Active power metering device, adjusting power metering device, metering method, and program

Abstract

To provide an active power measuring device capable of improving the quick response of electric power measurement.SOLUTION: An active power measuring device includes: a frequency estimation device for estimating the cycle and frequency of an AC which an object device transmits or receives between electric power systems on the basis of the time series of the voltage of the AC; and an active power measuring device for calculating the moving average value of instantaneous power in two or more cycles of the AC for each cycle of the AC to measure active power transmitted and received by the object device during one cycle of the AC from a difference between the calculated moving average value and the preceding calculated moving average value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an active power metering device, a regulating power metering device, a metering method, and a program used for power supply and demand adjustment of a power system and settlement of electricity charges.

Background Art

[0002] A typical power meter conventionally used obtains instantaneous power p from the product of the instantaneous voltage v and the instantaneous current i of a power system. Also, since the instantaneous voltage and current of an alternating current fluctuate with peaks and valleys in a sine wave shape, the instantaneous power does not become a constant value on a time scale shorter than the period of the alternating current. Therefore, it is common to represent the alternating current power by its time average value. For example, the power meter described in Patent Document 1 calculates and outputs the active power P at time t t as a moving average value of the instantaneous power as shown in Equation (1).

[0003]

Equation

[0004] Ideally, the sample size N of the moving average should make the length of the time window for moving average an integer multiple of the period of the alternating current. For example, if the instantaneous power is sampled 32 times for one period and the width of the moving average window is set to 10 periods, then N is 320.

[0005] Assume that the starting point of the time window for moving average is 0 seconds and the ending point is t1 (denoted as [0, t1]). In contrast, assume that the period of the alternating current is [0, T]. For example, if t1 < T, the instantaneous power in the interval [t1, T] is not included in the moving average. Therefore, if the instantaneous power reaches a peak in the interval [t1, Y], the moving average value is biased to the smaller side than the true value. On the other hand, if the instantaneous power reaches a valley in the interval [t1, T], the moving average value is biased to the larger side than the true value. One way to prevent the bias is to set t1 = T. However, due to the imbalance between power supply and demand, the frequency of the power system constantly fluctuates, so t1 = T does not hold.

[0006] Therefore, in the prior art, the width of the time window for the moving average has been extended to, for example, 10 periods to deal with errors due to the shift in periods. Specifically, in Patent Document 1, the moving average of instantaneous power for 10 periods is calculated, and active power is calculated based on this moving average.

[0007] Furthermore, electricity demand in offices, factories, and ordinary homes fluctuates from moment to moment. To contribute to balancing supply and demand in the power grid, it is effective to increase the power supply (or reduce power demand) if there is a power shortage, and to reduce the power supply (or increase power demand) if there is an excess. In this way, "increasing / reducing" the power supply (or "reducing / increasing" the power demand) will have opposite positive and negative signs depending on whether the power supply is insufficient or excessive at the time. Therefore, simply accumulating the power, as with existing watt-hour meters, will cancel out the positive and negative signs, making it impossible to measure the contribution to balancing supply and demand. To measure the power that has contributed to balancing supply and demand, it is necessary to take into account the surplus or shortage of power supply at any given time. To do this, technology is needed to measure active power on a shorter time scale.

[0008] Supply and demand adjustment is mainly carried out by power plants adjusting the amount of power they generate to keep the frequency of the power grid constant. This is typically done by governor-free operation, as shown in equation (2).

[0009]

number

[0010] In equation (2), Pn is the rated power output (kW), and fn is the reference frequency (Hz) of the power grid. Δf is the deviation from the reference frequency (e.g., 50 Hz or 60 Hz), and the generated power is proportionally reduced by ΔP. δ is the arbitration ratio, a value set in the power plant's control device. Typically, the arbitration ratio is set to a value around 0.04. This ratio specifies the relationship between the frequency deviation Δf from the reference frequency and the corresponding power reduction ΔP. When the arbitration ratio is 0.04, an increase in frequency by 0.04 × fn (Hz) reduces ΔP by Pn (kW). For example, if the frequency increases by 0.04 × fn (2.0 Hz if the reference frequency is 50 Hz) while operating at the rated power output, the power output is adjusted to reduce Δf to 0. By rapidly adjusting power generation in this way, the power plant maintains a constant power grid frequency.

[0011] In equation (2), Δ is explained as the deviation from the reference value. For example, we explained that Δf is the deviation between the current frequency and the reference frequency. However, the same thing happens if Δ is the previous value. For example, suppose metering calculations are performed every Δt seconds. In this case, equation (2) still holds even if Δf is considered the difference between the frequency of the current calculation cycle and the frequency of the previous control cycle, and ΔP is considered the difference between the active power of the current control cycle and the active power of the previous calculation cycle. Therefore, as in equation (2), if the surplus or shortage of power supply and demand is measured using Δf, and if Δf is negative but ΔP is positive, then that ΔP contributes to supply and demand adjustment and the absolute value of ΔP is added. If ΔP is negative even though Δf is negative, then that ΔP hinders supply and demand adjustment and the absolute value of ΔP is subtracted. For example, the power that contributes to supply and demand adjustment can be measured using equation (3).

[0012]

number

[0013] To calculate equation (3), the time difference ΔP of active power is required. As mentioned above, in conventional technology, active power P is calculated as the moving average of the power system frequency, with the moving average interval being approximately 10 periods. If the frequency is 50 Hz, 10 periods is 200 ms, so equation (3) is calculated every 200 ms. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Patent No. 5000441 Summary of the Invention [Problem to be solved by the invention]

[0015] Governor-free operation plays a central role in balancing supply and demand in power grids. As we move toward a decarbonized society, the proportion of variable power generation sources such as solar and wind power will increase year by year. In order to accommodate these fluctuations in power generation, it is necessary to simultaneously improve the capabilities of governor-free operation.

[0016] Because governor-free regulation is performed autonomously by each power source without relying on commands, the regulation power generated by power sources on a short cycle is not measured, is not settled, and power companies cannot receive compensation. Not only governor-free systems, but the kinetic energy of generators and external combustion engines or internal combustion engines connected to them also plays an important role. For example, when the frequency of the power grid drops, the rotational speed of the generator also decreases accordingly, but the decrease in kinetic energy due to fluctuations in rotational speed is supplied to the power grid and functions as regulation power.

[0017] In order to improve the supply-demand adjustment capability of the power system, it is essential to measure and compensate for governor-free and kinetic energy adjustment capabilities. However, conventional wattmeters such as those described in Patent Document 1 do not have a function to measure adjustment capabilities.

[0018] Furthermore, in order to stabilize the power grid, it is valuable to be able to adjust to frequency fluctuations without delay, and the changes in inertial energy that act to suppress system fluctuations when a generator synchronizes with the power grid frequency are attracting attention as a rapid supply-demand adjustment force (inertia force). In order to measure rapid adjustment forces such as inertia force, the shorter the power measurement cycle, the better. However, as mentioned above, the current lower limit of the measurement cycle is 200 ms.

[0019] An object of the present disclosure is to provide an active power metering device, an adjustable power metering device, a metering method, and a program that can improve the responsiveness of power measurement. [Means for solving the problem]

[0020] According to one aspect of the present disclosure, an active power metering device includes: a frequency estimator that estimates a period and frequency of an AC current based on a time series of AC voltage that a target device transmits or receives between the target device and a power grid; and an active power meter that calculates, for each AC period, a moving average value of instantaneous power over multiple AC periods, and measures the active power exchanged by the target device in one AC period from the difference between the calculated moving average value and a previously calculated moving average value.

[0021] According to one aspect of the present disclosure, an active power metering device includes a frequency estimator that estimates the period and frequency of an AC current based on a time series of the voltage of the AC current that a target device transmits to or receives from a power grid, and an active power meter that measures the active power exchanged by the target device from an integrated value of instantaneous power in one period of the AC current.

[0022] According to one aspect of the present disclosure, an active power metering device includes: a frequency estimator that estimates the period and frequency of the AC based on a time series of the voltage of the AC that a target device transmits or receives between the target device and a power grid; an instantaneous power calculator that calculates the instantaneous power of the AC at a frequency that is an integer multiple of the frequency of the AC and outputs a discrete-time signal of the instantaneous power in one period of the AC; and an active power meter that measures the active power exchanged by the target device by filtering the discrete signal of the instantaneous power with the finite impulse response filter.

