Securing against malicious control of circuit breakers in electrical substations
View Patent ↗An example method for detecting and mitigating attacks on electric power substations comprises detecting a command to open or close a circuit breaker in the electric power substation. A modified extended substation model for the electric power substation is generated, based on the detected command and based on measurements in substation, where the modified extended substation model is a power flow model for the substation and for one or more directly connected neighboring substations. A power flow analysis is performed, using the modified extended substation model, to generate a predicted voltage for each of a plurality of nodes in the substation and in the one or more directly connected neighboring substations. Each predicted voltage is compared to a corresponding allowable voltage range, and execution of the command is blocked in response to determining that one or more of the voltages is outside the corresponding allowable voltage range.
1. A method, performed in at least one device in an electric power substation, the method comprising:
detecting a command to open or close a circuit breaker in the electric power substation;
generating a modified extended substation model for the electric power substation, based on the detected command and based on measurements in the electric power substation, wherein the modified extended substation model is a power flow model for the electric power substation and for one or more directly connected neighboring substations;
performing a power flow analysis, using the modified extended substation model, to generate a plurality of predicted voltages, each of the predicted voltages for each of a plurality of nodes in the electric power substation and in the one or more directly connected neighboring substations;
compare the each of the predicted voltages to a corresponding allowable voltage range; and
blocking execution of the command in response to determining that one or more of the predicted voltages are outside the corresponding allowable voltage range.
2. The method of claim 1 , wherein the method further comprises generating a base extended substation model for the electric power substation, based on measurements in the electric power substation and status information for the one or more directly connected neighboring substations, the base extended substation model comprising an admittance matrix representing the connectivity in the electric power substation and in and to the directly connected neighboring substations, and wherein generating the modified extended substation model for the electric power substation comprises modifying the admittance matrix to reflect a connectivity that would result from executing the command to open or close the circuit breaker.
3. The method of claim 2 , wherein generating the base extended substation model is triggered by the detecting the command to open or close the circuit breaker, and wherein said generating comprises retrieving current measurement data for each of a plurality of monitored points in the electric power substation, for use in performing the power flow analysis.
4. The method of claim 1 , wherein performing the power flow analysis, using the modified extended substation model, comprises detecting power system islands, based on the modified extended substation model, and running a power flow analysis for each detected power system island that includes a generator.
5. A control device for use in an electric power substation, the control device comprising:
an input circuit configured to receive, for each of one or more switches in the electric power substation, direct control commands for opening and/or closing the switch;
an interface circuit configured to receive measurement data for a plurality of monitored points in the electric power substation and to receive communicated status information from one or more neighboring substations directly connected to the electric power substation; and
a processing circuit operatively connected to the interface circuit and the input circuit configured to:
detect a command to open or close a circuit breaker in the electric power substation;
generate a modified extended substation model for the electric power substation, based on the detected command and based on measurements in the electric power substation, wherein the modified extended substation model is a power flow model for the electric power substation and for one or more directly connected neighboring substations;
perform a power flow analysis, using the modified extended substation model, to generate a plurality of predicted voltages, each of the predicted voltages for each of a plurality of nodes in the electric power substation and in the one or more directly connected neighboring substations;
compare the each of the predicted voltages to a corresponding allowable voltage range; and
block execution of the command in response to determining that one or more of the predicted voltages are outside the corresponding allowable voltage range.
6. The control device of claim 5 , further comprising, a switching circuit coupled to the processing circuit and operative to selectively connect direct control commands received at each input of the input circuit to a corresponding output, under the control of the processing circuit, wherein the processing circuit is configured to allow execution of a direct control command by controlling the switching circuit to connect the direct control command received at a given input of the input circuit to the corresponding output of the switching circuit and to block execution of a direct control command by refraining from controlling the switching circuit to connect the direct control command received at a given input of the input circuit to the corresponding output of the switching circuit.
7. The control device of claim 5 , wherein the processing circuit is further configured to generate a base extended substation model for the electric power substation, based on measurements in the electric power substation and status information for the one or more directly connected neighboring substations, the base extended substation model comprising an admittance matrix representing the connectivity in the electric power substation and in and to the directly connected neighboring substations, and wherein the processing circuit is configured to generate the modified extended substation model for the electric power substation by modifying the admittance matrix to reflect a connectivity that would result from executing the command to open or close the circuit breaker.
8. The control device of claim 7 , wherein the processing circuit is configured to generate the base extended substation model in response to detecting the command to open or close the circuit breaker, and wherein said generating comprises retrieving current measurement data for each of a plurality of monitored points in the electric power substation, for use in performing the power flow analysis.
9. The control device of claim 5 , wherein the processing circuit is configured to perform the power flow analysis, using the modified extended substation model, such that said power flow analysis comprises detecting power system islands, based on the modified extended substation model, and running a power flow analysis for each detected power system island that includes a generator.