# US 10,371,592 B2 · System stability monitoring apparatus and method

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 10,371,592 B2
- Document ID: US10371592B2
- Status: Granted
- Kind: B2
- Application number: 15/127,822
- Filed: 2014-09-19
- Published: 2017-04-06
- Granted: 2019-08-06
- Earliest claimed: 2014-03-31
- Assignees: Hitachi, Ltd.
- Applicants: Hitachi, Ltd.
- Inventors: Jun Yamazaki; Masahiro Yatsu; Sumito Tobe; Yasuo Sato; Osamu Tomobe; Eisuke Kuroda
- Web page: https://patentgrep.com/patent/US10371592B2

## CPC

- H02J 13/1337: {involving the use of Internet protocols}
- G01M 1/14: Determining imbalance (G01M1/30 takes precedence)
- G01N 29/11: by measuring attenuation of acoustic waves
- G01N 29/12: by measuring frequency or resonance of acoustic waves {(measuring frequency or resonant frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04, G01H13/00; acoustic resonators G10K11/04; vibration or shock testing of structures G01M7/00)}
- G01N 29/4445: {Classification of defects}
- G01N 29/48: by amplitude comparison
- H02J 3/381: {Dispersed generators}
- H02J 13/10: characterised by displaying of information or by user interaction, e.g. supervisory control and data acquisition [SCADA] systems
- H02J 13/333: the equipment forming part of substations
- H02J 50/20: using microwaves or radio frequency waves
- H02S 50/00: Monitoring or testing of PV systems, e.g. load balancing or fault identification
- H02S 50/10: Testing of PV devices, e.g. of PV modules or single PV cells (testing of semiconductor devices during manufacturing {H10P74/00})
- H02J 3/1821: using shunt compensators
- H02J 2101/24: Photovoltaics
- H02J 2101/28: Wind energy
- H02J 2101/40: Hybrid power plants, i.e. a plurality of different generation technologies being operated at one power plant
- Y02E 10/56: Power conversion systems, e.g. maximum power point trackers
- Y02E 10/76: Power conversion electric or electronic aspects
- Y02E 40/30: Reactive power compensation
- Y02E 40/70: Smart grids as climate change mitigation technology in the energy generation sector
- Y04S 10/123: the energy generation units being or involving renewable energy sources
- Y04S 10/22: Flexible AC transmission systems [FACTS] or power factor or reactive power compensating or correcting units
- Y04S 10/40: Display of information, e.g. of data or controls
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- H02S: GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES (obtaining electrical energy from radioactive sources G21H1/12; light sensitive inorganic semiconductor devices H10F; light sensitive organic semiconductor devices H10K30/00; thermoelectric devices H10N10/00; pyroelectric devices H10N15/00)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y04S: SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS

## Abstract

When vibration information calculated using measurement information is classified using a distance between measurement points which is calculated using the point information, even in a case in which a plurality of vibration modes with close vibration frequencies are present at the same time, stability determination at a high speed and a high accuracy is realized. A system stability monitoring apparatus which monitors system stability of a power system includes a measurement information collecting unit that collects measurement information of a plurality of points in the power system, a vibration analyzing unit that calculates vibration information indicating vibration of a system state in the plurality of points using the measurement information, an information storage unit that stores point information including position information of the plurality of points, and a vibration classifying unit that classifies the vibration information based on the point information.

## Claims

### Claim 1

A system stability monitoring apparatus which monitors system stability of a power system comprising:
a measurement information collecting unit that collects measurement information of a plurality of points in the power system at a plurality of times;
a vibration analyzing unit that calculates vibration information at the plurality of points using the measurement information, the vibration information including a plurality of vibration frequencies, a plurality of attenuation coefficients, a plurality of amplitudes, and a plurality of initial phases;
an information storage unit that stores point information including position information for each of the plurality of points;
a vibration classifying unit that classifies the vibration information as a plurality of vibrations based on the point information to distinguish the plurality of vibrations at the plurality of points, where each of the vibrations includes at least one of the respective vibration frequencies, one or more points corresponding to at least one of the respective vibration frequencies, and respective attenuation coefficients, respective amplitudes and respective initial phases corresponding to the one or more of the points corresponding to the at least one of the respective vibration frequencies, and
the vibration classifying unit calculates a respective importance degree for each of the plurality of vibrations based on the respective amplitudes and the respective attenuation coefficients thereof; and
a display unit that displays the vibration information for at least a first vibration and a second vibration of the plurality of vibrations and displays a system diagram of the power system which includes a first region indicating the one or more points corresponding to the first vibration and a second region indicating the one or more points corresponding to the second vibration,
wherein the respective importance degree for the first vibration and the respective importance degree for the second vibration are higher than a predetermined value,
wherein the vibration classifying unit classifies the at least one of the respective vibration frequencies in a predetermined range as a same one of the vibrations.

### Claim 2 (depends on 1)

The system stability monitoring apparatus according to claim 1,
wherein the respective importance degree is calculated for each of the plurality of vibrations according to the equation:
S
i
=
max
j
⁢
(
a
ij
⁢
R
ij
)
+
max
j
⁢
(
b
ij
⁢
σ
ij
)
,
where Si is the respective importance degree of an i-th vibration, Rij is a j-th amplitude of the i-th vibration, σij is a j-th attenuation coefficient of the i-th vibration and aij and bij are predetermined coefficients.