[0023] According to one aspect of the present disclosure, an active power metering device includes: a frequency estimator that estimates the period and frequency of the AC based on a time series of the voltage of the AC that a target device transmits or receives between the target device and a power grid; an instantaneous power calculator that calculates the instantaneous power of the AC at a frequency that is an integer multiple of the frequency of the AC and outputs a discrete-time signal of the instantaneous power in one period of the AC; and an active power meter that filters the discrete signal of the instantaneous power with a finite impulse response filter that blocks components corresponding to the oscillation frequency of the AC and measures the active power exchanged by the target device.

[0024] According to one aspect of the present disclosure, an active power metering device includes a frequency estimator that estimates the frequency of at least one phase of three-phase AC based on a time series of voltage of the three-phase AC that a target device transmits or receives power to or from a power grid, and an active power meter that measures the active power of all three phases of the target device from a moving average value of the sum of instantaneous power of each phase of the three-phase AC.

[0025] According to one aspect of the present disclosure, an active power metering device includes a synchronous motor model that receives as input the instantaneous voltage of AC power transmitted or received by a target device to or from a power grid, calculates the rotation speed of a synchronous motor possessed by the target device, and outputs the frequency of the AC power, and an active power meter that measures the active power exchanged by the target device in one cycle of the AC power based on the instantaneous current of the AC power, the instantaneous voltage, and the frequency output from the synchronous motor model.

[0026] According to one aspect of the present disclosure, an adjustment power metering device includes an active power metering device described in any one of the above aspects, and an adjustment power meter that calculates the supply and demand adjustment power of the target device based on the time difference of the active power and the time difference of the frequency.

[0027] According to one aspect of the present disclosure, a measurement method includes the steps of: estimating a period and frequency of an AC current based on a time series of the voltage of the AC current transmitted to or received from a target device between the target device and a power grid; calculating the instantaneous power of the AC current at a frequency that is an integer multiple of the frequency of the AC current and outputting a discrete-time signal of the instantaneous power in one period of the AC current; and filtering the discrete signal of the instantaneous power with a finite impulse response filter having a coefficient that is a Hanning window whose tap length matches the calculation frequency of the instantaneous power, thereby measuring the active power transmitted and received by the target device.

[0028] According to one aspect of the present disclosure, the program causes an active power metering device to perform the following steps: estimating a period and frequency of the AC based on a time series of the voltage of the AC that the target device transmits to or receives from a power grid; calculating the instantaneous power of the AC at a frequency that is an integer multiple of the frequency of the AC and outputting a discrete-time signal of the instantaneous power in one period of the AC; and filtering the discrete signal of the instantaneous power with a finite impulse response filter whose coefficient is a Hanning window whose tap length matches the calculation frequency of the instantaneous power, thereby measuring the active power exchanged by the target device. [Effects of the Invention]

[0029] According to the above aspect, it is possible to improve the responsiveness of power measurement. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a diagram showing the functional configuration of an adjustment power measuring device according to a first embodiment. FIG. [Figure 2] FIG. 2 is a first diagram for explaining the function of the active power meter device according to the first embodiment. [Figure 3] FIG. 2 is a second diagram for explaining the function of the active power meter device according to the first embodiment. [Figure 4] FIG. 10 is a diagram illustrating a functional configuration of a frequency estimator according to a first modification of the first embodiment. [Figure 5] FIG. 10 is a diagram showing the functional configuration of an adjustment power measuring device according to Modification 2 of the first embodiment. [Figure 6] FIG. 10 is a diagram for explaining the function of an active power metering device according to a second modification of the first embodiment. [Figure 7] FIG. 10 is a diagram showing the functional configuration of an adjustment power measuring device according to a third modification of the first embodiment. [Figure 8] FIG. 10 is a diagram illustrating a functional configuration of an active power meter according to a second embodiment. [Figure 9] FIG. 10 is a first diagram for explaining the function of an active power metering device according to a second embodiment. [Figure 10] FIG. 2 is a second diagram for explaining the function of the active power meter device according to the second embodiment. [Figure 11] FIG. 10 is a third diagram for explaining the function of the active power meter device according to the second embodiment. [Figure 12] FIG. 4 is a fourth diagram for explaining the function of the active power meter device according to the second embodiment. [Figure 13] FIG. 10 is a diagram for explaining the function of an active power metering device according to a third embodiment. [Figure 14] FIG. 10 is a diagram illustrating a functional configuration of an active power meter according to a fourth embodiment. [Figure 15]FIG. 13 is a diagram illustrating a functional configuration of an active power meter according to a modified example of the fifth embodiment. [Figure 16] FIG. 10 is a diagram showing the functional configuration of an adjustment power measuring device according to a sixth embodiment. [Figure 17] FIG. 13 is a diagram showing the functional configuration of an adjustment power measuring device according to an eighth embodiment. [Figure 18] FIG. 1 is a schematic block diagram illustrating the configuration of a computer according to at least one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0031] First Embodiment The first embodiment will be described in detail below with reference to FIGS.

[0032] (Functional configuration of the adjustment power metering device) FIG. 1 is a diagram showing the functional configuration of an adjustment power measuring device according to the first embodiment. As shown in Fig. 1, an adjustment capability providing means 2 is connected to an AC power system G. The adjustment capability providing means 2 is a generator or a load. Furthermore, an adjustment capability metering device 1 is provided, for example, at the connection point between the AC power system G and the adjustment capability providing means 2. The adjustment capability metering device 1 according to this embodiment measures the supply and demand adjustment performed by the adjustment capability providing means 2 on the AC power system G as an adjustment power amount.

[0033] The adjustable power metering device 1 includes an active power metering device 10 and an adjustable power meter 15. The active power metering device 10 includes a voltage detector 11, a current detector 12, a frequency estimator 13, and an active power meter 14.

[0034] The voltage detector 11 outputs a voltage signal v which is a measurement value of the voltage of the power that the adjustment capability providing means 2 transmits to or receives from the AC power system G. For example, the voltage detector 11 measures the voltage at the connection point between the AC power system G and the adjustment capability providing means 2, or at the entrance / exit of the adjustment capability providing means 2 on the AC power system G side. Measure the voltage.

[0035] The current detector 12 outputs a current signal i which is a measurement value of the current of the power that the adjustment capability providing means 2 transmits to or receives from the AC power system G. For example, the current detector 12 measures the current at the connection point between the AC power system G and the adjustment capability providing means 2, or at the entrance / exit of the adjustment capability providing means 2 on the AC power system G side.

[0036] The frequency estimator 13 estimates the period and frequency f of the AC that the regulation capability providing means 2 exchanges with the AC power system G, based on the time series of the voltage signal v.

[0037] The active power meter 14 measures the active power P of the power exchanged between the adjustment capability providing means 2 and the AC power system G from the moving average value of the instantaneous power over multiple AC cycles.

[0038] The adjustment power meter 15 calculates the power supply and demand adjustment capability M based on the time difference in the active power and the time difference in the frequency.

[0039] (Regarding the treatment of regulating power metering devices) Next, the processing of the adjustment power measuring device 1 will be described in detail.

[0040] The active power meter 14 reads the voltage signal v and the current signal i at least every calculation period of the active power. t and the current signal i at time t t From this, the instantaneous active power p t (hereinafter, also simply referred to as "instantaneous power"). In addition, the active power meter 14 calculates the instantaneous power p t The moving average of the past values ​​is used to calculate the active power P t Output as

[0041] In this embodiment, the calculation period of the active power is set to match the AC period. For example, when the reference frequency of the AC power system G is 50 Hz, the calculation period of the active power is 20 ms. The active power meter 14 calculates the instantaneous power p 32 times per period. In addition, the active power meter 14 calculates the active power P by taking a moving average of the instantaneous power p for 10 periods for each calculation period.

[0042] The frequency estimator 13 receives the voltage signal v and calculates the AC frequency f from the time interval when the voltage v alternates and crosses zero. The voltage v has two crossings in one period: one from a positive voltage to a negative voltage and one from a negative voltage to a positive voltage. The time of the first crossing in the time interval (a period of 10 periods) of the moving average of Equation (1) is defined as t X,start-1 , the time of the last crossing tX,start , the number of crossings is n X Then, the frequency of the moving average interval in equation (1) can be calculated using the following equation (4): If we consider the direction of the crossing, for example, if we only consider voltages crossing zero from positive to negative, the crossing occurs once per period, and the 1 / 2 multiplication on the right hand side of equation (9) is unnecessary.

