k is the total capacity of the capacitor group to be put into operation, C k is the nominal capacity of the kth capacitor, β is the switching action cost coefficient, and the switching action times are the total number of switches to be operated this time.

[0042] Further, the step S5, the temperature drift capacity calibration specifically includes the following steps:

[0043] Step S51: Real-time monitoring of capacitor shell temperature T;

[0044] Step S52: Correct the actual capacity value according to temperature:

[0045] C actual =C nom ×[1-γ×(T-T ref ) 2 ], (γ=5×10 -5 / ℃ 2 );

[0046] In the formula, C actual is the actual capacity of the capacitor after temperature calibration, C nom is the nominal capacity of the capacitor, γ is the temperature coefficient, T is the real-time monitored capacitor shell temperature, and T ref is the reference temperature.

[0047] Further, the step S6, the specific steps of executing flexible switching and verification are:

[0048] Step S61: Generate a trigger pulse timing, trigger a thyristor (SCR) within a ±15μs window of voltage zero to achieve current zero soft switching to suppress inrush current;

[0049] Step S62: wait for 100 milliseconds after completing the switching operation for system transient stability, and then return to step S1 to reacquire the electrical parameters, verify the compensation effect and start the next round of control.

[0050] The present application has the following advantages:

[0051] 1. The present application constructs a harmonic weight factor by analyzing the discrete characteristics of the harmonic phase in real time, expands the traditional reactive power calculation model into a harmonic-related nonlinear mapping relationship; compared with the prior art which only relies on the total harmonic distortion, this scheme can distinguish between transient harmonic interference and steady-state distortion, avoid compensation misjudgment caused by random fluctuations in the harmonic phase; in the scene of complex and variable harmonic frequency spectrum of industrial loads, it can realize dynamic and accurate correction of the fundamental reactive power, make the capacitor bank switching decision more suitable for the actual power grid demand, and essentially improve the compensation accuracy.

[0052] 2. The weight factor generated based on the harmonic phase dispersion directly participates in the switching strategy optimization, actively avoids specific harmonic frequency bands that can easily cause system resonance; at the same time, combined with the quadratic function capacity calibration model of temperature drift, the nonlinear characteristics of capacitor dielectric materials in the temperature change environment can be reflected; the double mechanism cooperatively suppresses overcompensation / undercompensation, reduces equipment overload and insulation aging caused by harmonic amplification, effectively prolongs the service life of the capacitor bank and associated switching devices, and reduces maintenance costs.

[0053] 3. The present application embeds the harmonic phase stability evaluation and temperature real-time calibration into the closed-loop control process, so that the compensation amount calculation has multi-physical field coupling adaptability; the thyristor flexible switching mechanism combines the decision optimization objective function to minimize the switching action frequency under the premise of meeting the reactive power demand; such design can suppress voltage flicker and current impact caused by frequent switching, improve the transient stability of the power supply system, and is suitable for industrial substation scenes with rapid load fluctuations.

[0054] Of course, implementing any product of the present application does not necessarily need to achieve all the advantages described above at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0055] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0056] Figure 1 is a schematic structural view of a power supply system of a substation device of the present application;

[0057] Figure 2A flowchart of a power supply method for a substation device. DETAILED DESCRIPTION

[0058] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0059] Referring to Figure 1 The present application is a power supply system for a substation device, and the power supply system comprises:

[0060] A data acquisition module is configured to synchronously acquire three-phase voltage and current signals of a load of the substation.

[0061] A harmonic feature analysis module is configured to perform harmonic analysis on the acquired signals, and calculate amplitudes of each harmonic and phase dispersion.

[0062] A dynamic weight calculation module is configured to calculate a dynamic harmonic weight factor according to the harmonic analysis result, and suppress the influence of the harmonic with unstable phase.

[0063] An equivalent reactive power decision module is configured to calculate equivalent reactive power and generate an optimal capacitor switching instruction in combination with the harmonic weight and temperature compensation.

[0064] A temperature compensation module is configured to monitor capacitor temperature in real time, and calibrate actual capacity of the capacitor.

[0065] A flexible switching execution module is configured to trigger a thyristor near a voltage zero-crossing point, and realize capacitor switching without inrush current.