### Claim 3 (depends on 1)

The system stability monitoring apparatus according to claim 1,
wherein, based on past vibration information, the vibration classifying unit increases the respective importance degree in a case in which a change of the vibration information thereof is continuous over a predetermined period, or lowers the respective importance degree in a case in which the change of the vibration information thereof is not continuous over the predetermined period.

### Claim 4 (depends on 1)

The system stability monitoring apparatus according to claim 1,
wherein the vibration analyzing unit calculates the vibration information using any one method of a Fourier analysis, a wavelet analysis, a Purony's method, a Matrix Pencil method, and a Hankel Total Least Squares (HTLS) method.

### Claim 5 (depends on 1)

The system stability monitoring apparatus according to claim 1,
wherein the first region includes at least one point which is also included in the second region.

### Claim 6 (depends on 5)

The system stability monitoring apparatus according to claim 5,
wherein the display unit displays the vibration information for at least the first vibration and the second vibration on a priority basis.

### Claim 7

A system stability monitoring apparatus which monitors system stability of a power system comprising:
a measurement information collecting unit that collects measurement information at a plurality of points in the power system at a plurality of times, where each of the points is associated with a respective power generator, a respective load, or a respective phase modifier;
a vibration analyzing unit that calculates vibration information at the plurality of points using the measurement information, the vibration information including a plurality of vibration frequencies, a plurality of attenuation coefficients, a plurality of amplitudes, and a plurality of initial phases;
an information storage unit that stores point information including position information for each of the plurality of points;
a vibration classifying unit that classifies the vibration information as a plurality of vibrations based on the point information to distinguish the plurality of vibrations at the plurality of points, where each of the vibrations includes a respective vibration frequency, one or more points corresponding to the respective vibration frequency, and respective attenuation coefficients, respective amplitudes and respective initial phases corresponding to the one or more of the points corresponding to the respective vibration frequency; and
a display unit that displays the vibration information for at least a first vibration and a second vibration of the plurality of vibrations and displays a system diagram of the power system which includes a first region indicating the one or more points corresponding to the first vibration and a second region indicating the one or more points corresponding to the second vibration,
wherein the point information includes at least one of latitude information and longitude information of each the plurality of points, impedance information between the plurality of points, and characteristic information of at least one of the respective power generator, the respective load, and the respective phase modifier associated with the each of the plurality of points.

### Claim 8 (depends on 7)

The system stability monitoring apparatus according to claim 7,
wherein, based on the impedance information and the characteristic information, the vibration classifying unit calculates a plurality of electrical distances between the plurality of points, and classifies the vibration information as the plurality of vibrations based on the plurality of electrical distances.

### Claim 9 (depends on 7)

The system stability monitoring apparatus according to claim 7,
wherein, based on the latitude information and longitude information of each the plurality of points, the vibration classifying unit calculates a plurality of physical distances between the plurality of points, and classifies the vibration information as the plurality of vibrations based on the plurality of physical distances.

### Claim 10

A system stability monitoring method which monitors system stability of a power system comprising:
collecting measurement information of a plurality of points in the power system at a plurality of points;
calculating vibration information at the plurality of points using the measurement information, the vibration information including a plurality of vibration frequencies, a plurality of attenuation coefficients, a plurality of amplitudes, and a plurality of initial phases; and
classifying the vibration information as a plurality of vibrations based on point information, that includes geographic position information for each of the plurality of points, to distinguish the plurality of vibrations at the plurality of points, where each of the vibrations includes at least one of the respective vibration frequencies, one or more points corresponding to the at least one of the respective vibration frequencies, and respective attenuation coefficients, respective amplitudes and respective initial phases corresponding to the one or more of the points corresponding to the at least one of the respective vibration frequencies;
calculating a respective importance degree for each of the plurality of vibrations based on the respective amplitudes and the respective attenuation coefficients thereof; and
displaying the vibration information for at least a first vibration and a second vibration of the plurality of vibrations and a system diagram of the power system which includes a first region indicating the one or more points corresponding to the first vibration and a second region indicating the one or more points corresponding to the second vibration,
wherein the respective importance degree for the first vibration and the respective importance degree for the second vibration are higher than a predetermined value.

### Claim 11 (depends on 10)

The system stability monitoring method according to claim 10,
wherein the point information includes at least one of latitude information and longitude information of each the plurality of points, impedance information between the plurality of points, and characteristic information of at least one of the respective power generator, the respective load, and the respective phase modifier associated with the each of the plurality of points.

### Claim 12 (depends on 11)

The system stability monitoring apparatus according to claim 11, further comprising:
calculating a plurality of electrical distances between the plurality of points based on the impedance information and the characteristic information, and
wherein the vibration information is classified as the plurality of vibrations based on the plurality of electrical distances.

### Claim 13 (depends on 11)

The system stability monitoring apparatus according to claim 11, further comprising:
calculating a plurality of physical distances between the plurality of points based on the latitude information and longitude information of each the plurality of points,
wherein the vibration information is classified as the plurality of vibrations based on the plurality of physical distances.