[0043]

number

[0044] The adjustment power meter 15 calculates the difference between the active power P and frequency f of the previous time (time t-1) for each time interval N of the moving average of equation (1) using equations (5) and (6).

[0045]

number

[0046]

number

[0047] FIG. 2 is a first diagram for explaining the function of the active power meter device according to the first embodiment. For example, as shown in Figure 2, the active power P t is the moving average value of instantaneous power p for the past 10 periods (periods 1, 0, -1, -2, ..., -8) from time t, and active power P t-1 is the moving average value of the instantaneous power p for the past 10 periods (periods 0, -1, -2, -3, ..., -9) from the previous period. Also, the frequency f t is the average value of the frequency for the past 10 periods (periods 1, 0, -1, -2, ..., -8) from time t. Frequency f t-1 is the average value of the frequency over the past 10 periods (periods 0, -1, -2, -3, ..., -9) from the previous period. That is, the adjustment power meter 15 calculates the difference ΔP between the moving average values ​​of the active power P and the difference Δf between the average values ​​of the frequency f in two periods that are shifted by one period.

[0048] Then, the adjustment power amount meter 15 calculates the adjustment power amount M using equation (3).

[0049] FIG. 3 is a second diagram for explaining the function of the active power metering device according to the first embodiment. The time t when the voltages cross x The calculation of is explained with reference to Figure 3. As shown in Figure 3, the voltage crosses 0V between time t1 and time t2, when the sign of the voltage is inverted at adjacent times. X is calculated using the following equation (7).

[0050]

number

[0051] (Action, effect) The adjustment power metering device 1 according to the first embodiment includes a frequency estimator 13 that estimates the period and frequency of AC based on the time series of AC voltage v transmitted or received by the adjustment power providing means 2, an active power meter 14 that measures active power P from the moving average value of instantaneous power p over multiple AC periods (e.g., 10 periods), and an adjustment power meter 15 that calculates the power supply and demand adjustment power M based on the temporal difference between the active power P and the frequency (the difference over one period).

[0052] In this way, the adjustment capability metering device 1 can determine the difference between the active power P and the frequency f for each AC cycle, and calculate the supply and demand adjustment capability M for each cycle from these differences. For example, if the AC reference frequency is 50 Hz, one cycle is 20 ms. Therefore, the adjustment capability metering device 1 can improve the responsiveness of measurements. This allows the adjustment capability metering device 1 to measure fast adjustment capabilities such as inertial forces.

[0053] Although FIG. 1 shows an example in which the active power metering device 10 is provided inside the adjustable power metering device 1, this is not limiting. In other embodiments, the active power metering device 10 may be provided independently as a device separate from the adjustable power metering device 1. For example, the active power metering device 10 is provided on a power line connected to the outlet of a generator and measures the active power P of the power transmitted by the generator. In yet another embodiment, the active power metering device 10 is provided on a power line connected to the inlet of a load and measures the active power P of the power received by the load. The generator or the load is an example of a target device whose active power is measured by the active power metering device 10. In this case, the active power meter 14 of the active power metering device 10 measures the active power exchanged by the target device during one AC cycle using equation (5). This improves the responsiveness of the active power measurement. The active power for one cycle measured by the active power metering device 10 is used, for example, in a generator control device for automatic output control. Since the active power metering device 10 can measure the active power of the generator without delay, the control performance of the generator can also be improved.

[0054] (Variation 1) FIG. 4 is a diagram illustrating a functional configuration of a frequency estimator according to the first modification of the first embodiment. As shown in FIG. 4, the frequency estimator 13 detects the crossing time t X You may ask for:

[0055] The output of the ZC detector 131 changes stepwise at the moment when the voltage signal crosses 0V. The output of the ZC detector 131 and the time of the timer 130 are input to the sampler 132. The sampler 132 outputs the time of the timer 130 at the moment when the output of the ZC detector 131 changes stepwise. This is t X There are two zero crossings in one period. X And this time X The difference between the previous and current t X The difference is Δ2t X and the inverse of this is calculated as the frequency f.

[0056] (Variation 2) FIG. 5 is a diagram showing the functional configuration of an adjustment power measuring device according to Modification 2 of the first embodiment. 5, the active power meter 14 may be configured with an instantaneous power integrator 142, a sampler 143, and an active power calculation unit 144. The frequency estimator 13 used is that of the first modified example.

[0057] Instantaneous power oscillates at 2f, twice the AC frequency f. Therefore, if you take a moving average of the instantaneous power over the oscillation period of 1 / 2f seconds, or an integer multiple of that, the oscillation component will cancel out and you can obtain the active power, which is the average value of the instantaneous power.

[0058] According to conventional technology, the active power is calculated by taking a moving average of the instantaneous power over a period of, for example, 10 periods of the reference frequency. Since the frequency of an AC power system constantly fluctuates, the period of one period also constantly fluctuates. Therefore, conventional technology approximates it by smoothing it over a period of 10 periods. Smoothing it in this way degrades the speed of response in detecting the active power. As long as the wattmeter is used for the purpose of billing electricity, speed of response is not important. For example, it is sufficient to know the integrated value of one month's worth of power. However, to accurately measure the adjustment power exerted by a governor-free system, inertia system, or system stabilization device, it is meaningful to estimate one AC period and accurately calculate the active power for one period.

[0059] In the first embodiment, for example, active power is calculated from a moving average of 10 cycles of AC. If the reference frequency of AC is 50 Hz, the width of the time window for the moving average is 200 ms. In the present modification 2, the width of the time window for the moving average can be set to one cycle (20 ms). This makes it possible to measure the fast-changing component of the adjustment ability of power supply and demand.

[0060] The specific processing will be described with reference to FIG. 5. The difference from the first embodiment is that the active power is measured for each cycle. In this second modification, in order to emphasize that the active power is measured for each cycle, the active power is expressed as P X It is expressed as:

[0061] Since there are two zero crossings in one period, the effective power P X is calculated using the difference in the amount of power every two zero crossings using the following equation (8).

[0062]

number

[0063] where t X is the time of the most recent zero crossing, t X,prev2 is the zero crossing time two times before that, W tX is time t X The amount of electricity in

[0064] FIG. 6 is a diagram for explaining the function of an active power metering device according to the second modification of the first embodiment. As shown in Figure 6, t1 is the time of integration calculation just before the zero crossing, and t2 is the time of integration calculation just after the zero crossing. tX is determined by the following equation (9).

[0065]

number

[0066] If the difference between every two zero crossings is denoted as Δ2, the amount of adjustment power for every two crossings (that is, once per period) may be calculated using the following equation (10).

[0067]

number

[0068] Alternatively, it may be calculated for each crossing using the following equation (11): Δ is the difference for each zero crossing.

[0069]

number

[0070] According to the second modification, it is possible to accurately calculate the active power per AC cycle. This makes it possible to measure the power supply and demand adjustment capability for each AC cycle. As a result, it becomes possible to measure the fast component of the adjustment capability, which is derived from, for example, inertial force.

[0071] (Variation 3) FIG. 7 is a diagram showing the functional configuration of an adjustment power measuring device according to Modification 3 of the first embodiment. The calculation of the instantaneous power integrator 142 in the second modification is not strictly synchronized with the AC cycle. Therefore, the zero crossing time t X Amount of power in W tXwas estimated. In the third modification, the calculation of the instantaneous power integrator 142 is matched to the AC cycle, eliminating the need for interpolation approximation. As shown in FIG. 7, the instantaneous power integrator 142_1 receives the multiplied ZC signal. The multiplied ZC signal is a signal obtained by multiplying the frequency of the ZC signal by the multiplier 145. For example, if the ZC signal is 100 Hz, the multiplied ZC signal is 320 Hz. Furthermore, the ZC detection unit 146 adjusts the phase of the multiplied ZC signal so that it turns ON simultaneously with the timing when the ZC signal turns ON.

[0072] The instantaneous power integrator 142_1 calculates the instantaneous power p from the voltage v and current i based on the multiplied ZC signal, and calculates the integrated value W of the active power. tXm / 2 The integration calculation requires the period of the multiplied ZC signal, which is the time t when the multiplied ZC signal output by the timer 147 and the sampler 148 turns ON. Xm According to this calculation process, the AC cycle and the integrated value of the effective power W tXm / 2 Since the calculation cycles of are synchronized, the interpolation approximation of equation (8) is not required, and the calculation is simple.