[0066] Referring to Figure 2 The present application is a power supply method for a substation device, and the power supply method comprises the following steps:

[0067] Step S1, acquiring electrical parameters in real time: synchronously acquiring three-phase current and bus voltage signals of a load by using a high-precision sensor, and generating a discrete sequence by an analog-to-digital converter;

[0068] Step S2, harmonic spectrum and phase analysis: performing spectrum analysis on the current signal, extracting fundamental and harmonic components, and calculating the dispersion degree of the phase of each harmonic;

[0069] Step S3, generating a harmonic weight factor: dynamically generating a weight factor in combination with the harmonic amplitude and phase stability, and performing nonlinear correction on the fundamental reactive power based on the factor;

[0070] Step S4, optimization of capacitor switching decision: disable the branch prone to resonance according to the harmonic risk, and select the combination scheme that meets the reactive power demand and has the least switching action;

[0071] Step S5, temperature drift capacity calibration: real-time monitoring of capacitor temperature, calibration of actual capacity through nonlinear model;

[0072] Step S6, perform flexible switching and verification: trigger thyristor switching at voltage zero crossing point, return to step S1 for effect verification after delay.

[0073] Step S1, real-time acquisition of electrical parameters, specifically including the following steps:

[0074] Step S11: use high-precision current sensor to collect load three-phase current signal i a (t),i b (t),i c (t);

[0075] Step S12: synchronously collect bus voltage signal v a (t),v b (t),v c (t);

[0076] Step S13: convert analog signals to discrete sequences i a [n],v a [n] by 16-bit ADC.

[0077] Step S2, harmonic spectrum and phase analysis, specifically including the following steps:

[0078] Step S21: perform FFT transform on the discrete sequence to obtain the fundamental component I1∠θ1 and each harmonic component I h ∠θ h (h=2,3,…,50);

[0079] Step S22: calculate the phase dispersion factor of each harmonic:

[0080]

[0081] In the formula, δ h is the phase dispersion of the hth harmonic, h is the harmonic order, M is the total number of grid cycles in the sliding window, k is the cycle number, θ h [k] is the instantaneous phase angle of the hth harmonic in the kth cycle, is the average value of the hth harmonic phase in M cycles, and |·| 2 is the modulo square operation.

[0082] Step S3, generating dynamic harmonic weight factor, specifically including the following steps:

[0083] Step S31: Dynamic harmonic weight factor generation based on the harmonic spectrum features extracted in step S2, formula:

[0084]

[0085] In the formula, K H is the dynamic harmonic weight factor, I h is the amplitude of the hth harmonic current, I1 is the fundamental current amplitude, δ h is the phase dispersion inherited from step S2, λ is the attenuation coefficient, is the exponential decay function, and ∈ is a small value to prevent the denominator from being zero.

[0086] Step S32: Nonlinear correction of fundamental reactive power based on the harmonic weight factor to suppress the risk of overcompensation caused by harmonic pollution and ensure that the output value accurately reflects the actual compensation demand, formula:

[0087] Q eff = Q fund ×(1+α×arctan(K H )), (α=0.15);

[0088] In the formula, Q eff is the corrected equivalent reactive power, Q fund is the fundamental reactive power, α is the nonlinear correction coefficient, and arctan(K H ) is the inverse tangent function.

[0089] Step S4, the specific steps of optimizing the capacitor switching decision are:

[0090] Establish a switching priority rule:

[0091] Rule 1: When K H >0.3, disable the capacitor branch that is at risk of 5 / 7 harmonic resonance to avoid risks;

[0092] Rule 2: Traverse all feasible capacitor combination schemes, select an optimal switching scheme, and output the corresponding capacitor number instruction, select the switching combination C k that satisfies:

[0093] min|Q eff -∑C k |+β×(switching action times);

[0094] In the formula, Q eff is the equivalent reactive power of step S4, ∑C k is the total capacity of the capacitor group being put into operation, and C kCk is the nominal capacity of the kth capacitor group, β is the switching action cost coefficient, and the switching action number is the total number of switches that need to be operated in this decision.

