Power system control system and distributed controller used in same

Patent metadata

Field	Value
Publication number	US-9780563-B2
Application number	US-201314768938-A
Country	US
Kind code	B2
Filing date	Feb 28, 2013
Priority date	Feb 28, 2013
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A distributed controller collects measurement value data of a voltage and a current in an own node and in another node; using the measurement voltage and the current of the own node and the measurement voltage and current of another node as input data, estimates a voltage or a current as a state quantity of the electric power system regarding another node from which the measurement value data cannot be collected, and outputs the estimate values; using the measurement data, the estimate value outputted from the state estimation functional unit and a voltage target value that has been set for each node, outputs the control commands for voltage controllers based on voltage change amounts to be distributed to the voltage control devices of the nodes including the own node. The voltages in the electric power system are controlled by superposition of voltage change amounts by the voltage control devices.

First claim

The invention claimed is:

1. An electric power system control system controlling voltages in an electric power system to which loads and voltage control devices are connected via nodes, comprising:
at least two distributed controllers making control commands for the voltage control devices, wherein
the distributed controller includes a measurement value data collection functional unit, a state estimation functional unit, and an optimum control functional unit,
the measurement value data collection functional unit collects measurement value data from sensors measuring a voltage and a current in an own node to which the measurement value data collection functional unit belongs and measurement value data from sensors measuring a voltage and a current in another node to which the measurement value data collection functional unit does not belong,
the state estimation functional unit, using the measurement values of the voltage and the current of the own node and the measurement values of a voltage and a current of another node as input data, estimates a voltage or a current as a state quantity of the electric power system regarding another node from which the measurement value data cannot be collected, and outputs the estimate values,
the optimum control functional unit, using the measurement value data, the estimate value outputted from the state estimation functional unit and a voltage target value that has been set for each node as input, outputs the control commands based on operation amounts to be distributed to the voltage control devices of the nodes including the own node, and
the voltages in the electric power system are controlled by superposition of voltage change amounts by the voltage control devices, and
the state estimation functional unit calculates the estimate value of the voltage or the current of each of the nodes by solving a least square problem for minimizing an error with respect to a power equation regarding the voltage or the current between each node and an adjacent node and an error with respect to the measurement values of the voltage or the current of each node.

2. The electric power system control system according to claim 1 , wherein estimate values further reducing the error with respect to highly accurate measurement values are calculated by weighting the least square problem with reliability which represents the degree of accuracy of each of the measurement values.

3. The electric power system control system according to claim 1 , wherein the optimum control functional unit calculates the operation amount of each of the voltage control devices by solving a least square problem for minimizing a deviation with respect to the voltage target value of each node and an error with respect to a restriction value of the operation amount of each of the voltage control devices.

4. The electric power system control system according to claim 3 , wherein operation amounts further reducing the deviation with respect to target values having high priority are calculated by weighting the least square problem with priority regarding achievement of the target value.

5. The electric power system control system according to claim 3 , wherein operation amounts further reducing the error with respect to highly restrictive restriction values are calculated by weighting the least square problem with a restriction degree which represents the strength of the restriction by each restriction value.

6. The electric power system control system according to claim 1 , wherein the measurement value data collection functional unit collects the measurement values of the other nodes via a communication line.

7. The electric power system control system according to claim 1 , wherein the voltage control devices each include an automatic voltage regulator (SVR: Step Voltage Regulator), a reactive power compensator (SVC: Static Var Compensator), a distribution voltage control system (DMS: Distribution Management System), a power conditioner (PCS: Power Conditioning System), an instantaneous voltage compensation device (DVR: Dynamic Voltage Restorer), an uninterruptible power supply (UPS), a home energy management system (HEMS), or a distribution transformer having the voltage regulation function.

8. An apparatus for controlling voltages in an electric power system to which loads and voltage control devices are connected via nodes, the apparatus comprising:
a distributed controller that includes a measurement value data collection functional unit, a state estimation functional unit, and an optimum control functional unit, wherein
the measurement value data collection functional unit collects measurement value data from sensors measuring a voltage and a current in an own node to which the measurement value data collection functional unit belongs and measurement value data from sensors measuring a voltage and a current in another node to which the measurement value data collection functional unit does not belong,
the state estimation functional unit, using the measurement values of the voltage and the current of the own node and the measurement values of a voltage and a current of another node as input data, estimates voltage or a current as a state quantity of the electric power system regarding another node from which the measurement value data cannot be collected, and outputs the estimate values,
the optimum control functional unit, using the measurement value data, the estimate value outputted from the state estimation functional unit and a voltage target value that has been set for each node as input, outputs the control commands based on operation amounts to be distributed to the voltage control devices of the nodes including the own node, and
the voltages in the electric power system are controlled superposition of voltage change amounts by the voltage control devices, and
the state estimation functional unit calculates the estimate value of the voltage or the current of each of the nodes by solving a least square problem for minimizing an error with respect to a power equation regarding the voltage or the current between each node and an adjacent node and an error with respect to the measurement values of the voltage or the current of each node.

9. The apparatus according to claim 8 , wherein the voltage control devices each include an automatic voltage regulator (SVR: Step Voltage Regulator), a reactive power compensator (SVC: Static Var Compensator), a distribution voltage control system (DMS: Distribution Management System), a power conditioner (PCS: Power Conditioning System), an instantaneous voltage compensation device (DVR: Dynamic Voltage Restorer), an uninterruptible power supply (UPS), a home energy management system (HEMS), or a distribution transformer having the voltage regulation function.

10. An electric power system control system controlling voltages in an electric power system to which loads and voltage control devices are connected via nodes, comprising at least two distributed controllers making control commands for the voltage control devices, wherein
the distributed controller includes a measurement value data collection functional unit, a state estimation functional unit, and an optimum control functional unit, wherein
the measurement value data collection functional unit collects measurement value data from sensors measuring a voltage and a current in an own node to which the measurement value data collection functional unit belongs and measurement value data from sensors measuring a voltage and a current in another node to which the measurement value data collection functional unit does not belong, wherein
the state estimation functional unit, using the measurement values of the voltage and the curre

Assignees

• Hitachi Ltd

Inventors

• Kumagai Masatoshi
• OMI Shota
• Yamane Kenichiro
• Harada Yasushi
• Watanabe Masahiro
• Sato Yasuo
• Tomita Yasushi

Classifications

• H02J2103/30

  Simulating, planning, modelling, reliability check or computer assisted design [CAD] of electric power networks · CPC title

• H02J3/16 Primary

  by adjustment of reactive power · CPC title

• G01R19/25

  using digital measurement techniques · CPC title

• Y02E60/76

  Cross-Sectional Technologies · mapped topic

• Y04S40/22

  Cross-Sectional Technologies · mapped topic