[0073] <Second embodiment> Next, the second embodiment will be described in detail with reference to Figures 8 to 12. Components common to the above-described embodiment will be given the same reference numerals and detailed description will be omitted.

[0074] (Functional configuration of active power meter) FIG. 8 is a diagram showing the functional configuration of an active power meter according to the second embodiment. As shown in FIG. 8, in the adjustment power metering device 1 according to this embodiment, the active power meter 14 is characterized by including an instantaneous power calculator 140 and a finite impulse response filter 141 (hereinafter also referred to as an “FIR filter”).

[0075] The instantaneous power calculator 140 calculates the instantaneous power of the AC at a frequency f that is an integer multiple m of the AC frequency f. s (sampling frequency) and outputs a discrete-time signal of the instantaneous power in one cycle of AC.

[0076] The FIR filter 141 uses a Hanning window coefficient whose tap length is equal to (m+1), which is the instantaneous power calculation frequency m plus 1. The FIR filter 141 filters the discrete-time signal of instantaneous power input from the instantaneous power calculator 140, and outputs active power.

[0077] (Regarding the treatment of active power meters) In the second embodiment, the active power meter 14 operates at a calculation frequency f s This embodiment differs from the first embodiment in that the frequency f of the AC power is set to an integer multiple m of the frequency f of the AC power, and an FIR filter 141 is used in which the coefficient is a Hanning window with a tap length of m+1 instead of a moving average. Note that in this embodiment, a reference frequency (for example, 50 Hz) is used as the frequency f of the AC power.

[0078] The moving average process of equation (1) used in the first embodiment is equivalent to multiplying the instantaneous power by a rectangular window function. Therefore, equation (1) is expressed as a weighting coefficient w∈R of a rectangular window of length N shown in equation (12). N This can be expressed as in equation (13).

[0079]

number

[0080]

number

[0081] If the instantaneous power is sampled 32 times per period, that is, m is 32, and the width of the moving average window is 10 periods, then the value of N is 320. If the number of samples of instantaneous power per period is set to an integer m, then the sampling frequency f s is m times the frequency f.

[0082] In the second embodiment, a Hanning window is used. The length of the Hanning window is m+1. The weighting coefficient h∈R of the Hanning window is m+1 is expressed by the following equation (14).

[0083]

number

[0084] Since the Hanning window reduces the steady-state gain of the signal, the correction coefficient c H Correct with.

[0085]

number

[0086] Finally, the weighting coefficient of the Hanning window is given by the following equation (16).

[0087]

number

[0088] Moreover, the effective power calculated by the Hanning window is expressed by the following equation (17).

[0089]

number

[0090] FIG. 9 is a first diagram for explaining the function of the active power metering device according to the second embodiment. Figure 9 shows a comparison between the Hanning window function h after gain correction and the moving average rectangular window function w. The length of the Hanning window is m+1=33 in terms of the number of time steps, which is approximately 1 / 10 of the length of the rectangular window N=320.

[0091] FIG. 10 is a second diagram for explaining the function of the active power meter device according to the second embodiment. Figure 10 shows a comparison of the frequency characteristics of the response of active power P to instantaneous power p for a Hanning window and a rectangular window. With the rectangular window, the response gain drops from around 2 Hz. On the other hand, with the Hanning window, the gain does not drop until around 30 Hz, so the Hanning window has a faster response than the rectangular window.

[0092] Furthermore, in the rectangular window, there are valleys in the response at 5 Hz, 10 Hz, 15 Hz, 20 Hz, 25 Hz, etc. This means that even if the instantaneous power fluctuates at, for example, 5 Hz, it will not be observed as a fluctuation in active power, which is undesirable in measuring the power supply and demand adjustment capacity.

[0093] FIG. 11 is a third diagram for explaining the function of the active power metering device according to the second embodiment. Furthermore, in order to demonstrate that the difference between the Hanning window and the rectangular window is not simply due to the difference in the length of the window function, the rectangular window is changed to N=32, which corresponds to the length of one period, and an evaluation is performed. Figure 11 shows a comparison between a rectangular window function w with a length of N=32 and a Hanning window function h with a length of m+1=33.

[0094] FIG. 12 is a fourth diagram for explaining the function of the active power metering device according to the second embodiment. Figure 12 shows a comparison of the frequency characteristics of a rectangular window w and a Hanning window h when the length of the rectangular window w is changed to N = 32. The gain of the rectangular window w starts to decrease from 20 Hz, while that of the Hanning window h starts from 30 Hz. Therefore, the Hanning window can measure higher frequencies than the rectangular window.

[0095] Furthermore, the instantaneous power of a single-phase AC oscillates at twice the AC frequency. In a 50 Hz AC power system G, the oscillation of the instantaneous power corresponds to 100 Hz. Both the Hanning window and the rectangular window have a valley in the response gain near 100 Hz, and are therefore able to eliminate this oscillation. Comparing the two, the Hanning window has a wider valley than the rectangular window, so it can better eliminate this oscillation even when the AC frequency fluctuates. Furthermore, the response gain at 100 Hz and frequencies around it is about 10 dB smaller for the Hanning window than for the rectangular window (about 1 / 3 the gain), making the Hanning window more suitable for measuring active power.

[0096] (Action, effect) The adjusting power metering device 1 of the second embodiment has, instead of the active power meter of the first embodiment, an instantaneous power calculator 140 that calculates the instantaneous power of AC at a frequency that is an integer multiple of the AC frequency and outputs a discrete-time signal of the instantaneous power in one cycle of the AC, and an FIR filter 141 that uses a Hanning window as a coefficient and whose tap length matches the calculation frequency of the instantaneous power calculator 140, and is equipped with an active power meter 14 that filters the discrete signal of instantaneous power with the FIR filter to measure the active power P.

[0097] The active power meter according to the first embodiment had to calculate a moving average over, for example, ten AC cycles. In contrast, the active power meter 14 according to the second embodiment can calculate active power over only one cycle, further improving the responsiveness of active power metering. This enables the adjustment capacity metering device 1 to measure the fast-changing component of the power supply and demand adjustment capacity.

[0098] Furthermore, the adjusting power metering device 1 according to the second embodiment can eliminate instantaneous power fluctuations more effectively than the first embodiment, thereby enabling the adjusting power metering device 1 to accurately measure the power supply and demand adjusting power.

[0099] <Third embodiment> Next, the third embodiment will be described in detail with reference to Fig. 13. Components common to the above-described embodiments will be given the same reference numerals and detailed description will be omitted. In the second embodiment, an example was described in which an FIR filter is used that uses a Hanning window coefficient whose tap length matches the calculation frequency (m+1) of instantaneous power. In contrast, the third embodiment is characterized by using an FIR filter 141 that cuts off components corresponding to a frequency 2f (oscillation frequency) that is twice the frequency f of the AC power. In this embodiment, a reference frequency (for example, 50 Hz) is used as the frequency f of the AC power.

[0100] (Regarding the treatment of active power meters) frequency f sConsider an FIR system discretized by the following equation: The FIR system is assumed to be expressed by the transfer function H(z) of equation (18). m is the tap length of the FIR filter 141. The determination of m will be described later.

[0101]

number

[0102] The frequency response of the FIR filter 141 can be determined from the transfer function. For example, to obtain the gain for a frequency f, use the formula (19) z=exp(±j2πff s -1 ) into H and take the absolute value of the resulting complex number.

[0103]

number

[0104] It is known that single-phase instantaneous power oscillates with a fundamental frequency of 2f, twice the AC frequency f. Hereinafter, 2f will also be referred to as the AC oscillation frequency. For example, assume that the current i and voltage v are both expressed as cos(2πft). In this case, the instantaneous power is given by equation (20), oscillating at a frequency of 2f centered around 1 / 2.

[0105]

number

[0106] The active power is the time average value represented by the first term on the right-hand side. The purpose of the FIR filter 141 is to remove the second term on the right-hand side and leave the first term on the right-hand side. To remove the second term on the right-hand side, the value of the numerator polynomial of the transfer function H(z) is z=exp(±2πjff s -1 ) is sufficient. The solution of the numerator polynomial of the transfer function = 0 is called a zero. exp(±j2πff) on the unit circle of the complex plane s -1), the transfer function becomes 0 at 2π·2fHz, and the 2π·2fHz component can be blocked.