[0095] Step S5, the temperature drift capacity calibration specifically includes the following steps:

[0096] Step S51: Real-time monitoring of the capacitor shell temperature T;

[0097] Step S52: Correct the actual capacity value according to the temperature:

[0098] C actual = C nom × [1-γ×(T-T ref ) 2 ], (γ = 5 × 10 -5 / ℃ 2 );

[0099] In the formula, C actual is the actual capacity of the capacitor after temperature calibration, C nom is the nominal capacity of the capacitor, γ is the temperature coefficient, T is the real-time monitored capacitor shell temperature, and T ref is the reference temperature.

[0100] Step S6, the flexible switching and verification specifically includes the following steps:

[0101] Step S61: Generate a trigger pulse timing, trigger the thyristor (SCR) within the ±15μs window of voltage zero crossing, realize current zero crossing soft switching to suppress inrush current;

[0102] Step S62: After completing the switching operation, wait for 100 milliseconds of system transient stability, and then return to step S1 to reacquire electrical parameters, verify the compensation effect and start the next round of control.

[0103] One specific application of this embodiment is:

[0104] Implementation background: A 220kV substation 10kV bus intelligent capacitor bank power supply system, the load is a group of thyristor controlled rolling motors, generating 5 / 7 / 11 characteristic harmonics;

[0105] Step S1: Real-time acquisition of electrical parameters

[0106] At 2025-03-0114:05:30:

[0107] The current sensor acquires the A-phase current instantaneous value (sampling rate 10kHz):

[0108] i a (t) = 1250sin(100πt+0.12) + 210sin(500πt-1.85) + …;

[0109] Voltage transformer collects A-phase voltage:

[0110]

[0111] Discrete sequence after ADC conversion (N = 1024 points / cycle):

[0112] i a [n] = {0, 156.3, 302.1,...}, v a [n] = {0, 8.48, 16.72,...}.

[0113] Step S2: Harmonic spectrum feature extraction

[0114] FFT is performed on i a [n] as shown in the following table:

[0115] Harmonic number Amplitude Phase 1 (fundamental) 1250.2 0.12 5 210.5 -1.85 7 95.8 2.37

[0116] Calculate the 5th harmonic phase dispersion (M = 10 cycles):

[0117]

[0118] Step S3: Dynamic harmonic weight factor generation

[0119] Substitute step 2 data:

[0120]

[0121] (The 5th harmonic weight of high phase jitter is reduced to 82% of the standard value);

[0122] Step S4: Equivalent reactive power calculation

[0123] Fundamental reactive power:

[0124] Corrected equivalent reactive power: Q eff = 472.3 x (1 + 0.15 x arctan(0.038)) = 478.6 kvar;

[0125] Step S5: Capacitor bank switching decision optimization

[0126] Condition judgment:

[0127] K H = 0.038 < 0.3 → Allow switching of all branches;

[0128] Currently in: 3# branch (200 kvar) + 5# branch (200 kvar);

[0129] Optimization target (β = 0.2):

[0130] min | 478.6 - ∑C k | + 0.2 x (new action times);

[0131] Candidate solutions:

[0132] Increase 7# branch (200 kvar) → deviation | 478.6 - 600 | = 121.4, cost = 0.2 x 1;

[0133] Increase 2# branch (100 kvar) → deviation | 478.6 - 500 | = 21.4, cost = 0.2 x 1; Decision result: select increase 2# branch (100 kvar);

[0134] Step S6: Temperature drift capacity calibration

[0135] Infrared sensor detects 2# capacitor shell temperature T = 48℃ (T ref = 25℃):

[0136] C actual = 100 x [1 - 5 x 10 -5 x (48 - 25) 2 ] = 98.7 kvar;

[0137] Step S7: Triggering thyristor flexible switching

[0138] Trigger 2# branch SCR 10μs after B-phase voltage zero crossing (timing error < 1μs);

[0139] Total compensation amount after switching: 200 + 200 + 98.7 = 498.7 kvar;

[0140] After 100ms delay, the actual Q eff = 485.2 kvar, error ≤ 2.8%.

[0141] In the description of the present specification, the description referring to the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0142] The preferred embodiments of the application disclosed above are only to facilitate the elucidation of the application. The preferred embodiments do not describe all the details of the application and limit the application to the specific embodiments described. Obviously, many modifications and variations can be made in light of the teachings above. The description is chosen and described in order to best explain the principles of the application and its practical application to thereby enable others skilled in the art to best utilize the application and get the best results from the application. The application is only limited by the claims and their full scope and equivalents.