[0107] FIG. 13 is a diagram for explaining the function of the active power metering device according to the third embodiment. To set a plurality of cutoff frequencies, as shown in FIG. 13, the FIR filter 141 is arranged at positions {a1±jb1, a2±jb2, . . . , a m / 2 ±jb m / 2 For example, if you want to block the harmonic components {2f0, 4f0, 6f0} Hz that are 2, 4, and 6 times the instantaneous power, the zeros are determined as shown in the following equation (21).

[0108]

number

[0109] A temporary FIR filter is determined from the zero points. The numerator polynomial of the transfer function of the temporary FIR filter is N(z), the denominator polynomial is D(z), and the whole is expressed as N(z) / D(z).

[0110] If the number of zeros is m, the tap length of the temporary FIR filter is m+1. In this example, m=6, and the tap length of the temporary FIR filter is m+1=7. The numerator of the temporary FIR filter is determined according to the zeros. The polynomial of the numerator of the FIR filter is given by the following equation (22).

[0111]

number

[0112] The denominator polynomial of the temporary FIR filter is given by the following equation (23).

[0113]

number

[0114] If the instantaneous power value is steadily 1, then the active power will also be 1. For this to happen, the FIR filter must have a gain of 1 for DC signals. The DC gain of the hypothetical FIR filter is the value obtained by substituting z=1 into N(z) / D(z). First, calculate the value N0 of the numerator polynomial N(z) for DC signals using the following equation (24).

[0115]

number

[0116] The value D0 of the denominator polynomial for a DC signal is given by the following equation (25).

[0117]

number

[0118] The final FIR filter H(z) is obtained by correcting the temporary FIR filter using the following equation (26) so that its DC gain becomes 1.

[0119]

number

[0120] In this embodiment, the case where the number of zeros is six has been described. This is just an example, and the number of zeros is not limited to six. If the number of zeros is odd, an odd number of zeros can be set on the real axis, for example, -1+j0, and this embodiment can be applied to the remaining even number of zeros. Furthermore, in this embodiment, the zeros are set at 2, 4, and 6 times the AC frequency, but this is not limiting. In other embodiments, zeros may be added at 8 times, 10 times, etc., or even 3 times, 5 times, 7 times, etc.

[0121] (Action, effect) In the adjustment power metering device 1 according to the third embodiment, the active power meter 14 has an FIR filter 141 that blocks components corresponding to the oscillation frequency of the AC, instead of the FIR filter of the second embodiment. The oscillation frequency of the AC is twice the value of the reference frequency of the AC. Specifically, the FIR filter 141 has a zero point on a unit circle in a complex plane at a position where the argument corresponds to 1 time the oscillation frequency.

[0122] In this way, the adjustment power metering device 1 can effectively remove oscillations in instantaneous power, as in the second embodiment, and can therefore accurately measure the power supply and demand adjustment power.

[0123] Furthermore, FIR filter 141 may block components corresponding to frequencies that are two or more integer multiples of the vibration frequency. Specifically, FIR filter 141 has zeros on a unit circle in the complex plane at positions where the argument corresponds to two, three, or more integer multiples of the vibration frequency.

[0124] By doing so, for example, harmonic components that are two, three or more times the vibration frequency can also be blocked in the same way.

[0125] <Fourth embodiment> Next, the fourth embodiment will be described in detail with reference to Fig. 14. Components common to the above-described embodiments will be given the same reference numerals and detailed description will be omitted.

[0126] (Functional configuration of active power meter) FIG. 14 is a diagram showing the functional configuration of an active power meter according to the fourth embodiment. 14, the active power meter 14 is characterized in that a plurality of low-order FIR filters 141_1, 141_2, ..., 141_m are connected in series to calculate active power P. Each of the low-order FIR filters 141_1 to 141_m has a coefficient tap length of 3 and has one conjugate pair of zero points on a unit circle in a complex plane.

[0127] (Regarding the treatment of active power meters) In this embodiment, the FIR filter H(z) is expressed as a product of low-order FIR filters 141_1 to 141_m each having a tap length of 3, as shown in the following equation (27).

[0128]

number

[0129] For example, low-order FIR filter 141_1 cuts off a response with a frequency equal to one time the vibration frequency, low-order FIR filter 141_2 cuts off a response with a frequency equal to two times the vibration frequency, and low-order FIR filter 141_m cuts off a response with a frequency equal to m times the vibration frequency. In this way, by passing the signal through each low-order FIR filter in turn, it is possible to effectively remove oscillations in instantaneous power at frequencies equal to one, two, ..., m times the vibration frequency.

[0130] (Action, effect) In the adjustment power metering device 1 according to the fourth embodiment, the active power meter 14 calculates the active power P by connecting in series a plurality of low-order FIR filters, each having a coefficient tap length of 3 and each having a conjugate pair of zeros on the unit circle of the complex plane.

[0131] In the third embodiment, m coefficients and 2m storage variables were required for the FIR filter, whereas in the fourth embodiment, the low-order FIR filter 141 requires m / 2 coefficients (3 in this embodiment) and m storage variables (6 in this embodiment), which is simpler since only half the number is required.

[0132] <Fifth embodiment> In the second to fourth embodiments, an example was described in which a reference frequency (for example, 50 Hz) is used as the frequency f of the AC power. In contrast, the fifth embodiment is characterized in that the coefficients of the FIR filter 141 are made variable based on the actual frequency f of the AC.

[0133] (Regarding the treatment of active power meters) In this embodiment, the active power meter 14 removes the oscillation component of the instantaneous power at frequency 2f by constantly tuning the cutoff frequency of the FIR filter 141 to 2f.

[0134] Specifically, in the adjustment power metering device 1 according to the second embodiment, instead of equation (14), the value of f estimated by the frequency estimator 13 is substituted for f in the following equation (28) to recalculate the weighting coefficient of the Hanning window.

[0135]

number

[0136] According to equation (28), when the frequency f is higher (for example, 50.1 Hz) than the reference frequency (for example, 50 Hz), the coefficient ω k is adjusted so that it does not exceed 2π (so as not to include data for the next period). Furthermore, when the frequency f is lower than the reference frequency (for example, 49.9 Hz), the tap length may be set longer than in the second embodiment (for example, 34) so ​​that samples for one period are not missed due to the extension of the waveform. In this case, if the frequency f is 50 Hz and the number of samples that can be acquired is 32, the values ​​of the 33rd and 34th samples are set to 0. This makes it possible to properly acquire the required samples even if the frequency f fluctuates.

[0137] Furthermore, in the adjustment power metering device 1 according to the third and fourth embodiments, instead of equation (21), the value of f estimated by the frequency estimator 13 is substituted for f in the following equation (29) to determine the zero point.

[0138]

number

[0139] (Action, effect) In the adjustment power metering device 1 according to the fifth embodiment, the active power meter 14 changes the coefficient of the FIR filter 141 based on the frequency estimated by the frequency estimator 13.

[0140] In this way, the adjustment power metering device 1 can measure active power with higher accuracy by changing the coefficient of the FIR filter 141 in accordance with the frequency f that varies from moment to moment.

[0141] (Variation 1) FIG. 15 is a diagram showing the functional configuration of an active power meter according to a modification of the fifth embodiment. In the first modification, the calculation of the FIR filter 141 is synchronized with the AC cycle, thereby eliminating the need to recalculate the weighting coefficients of the Hanning window. This will be described with reference to Fig. 15. The instantaneous power calculator 140_1 of the first modification receives the multiplied ZC signal shown in Fig. 7, calculates a discrete-time signal of instantaneous power p from the voltage v and current i based on the multiplied ZC signal, and outputs the calculated signal. The FIR filter 141 is the same as that of the fifth embodiment. The FIR filter 141 receives the discrete-time signal of instantaneous power p and calculates active power P.

[0142] Sixth Embodiment Next, the sixth embodiment will be described in detail with reference to Fig. 16. Components common to the above-described embodiments will be given the same reference numerals and detailed description will be omitted.

[0143] (Functional configuration of the adjustment power metering device) FIG. 16 is a diagram showing the functional configuration of an adjustment power measuring device according to the sixth embodiment. As shown in FIG. 16, an AC power system G according to the sixth embodiment uses three-phase AC.

[0144] The voltage detector 11 measures and outputs the phase voltage of each of the three-phase AC phases.

[0145] The current detector 12 detects and outputs currents of two phases of the three-phase AC.

[0146] The frequency estimator 13 estimates the frequency f of at least one phase of the three-phase AC.

[0147] The active power meter 14 estimates the active power P of all three phases from the moving average value of the sum of the instantaneous power of each phase of the three-phase AC.

[0148] The adjustment power meter 15 calculates the power supply and demand adjustment capability M based on the time difference ΔP in the active power P across all three phases and the time difference Δf in the frequency f.

[0149] (Regarding the treatment of regulating power metering devices) In the case of single-phase AC, even if the AC current and voltage are constant, the instantaneous active power fluctuates periodically at twice the frequency of the AC. Therefore, when calculating active power, the width of the moving average time window must be an integer multiple of the AC period. For example, in the case of 50 Hz AC, the width of the moving average window must be an integer multiple of 2 ms to measure active power. Therefore, if the active power value is calculated at a certain time, it is necessary to wait 2 ms before the active power value can be calculated using the newly measured instantaneous power. Note that when the AC is symmetrical up and down, 1 ms, which is half the AC period, is sufficient.

[0150] However, when measuring three-phase AC, if the current and voltage are constant, the sum of the three-phase instantaneous active power is constant over time. Therefore, the length of the moving average window can be determined independently of the AC period, just as in the case of single-phase active power.

[0151] In this embodiment, the voltage detector 11 measures the phase voltage v of each of the three-phase AC. The current detector 12 detects the current i of two of the three phases. If each of the three phases is represented by the symbols {a, b, c}, the total instantaneous power p of the three phases is expressed as follows, as shown in equation (30): abc It is sufficient to calculate the sum of the two powers from Blondel's theorem.

[0152]

number

[0153] As mentioned above, the sum of the instantaneous active power of the three phases is constant over time, so the sum of the instantaneous active power of the three phases p abcrepresents the active power. Therefore, the value of the three-phase active power can be determined by the frequency of instantaneous active power calculations.

[0154] On the other hand, the frequency estimator 13 calculates the frequency f from the time of the zero crossing of the voltage. For one phase, there are two zero crossings per cycle. In the case of three phases, there are six zero crossings per cycle, so the frequency value can be found at a frequency of six times per cycle. The time of the zero crossing can be calculated as t without distinguishing between phases and whether it is a zero crossing from positive to negative or negative to positive. X Then, the frequency can be calculated using methods such as equation (31), equation (32), and equation (33).

[0155]

number

[0156]

number

[0157]

number

[0158] Equation (31) calculates the frequency from the time difference of the previous zero crossing. Equation (32) calculates it from the time difference with the zero crossing three times before. This distinguishes the phase and calculates the frequency from the time difference with the zero crossing half a cycle before of the same phase. Equation (33) distinguishes the phase and calculates the frequency from the time difference with the zero crossing one cycle before of the same phase. In addition to these equations, various other equations can be considered for calculating the frequency. Generalizing it, it can be expressed as equation (34) using a weighting coefficient β. t X,0 represents the time of the nearest zero crossing. X,-1 is the time of the previous zero crossing. For example, if β={6,-6,0,0,0,0,0,0,0,…}, the result is the same as equation (22).

[0159]

number

[0160] The frequency estimator 13 calculates a ZC signal representing the occurrence of a zero crossing, a time t X , and frequency f.

[0161] The active power meter 14 calculates the average active power in the time interval of the frequency calculation in synchronization with the frequency calculation based on the output signal of the frequency estimator 13. If the frequency is calculated using equation (31), the calculation of the average active power is expressed by equation (35).

[0162]

number

[0163] The adjustment power amount meter 15 measures the adjustment power amount using the following equation (36), similar to equation (11).

[0164]

number

[0165] (Action, effect) The adjustment power metering device 1 according to the sixth embodiment includes a frequency estimator 13 that estimates the frequency of at least one phase of three-phase AC, an active power meter 14 that measures the active power of all three phases from the moving average value of the sum of the instantaneous power of each phase of the three-phase AC, and an adjustment power meter 15 that calculates the power supply and demand adjustment power based on the time difference in the active power and the time difference in the frequency.

[0166] By doing so, the adjusting power measuring device 1, unlike the first embodiment, can determine the length of the moving average window independently of the AC cycle.

[0167] Seventh Embodiment In the seventh embodiment, in the adjustment power metering device 1, the adjustment power meter 15 may calculate the power supply and demand adjustment power based on the time difference of the AC frequency, the time second difference of the frequency, the weighted sum of the deviation of the frequency from the reference frequency, and the time difference of the active power. Note that, for other configurations, any of the above-mentioned first to sixth embodiments is applied.

[0168] In the explanation of the prior art, governor-free operation of equation (2) was explained as a specific example of power system supply and demand adjustment. Governor-free operation can be achieved with a proportional controller because there is a proportional relationship between the time difference of frequency and the time difference of active power. A commonly known proportional controller is a PID controller. The P in PID stands for proportional, I for integral, and D for differential. When a PID controller is applied to power supply and demand adjustment, its output is expressed as equation (37) as the weighted sum of the outputs of the proportional controller, integral controller, and differential controller. Δ2 means the second-order temporal difference.

[0169]

number

[0170] Applying ΔP given by equation (37) to equation (3) for the adjustment force, we obtain the following equation (38) as the supply and demand adjustment force for the PID controller.

[0171]

number

[0172] α, β, and γ are weighting coefficients for proportional control, integral control, and differential control, respectively. In addition to proportional, integral, and differential control, a transfer function may also be used.

[0173] In this way, the adjustment power metering device 1 can accurately evaluate, based on various parameters, whether the direction in which it should respond to frequency fluctuations matches the direction of actual changes in power supply and demand.

[0174] Eighth Embodiment Next, the eighth embodiment will be described in detail with reference to Fig. 17. Components common to the above-described embodiments will be given the same reference numerals and detailed description will be omitted.

[0175] In the prior art, as mentioned above, active power P was calculated from the moving average of instantaneous power p over n AC cycles (for example, 10 cycles). The time length of n cycles varies with the AC frequency, and as a result, ripple remains in the active power. In order to more reliably remove the effects of ripple, it is conceivable to increase the period for the moving average to, for example, 50 or 100 cycles. However, in this case, the moving average value will be delayed in time, and it will be impossible to measure fast-response components of less than one second.

[0176] In consideration of these problems, in the above-described embodiments, a technology has been described in which the active power for each AC cycle is calculated and the adjustment capability is measured based on this active power in order to reduce the ripple. In contrast, in the present embodiment, a technology will be described in which the adjustment capability is measured based on the instantaneous power of the AC and the AC frequency calculated by the synchronous motor model 17, without calculating the active power.

[0177] FIG. 17 is a diagram showing the functional configuration of an adjustment power measuring device according to the eighth embodiment. As shown in FIG. 17, the adjustment power metering device 1 according to this embodiment includes an instantaneous power calculator 16 and a synchronous motor model 17.

[0178] The instantaneous power calculator 16 calculates the instantaneous voltage v measured by the voltage detector 11 and the current detector 12. t and the instantaneous current i t Therefore, the AC instantaneous power p exchanged between the AC power system G and the adjustment capability providing means 2 is t Calculate.

[0179] The synchronous motor model 17 has an instantaneous voltage v t is input, the rotation speed of the synchronous motor of the regulation capability providing means 2 is calculated, and the AC frequency f t’Conventionally, the rotation speed of a synchronous motor is calculated by detecting zero crossings, so the rotation speed could only be measured intermittently (once or twice per cycle). However, in this embodiment, the rotation speed of a synchronous motor is calculated by detecting the instantaneous voltage v t Since it is possible to calculate the input frequency virtually continuously, and the number of rotations can be converted to frequency, the AC frequency can be measured virtually continuously by using the synchronous motor model 17. "Visibly continuously" means that it is a discrete signal that is dense in time, for example, 32 times or more per period, and is continuous in contrast to once or twice per period.

[0180] Moreover, the adjustment power meter 15 according to this embodiment calculates the adjustment power M at time t using the following equation (39) instead of the above equation (3): t Calculate.

[0181]

number

[0182] In this way, the adjustment power measuring device 1 can improve the responsiveness of the adjustment power measurement.