Claims

1. A power supply system for substation equipment, characterized in that, The power supply system includes: The data acquisition module is used to synchronously acquire the three-phase voltage and current signals of the substation load; The harmonic characteristic analysis module is used to perform harmonic analysis on the acquired signal and calculate the amplitude and phase dispersion of each harmonic. The dynamic weight calculation module is used to calculate the dynamic harmonic weight factor based on the harmonic analysis results, thereby suppressing the influence of phase-unstable harmonics. The equivalent reactive power decision module is used to calculate the equivalent reactive power and generate the optimal capacitor switching command by combining harmonic weights and temperature compensation. The temperature compensation module is used to monitor the capacitor temperature in real time and calibrate the actual capacitance of the capacitor. The flexible switching execution module is used to trigger the thyristor near the voltage zero crossing point to achieve capacitor switching without inrush current.

2. A power supply method for substation equipment, characterized in that, The power supply method specifically includes the following steps: Step S1: Real-time acquisition of electrical parameters: Use high-precision sensors to synchronously acquire the three-phase current of the load and the bus voltage signal, and generate a discrete sequence through an analog-to-digital converter; Step S2, Harmonic Spectrum and Phase Analysis: Perform spectrum analysis on the current signal, extract the fundamental and harmonic components, and calculate the dispersion of the phase of each harmonic. Step S3: Generate harmonic weighting factor: Combine harmonic amplitude and phase stability to dynamically generate weighting factor, and perform nonlinear correction on fundamental reactive power based on this factor; Step S4: Optimize capacitor switching decisions: Disable easily resonant branches based on harmonic risks and select a combination scheme that meets reactive power requirements and minimizes switching operations. Step S5, Temperature Drift Capacitance Calibration: Monitor the capacitor temperature in real time and calibrate the actual capacitance using a nonlinear model; Step S6: Perform flexible switching and verification: Precisely trigger thyristor switching at the voltage zero crossing point, and after a delay, return to step S1 to verify the effect.

3. The power supply method for substation equipment according to claim 2, characterized in that, Step S1, which involves real-time acquisition of electrical parameters, specifically includes the following steps: Step S11: Use a high-precision current sensor to acquire the three-phase current signal of the load; Step S12: Synchronously acquire bus voltage signals; Step S13: Convert the analog signal into a discrete sequence using a 16-bit ADC.

4. The power supply method for substation equipment according to claim 2, characterized in that, Step S2, harmonic spectrum and phase analysis, specifically includes the following steps: Step S21: Perform FFT transformation on the discrete sequence to obtain the fundamental component and each harmonic component; Step S22: Calculate the phase dispersion factor of each harmonic.

5. A power supply method for substation equipment according to claim 2, characterized in that, Step S3, generating the dynamic harmonic weighting factor, specifically includes the following steps: Step S31: Generate dynamic harmonic weighting factors based on the harmonic spectrum features extracted in step S2; Step S32: Based on the harmonic weighting factor, perform nonlinear correction on the fundamental reactive power to suppress the overcompensation risk caused by harmonic pollution and ensure that the output value accurately reflects the actual compensation requirements.

6. A power supply method for substation equipment according to claim 2, characterized in that, Step S4, optimizing the capacitor switching decision, specifically involves the following steps: The harmonic pollution level of the system is determined based on the harmonic weighting factor: when the level of harmonic pollution exceeds the safety threshold, the capacitor branch that is prone to causing 5th or 7th harmonic resonance is automatically disabled. Iterate through all feasible capacitor combination schemes, select an optimal switching scheme, and output the corresponding capacitor number instruction.

7. A power supply method for substation equipment according to claim 2, characterized in that, Step S5, temperature drift capacity calibration, specifically includes the following steps: Step S51: Monitor the capacitor casing temperature in real time; Step S52: Correct the actual capacity value according to temperature.

8. A power supply method for substation equipment according to claim 2, characterized in that, Step S6, which involves flexible deployment and verification, specifically includes the following steps: Step S61: Generate trigger pulse timing to trigger the thyristor within a very short time window at the voltage zero crossing point, thereby achieving soft switching at the current zero crossing to suppress inrush current; Step S62: After completing the switching operation, wait for the system to stabilize transiently, then return to step S1 to re-acquire electrical parameters, verify the compensation effect, and start the next round of control.

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