[0183] In this embodiment, the synchronous motor model 17 calculates the instantaneous voltage v t The AC frequency f of the synchronous motor is taken as input. t’ However, in other embodiments, the synchronous motor model 17 outputs the rotation speed of the synchronous motor, and the adjustment power meter 15 calculates the AC frequency f from the rotation speed of the synchronous motor. t’ may be calculated.

[0184] Furthermore, the adjustment power metering device 1 according to this embodiment may function as an active power metering device 10 having an active power meter 14. In this case, the frequency f of the AC output from the synchronous motor t’The ZC signal and the multiplied ZC signal may be generated from the above. The frequency represents the phase velocity, and by integrating it over time, the phase angle can be obtained. For example, if the phase angle when the voltage v crosses zero is defined as 0 degrees, the phase angle of the voltage v can be determined. If a signal is transmitted every time the phase angle of the voltage v crosses 0 degrees, it can be used as a substitute for the ZC signal. Furthermore, if a ZC signal is transmitted every time the phase angle exceeds 0 degrees, 90 degrees, 180 degrees, or 270 degrees, it can be used as a substitute for the multiplied ZC signal. The multiplied ZC signal generator 146_1 in FIG. 17 generates a signal of an AC frequency f t’ is input, the above-mentioned processing is performed, and a multiplied ZC signal is output. When the multiplied ZC signal is input to the instantaneous power calculator 140, the ripple is removed by the FIR filter 141, and the active power P can be calculated. By using the synchronous motor model 17, the multiplication rate of the multiplied ZC signal can be freely determined. For example, it is possible to transmit a multiplied ZC signal for every degree of motor rotation, which improves the responsiveness of active power measurement.

[0185] <Computer configuration> FIG. 18 is a schematic block diagram illustrating the configuration of a computer according to at least one embodiment. As shown in FIG. 18, a computer 90 includes a processor 91, a main memory 92, a storage 93, and an interface 94.

[0186] The above-described adjusting power metering device 1 is implemented in a computer 90. The operations of the above-described processing units are stored in the form of a program in a storage 93. A processor 91 reads the program from the storage 93, loads it into a main memory 92, and executes the above-described processing in accordance with the program. The processor 91 also allocates storage areas in the main memory 92 corresponding to the above-described storage units in accordance with the program.

[0187] The program may be for realizing some of the functions to be performed by the computer 90. For example, the program may be combined with other programs already stored in storage or other programs implemented in other devices to perform the functions. In other embodiments, the computer may include a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions realized by the processor may be realized by the integrated circuit.

[0188] Examples of storage 93 include a hard disk drive (HDD), a solid state drive (SSD), a magnetic disk, a magneto-optical disk, a compact disc read-only memory (CD-ROM), a digital versatile disc read-only memory (DVD-ROM), and a semiconductor memory. Storage 93 may be an internal medium directly connected to the bus of computer 90, or an external medium connected to computer 90 via interface 94 or a communication line. Furthermore, when this program is distributed to computer 90 via a communication line, computer 90 that receives the program may load the program into main memory 92 and execute the above-described processing. In at least one embodiment, storage 93 is a non-transitory tangible storage medium.

[0189] As described above, several embodiments according to the present disclosure have been described, but all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as defined in the claims, as well as in the scope and spirit of the invention.

[0190] <Additional Notes> The above-described embodiments can be understood, for example, as follows.

[0191] (1) According to the first aspect, the active power metering device 10 includes a frequency estimator 13 that estimates the period and frequency of the AC based on the time series of the voltage of the AC that the target device 2 transmits or receives between the target device 2 and the power grid, and an active power meter 14 that calculates, for each AC period, a moving average value of the instantaneous power over multiple AC periods, and measures the active power exchanged by the target device 2 in one AC period from the difference between the calculated moving average value and the previously calculated moving average value.

[0192] In this way, the active power metering device 10 can measure active power at short intervals of one cycle. For example, if the AC reference frequency is 50 Hz, one cycle is 20 ms. Therefore, the active power metering device 10 can significantly improve the measurement speed compared to the conventional technology, which can only measure every 10 cycles (200 ms).

[0193] (2) According to the second aspect, the active power metering device 10 includes a frequency estimator 13 that estimates the period and frequency of the AC based on the time series of the voltage of the AC that the target device 2 transmits or receives between the target device 2 and the power grid, and an active power meter 14 that measures the active power that the target device 2 receives and transmits from the target device 2 based on the integrated value of the instantaneous power in one AC period.

[0194] In this way, the active power metering device 10 can accurately calculate the active power per cycle of the AC current.

[0195] (3) According to a third aspect, the active power metering device 10 includes a frequency estimator 13 that estimates the period and frequency of the AC based on the time series of the AC voltage that the target device 2 transmits or receives between the target device 2 and the power grid; an instantaneous power calculator 140 that calculates the AC instantaneous power at a frequency that is an integer multiple of the AC frequency and outputs a discrete-time signal of the instantaneous power in one AC period; and an active power meter 14 that has a finite impulse response filter 141 whose coefficient is a Hanning window whose tap length matches the calculation frequency of the instantaneous power and filters the discrete signal of the instantaneous power with the finite impulse response filter 141 to measure the active power exchanged by the target device 2.

[0196] In this way, the active power meter 14 can perform the calculation of the active power for only one cycle, thereby further improving the responsiveness of the active power meter.

[0197] (4) According to the fourth aspect, the active power metering device 10 includes a frequency estimator 13 that estimates the period and frequency of the AC based on the time series of the AC voltage that the target device 2 transmits or receives between the target device 2 and the power grid; an instantaneous power calculator 140 that calculates the AC instantaneous power at a frequency that is an integer multiple of the AC frequency and outputs a discrete-time signal of the instantaneous power in one AC period; and an active power meter 14 that filters the discrete signal of the instantaneous power with a finite impulse response filter 141 that blocks components corresponding to the AC oscillation frequency and measures the active power exchanged by the target device 2.

[0198] In this way, the active power metering device 10 can effectively eliminate oscillations in the instantaneous power, and can therefore measure the active power with high accuracy.

[0199] (5) According to the fifth aspect, in the active power metering device 10 according to the fourth aspect, the finite impulse response filter 141 has a zero point on a unit circle in a complex plane at a position where the argument corresponds to an integer multiple of 1 or 2 or more times the vibration frequency.

[0200] By doing so, it is possible to similarly block harmonic components, such as those twice or three times the vibration frequency.

[0201] (6) According to the sixth aspect, the active power metering device according to the fourth aspect In device 10, finite impulse response filter 141 has a coefficient tap length of 3 and is configured by connecting in series a plurality of low-order finite impulse response filters, each having one conjugate pair of zeros on a unit circle in the complex plane.

[0202] By doing this, the number of coefficients of the low-order FIR filter 141 becomes m / 2 (3 in the example of the embodiment described above) and the number of stored variables becomes m (6 in the example of the embodiment described above), which is simple as it is only necessary to reduce each by half.

[0203] (7) According to the seventh aspect, the active power metering device 10 includes a frequency estimator 13 that estimates the frequency of at least one phase of the three-phase AC based on a time series of the voltage of the three-phase AC that the target device 2 transmits or receives between the target device 2 and the power grid, and an active power meter 14 that measures the active power of the target device 2 across all three phases from a moving average value of the sum of the instantaneous power of each phase of the three-phase AC.

[0204] In this way, the active power metering device 10 can determine the length of the window for the moving average of the active power independently of the AC cycle.

[0205] (8) According to the eighth aspect, in the active power metering device 10 according to any one of the third to sixth aspects, the active power meter 14 changes the coefficient of the finite impulse response filter 141 based on the frequency estimated by the frequency estimator 13.

[0206] In this way, the active power metering device 10 can measure active power with higher accuracy by changing the coefficient of the FIR filter 141 in accordance with the frequency f that varies from moment to moment.

[0207] (9) According to the ninth aspect, the active power metering device 10 includes a synchronous motor model 17 that receives as input an instantaneous voltage v of AC power transmitted or received between the target device 2 and a power grid, calculates the rotation speed of a synchronous motor possessed by the target device 2, and outputs an AC frequency f, and an active power meter 14 that measures the active power P exchanged by the target device 2 in one AC cycle based on the instantaneous AC current i, the instantaneous voltage v, and the frequency f output from the synchronous motor model 17.

[0208] In this way, the active power metering device 10 can reliably eliminate the influence of ripples and improve the response of measurements.

[0209] (10) According to the tenth aspect, the adjustment power metering device 1 includes an active power metering device 10 according to any one of the first to ninth aspects, and an adjustment power metering device 15 that calculates the supply and demand adjustment power of the target device 2 based on the time difference in active power and the time difference in frequency.

[0210] In this way, the adjustment power metering device 1 can obtain the difference between the active power P and the frequency f for each AC cycle and calculate the supply and demand adjustment power M for each cycle from these differences, thereby improving the responsiveness of adjustment power measurement. This allows the adjustment power metering device 1 to measure fast adjustment power such as inertial force.

[0211] (11) According to the eleventh aspect, in the adjustment power metering device 1 relating to the tenth aspect, the adjustment power meter 15 calculates the supply and demand adjustment power based on the time difference of the AC frequency, the second-order time difference of the frequency, the weighted sum of the deviation of the frequency from the reference frequency, and the time difference of the active power.

[0212] By doing this, the adjustment power metering device 1 can accurately evaluate, based on various parameters, whether the direction in which it should respond to frequency oscillations matches the direction of actual changes in power supply and demand.

[0213] (12) According to the twelfth aspect, the measurement method includes the steps of estimating a period and a frequency of AC based on a time series of AC voltage transmitted to or received from the target device 2 between the target device 2 and a power grid, calculating the AC instantaneous power at a frequency that is an integer multiple of the AC frequency and outputting a discrete-time signal of the instantaneous power in one AC period, and filtering the discrete signal of the instantaneous power with a finite impulse response filter 141 having a coefficient of a Hanning window whose tap length matches the calculation frequency of the instantaneous power, thereby measuring the active power exchanged by the target device 2.

[0214] (13) According to the thirteenth aspect, the program causes the active power metering device 10 to execute the following steps: estimating the period and frequency of the AC based on the time series of the voltage of the AC that the target device 2 transmits or receives between the target device 2 and the power grid; calculating the instantaneous power of the AC at a frequency that is an integer multiple of the AC frequency and outputting a discrete-time signal of the instantaneous power in one AC period; and filtering the discrete signal of the instantaneous power with a finite impulse response filter 141 having a coefficient that is a Hanning window whose tap length matches the calculation frequency of the instantaneous power, thereby measuring the active power exchanged by the target device. [Explanation of symbols]

[0215] 1 Adjustment force measuring device 2 Adjustment force providing means 10. Active power metering device 11 Voltage detector 12 Current detector 13 Frequency Estimator 130 Timer 131 Zero Cross Detector (ZC Detector) 132 Sampler 133 Frequency calculation unit 14 Active power meter 140 Instantaneous power calculator 141 Finite Impulse Response Filter (FIR Filter) 141,141_1,141_2,141_m Low-order FIR filters 142 Instantaneous power integrator 143 Sampler 144 Active power calculation section 15 Adjustment energy meter 16 Instantaneous power calculator 17 Synchronous motor model

Claims

1. a frequency estimator that estimates a period and a frequency of an AC current based on a time series of a voltage of the AC current that the target device transmits or receives to or from the power grid; an active power meter that calculates a moving average value of instantaneous power over a plurality of cycles of the AC for each cycle of the AC, and measures the active power exchanged by the target device in one cycle of the AC from the difference between the calculated moving average value and a previously calculated moving average value; An active power metering device comprising:

2. a frequency estimator that estimates a period and a frequency of an AC current based on a time series of a voltage of the AC current that the target device transmits or receives to or from the power grid; an active power meter that measures the active power exchanged by the target device from an integrated value of instantaneous power in one cycle of the AC; Equipped with the frequency estimator detects a zero-cross time at which a voltage of the AC changes between positive and negative from the estimated period and frequency of the AC; the active power meter calculates an integrated value of instantaneous power at the zero cross time based on an integrated value of instantaneous power accumulated at an integration time immediately before the zero cross time and an integrated value of instantaneous power accumulated at a second time immediately after the zero cross time, and measures the active power in one cycle of the AC current based on a difference between the integrated value of instantaneous power at the zero cross time and the integrated value of instantaneous power at the zero cross time two times before the zero cross time. Active power metering device.

3. a frequency estimator that estimates a period and a frequency of an AC current based on a time series of a voltage of the AC current that the target device transmits or receives to or from the power grid; an instantaneous power calculator that calculates the instantaneous power of the AC at a frequency that is an integer multiple of the frequency of the AC and outputs a discrete-time signal of the instantaneous power in one cycle of the AC; and an active power meter that has a finite impulse response filter that uses a Hanning window as a coefficient and whose tap length matches the calculation frequency of the instantaneous power, filtering the discrete signal of the instantaneous power with the finite impulse response filter to measure the active power exchanged by the target device; An active power metering device comprising:

4. a frequency estimator that estimates a period and a frequency of an AC current based on a time series of a voltage of the AC current that the target device transmits or receives to or from the power grid; an instantaneous power calculator that calculates the instantaneous power of the AC at a frequency that is an integer multiple of the frequency of the AC and outputs a discrete-time signal of the instantaneous power in one cycle of the AC; an active power meter that filters the discrete signal of the instantaneous power with a finite impulse response filter that blocks components corresponding to the vibration frequency of the AC power, and measures the active power exchanged with the target device; An active power metering device comprising:

5. the finite impulse response filter has zeros on a unit circle in a complex plane at positions where the argument corresponds to an integer multiple of 1, 2, or more of the vibration frequency; 5. The active power metering device according to claim 4.

6. the finite impulse response filter has a coefficient tap length of 3 and is configured by serially connecting a plurality of low-order finite impulse response filters, each having one conjugate pair of zeros on a unit circle in a complex plane; 5. The active power metering device according to claim 4.

7. a frequency estimator that estimates a frequency of at least one phase of three-phase AC based on a time series of a voltage of the three-phase AC that a target device transmits or receives power to or from a power grid; an active power meter that measures the active power of the entire three phases of the target device from a moving average value of the sum of instantaneous power of each of the three-phase AC phases; An active power metering device comprising:

8. the active power meter changes a coefficient of the finite impulse response filter based on the frequency estimated by the frequency estimator; 4. The active power metering device according to claim 3.

9. a synchronous motor model that receives as input an instantaneous voltage of an AC current that a target device transmits or receives between the target device and a power grid, calculates the rotation speed of a synchronous motor included in the target device, and outputs the frequency of the AC current; an active power meter that measures active power exchanged by the target device in one cycle of the AC current based on the instantaneous current, the instantaneous voltage, and the frequency output from the synchronous motor model; Equipped with The active power meter includes an instantaneous power calculator that calculates the instantaneous power of the AC at a frequency that is an integer multiple of the frequency of the AC and outputs a discrete-time signal of the instantaneous power in one cycle of the AC, and a finite impulse response filter that uses a Hanning window as a coefficient and whose tap length matches the calculation frequency of the instantaneous power, and measures the active power by filtering the discrete signal of the instantaneous power with the finite impulse response filter. Active power metering device.

10. An active power metering device according to any one of claims 1 to 9; an adjustment power meter that calculates a supply and demand adjustment capability of the target device based on a time difference between the active power and the frequency; An adjustment force metering device comprising:

11. The adjustment electric energy meter calculates the supply and demand adjustment capacity based on a time difference of the frequency of the AC, a time second difference of the frequency, a weighted sum of a deviation of the frequency from a reference frequency, and a time difference of the active power. The adjustment force measuring device according to claim 10.

12. estimating a period and a frequency of an AC current based on a time series of a voltage of the AC current that the target device transmits or receives to or from the power grid; calculating the instantaneous power of the AC at a frequency that is an integer multiple of the frequency of the AC, and outputting a discrete-time signal of the instantaneous power in one cycle of the AC; a step of filtering the discrete signal of the instantaneous power with a finite impulse response filter having a coefficient of a Hanning window whose tap length matches the calculation frequency of the instantaneous power, and measuring the active power exchanged by the target device; A weighing method having the following.

13. estimating a period and a frequency of an AC current based on a time series of a voltage of the AC current that the target device transmits or receives to or from the power grid; calculating the instantaneous power of the AC at a frequency that is an integer multiple of the frequency of the AC, and outputting a discrete-time signal of the instantaneous power in one cycle of the AC; filtering the discrete signal of the instantaneous power with a finite impulse response filter having a coefficient of a Hanning window whose tap length matches the calculation frequency of the instantaneous power, thereby measuring the active power exchanged by the target device; A program that causes an active power metering device to execute the above.

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